DPT Portfolios

The prevention of Anterior Cruciate Ligament (ACL) injuries in soccer players: an exploration of the common mechanisms of ACL injury and prevention protocolsIntroduction: Soccer is one of the most popular sports in the world with an estimated 265 million people participating in soccer.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1007/s00167-009-0813-1","First":false,"Last":false,"PMID":"19452139","author":[{"family":"Alentorn-Geli","given":"Eduard"},{"family":"Myer","given":"Gregory D"},{"family":"Silvers","given":"Holly J"},{"family":"Samitier","given":"Gonzalo"},{"family":"Romero","given":"Daniel"},{"family":"Lázaro-Haro","given":"Cristina"},{"family":"Cugat","given":"Ramón"}],"citation-label":"2595869","container-title":"Knee Surgery, Sports Traumatology, Arthroscopy","container-title-short":"Knee Surg. Sports Traumatol. Arthrosc.","id":"2595869","invisible":false,"issue":"7","issued":{"date-parts":[["2009","7"]]},"journalAbbreviation":"Knee Surg. Sports Traumatol. Arthrosc.","page":"705-729","suppress-author":false,"title":"Prevention of non-contact anterior cruciate ligament injuries in soccer players. Part 1: Mechanisms of injury and underlying risk factors.","type":"article-journal","volume":"17"}]1 Soccer is one of the most widely growing sports in the United States.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1002/art.20589","First":false,"Last":false,"PMID":"15476248","abstract":"OBJECTIVE: To determine the prevalence of radiographic knee osteoarthritis (OA) as well as knee-related symptoms and functional limitations in female soccer players 12 years after an anterior cruciate ligament (ACL) injury. METHODS: Female soccer players who sustained an ACL injury 12 years earlier were examined with standardized weight-bearing knee radiography and 2 self-administered patient questionnaires, the Knee Injury and Osteoarthritis Outcome Score questionnaire and the Short Form 36-item health survey. Joint space narrowing and osteophytes were graded according to the radiographic atlas of the Osteoarthritis Research Society International. The cutoff value to define radiographic knee OA approximated a Kellgren/Lawrence grade of 2. RESULTS: Of the available cohort of 103 female soccer players, 84 (82%) answered the questionnaires and 67 (65%) consented to undergo knee radiography. The mean age at assessment was 31 years (range 26-40 years) and mean body mass index was 23 kg/m2 (range 18-40 kg/m2). Fifty-five women (82%) had radiographic changes in their index knee, and 34 (51%) fulfilled the criterion for radiographic knee OA. Of the subjects answering the questionnaires, 63 (75%) reported having symptoms affecting their knee-related quality of life, and 28 (42%) were considered to have symptomatic radiographic knee OA. Slightly more than 60% of the players had undergone reconstructive surgery of the ACL. Using multivariate analyses, surgical reconstruction was found to have no significant influence on knee symptoms. CONCLUSION: A very high prevalence of radiographic knee OA, pain, and functional limitations was observed in young women who sustained an ACL tear during soccer play 12 years earlier. These findings constitute a strong rationale to direct increased efforts toward prevention and better treatment of knee injury. Copyright 2004 American College of Rheumatology","author":[{"family":"Lohmander","given":"L S"},{"family":"Ostenberg","given":"A"},{"family":"Englund","given":"M"},{"family":"Roos","given":"H"}],"citation-label":"3806821","container-title":"Arthritis and Rheumatism","container-title-short":"Arthritis Rheum.","id":"3806821","invisible":false,"issue":"10","issued":{"date-parts":[["2004","10"]]},"journalAbbreviation":"Arthritis Rheum.","page":"3145-3152","suppress-author":false,"title":"High prevalence of knee osteoarthritis, pain, and functional limitations in female soccer players twelve years after anterior cruciate ligament injury.","type":"article-journal","volume":"50"}]2 Over 17 million people in the US alone participate in organized soccer.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1002/art.20589","First":false,"Last":false,"PMID":"15476248","abstract":"OBJECTIVE: To determine the prevalence of radiographic knee osteoarthritis (OA) as well as knee-related symptoms and functional limitations in female soccer players 12 years after an anterior cruciate ligament (ACL) injury. METHODS: Female soccer players who sustained an ACL injury 12 years earlier were examined with standardized weight-bearing knee radiography and 2 self-administered patient questionnaires, the Knee Injury and Osteoarthritis Outcome Score questionnaire and the Short Form 36-item health survey. Joint space narrowing and osteophytes were graded according to the radiographic atlas of the Osteoarthritis Research Society International. The cutoff value to define radiographic knee OA approximated a Kellgren/Lawrence grade of 2. RESULTS: Of the available cohort of 103 female soccer players, 84 (82%) answered the questionnaires and 67 (65%) consented to undergo knee radiography. The mean age at assessment was 31 years (range 26-40 years) and mean body mass index was 23 kg/m2 (range 18-40 kg/m2). Fifty-five women (82%) had radiographic changes in their index knee, and 34 (51%) fulfilled the criterion for radiographic knee OA. Of the subjects answering the questionnaires, 63 (75%) reported having symptoms affecting their knee-related quality of life, and 28 (42%) were considered to have symptomatic radiographic knee OA. Slightly more than 60% of the players had undergone reconstructive surgery of the ACL. Using multivariate analyses, surgical reconstruction was found to have no significant influence on knee symptoms. CONCLUSION: A very high prevalence of radiographic knee OA, pain, and functional limitations was observed in young women who sustained an ACL tear during soccer play 12 years earlier. These findings constitute a strong rationale to direct increased efforts toward prevention and better treatment of knee injury. Copyright 2004 American College of Rheumatology","author":[{"family":"Lohmander","given":"L S"},{"family":"Ostenberg","given":"A"},{"family":"Englund","given":"M"},{"family":"Roos","given":"H"}],"citation-label":"3806821","container-title":"Arthritis and Rheumatism","container-title-short":"Arthritis Rheum.","id":"3806821","invisible":false,"issue":"10","issued":{"date-parts":[["2004","10"]]},"journalAbbreviation":"Arthritis Rheum.","page":"3145-3152","suppress-author":false,"title":"High prevalence of knee osteoarthritis, pain, and functional limitations in female soccer players twelve years after anterior cruciate ligament injury.","type":"article-journal","volume":"50"}]2 Playing soccer places an athlete at an increased risk of injury. Soccer is associated with a rate of injury of between 14-35 injuries per 1,000 game hours or 2-8 injuries per 1,000 practice hours.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1002/art.20589","First":false,"Last":false,"PMID":"15476248","abstract":"OBJECTIVE: To determine the prevalence of radiographic knee osteoarthritis (OA) as well as knee-related symptoms and functional limitations in female soccer players 12 years after an anterior cruciate ligament (ACL) injury. METHODS: Female soccer players who sustained an ACL injury 12 years earlier were examined with standardized weight-bearing knee radiography and 2 self-administered patient questionnaires, the Knee Injury and Osteoarthritis Outcome Score questionnaire and the Short Form 36-item health survey. Joint space narrowing and osteophytes were graded according to the radiographic atlas of the Osteoarthritis Research Society International. The cutoff value to define radiographic knee OA approximated a Kellgren/Lawrence grade of 2. RESULTS: Of the available cohort of 103 female soccer players, 84 (82%) answered the questionnaires and 67 (65%) consented to undergo knee radiography. The mean age at assessment was 31 years (range 26-40 years) and mean body mass index was 23 kg/m2 (range 18-40 kg/m2). Fifty-five women (82%) had radiographic changes in their index knee, and 34 (51%) fulfilled the criterion for radiographic knee OA. Of the subjects answering the questionnaires, 63 (75%) reported having symptoms affecting their knee-related quality of life, and 28 (42%) were considered to have symptomatic radiographic knee OA. Slightly more than 60% of the players had undergone reconstructive surgery of the ACL. Using multivariate analyses, surgical reconstruction was found to have no significant influence on knee symptoms. CONCLUSION: A very high prevalence of radiographic knee OA, pain, and functional limitations was observed in young women who sustained an ACL tear during soccer play 12 years earlier. These findings constitute a strong rationale to direct increased efforts toward prevention and better treatment of knee injury. Copyright 2004 American College of Rheumatology","author":[{"family":"Lohmander","given":"L S"},{"family":"Ostenberg","given":"A"},{"family":"Englund","given":"M"},{"family":"Roos","given":"H"}],"citation-label":"3806821","container-title":"Arthritis and Rheumatism","container-title-short":"Arthritis Rheum.","id":"3806821","invisible":false,"issue":"10","issued":{"date-parts":[["2004","10"]]},"journalAbbreviation":"Arthritis Rheum.","page":"3145-3152","suppress-author":false,"title":"High prevalence of knee osteoarthritis, pain, and functional limitations in female soccer players twelve years after anterior cruciate ligament injury.","type":"article-journal","volume":"50"}]2 Anterior Cruciate Ligament (ACL) injuries account of roughly 1.3% of injuries in male soccer players and 3.7% in female soccer players.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1007/s00167-009-0813-1","First":false,"Last":false,"PMID":"19452139","author":[{"family":"Alentorn-Geli","given":"Eduard"},{"family":"Myer","given":"Gregory D"},{"family":"Silvers","given":"Holly J"},{"family":"Samitier","given":"Gonzalo"},{"family":"Romero","given":"Daniel"},{"family":"Lázaro-Haro","given":"Cristina"},{"family":"Cugat","given":"Ramón"}],"citation-label":"2595869","container-title":"Knee Surgery, Sports Traumatology, Arthroscopy","container-title-short":"Knee Surg. Sports Traumatol. Arthrosc.","id":"2595869","invisible":false,"issue":"7","issued":{"date-parts":[["2009","7"]]},"journalAbbreviation":"Knee Surg. Sports Traumatol. Arthrosc.","page":"705-729","suppress-author":false,"title":"Prevention of non-contact anterior cruciate ligament injuries in soccer players. Part 1: Mechanisms of injury and underlying risk factors.","type":"article-journal","volume":"17"}]1 The rate of ACL injuries varies between 0.06-3.7 per 1,000 hours of play (game or practice).ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1007/s00167-009-0813-1","First":false,"Last":false,"PMID":"19452139","author":[{"family":"Alentorn-Geli","given":"Eduard"},{"family":"Myer","given":"Gregory D"},{"family":"Silvers","given":"Holly J"},{"family":"Samitier","given":"Gonzalo"},{"family":"Romero","given":"Daniel"},{"family":"Lázaro-Haro","given":"Cristina"},{"family":"Cugat","given":"Ramón"}],"citation-label":"2595869","container-title":"Knee Surgery, Sports Traumatology, Arthroscopy","container-title-short":"Knee Surg. Sports Traumatol. Arthrosc.","id":"2595869","invisible":false,"issue":"7","issued":{"date-parts":[["2009","7"]]},"journalAbbreviation":"Knee Surg. Sports Traumatol. Arthrosc.","page":"705-729","suppress-author":false,"title":"Prevention of non-contact anterior cruciate ligament injuries in soccer players. Part 1: Mechanisms of injury and underlying risk factors.","type":"article-journal","volume":"17"}]1 The aims of this paper are to identify mechanisms of injury, risk factors and long-term implications of ACL injuries among soccer players, and to explore current evidence-based injury prevention programs aimed at reducing risk of sustaining an ACL injury in soccer players. Long term implications of an ACL injury:ACL injuries can come at a serious cost. Not only are they associated with significant time lost in sport and high financial cost, but they can also lead to increased risk of damage to the knee and soft tissue.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bjsm.2005.018341","First":false,"Last":false,"PMCID":"PMC1725226","PMID":"15911600","abstract":"Anterior cruciate ligament (ACL) injuries are a growing cause of concern, as these injuries can have serious consequences for the athlete with a greatly increased risk of early osteoarthrosis. Using specific training programmes, it may be possible to reduce the incidence of knee and ankle injuries. However, it is not known which programme components are the key to preventing knee and ankle injuries or how the exercises work to reduce injury risk. Our ability to design specific prevention programmes, whether through training or other preventive measures, is currently limited by an incomplete understanding of the causes of injuries. A multifactorial approach should be used to account for all the factors involved-that is, the internal and external risk factors as well as the inciting event (the injury mechanism). Although such models have been presented previously, we emphasise the need to use a comprehensive model, which accounts for the events leading to the injury situation (playing situation, player and opponent behaviour), as well as to include a description of whole body and joint biomechanics at the time of injury.","author":[{"family":"Bahr","given":"R"},{"family":"Krosshaug","given":"T"}],"citation-label":"5292747","container-title":"British Journal of Sports Medicine","container-title-short":"Br. J. Sports Med.","id":"5292747","invisible":false,"issue":"6","issued":{"date-parts":[["2005","6"]]},"journalAbbreviation":"Br. J. Sports Med.","page":"324-329","suppress-author":false,"title":"Understanding injury mechanisms: a key component of preventing injuries in sport.","type":"article-journal","volume":"39"}]3,ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/0363546516648439","First":false,"Last":false,"PMID":"27261476","abstract":"BACKGROUND: Female soccer players have a well-known risk for anterior cruciate ligament (ACL) injury, but few studies have reported on second ACL injuries in this population. PURPOSE: To (1) report the rates of subsequent ACL injury (ipsilateral graft rupture or contralateral tear) in competitive female soccer players, (2) compare these rates with those of other female athletes of similar competitive level, (3) determine risk factors for second ACL injury, and (4) report clinical outcome scores in this population. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: The medical records at a single institution were reviewed for female patients who were injured during a competitive athletic event and treated with primary ACL reconstruction (ACLR) between 1998 and 2013. Patients were followed for a mean of 68.8 months postoperatively (range, 24-115.2 months). Clinical outcome was obtained via Lysholm and International Knee Documentation Committee (IKDC) scores. Soccer players were matched 1:1 to non-soccer athletes for age, activity level, and graft type. RESULTS: A total of 180 female ACLR patients with a mean ± SD age of 19.6 ± 6.9 years met the study inclusion and exclusion criteria (90 soccer players and 90 non-soccer players). Soccer players sustained more second ACL injuries, including both graft failures (11% vs 1%; P < .01) and contralateral ACL tears (17% vs 4%; P < .01), compared with non-soccer players. Of the 67 patients who returned to soccer after ACLR (mean age, 17.5 years; range, 13-27 years), significantly more had graft tears compared with those who did not return to soccer (15% vs 0%, respectively; P = .04); however, the difference in contralateral ACL tears (19% for returning players vs 9% for those who did not return; P = .34) was not significant. Relatively older age (odds ratio, 1.5 per year; P = .03) was a significant risk factor for ACL graft tear but not for contralateral ACL injury. Both groups had similar mean Lysholm (96 vs 95) and IKDC scores (95 vs 96) at final follow-up. CONCLUSION: Twenty-eight percent of all female soccer players and 34% of those players who returned to soccer had a second ACL tear. Soccer players had an increased rate of both graft tear and contralateral ACL injury compared with similar non-soccer athletes. Older age and return to soccer were significant risk factors for graft rupture. ? 2016 The Author(s).","author":[{"family":"Allen","given":"Melissa M"},{"family":"Pareek","given":"Ayoosh"},{"family":"Krych","given":"Aaron J"},{"family":"Hewett","given":"Timothy E"},{"family":"Levy","given":"Bruce A"},{"family":"Stuart","given":"Michael J"},{"family":"Dahm","given":"Diane L"}],"citation-label":"6053540","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"6053540","invisible":false,"issue":"10","issued":{"date-parts":[["2016","6","3"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"2492-2498","suppress-author":false,"title":"Are female soccer players at an increased risk of second anterior cruciate ligament injury compared with their athletic peers?","type":"article-journal","volume":"44"}]4 Approximately 200,000 ACL injuries occur annually in the US, amounting to $4 billion in operational costs and $7.6 billion in annual total costs.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1016/j.jshs.2014.06.002","First":false,"Last":false,"abstract":"Anterior cruciate ligament (ACL) injuries are common in soccer. Understanding ACL loading mechanisms and risk factors for ACL injury is critical for designing effective prevention programs. The purpose of this review is to summarize the relevant literature on ACL loading mechanisms, ACL injury risk factors, and current ACL injury prevention programs for soccer players. Literature has shown that tibial anterior translation due to shear force at the proximal end of tibia is the primary ACL loading mechanism. No evidence has been found showing that knee valgus moment is the primary ACL loading mechanism. ACL loading mechanisms are largely ignored in previous studies on risk factors for ACL injury. Identified risk factors have little connections to ACL loading mechanisms. The results of studies on ACL injury prevention programs for soccer players are inconsistent. Current ACL injury prevention programs for soccer players are clinically ineffective due to low compliance. Future studies are urgently needed to identify risk factors for ACL injury in soccer that are connected to ACL loading mechanisms and have cause-and-effect relationships with injury rate, and to develop new prevention programs to improve compliance. Copyright 2014, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.","author":[{"family":"Dai","given":"Boyi"},{"family":"Mao","given":"Dewei"},{"family":"Garrett","given":"William E."},{"family":"Yu","given":"Bing"}],"citation-label":"1278040","container-title":"Journal of sport and health science","container-title-short":"J. Sport Health Sci.","id":"1278040","invisible":false,"issue":"4","issued":{"date-parts":[["2014","12"]]},"journalAbbreviation":"J. Sport Health Sci.","page":"299-306","suppress-author":false,"title":"Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and prevention programs","type":"article-journal","volume":"3"}]5 ACL injuries are also associated with the development of arthritis.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/0363546516648439","First":false,"Last":false,"PMID":"27261476","abstract":"BACKGROUND: Female soccer players have a well-known risk for anterior cruciate ligament (ACL) injury, but few studies have reported on second ACL injuries in this population. PURPOSE: To (1) report the rates of subsequent ACL injury (ipsilateral graft rupture or contralateral tear) in competitive female soccer players, (2) compare these rates with those of other female athletes of similar competitive level, (3) determine risk factors for second ACL injury, and (4) report clinical outcome scores in this population. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: The medical records at a single institution were reviewed for female patients who were injured during a competitive athletic event and treated with primary ACL reconstruction (ACLR) between 1998 and 2013. Patients were followed for a mean of 68.8 months postoperatively (range, 24-115.2 months). Clinical outcome was obtained via Lysholm and International Knee Documentation Committee (IKDC) scores. Soccer players were matched 1:1 to non-soccer athletes for age, activity level, and graft type. RESULTS: A total of 180 female ACLR patients with a mean ± SD age of 19.6 ± 6.9 years met the study inclusion and exclusion criteria (90 soccer players and 90 non-soccer players). Soccer players sustained more second ACL injuries, including both graft failures (11% vs 1%; P < .01) and contralateral ACL tears (17% vs 4%; P < .01), compared with non-soccer players. Of the 67 patients who returned to soccer after ACLR (mean age, 17.5 years; range, 13-27 years), significantly more had graft tears compared with those who did not return to soccer (15% vs 0%, respectively; P = .04); however, the difference in contralateral ACL tears (19% for returning players vs 9% for those who did not return; P = .34) was not significant. Relatively older age (odds ratio, 1.5 per year; P = .03) was a significant risk factor for ACL graft tear but not for contralateral ACL injury. Both groups had similar mean Lysholm (96 vs 95) and IKDC scores (95 vs 96) at final follow-up. CONCLUSION: Twenty-eight percent of all female soccer players and 34% of those players who returned to soccer had a second ACL tear. Soccer players had an increased rate of both graft tear and contralateral ACL injury compared with similar non-soccer athletes. Older age and return to soccer were significant risk factors for graft rupture. ? 2016 The Author(s).","author":[{"family":"Allen","given":"Melissa M"},{"family":"Pareek","given":"Ayoosh"},{"family":"Krych","given":"Aaron J"},{"family":"Hewett","given":"Timothy E"},{"family":"Levy","given":"Bruce A"},{"family":"Stuart","given":"Michael J"},{"family":"Dahm","given":"Diane L"}],"citation-label":"6053540","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"6053540","invisible":false,"issue":"10","issued":{"date-parts":[["2016","6","3"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"2492-2498","suppress-author":false,"title":"Are female soccer players at an increased risk of second anterior cruciate ligament injury compared with their athletic peers?","type":"article-journal","volume":"44"}]4 Lohmander et al. found that ? of female soccer players reported symptoms that affected their knee-related quality of life 12 years following the initial injury.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1002/art.20589","First":false,"Last":false,"PMID":"15476248","abstract":"OBJECTIVE: To determine the prevalence of radiographic knee osteoarthritis (OA) as well as knee-related symptoms and functional limitations in female soccer players 12 years after an anterior cruciate ligament (ACL) injury. METHODS: Female soccer players who sustained an ACL injury 12 years earlier were examined with standardized weight-bearing knee radiography and 2 self-administered patient questionnaires, the Knee Injury and Osteoarthritis Outcome Score questionnaire and the Short Form 36-item health survey. Joint space narrowing and osteophytes were graded according to the radiographic atlas of the Osteoarthritis Research Society International. The cutoff value to define radiographic knee OA approximated a Kellgren/Lawrence grade of 2. RESULTS: Of the available cohort of 103 female soccer players, 84 (82%) answered the questionnaires and 67 (65%) consented to undergo knee radiography. The mean age at assessment was 31 years (range 26-40 years) and mean body mass index was 23 kg/m2 (range 18-40 kg/m2). Fifty-five women (82%) had radiographic changes in their index knee, and 34 (51%) fulfilled the criterion for radiographic knee OA. Of the subjects answering the questionnaires, 63 (75%) reported having symptoms affecting their knee-related quality of life, and 28 (42%) were considered to have symptomatic radiographic knee OA. Slightly more than 60% of the players had undergone reconstructive surgery of the ACL. Using multivariate analyses, surgical reconstruction was found to have no significant influence on knee symptoms. CONCLUSION: A very high prevalence of radiographic knee OA, pain, and functional limitations was observed in young women who sustained an ACL tear during soccer play 12 years earlier. These findings constitute a strong rationale to direct increased efforts toward prevention and better treatment of knee injury. Copyright 2004 American College of Rheumatology","author":[{"family":"Lohmander","given":"L S"},{"family":"Ostenberg","given":"A"},{"family":"Englund","given":"M"},{"family":"Roos","given":"H"}],"citation-label":"3806821","container-title":"Arthritis and Rheumatism","container-title-short":"Arthritis Rheum.","id":"3806821","invisible":false,"issue":"10","issued":{"date-parts":[["2004","10"]]},"journalAbbreviation":"Arthritis Rheum.","page":"3145-3152","suppress-author":false,"title":"High prevalence of knee osteoarthritis, pain, and functional limitations in female soccer players twelve years after anterior cruciate ligament injury.","type":"article-journal","volume":"50"}]2 Of this sample, roughly 60% had undergone ACL reconstruction surgery.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1002/art.20589","First":false,"Last":false,"PMID":"15476248","abstract":"OBJECTIVE: To determine the prevalence of radiographic knee osteoarthritis (OA) as well as knee-related symptoms and functional limitations in female soccer players 12 years after an anterior cruciate ligament (ACL) injury. METHODS: Female soccer players who sustained an ACL injury 12 years earlier were examined with standardized weight-bearing knee radiography and 2 self-administered patient questionnaires, the Knee Injury and Osteoarthritis Outcome Score questionnaire and the Short Form 36-item health survey. Joint space narrowing and osteophytes were graded according to the radiographic atlas of the Osteoarthritis Research Society International. The cutoff value to define radiographic knee OA approximated a Kellgren/Lawrence grade of 2. RESULTS: Of the available cohort of 103 female soccer players, 84 (82%) answered the questionnaires and 67 (65%) consented to undergo knee radiography. The mean age at assessment was 31 years (range 26-40 years) and mean body mass index was 23 kg/m2 (range 18-40 kg/m2). Fifty-five women (82%) had radiographic changes in their index knee, and 34 (51%) fulfilled the criterion for radiographic knee OA. Of the subjects answering the questionnaires, 63 (75%) reported having symptoms affecting their knee-related quality of life, and 28 (42%) were considered to have symptomatic radiographic knee OA. Slightly more than 60% of the players had undergone reconstructive surgery of the ACL. Using multivariate analyses, surgical reconstruction was found to have no significant influence on knee symptoms. CONCLUSION: A very high prevalence of radiographic knee OA, pain, and functional limitations was observed in young women who sustained an ACL tear during soccer play 12 years earlier. These findings constitute a strong rationale to direct increased efforts toward prevention and better treatment of knee injury. Copyright 2004 American College of Rheumatology","author":[{"family":"Lohmander","given":"L S"},{"family":"Ostenberg","given":"A"},{"family":"Englund","given":"M"},{"family":"Roos","given":"H"}],"citation-label":"3806821","container-title":"Arthritis and Rheumatism","container-title-short":"Arthritis Rheum.","id":"3806821","invisible":false,"issue":"10","issued":{"date-parts":[["2004","10"]]},"journalAbbreviation":"Arthritis Rheum.","page":"3145-3152","suppress-author":false,"title":"High prevalence of knee osteoarthritis, pain, and functional limitations in female soccer players twelve years after anterior cruciate ligament injury.","type":"article-journal","volume":"50"}]2 Half of the sample had radiographic evidence of knee osteoarthritis (OA), and 82% had radiographic knee changes after 12 years.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1002/art.20589","First":false,"Last":false,"PMID":"15476248","abstract":"OBJECTIVE: To determine the prevalence of radiographic knee osteoarthritis (OA) as well as knee-related symptoms and functional limitations in female soccer players 12 years after an anterior cruciate ligament (ACL) injury. METHODS: Female soccer players who sustained an ACL injury 12 years earlier were examined with standardized weight-bearing knee radiography and 2 self-administered patient questionnaires, the Knee Injury and Osteoarthritis Outcome Score questionnaire and the Short Form 36-item health survey. Joint space narrowing and osteophytes were graded according to the radiographic atlas of the Osteoarthritis Research Society International. The cutoff value to define radiographic knee OA approximated a Kellgren/Lawrence grade of 2. RESULTS: Of the available cohort of 103 female soccer players, 84 (82%) answered the questionnaires and 67 (65%) consented to undergo knee radiography. The mean age at assessment was 31 years (range 26-40 years) and mean body mass index was 23 kg/m2 (range 18-40 kg/m2). Fifty-five women (82%) had radiographic changes in their index knee, and 34 (51%) fulfilled the criterion for radiographic knee OA. Of the subjects answering the questionnaires, 63 (75%) reported having symptoms affecting their knee-related quality of life, and 28 (42%) were considered to have symptomatic radiographic knee OA. Slightly more than 60% of the players had undergone reconstructive surgery of the ACL. Using multivariate analyses, surgical reconstruction was found to have no significant influence on knee symptoms. CONCLUSION: A very high prevalence of radiographic knee OA, pain, and functional limitations was observed in young women who sustained an ACL tear during soccer play 12 years earlier. These findings constitute a strong rationale to direct increased efforts toward prevention and better treatment of knee injury. Copyright 2004 American College of Rheumatology","author":[{"family":"Lohmander","given":"L S"},{"family":"Ostenberg","given":"A"},{"family":"Englund","given":"M"},{"family":"Roos","given":"H"}],"citation-label":"3806821","container-title":"Arthritis and Rheumatism","container-title-short":"Arthritis Rheum.","id":"3806821","invisible":false,"issue":"10","issued":{"date-parts":[["2004","10"]]},"journalAbbreviation":"Arthritis Rheum.","page":"3145-3152","suppress-author":false,"title":"High prevalence of knee osteoarthritis, pain, and functional limitations in female soccer players twelve years after anterior cruciate ligament injury.","type":"article-journal","volume":"50"}]2 Non-operative management of ACL injuries further increase the risk of development of OA.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bjsports-2013-093258","First":false,"Last":false,"PMID":"25824447","abstract":"BACKGROUND: Anterior cruciate ligament (ACL) injury is an important risk factor for development of knee osteoarthritis (OA). To identify those ACL injured patients at increased risk for knee OA, it is necessary to understand risk factors for OA. AIM: To summarise the evidence for determinants of (1) tibiofemoral OA and (2) patellofemoral OA in ACL injured patients. METHODS: MEDLINE, EMBASE, Web of Science and CINAHL databases were searched up to 20 December 2013. Additionally, reference lists of eligible studies were manually and independently screened by two reviewers. 2348 studies were assessed for the following main inclusion criteria: ≥20 patients; ACL injured patients treated operatively or non-operatively; reporting OA as outcome; description of relationship between OA outcome and determinants; and a follow-up period ≥2?years. Two reviewers extracted the data, assessed the risk of bias and performed a best-evidence synthesis. RESULTS: Sixty-four publications were included and assessed for quality. Two studies were classified as low risk of bias. Medial meniscal injury/meniscectomy showed moderate evidence for influencing OA development (tibiofemoral OA and compartment unspecified). Lateral meniscal injury/meniscectomy showed moderate evidence for no relationship (compartment unspecified), as did time between injury and reconstruction (tibiofemoral and patellofemoral OA). CONCLUSIONS: Medial meniscal injury/meniscectomy after ACL rupture increased the risk of OA development. In contrast, it seems that lateral meniscal injury/meniscectomy has no relationship with OA development. Our results suggest that time between injury and reconstruction does not influence patellofemoral and tibiofemoral OA development. Many determinants showed conflicting and limited evidence and no determinant showed strong evidence. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to .","author":[{"family":"van Meer","given":"Belle L"},{"family":"Meuffels","given":"Duncan E"},{"family":"van Eijsden","given":"Wilbert A"},{"family":"Verhaar","given":"Jan A N"},{"family":"Bierma-Zeinstra","given":"Sita M A"},{"family":"Reijman","given":"Max"}],"citation-label":"4082498","container-title":"British Journal of Sports Medicine","container-title-short":"Br. J. Sports Med.","id":"4082498","invisible":false,"issue":"15","issued":{"date-parts":[["2015","8"]]},"journalAbbreviation":"Br. J. Sports Med.","page":"975-983","suppress-author":false,"title":"Which determinants predict tibiofemoral and patellofemoral osteoarthritis after anterior cruciate ligament injury? A systematic review.","type":"article-journal","volume":"49"}]6 Approximately 70% or more of those who have had an ACL injury, independent to treatment choice, will develop OA after 15-20 years.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bjsm.2005.018341","First":false,"Last":false,"PMCID":"PMC1725226","PMID":"15911600","abstract":"Anterior cruciate ligament (ACL) injuries are a growing cause of concern, as these injuries can have serious consequences for the athlete with a greatly increased risk of early osteoarthrosis. Using specific training programmes, it may be possible to reduce the incidence of knee and ankle injuries. However, it is not known which programme components are the key to preventing knee and ankle injuries or how the exercises work to reduce injury risk. Our ability to design specific prevention programmes, whether through training or other preventive measures, is currently limited by an incomplete understanding of the causes of injuries. A multifactorial approach should be used to account for all the factors involved-that is, the internal and external risk factors as well as the inciting event (the injury mechanism). Although such models have been presented previously, we emphasise the need to use a comprehensive model, which accounts for the events leading to the injury situation (playing situation, player and opponent behaviour), as well as to include a description of whole body and joint biomechanics at the time of injury.","author":[{"family":"Bahr","given":"R"},{"family":"Krosshaug","given":"T"}],"citation-label":"5292747","container-title":"British Journal of Sports Medicine","container-title-short":"Br. J. Sports Med.","id":"5292747","invisible":false,"issue":"6","issued":{"date-parts":[["2005","6"]]},"journalAbbreviation":"Br. J. Sports Med.","page":"324-329","suppress-author":false,"title":"Understanding injury mechanisms: a key component of preventing injuries in sport.","type":"article-journal","volume":"39"}]3,ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1016/j.jshs.2014.06.002","First":false,"Last":false,"abstract":"Anterior cruciate ligament (ACL) injuries are common in soccer. Understanding ACL loading mechanisms and risk factors for ACL injury is critical for designing effective prevention programs. The purpose of this review is to summarize the relevant literature on ACL loading mechanisms, ACL injury risk factors, and current ACL injury prevention programs for soccer players. Literature has shown that tibial anterior translation due to shear force at the proximal end of tibia is the primary ACL loading mechanism. No evidence has been found showing that knee valgus moment is the primary ACL loading mechanism. ACL loading mechanisms are largely ignored in previous studies on risk factors for ACL injury. Identified risk factors have little connections to ACL loading mechanisms. The results of studies on ACL injury prevention programs for soccer players are inconsistent. Current ACL injury prevention programs for soccer players are clinically ineffective due to low compliance. Future studies are urgently needed to identify risk factors for ACL injury in soccer that are connected to ACL loading mechanisms and have cause-and-effect relationships with injury rate, and to develop new prevention programs to improve compliance. Copyright 2014, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.","author":[{"family":"Dai","given":"Boyi"},{"family":"Mao","given":"Dewei"},{"family":"Garrett","given":"William E."},{"family":"Yu","given":"Bing"}],"citation-label":"1278040","container-title":"Journal of sport and health science","container-title-short":"J. Sport Health Sci.","id":"1278040","invisible":false,"issue":"4","issued":{"date-parts":[["2014","12"]]},"journalAbbreviation":"J. Sport Health Sci.","page":"299-306","suppress-author":false,"title":"Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and prevention programs","type":"article-journal","volume":"3"}]5 Of these, 13-15% require a total knee arthroplasty.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1016/j.jshs.2014.06.002","First":false,"Last":false,"abstract":"Anterior cruciate ligament (ACL) injuries are common in soccer. Understanding ACL loading mechanisms and risk factors for ACL injury is critical for designing effective prevention programs. The purpose of this review is to summarize the relevant literature on ACL loading mechanisms, ACL injury risk factors, and current ACL injury prevention programs for soccer players. Literature has shown that tibial anterior translation due to shear force at the proximal end of tibia is the primary ACL loading mechanism. No evidence has been found showing that knee valgus moment is the primary ACL loading mechanism. ACL loading mechanisms are largely ignored in previous studies on risk factors for ACL injury. Identified risk factors have little connections to ACL loading mechanisms. The results of studies on ACL injury prevention programs for soccer players are inconsistent. Current ACL injury prevention programs for soccer players are clinically ineffective due to low compliance. Future studies are urgently needed to identify risk factors for ACL injury in soccer that are connected to ACL loading mechanisms and have cause-and-effect relationships with injury rate, and to develop new prevention programs to improve compliance. Copyright 2014, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.","author":[{"family":"Dai","given":"Boyi"},{"family":"Mao","given":"Dewei"},{"family":"Garrett","given":"William E."},{"family":"Yu","given":"Bing"}],"citation-label":"1278040","container-title":"Journal of sport and health science","container-title-short":"J. Sport Health Sci.","id":"1278040","invisible":false,"issue":"4","issued":{"date-parts":[["2014","12"]]},"journalAbbreviation":"J. Sport Health Sci.","page":"299-306","suppress-author":false,"title":"Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and prevention programs","type":"article-journal","volume":"3"}]5 Concurrent medial meniscus injury and/or meniscectomy follow an ACL injury also further increase the risk of the development of OA following an ACL rupture.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bjsports-2013-093258","First":false,"Last":false,"PMID":"25824447","abstract":"BACKGROUND: Anterior cruciate ligament (ACL) injury is an important risk factor for development of knee osteoarthritis (OA). To identify those ACL injured patients at increased risk for knee OA, it is necessary to understand risk factors for OA. AIM: To summarise the evidence for determinants of (1) tibiofemoral OA and (2) patellofemoral OA in ACL injured patients. METHODS: MEDLINE, EMBASE, Web of Science and CINAHL databases were searched up to 20 December 2013. Additionally, reference lists of eligible studies were manually and independently screened by two reviewers. 2348 studies were assessed for the following main inclusion criteria: ≥20 patients; ACL injured patients treated operatively or non-operatively; reporting OA as outcome; description of relationship between OA outcome and determinants; and a follow-up period ≥2?years. Two reviewers extracted the data, assessed the risk of bias and performed a best-evidence synthesis. RESULTS: Sixty-four publications were included and assessed for quality. Two studies were classified as low risk of bias. Medial meniscal injury/meniscectomy showed moderate evidence for influencing OA development (tibiofemoral OA and compartment unspecified). Lateral meniscal injury/meniscectomy showed moderate evidence for no relationship (compartment unspecified), as did time between injury and reconstruction (tibiofemoral and patellofemoral OA). CONCLUSIONS: Medial meniscal injury/meniscectomy after ACL rupture increased the risk of OA development. In contrast, it seems that lateral meniscal injury/meniscectomy has no relationship with OA development. Our results suggest that time between injury and reconstruction does not influence patellofemoral and tibiofemoral OA development. Many determinants showed conflicting and limited evidence and no determinant showed strong evidence. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to .","author":[{"family":"van Meer","given":"Belle L"},{"family":"Meuffels","given":"Duncan E"},{"family":"van Eijsden","given":"Wilbert A"},{"family":"Verhaar","given":"Jan A N"},{"family":"Bierma-Zeinstra","given":"Sita M A"},{"family":"Reijman","given":"Max"}],"citation-label":"4082498","container-title":"British Journal of Sports Medicine","container-title-short":"Br. J. Sports Med.","id":"4082498","invisible":false,"issue":"15","issued":{"date-parts":[["2015","8"]]},"journalAbbreviation":"Br. J. Sports Med.","page":"975-983","suppress-author":false,"title":"Which determinants predict tibiofemoral and patellofemoral osteoarthritis after anterior cruciate ligament injury? A systematic review.","type":"article-journal","volume":"49"}]6 Individuals who suffer an ACL injury and have subsequent reconstruction often have reduced strength, proprioception, balance and altered neuromuscular control versus a peer who has not sustained an injury.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1016/j.jshs.2014.06.002","First":false,"Last":false,"abstract":"Anterior cruciate ligament (ACL) injuries are common in soccer. Understanding ACL loading mechanisms and risk factors for ACL injury is critical for designing effective prevention programs. The purpose of this review is to summarize the relevant literature on ACL loading mechanisms, ACL injury risk factors, and current ACL injury prevention programs for soccer players. Literature has shown that tibial anterior translation due to shear force at the proximal end of tibia is the primary ACL loading mechanism. No evidence has been found showing that knee valgus moment is the primary ACL loading mechanism. ACL loading mechanisms are largely ignored in previous studies on risk factors for ACL injury. Identified risk factors have little connections to ACL loading mechanisms. The results of studies on ACL injury prevention programs for soccer players are inconsistent. Current ACL injury prevention programs for soccer players are clinically ineffective due to low compliance. Future studies are urgently needed to identify risk factors for ACL injury in soccer that are connected to ACL loading mechanisms and have cause-and-effect relationships with injury rate, and to develop new prevention programs to improve compliance. Copyright 2014, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.","author":[{"family":"Dai","given":"Boyi"},{"family":"Mao","given":"Dewei"},{"family":"Garrett","given":"William E."},{"family":"Yu","given":"Bing"}],"citation-label":"1278040","container-title":"Journal of sport and health science","container-title-short":"J. Sport Health Sci.","id":"1278040","invisible":false,"issue":"4","issued":{"date-parts":[["2014","12"]]},"journalAbbreviation":"J. Sport Health Sci.","page":"299-306","suppress-author":false,"title":"Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and prevention programs","type":"article-journal","volume":"3"}]5 These factors can increase the risk of re-injury.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1016/j.jshs.2014.06.002","First":false,"Last":false,"abstract":"Anterior cruciate ligament (ACL) injuries are common in soccer. Understanding ACL loading mechanisms and risk factors for ACL injury is critical for designing effective prevention programs. The purpose of this review is to summarize the relevant literature on ACL loading mechanisms, ACL injury risk factors, and current ACL injury prevention programs for soccer players. Literature has shown that tibial anterior translation due to shear force at the proximal end of tibia is the primary ACL loading mechanism. No evidence has been found showing that knee valgus moment is the primary ACL loading mechanism. ACL loading mechanisms are largely ignored in previous studies on risk factors for ACL injury. Identified risk factors have little connections to ACL loading mechanisms. The results of studies on ACL injury prevention programs for soccer players are inconsistent. Current ACL injury prevention programs for soccer players are clinically ineffective due to low compliance. Future studies are urgently needed to identify risk factors for ACL injury in soccer that are connected to ACL loading mechanisms and have cause-and-effect relationships with injury rate, and to develop new prevention programs to improve compliance. Copyright 2014, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.","author":[{"family":"Dai","given":"Boyi"},{"family":"Mao","given":"Dewei"},{"family":"Garrett","given":"William E."},{"family":"Yu","given":"Bing"}],"citation-label":"1278040","container-title":"Journal of sport and health science","container-title-short":"J. Sport Health Sci.","id":"1278040","invisible":false,"issue":"4","issued":{"date-parts":[["2014","12"]]},"journalAbbreviation":"J. Sport Health Sci.","page":"299-306","suppress-author":false,"title":"Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and prevention programs","type":"article-journal","volume":"3"}]5 A previous ACL injury places a soccer player at an elevated risk of a secondary ACL tear.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/0363546516648439","First":false,"Last":false,"PMID":"27261476","abstract":"BACKGROUND: Female soccer players have a well-known risk for anterior cruciate ligament (ACL) injury, but few studies have reported on second ACL injuries in this population. PURPOSE: To (1) report the rates of subsequent ACL injury (ipsilateral graft rupture or contralateral tear) in competitive female soccer players, (2) compare these rates with those of other female athletes of similar competitive level, (3) determine risk factors for second ACL injury, and (4) report clinical outcome scores in this population. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: The medical records at a single institution were reviewed for female patients who were injured during a competitive athletic event and treated with primary ACL reconstruction (ACLR) between 1998 and 2013. Patients were followed for a mean of 68.8 months postoperatively (range, 24-115.2 months). Clinical outcome was obtained via Lysholm and International Knee Documentation Committee (IKDC) scores. Soccer players were matched 1:1 to non-soccer athletes for age, activity level, and graft type. RESULTS: A total of 180 female ACLR patients with a mean ± SD age of 19.6 ± 6.9 years met the study inclusion and exclusion criteria (90 soccer players and 90 non-soccer players). Soccer players sustained more second ACL injuries, including both graft failures (11% vs 1%; P < .01) and contralateral ACL tears (17% vs 4%; P < .01), compared with non-soccer players. Of the 67 patients who returned to soccer after ACLR (mean age, 17.5 years; range, 13-27 years), significantly more had graft tears compared with those who did not return to soccer (15% vs 0%, respectively; P = .04); however, the difference in contralateral ACL tears (19% for returning players vs 9% for those who did not return; P = .34) was not significant. Relatively older age (odds ratio, 1.5 per year; P = .03) was a significant risk factor for ACL graft tear but not for contralateral ACL injury. Both groups had similar mean Lysholm (96 vs 95) and IKDC scores (95 vs 96) at final follow-up. CONCLUSION: Twenty-eight percent of all female soccer players and 34% of those players who returned to soccer had a second ACL tear. Soccer players had an increased rate of both graft tear and contralateral ACL injury compared with similar non-soccer athletes. Older age and return to soccer were significant risk factors for graft rupture. ? 2016 The Author(s).","author":[{"family":"Allen","given":"Melissa M"},{"family":"Pareek","given":"Ayoosh"},{"family":"Krych","given":"Aaron J"},{"family":"Hewett","given":"Timothy E"},{"family":"Levy","given":"Bruce A"},{"family":"Stuart","given":"Michael J"},{"family":"Dahm","given":"Diane L"}],"citation-label":"6053540","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"6053540","invisible":false,"issue":"10","issued":{"date-parts":[["2016","6","3"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"2492-2498","suppress-author":false,"title":"Are female soccer players at an increased risk of second anterior cruciate ligament injury compared with their athletic peers?","type":"article-journal","volume":"44"}]4 A cohort study found that roughly ? of female soccer players who tore their ACL had a second tear (either graft rupture or a contralateral ACL injury).ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/0363546516648439","First":false,"Last":false,"PMID":"27261476","abstract":"BACKGROUND: Female soccer players have a well-known risk for anterior cruciate ligament (ACL) injury, but few studies have reported on second ACL injuries in this population. PURPOSE: To (1) report the rates of subsequent ACL injury (ipsilateral graft rupture or contralateral tear) in competitive female soccer players, (2) compare these rates with those of other female athletes of similar competitive level, (3) determine risk factors for second ACL injury, and (4) report clinical outcome scores in this population. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: The medical records at a single institution were reviewed for female patients who were injured during a competitive athletic event and treated with primary ACL reconstruction (ACLR) between 1998 and 2013. Patients were followed for a mean of 68.8 months postoperatively (range, 24-115.2 months). Clinical outcome was obtained via Lysholm and International Knee Documentation Committee (IKDC) scores. Soccer players were matched 1:1 to non-soccer athletes for age, activity level, and graft type. RESULTS: A total of 180 female ACLR patients with a mean ± SD age of 19.6 ± 6.9 years met the study inclusion and exclusion criteria (90 soccer players and 90 non-soccer players). Soccer players sustained more second ACL injuries, including both graft failures (11% vs 1%; P < .01) and contralateral ACL tears (17% vs 4%; P < .01), compared with non-soccer players. Of the 67 patients who returned to soccer after ACLR (mean age, 17.5 years; range, 13-27 years), significantly more had graft tears compared with those who did not return to soccer (15% vs 0%, respectively; P = .04); however, the difference in contralateral ACL tears (19% for returning players vs 9% for those who did not return; P = .34) was not significant. Relatively older age (odds ratio, 1.5 per year; P = .03) was a significant risk factor for ACL graft tear but not for contralateral ACL injury. Both groups had similar mean Lysholm (96 vs 95) and IKDC scores (95 vs 96) at final follow-up. CONCLUSION: Twenty-eight percent of all female soccer players and 34% of those players who returned to soccer had a second ACL tear. Soccer players had an increased rate of both graft tear and contralateral ACL injury compared with similar non-soccer athletes. Older age and return to soccer were significant risk factors for graft rupture. ? 2016 The Author(s).","author":[{"family":"Allen","given":"Melissa M"},{"family":"Pareek","given":"Ayoosh"},{"family":"Krych","given":"Aaron J"},{"family":"Hewett","given":"Timothy E"},{"family":"Levy","given":"Bruce A"},{"family":"Stuart","given":"Michael J"},{"family":"Dahm","given":"Diane L"}],"citation-label":"6053540","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"6053540","invisible":false,"issue":"10","issued":{"date-parts":[["2016","6","3"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"2492-2498","suppress-author":false,"title":"Are female soccer players at an increased risk of second anterior cruciate ligament injury compared with their athletic peers?","type":"article-journal","volume":"44"}]4 This risk for a secondary tear increased to 34% for those female athletes who returned to play.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/0363546516648439","First":false,"Last":false,"PMID":"27261476","abstract":"BACKGROUND: Female soccer players have a well-known risk for anterior cruciate ligament (ACL) injury, but few studies have reported on second ACL injuries in this population. PURPOSE: To (1) report the rates of subsequent ACL injury (ipsilateral graft rupture or contralateral tear) in competitive female soccer players, (2) compare these rates with those of other female athletes of similar competitive level, (3) determine risk factors for second ACL injury, and (4) report clinical outcome scores in this population. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: The medical records at a single institution were reviewed for female patients who were injured during a competitive athletic event and treated with primary ACL reconstruction (ACLR) between 1998 and 2013. Patients were followed for a mean of 68.8 months postoperatively (range, 24-115.2 months). Clinical outcome was obtained via Lysholm and International Knee Documentation Committee (IKDC) scores. Soccer players were matched 1:1 to non-soccer athletes for age, activity level, and graft type. RESULTS: A total of 180 female ACLR patients with a mean ± SD age of 19.6 ± 6.9 years met the study inclusion and exclusion criteria (90 soccer players and 90 non-soccer players). Soccer players sustained more second ACL injuries, including both graft failures (11% vs 1%; P < .01) and contralateral ACL tears (17% vs 4%; P < .01), compared with non-soccer players. Of the 67 patients who returned to soccer after ACLR (mean age, 17.5 years; range, 13-27 years), significantly more had graft tears compared with those who did not return to soccer (15% vs 0%, respectively; P = .04); however, the difference in contralateral ACL tears (19% for returning players vs 9% for those who did not return; P = .34) was not significant. Relatively older age (odds ratio, 1.5 per year; P = .03) was a significant risk factor for ACL graft tear but not for contralateral ACL injury. Both groups had similar mean Lysholm (96 vs 95) and IKDC scores (95 vs 96) at final follow-up. CONCLUSION: Twenty-eight percent of all female soccer players and 34% of those players who returned to soccer had a second ACL tear. Soccer players had an increased rate of both graft tear and contralateral ACL injury compared with similar non-soccer athletes. Older age and return to soccer were significant risk factors for graft rupture. ? 2016 The Author(s).","author":[{"family":"Allen","given":"Melissa M"},{"family":"Pareek","given":"Ayoosh"},{"family":"Krych","given":"Aaron J"},{"family":"Hewett","given":"Timothy E"},{"family":"Levy","given":"Bruce A"},{"family":"Stuart","given":"Michael J"},{"family":"Dahm","given":"Diane L"}],"citation-label":"6053540","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"6053540","invisible":false,"issue":"10","issued":{"date-parts":[["2016","6","3"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"2492-2498","suppress-author":false,"title":"Are female soccer players at an increased risk of second anterior cruciate ligament injury compared with their athletic peers?","type":"article-journal","volume":"44"}]4 Further, the rate of secondary injury was elevated compared to non-soccer player playing age-matched athletic peers.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/0363546516648439","First":false,"Last":false,"PMID":"27261476","abstract":"BACKGROUND: Female soccer players have a well-known risk for anterior cruciate ligament (ACL) injury, but few studies have reported on second ACL injuries in this population. PURPOSE: To (1) report the rates of subsequent ACL injury (ipsilateral graft rupture or contralateral tear) in competitive female soccer players, (2) compare these rates with those of other female athletes of similar competitive level, (3) determine risk factors for second ACL injury, and (4) report clinical outcome scores in this population. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: The medical records at a single institution were reviewed for female patients who were injured during a competitive athletic event and treated with primary ACL reconstruction (ACLR) between 1998 and 2013. Patients were followed for a mean of 68.8 months postoperatively (range, 24-115.2 months). Clinical outcome was obtained via Lysholm and International Knee Documentation Committee (IKDC) scores. Soccer players were matched 1:1 to non-soccer athletes for age, activity level, and graft type. RESULTS: A total of 180 female ACLR patients with a mean ± SD age of 19.6 ± 6.9 years met the study inclusion and exclusion criteria (90 soccer players and 90 non-soccer players). Soccer players sustained more second ACL injuries, including both graft failures (11% vs 1%; P < .01) and contralateral ACL tears (17% vs 4%; P < .01), compared with non-soccer players. Of the 67 patients who returned to soccer after ACLR (mean age, 17.5 years; range, 13-27 years), significantly more had graft tears compared with those who did not return to soccer (15% vs 0%, respectively; P = .04); however, the difference in contralateral ACL tears (19% for returning players vs 9% for those who did not return; P = .34) was not significant. Relatively older age (odds ratio, 1.5 per year; P = .03) was a significant risk factor for ACL graft tear but not for contralateral ACL injury. Both groups had similar mean Lysholm (96 vs 95) and IKDC scores (95 vs 96) at final follow-up. CONCLUSION: Twenty-eight percent of all female soccer players and 34% of those players who returned to soccer had a second ACL tear. Soccer players had an increased rate of both graft tear and contralateral ACL injury compared with similar non-soccer athletes. Older age and return to soccer were significant risk factors for graft rupture. ? 2016 The Author(s).","author":[{"family":"Allen","given":"Melissa M"},{"family":"Pareek","given":"Ayoosh"},{"family":"Krych","given":"Aaron J"},{"family":"Hewett","given":"Timothy E"},{"family":"Levy","given":"Bruce A"},{"family":"Stuart","given":"Michael J"},{"family":"Dahm","given":"Diane L"}],"citation-label":"6053540","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"6053540","invisible":false,"issue":"10","issued":{"date-parts":[["2016","6","3"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"2492-2498","suppress-author":false,"title":"Are female soccer players at an increased risk of second anterior cruciate ligament injury compared with their athletic peers?","type":"article-journal","volume":"44"}]4 Given the long-term factors associated with an ACL injury beyond the extent of the acute injury, it is critical to focus attention into the prevention of these injuries in addition to treatment of the injuries if they do occur. Mechanism of ACL injuries and risk factors for soccer players:Understanding the mechanism of injury in sport can be essential for the development of injury prevention of injuries. Our current knowledge regarding effective injury prevention programs is in part limited by an incomplete understanding of the mechanism of injuries, such as an ACL injury.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bjsm.2005.018341","First":false,"Last":false,"PMCID":"PMC1725226","PMID":"15911600","abstract":"Anterior cruciate ligament (ACL) injuries are a growing cause of concern, as these injuries can have serious consequences for the athlete with a greatly increased risk of early osteoarthrosis. Using specific training programmes, it may be possible to reduce the incidence of knee and ankle injuries. However, it is not known which programme components are the key to preventing knee and ankle injuries or how the exercises work to reduce injury risk. Our ability to design specific prevention programmes, whether through training or other preventive measures, is currently limited by an incomplete understanding of the causes of injuries. A multifactorial approach should be used to account for all the factors involved-that is, the internal and external risk factors as well as the inciting event (the injury mechanism). Although such models have been presented previously, we emphasise the need to use a comprehensive model, which accounts for the events leading to the injury situation (playing situation, player and opponent behaviour), as well as to include a description of whole body and joint biomechanics at the time of injury.","author":[{"family":"Bahr","given":"R"},{"family":"Krosshaug","given":"T"}],"citation-label":"5292747","container-title":"British Journal of Sports Medicine","container-title-short":"Br. J. Sports Med.","id":"5292747","invisible":false,"issue":"6","issued":{"date-parts":[["2005","6"]]},"journalAbbreviation":"Br. J. Sports Med.","page":"324-329","suppress-author":false,"title":"Understanding injury mechanisms: a key component of preventing injuries in sport.","type":"article-journal","volume":"39"}]3,ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1016/j.jshs.2014.06.002","First":false,"Last":false,"abstract":"Anterior cruciate ligament (ACL) injuries are common in soccer. Understanding ACL loading mechanisms and risk factors for ACL injury is critical for designing effective prevention programs. The purpose of this review is to summarize the relevant literature on ACL loading mechanisms, ACL injury risk factors, and current ACL injury prevention programs for soccer players. Literature has shown that tibial anterior translation due to shear force at the proximal end of tibia is the primary ACL loading mechanism. No evidence has been found showing that knee valgus moment is the primary ACL loading mechanism. ACL loading mechanisms are largely ignored in previous studies on risk factors for ACL injury. Identified risk factors have little connections to ACL loading mechanisms. The results of studies on ACL injury prevention programs for soccer players are inconsistent. Current ACL injury prevention programs for soccer players are clinically ineffective due to low compliance. Future studies are urgently needed to identify risk factors for ACL injury in soccer that are connected to ACL loading mechanisms and have cause-and-effect relationships with injury rate, and to develop new prevention programs to improve compliance. Copyright 2014, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.","author":[{"family":"Dai","given":"Boyi"},{"family":"Mao","given":"Dewei"},{"family":"Garrett","given":"William E."},{"family":"Yu","given":"Bing"}],"citation-label":"1278040","container-title":"Journal of sport and health science","container-title-short":"J. Sport Health Sci.","id":"1278040","invisible":false,"issue":"4","issued":{"date-parts":[["2014","12"]]},"journalAbbreviation":"J. Sport Health Sci.","page":"299-306","suppress-author":false,"title":"Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and prevention programs","type":"article-journal","volume":"3"}]5 Bahr & Krosshaug (2015) proposed that understanding injury prevention first requires an understanding the extent of the problem, then an identification of the mechanism of injury, an introduction of a preventative measure, and finally an evaluation of the efficacy of the intervention.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bjsm.2005.018341","First":false,"Last":false,"PMCID":"PMC1725226","PMID":"15911600","abstract":"Anterior cruciate ligament (ACL) injuries are a growing cause of concern, as these injuries can have serious consequences for the athlete with a greatly increased risk of early osteoarthrosis. Using specific training programmes, it may be possible to reduce the incidence of knee and ankle injuries. However, it is not known which programme components are the key to preventing knee and ankle injuries or how the exercises work to reduce injury risk. Our ability to design specific prevention programmes, whether through training or other preventive measures, is currently limited by an incomplete understanding of the causes of injuries. A multifactorial approach should be used to account for all the factors involved-that is, the internal and external risk factors as well as the inciting event (the injury mechanism). Although such models have been presented previously, we emphasise the need to use a comprehensive model, which accounts for the events leading to the injury situation (playing situation, player and opponent behaviour), as well as to include a description of whole body and joint biomechanics at the time of injury.","author":[{"family":"Bahr","given":"R"},{"family":"Krosshaug","given":"T"}],"citation-label":"5292747","container-title":"British Journal of Sports Medicine","container-title-short":"Br. J. Sports Med.","id":"5292747","invisible":false,"issue":"6","issued":{"date-parts":[["2005","6"]]},"journalAbbreviation":"Br. J. Sports Med.","page":"324-329","suppress-author":false,"title":"Understanding injury mechanisms: a key component of preventing injuries in sport.","type":"article-journal","volume":"39"}]3 Identification of causes of sports injuries, such as ACL injuries can be complicated as they involve predisposing internal risk factors, external exposure risk factors, and an inciting event, all of which are composed of multiple elements.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bjsm.2005.018341","First":false,"Last":false,"PMCID":"PMC1725226","PMID":"15911600","abstract":"Anterior cruciate ligament (ACL) injuries are a growing cause of concern, as these injuries can have serious consequences for the athlete with a greatly increased risk of early osteoarthrosis. Using specific training programmes, it may be possible to reduce the incidence of knee and ankle injuries. However, it is not known which programme components are the key to preventing knee and ankle injuries or how the exercises work to reduce injury risk. Our ability to design specific prevention programmes, whether through training or other preventive measures, is currently limited by an incomplete understanding of the causes of injuries. A multifactorial approach should be used to account for all the factors involved-that is, the internal and external risk factors as well as the inciting event (the injury mechanism). Although such models have been presented previously, we emphasise the need to use a comprehensive model, which accounts for the events leading to the injury situation (playing situation, player and opponent behaviour), as well as to include a description of whole body and joint biomechanics at the time of injury.","author":[{"family":"Bahr","given":"R"},{"family":"Krosshaug","given":"T"}],"citation-label":"5292747","container-title":"British Journal of Sports Medicine","container-title-short":"Br. J. Sports Med.","id":"5292747","invisible":false,"issue":"6","issued":{"date-parts":[["2005","6"]]},"journalAbbreviation":"Br. J. Sports Med.","page":"324-329","suppress-author":false,"title":"Understanding injury mechanisms: a key component of preventing injuries in sport.","type":"article-journal","volume":"39"}]3 For example, while intrinsic risk factors such as age, sex, and anatomy may predispose an athlete, external factors such as sports equipment and field surface may make an athlete susceptible.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bjsm.2005.018341","First":false,"Last":false,"PMCID":"PMC1725226","PMID":"15911600","abstract":"Anterior cruciate ligament (ACL) injuries are a growing cause of concern, as these injuries can have serious consequences for the athlete with a greatly increased risk of early osteoarthrosis. Using specific training programmes, it may be possible to reduce the incidence of knee and ankle injuries. However, it is not known which programme components are the key to preventing knee and ankle injuries or how the exercises work to reduce injury risk. Our ability to design specific prevention programmes, whether through training or other preventive measures, is currently limited by an incomplete understanding of the causes of injuries. A multifactorial approach should be used to account for all the factors involved-that is, the internal and external risk factors as well as the inciting event (the injury mechanism). Although such models have been presented previously, we emphasise the need to use a comprehensive model, which accounts for the events leading to the injury situation (playing situation, player and opponent behaviour), as well as to include a description of whole body and joint biomechanics at the time of injury.","author":[{"family":"Bahr","given":"R"},{"family":"Krosshaug","given":"T"}],"citation-label":"5292747","container-title":"British Journal of Sports Medicine","container-title-short":"Br. J. Sports Med.","id":"5292747","invisible":false,"issue":"6","issued":{"date-parts":[["2005","6"]]},"journalAbbreviation":"Br. J. Sports Med.","page":"324-329","suppress-author":false,"title":"Understanding injury mechanisms: a key component of preventing injuries in sport.","type":"article-journal","volume":"39"}]3 When these external and internal factors are combined with an inciting event, such as a quick deceleration with internal rotation while the foot remains planted, it can lead to an injury.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bjsm.2005.018341","First":false,"Last":false,"PMCID":"PMC1725226","PMID":"15911600","abstract":"Anterior cruciate ligament (ACL) injuries are a growing cause of concern, as these injuries can have serious consequences for the athlete with a greatly increased risk of early osteoarthrosis. Using specific training programmes, it may be possible to reduce the incidence of knee and ankle injuries. However, it is not known which programme components are the key to preventing knee and ankle injuries or how the exercises work to reduce injury risk. Our ability to design specific prevention programmes, whether through training or other preventive measures, is currently limited by an incomplete understanding of the causes of injuries. A multifactorial approach should be used to account for all the factors involved-that is, the internal and external risk factors as well as the inciting event (the injury mechanism). Although such models have been presented previously, we emphasise the need to use a comprehensive model, which accounts for the events leading to the injury situation (playing situation, player and opponent behaviour), as well as to include a description of whole body and joint biomechanics at the time of injury.","author":[{"family":"Bahr","given":"R"},{"family":"Krosshaug","given":"T"}],"citation-label":"5292747","container-title":"British Journal of Sports Medicine","container-title-short":"Br. J. Sports Med.","id":"5292747","invisible":false,"issue":"6","issued":{"date-parts":[["2005","6"]]},"journalAbbreviation":"Br. J. Sports Med.","page":"324-329","suppress-author":false,"title":"Understanding injury mechanisms: a key component of preventing injuries in sport.","type":"article-journal","volume":"39"}]3 Appendix I provides a graphical representation of these factors proposed by Bahr & Krosshaug.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bjsm.2005.018341","First":false,"Last":false,"PMCID":"PMC1725226","PMID":"15911600","abstract":"Anterior cruciate ligament (ACL) injuries are a growing cause of concern, as these injuries can have serious consequences for the athlete with a greatly increased risk of early osteoarthrosis. Using specific training programmes, it may be possible to reduce the incidence of knee and ankle injuries. However, it is not known which programme components are the key to preventing knee and ankle injuries or how the exercises work to reduce injury risk. Our ability to design specific prevention programmes, whether through training or other preventive measures, is currently limited by an incomplete understanding of the causes of injuries. A multifactorial approach should be used to account for all the factors involved-that is, the internal and external risk factors as well as the inciting event (the injury mechanism). Although such models have been presented previously, we emphasise the need to use a comprehensive model, which accounts for the events leading to the injury situation (playing situation, player and opponent behaviour), as well as to include a description of whole body and joint biomechanics at the time of injury.","author":[{"family":"Bahr","given":"R"},{"family":"Krosshaug","given":"T"}],"citation-label":"5292747","container-title":"British Journal of Sports Medicine","container-title-short":"Br. J. Sports Med.","id":"5292747","invisible":false,"issue":"6","issued":{"date-parts":[["2005","6"]]},"journalAbbreviation":"Br. J. Sports Med.","page":"324-329","suppress-author":false,"title":"Understanding injury mechanisms: a key component of preventing injuries in sport.","type":"article-journal","volume":"39"}]3 In summary, an understanding of the ACL’s function, possible mechanisms of ACL injury as well as risk factors are essential prior to developing and evaluating ACL injury prevention programs.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bjsm.2005.018341","First":false,"Last":false,"PMCID":"PMC1725226","PMID":"15911600","abstract":"Anterior cruciate ligament (ACL) injuries are a growing cause of concern, as these injuries can have serious consequences for the athlete with a greatly increased risk of early osteoarthrosis. Using specific training programmes, it may be possible to reduce the incidence of knee and ankle injuries. However, it is not known which programme components are the key to preventing knee and ankle injuries or how the exercises work to reduce injury risk. Our ability to design specific prevention programmes, whether through training or other preventive measures, is currently limited by an incomplete understanding of the causes of injuries. A multifactorial approach should be used to account for all the factors involved-that is, the internal and external risk factors as well as the inciting event (the injury mechanism). Although such models have been presented previously, we emphasise the need to use a comprehensive model, which accounts for the events leading to the injury situation (playing situation, player and opponent behaviour), as well as to include a description of whole body and joint biomechanics at the time of injury.","author":[{"family":"Bahr","given":"R"},{"family":"Krosshaug","given":"T"}],"citation-label":"5292747","container-title":"British Journal of Sports Medicine","container-title-short":"Br. J. Sports Med.","id":"5292747","invisible":false,"issue":"6","issued":{"date-parts":[["2005","6"]]},"journalAbbreviation":"Br. J. Sports Med.","page":"324-329","suppress-author":false,"title":"Understanding injury mechanisms: a key component of preventing injuries in sport.","type":"article-journal","volume":"39"}]3,ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1016/j.jshs.2014.06.002","First":false,"Last":false,"abstract":"Anterior cruciate ligament (ACL) injuries are common in soccer. Understanding ACL loading mechanisms and risk factors for ACL injury is critical for designing effective prevention programs. The purpose of this review is to summarize the relevant literature on ACL loading mechanisms, ACL injury risk factors, and current ACL injury prevention programs for soccer players. Literature has shown that tibial anterior translation due to shear force at the proximal end of tibia is the primary ACL loading mechanism. No evidence has been found showing that knee valgus moment is the primary ACL loading mechanism. ACL loading mechanisms are largely ignored in previous studies on risk factors for ACL injury. Identified risk factors have little connections to ACL loading mechanisms. The results of studies on ACL injury prevention programs for soccer players are inconsistent. Current ACL injury prevention programs for soccer players are clinically ineffective due to low compliance. Future studies are urgently needed to identify risk factors for ACL injury in soccer that are connected to ACL loading mechanisms and have cause-and-effect relationships with injury rate, and to develop new prevention programs to improve compliance. Copyright 2014, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.","author":[{"family":"Dai","given":"Boyi"},{"family":"Mao","given":"Dewei"},{"family":"Garrett","given":"William E."},{"family":"Yu","given":"Bing"}],"citation-label":"1278040","container-title":"Journal of sport and health science","container-title-short":"J. Sport Health Sci.","id":"1278040","invisible":false,"issue":"4","issued":{"date-parts":[["2014","12"]]},"journalAbbreviation":"J. Sport Health Sci.","page":"299-306","suppress-author":false,"title":"Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and prevention programs","type":"article-journal","volume":"3"}]5a) Anatomy and Biomechanics: The ACL serves as the primary restraint of proximal tibia anterior translation on the femur. An anterior shear force applied to the proximal tibia loads the ACL. The magnitude of the force applied to the ACL with anterior shear is affected by the knee flexion angle and the ground reaction force.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1016/j.jshs.2014.06.002","First":false,"Last":false,"abstract":"Anterior cruciate ligament (ACL) injuries are common in soccer. Understanding ACL loading mechanisms and risk factors for ACL injury is critical for designing effective prevention programs. The purpose of this review is to summarize the relevant literature on ACL loading mechanisms, ACL injury risk factors, and current ACL injury prevention programs for soccer players. Literature has shown that tibial anterior translation due to shear force at the proximal end of tibia is the primary ACL loading mechanism. No evidence has been found showing that knee valgus moment is the primary ACL loading mechanism. ACL loading mechanisms are largely ignored in previous studies on risk factors for ACL injury. Identified risk factors have little connections to ACL loading mechanisms. The results of studies on ACL injury prevention programs for soccer players are inconsistent. Current ACL injury prevention programs for soccer players are clinically ineffective due to low compliance. Future studies are urgently needed to identify risk factors for ACL injury in soccer that are connected to ACL loading mechanisms and have cause-and-effect relationships with injury rate, and to develop new prevention programs to improve compliance. Copyright 2014, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.","author":[{"family":"Dai","given":"Boyi"},{"family":"Mao","given":"Dewei"},{"family":"Garrett","given":"William E."},{"family":"Yu","given":"Bing"}],"citation-label":"1278040","container-title":"Journal of sport and health science","container-title-short":"J. Sport Health Sci.","id":"1278040","invisible":false,"issue":"4","issued":{"date-parts":[["2014","12"]]},"journalAbbreviation":"J. Sport Health Sci.","page":"299-306","suppress-author":false,"title":"Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and prevention programs","type":"article-journal","volume":"3"}]5 A posterior ground reaction force causes a knee flexion moment. This knee flexion moment can be counteracted by the quadriceps producing a knee extension moment.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1016/j.jshs.2014.06.002","First":false,"Last":false,"abstract":"Anterior cruciate ligament (ACL) injuries are common in soccer. Understanding ACL loading mechanisms and risk factors for ACL injury is critical for designing effective prevention programs. The purpose of this review is to summarize the relevant literature on ACL loading mechanisms, ACL injury risk factors, and current ACL injury prevention programs for soccer players. Literature has shown that tibial anterior translation due to shear force at the proximal end of tibia is the primary ACL loading mechanism. No evidence has been found showing that knee valgus moment is the primary ACL loading mechanism. ACL loading mechanisms are largely ignored in previous studies on risk factors for ACL injury. Identified risk factors have little connections to ACL loading mechanisms. The results of studies on ACL injury prevention programs for soccer players are inconsistent. Current ACL injury prevention programs for soccer players are clinically ineffective due to low compliance. Future studies are urgently needed to identify risk factors for ACL injury in soccer that are connected to ACL loading mechanisms and have cause-and-effect relationships with injury rate, and to develop new prevention programs to improve compliance. Copyright 2014, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.","author":[{"family":"Dai","given":"Boyi"},{"family":"Mao","given":"Dewei"},{"family":"Garrett","given":"William E."},{"family":"Yu","given":"Bing"}],"citation-label":"1278040","container-title":"Journal of sport and health science","container-title-short":"J. Sport Health Sci.","id":"1278040","invisible":false,"issue":"4","issued":{"date-parts":[["2014","12"]]},"journalAbbreviation":"J. Sport Health Sci.","page":"299-306","suppress-author":false,"title":"Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and prevention programs","type":"article-journal","volume":"3"}]5 Along with the production of knee extension, the quadriceps also produce an anterior shearing force of the distal femur on the proximal tibia, loading the ACL. With increasing knee flexion, the anterior force generated by the quadriceps decreases secondary to the patella tendon-tibia shaft angle decreasing.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1016/j.jshs.2014.06.002","First":false,"Last":false,"abstract":"Anterior cruciate ligament (ACL) injuries are common in soccer. Understanding ACL loading mechanisms and risk factors for ACL injury is critical for designing effective prevention programs. The purpose of this review is to summarize the relevant literature on ACL loading mechanisms, ACL injury risk factors, and current ACL injury prevention programs for soccer players. Literature has shown that tibial anterior translation due to shear force at the proximal end of tibia is the primary ACL loading mechanism. No evidence has been found showing that knee valgus moment is the primary ACL loading mechanism. ACL loading mechanisms are largely ignored in previous studies on risk factors for ACL injury. Identified risk factors have little connections to ACL loading mechanisms. The results of studies on ACL injury prevention programs for soccer players are inconsistent. Current ACL injury prevention programs for soccer players are clinically ineffective due to low compliance. Future studies are urgently needed to identify risk factors for ACL injury in soccer that are connected to ACL loading mechanisms and have cause-and-effect relationships with injury rate, and to develop new prevention programs to improve compliance. Copyright 2014, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.","author":[{"family":"Dai","given":"Boyi"},{"family":"Mao","given":"Dewei"},{"family":"Garrett","given":"William E."},{"family":"Yu","given":"Bing"}],"citation-label":"1278040","container-title":"Journal of sport and health science","container-title-short":"J. Sport Health Sci.","id":"1278040","invisible":false,"issue":"4","issued":{"date-parts":[["2014","12"]]},"journalAbbreviation":"J. Sport Health Sci.","page":"299-306","suppress-author":false,"title":"Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and prevention programs","type":"article-journal","volume":"3"}]5 Appendix 2 provides a graphic representation of these concepts.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1016/j.jshs.2014.06.002","First":false,"Last":false,"abstract":"Anterior cruciate ligament (ACL) injuries are common in soccer. Understanding ACL loading mechanisms and risk factors for ACL injury is critical for designing effective prevention programs. The purpose of this review is to summarize the relevant literature on ACL loading mechanisms, ACL injury risk factors, and current ACL injury prevention programs for soccer players. Literature has shown that tibial anterior translation due to shear force at the proximal end of tibia is the primary ACL loading mechanism. No evidence has been found showing that knee valgus moment is the primary ACL loading mechanism. ACL loading mechanisms are largely ignored in previous studies on risk factors for ACL injury. Identified risk factors have little connections to ACL loading mechanisms. The results of studies on ACL injury prevention programs for soccer players are inconsistent. Current ACL injury prevention programs for soccer players are clinically ineffective due to low compliance. Future studies are urgently needed to identify risk factors for ACL injury in soccer that are connected to ACL loading mechanisms and have cause-and-effect relationships with injury rate, and to develop new prevention programs to improve compliance. Copyright 2014, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.","author":[{"family":"Dai","given":"Boyi"},{"family":"Mao","given":"Dewei"},{"family":"Garrett","given":"William E."},{"family":"Yu","given":"Bing"}],"citation-label":"1278040","container-title":"Journal of sport and health science","container-title-short":"J. Sport Health Sci.","id":"1278040","invisible":false,"issue":"4","issued":{"date-parts":[["2014","12"]]},"journalAbbreviation":"J. Sport Health Sci.","page":"299-306","suppress-author":false,"title":"Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and prevention programs","type":"article-journal","volume":"3"}]5 Patellar tendon tibia angle is greatest in low amounts of knee flexion (<30 degrees).ADDIN F1000_CSL_CITATION<~#@#~>[{"First":false,"Last":false,"PMID":"10875418","abstract":"This study examined the mechanisms of anterior cruciate ligament (ACL) injury. In the first part of the study, using a comprehensive, standardized questionnaire, 89 athletes (100 knees) were interviewed about the events surrounding their ACL injury. A noncontact mechanism was reported in 71 (72%) knees and a contact injury in 28 (28%) knees; one patient was unsure if there was any contact. Most of the injuries were sustained at footstrike with the knee close to full extension. Noncontact mechanisms were classified as sudden deceleration prior to a change of direction or landing motion, while contact injuries occurred as a result of valgus collapse of the knee. Hamstring flexibility parameters revealed a statistically higher level of laxity in the injured athletes compared with a matched group of 28 controls. In the second part of the study, videotapes of 27 separate ACL disruptions were reviewed and confirmed that most noncontact injuries occur with the knee close to extension during a sharp deceleration or landing maneuver. Because the knee is in a position to allow the extensor mechanism to strain the ACL and maximum, eccentric muscle force conditions usually apply, the quadriceps may play an important role in ACL disruption. Passive protection of the ACL by the hamstring muscles may be reduced in patients with above-average flexibility.","author":[{"family":"Boden","given":"B P"},{"family":"Dean","given":"G S"},{"family":"Feagin","given":"J A"},{"family":"Garrett","given":"W E"}],"citation-label":"3827539","container-title":"Orthopedics","container-title-short":"Orthopedics","id":"3827539","invisible":false,"issue":"6","issued":{"date-parts":[["2000","6"]]},"journalAbbreviation":"Orthopedics","page":"573-578","suppress-author":false,"title":"Mechanisms of anterior cruciate ligament injury.","type":"article-journal","volume":"23"}]7 Quadriceps contractions can be upwards of 2,000N in the average adult, and significantly higher in youth athletes, which can cause significant anterior shear force on the proximal tibia near full knee extension.ADDIN F1000_CSL_CITATION<~#@#~>[{"First":false,"Last":false,"PMID":"10875418","abstract":"This study examined the mechanisms of anterior cruciate ligament (ACL) injury. In the first part of the study, using a comprehensive, standardized questionnaire, 89 athletes (100 knees) were interviewed about the events surrounding their ACL injury. A noncontact mechanism was reported in 71 (72%) knees and a contact injury in 28 (28%) knees; one patient was unsure if there was any contact. Most of the injuries were sustained at footstrike with the knee close to full extension. Noncontact mechanisms were classified as sudden deceleration prior to a change of direction or landing motion, while contact injuries occurred as a result of valgus collapse of the knee. Hamstring flexibility parameters revealed a statistically higher level of laxity in the injured athletes compared with a matched group of 28 controls. In the second part of the study, videotapes of 27 separate ACL disruptions were reviewed and confirmed that most noncontact injuries occur with the knee close to extension during a sharp deceleration or landing maneuver. Because the knee is in a position to allow the extensor mechanism to strain the ACL and maximum, eccentric muscle force conditions usually apply, the quadriceps may play an important role in ACL disruption. Passive protection of the ACL by the hamstring muscles may be reduced in patients with above-average flexibility.","author":[{"family":"Boden","given":"B P"},{"family":"Dean","given":"G S"},{"family":"Feagin","given":"J A"},{"family":"Garrett","given":"W E"}],"citation-label":"3827539","container-title":"Orthopedics","container-title-short":"Orthopedics","id":"3827539","invisible":false,"issue":"6","issued":{"date-parts":[["2000","6"]]},"journalAbbreviation":"Orthopedics","page":"573-578","suppress-author":false,"title":"Mechanisms of anterior cruciate ligament injury.","type":"article-journal","volume":"23"}]7 The hamstrings can work to reduce the stress placed on the ACL through co-contraction. The hamstrings produce a posterior shear force of the distal femur on the proximal tibia, thus decreasing the magnitude of the anterior shear force generated from quadriceps contraction.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1016/j.jshs.2014.06.002","First":false,"Last":false,"abstract":"Anterior cruciate ligament (ACL) injuries are common in soccer. Understanding ACL loading mechanisms and risk factors for ACL injury is critical for designing effective prevention programs. The purpose of this review is to summarize the relevant literature on ACL loading mechanisms, ACL injury risk factors, and current ACL injury prevention programs for soccer players. Literature has shown that tibial anterior translation due to shear force at the proximal end of tibia is the primary ACL loading mechanism. No evidence has been found showing that knee valgus moment is the primary ACL loading mechanism. ACL loading mechanisms are largely ignored in previous studies on risk factors for ACL injury. Identified risk factors have little connections to ACL loading mechanisms. The results of studies on ACL injury prevention programs for soccer players are inconsistent. Current ACL injury prevention programs for soccer players are clinically ineffective due to low compliance. Future studies are urgently needed to identify risk factors for ACL injury in soccer that are connected to ACL loading mechanisms and have cause-and-effect relationships with injury rate, and to develop new prevention programs to improve compliance. Copyright 2014, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.","author":[{"family":"Dai","given":"Boyi"},{"family":"Mao","given":"Dewei"},{"family":"Garrett","given":"William E."},{"family":"Yu","given":"Bing"}],"citation-label":"1278040","container-title":"Journal of sport and health science","container-title-short":"J. Sport Health Sci.","id":"1278040","invisible":false,"issue":"4","issued":{"date-parts":[["2014","12"]]},"journalAbbreviation":"J. Sport Health Sci.","page":"299-306","suppress-author":false,"title":"Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and prevention programs","type":"article-journal","volume":"3"}]5 The pull of the hamstrings produces greater posterior forces with increased knee flexion angle versus in full extension (see appendix 2).ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1016/j.jshs.2014.06.002","First":false,"Last":false,"abstract":"Anterior cruciate ligament (ACL) injuries are common in soccer. Understanding ACL loading mechanisms and risk factors for ACL injury is critical for designing effective prevention programs. The purpose of this review is to summarize the relevant literature on ACL loading mechanisms, ACL injury risk factors, and current ACL injury prevention programs for soccer players. Literature has shown that tibial anterior translation due to shear force at the proximal end of tibia is the primary ACL loading mechanism. No evidence has been found showing that knee valgus moment is the primary ACL loading mechanism. ACL loading mechanisms are largely ignored in previous studies on risk factors for ACL injury. Identified risk factors have little connections to ACL loading mechanisms. The results of studies on ACL injury prevention programs for soccer players are inconsistent. Current ACL injury prevention programs for soccer players are clinically ineffective due to low compliance. Future studies are urgently needed to identify risk factors for ACL injury in soccer that are connected to ACL loading mechanisms and have cause-and-effect relationships with injury rate, and to develop new prevention programs to improve compliance. Copyright 2014, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.","author":[{"family":"Dai","given":"Boyi"},{"family":"Mao","given":"Dewei"},{"family":"Garrett","given":"William E."},{"family":"Yu","given":"Bing"}],"citation-label":"1278040","container-title":"Journal of sport and health science","container-title-short":"J. Sport Health Sci.","id":"1278040","invisible":false,"issue":"4","issued":{"date-parts":[["2014","12"]]},"journalAbbreviation":"J. Sport Health Sci.","page":"299-306","suppress-author":false,"title":"Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and prevention programs","type":"article-journal","volume":"3"}]5 Peak ACL loading, length, and stress thus happens in positions of limited knee flexion.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1016/j.jshs.2014.06.002","First":false,"Last":false,"abstract":"Anterior cruciate ligament (ACL) injuries are common in soccer. Understanding ACL loading mechanisms and risk factors for ACL injury is critical for designing effective prevention programs. The purpose of this review is to summarize the relevant literature on ACL loading mechanisms, ACL injury risk factors, and current ACL injury prevention programs for soccer players. Literature has shown that tibial anterior translation due to shear force at the proximal end of tibia is the primary ACL loading mechanism. No evidence has been found showing that knee valgus moment is the primary ACL loading mechanism. ACL loading mechanisms are largely ignored in previous studies on risk factors for ACL injury. Identified risk factors have little connections to ACL loading mechanisms. The results of studies on ACL injury prevention programs for soccer players are inconsistent. Current ACL injury prevention programs for soccer players are clinically ineffective due to low compliance. Future studies are urgently needed to identify risk factors for ACL injury in soccer that are connected to ACL loading mechanisms and have cause-and-effect relationships with injury rate, and to develop new prevention programs to improve compliance. Copyright 2014, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.","author":[{"family":"Dai","given":"Boyi"},{"family":"Mao","given":"Dewei"},{"family":"Garrett","given":"William E."},{"family":"Yu","given":"Bing"}],"citation-label":"1278040","container-title":"Journal of sport and health science","container-title-short":"J. Sport Health Sci.","id":"1278040","invisible":false,"issue":"4","issued":{"date-parts":[["2014","12"]]},"journalAbbreviation":"J. Sport Health Sci.","page":"299-306","suppress-author":false,"title":"Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and prevention programs","type":"article-journal","volume":"3"}]5 Loading decreases with increased knee flexion.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1016/j.jshs.2014.06.002","First":false,"Last":false,"abstract":"Anterior cruciate ligament (ACL) injuries are common in soccer. Understanding ACL loading mechanisms and risk factors for ACL injury is critical for designing effective prevention programs. The purpose of this review is to summarize the relevant literature on ACL loading mechanisms, ACL injury risk factors, and current ACL injury prevention programs for soccer players. Literature has shown that tibial anterior translation due to shear force at the proximal end of tibia is the primary ACL loading mechanism. No evidence has been found showing that knee valgus moment is the primary ACL loading mechanism. ACL loading mechanisms are largely ignored in previous studies on risk factors for ACL injury. Identified risk factors have little connections to ACL loading mechanisms. The results of studies on ACL injury prevention programs for soccer players are inconsistent. Current ACL injury prevention programs for soccer players are clinically ineffective due to low compliance. Future studies are urgently needed to identify risk factors for ACL injury in soccer that are connected to ACL loading mechanisms and have cause-and-effect relationships with injury rate, and to develop new prevention programs to improve compliance. Copyright 2014, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.","author":[{"family":"Dai","given":"Boyi"},{"family":"Mao","given":"Dewei"},{"family":"Garrett","given":"William E."},{"family":"Yu","given":"Bing"}],"citation-label":"1278040","container-title":"Journal of sport and health science","container-title-short":"J. Sport Health Sci.","id":"1278040","invisible":false,"issue":"4","issued":{"date-parts":[["2014","12"]]},"journalAbbreviation":"J. Sport Health Sci.","page":"299-306","suppress-author":false,"title":"Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and prevention programs","type":"article-journal","volume":"3"}]5 Small amounts of knee flexion (10-30*) are associated with increased anterior shear force and increased anterior translation of the tibia on the femur (see appendix 3).ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1016/j.jshs.2014.06.002","First":false,"Last":false,"abstract":"Anterior cruciate ligament (ACL) injuries are common in soccer. Understanding ACL loading mechanisms and risk factors for ACL injury is critical for designing effective prevention programs. The purpose of this review is to summarize the relevant literature on ACL loading mechanisms, ACL injury risk factors, and current ACL injury prevention programs for soccer players. Literature has shown that tibial anterior translation due to shear force at the proximal end of tibia is the primary ACL loading mechanism. No evidence has been found showing that knee valgus moment is the primary ACL loading mechanism. ACL loading mechanisms are largely ignored in previous studies on risk factors for ACL injury. Identified risk factors have little connections to ACL loading mechanisms. The results of studies on ACL injury prevention programs for soccer players are inconsistent. Current ACL injury prevention programs for soccer players are clinically ineffective due to low compliance. Future studies are urgently needed to identify risk factors for ACL injury in soccer that are connected to ACL loading mechanisms and have cause-and-effect relationships with injury rate, and to develop new prevention programs to improve compliance. Copyright 2014, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.","author":[{"family":"Dai","given":"Boyi"},{"family":"Mao","given":"Dewei"},{"family":"Garrett","given":"William E."},{"family":"Yu","given":"Bing"}],"citation-label":"1278040","container-title":"Journal of sport and health science","container-title-short":"J. Sport Health Sci.","id":"1278040","invisible":false,"issue":"4","issued":{"date-parts":[["2014","12"]]},"journalAbbreviation":"J. Sport Health Sci.","page":"299-306","suppress-author":false,"title":"Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and prevention programs","type":"article-journal","volume":"3"}]5,ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/03635465990270062501","First":false,"Last":false,"PMID":"10569374","abstract":"With today's increasing emphasis on sporting activities, the incidence of anterior cruciate ligament injuries has also increased. Epidemiologic studies estimate that the prevalence of anterior cruciate ligament injuries is about 1 per 3000 Americans. Management of these injuries has evolved from nonoperative treatment to extracapsular augmentation and primary ligament repair to anterior cruciate ligament reconstruction. Treatment of these injuries has significantly improved over the last few decades with the application of knowledge gained from both basic science and clinical research. This article is composed of two parts. The first part reviews the biology and biomechanics of the injured anterior cruciate ligament and the basic science of reconstruction. In the second part, to be published later, current operative concepts of reconstruction, as well as clinical correlations, are reviewed. Summarizing the latest information on basic scientific as well as clinical studies regarding the anterior cruciate ligament, this article intends to demonstrate the correlation between the application of basic science knowledge and improvement of clinical outcomes.","author":[{"family":"Fu","given":"F H"},{"family":"Bennett","given":"C H"},{"family":"Lattermann","given":"C"},{"family":"Ma","given":"C B"}],"citation-label":"6055142","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"6055142","invisible":false,"issue":"6","issued":{"date-parts":[["1999","12"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"821-830","suppress-author":false,"title":"Current trends in anterior cruciate ligament reconstruction. Part 1: Biology and biomechanics of reconstruction.","type":"article-journal","volume":"27"}]8 Based on these many factors, the ACL is at a higher risk of injury performing a soccer movement in positions of minimal knee flexion (10-30*) versus with significant knee flexion (>45 degrees).ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1016/j.jshs.2014.06.002","First":false,"Last":false,"abstract":"Anterior cruciate ligament (ACL) injuries are common in soccer. Understanding ACL loading mechanisms and risk factors for ACL injury is critical for designing effective prevention programs. The purpose of this review is to summarize the relevant literature on ACL loading mechanisms, ACL injury risk factors, and current ACL injury prevention programs for soccer players. Literature has shown that tibial anterior translation due to shear force at the proximal end of tibia is the primary ACL loading mechanism. No evidence has been found showing that knee valgus moment is the primary ACL loading mechanism. ACL loading mechanisms are largely ignored in previous studies on risk factors for ACL injury. Identified risk factors have little connections to ACL loading mechanisms. The results of studies on ACL injury prevention programs for soccer players are inconsistent. Current ACL injury prevention programs for soccer players are clinically ineffective due to low compliance. Future studies are urgently needed to identify risk factors for ACL injury in soccer that are connected to ACL loading mechanisms and have cause-and-effect relationships with injury rate, and to develop new prevention programs to improve compliance. Copyright 2014, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.","author":[{"family":"Dai","given":"Boyi"},{"family":"Mao","given":"Dewei"},{"family":"Garrett","given":"William E."},{"family":"Yu","given":"Bing"}],"citation-label":"1278040","container-title":"Journal of sport and health science","container-title-short":"J. Sport Health Sci.","id":"1278040","invisible":false,"issue":"4","issued":{"date-parts":[["2014","12"]]},"journalAbbreviation":"J. Sport Health Sci.","page":"299-306","suppress-author":false,"title":"Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and prevention programs","type":"article-journal","volume":"3"}]5 The ACL is also stressed with knee valgus, varus, and internal rotation loads.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1016/j.jshs.2014.06.002","First":false,"Last":false,"abstract":"Anterior cruciate ligament (ACL) injuries are common in soccer. Understanding ACL loading mechanisms and risk factors for ACL injury is critical for designing effective prevention programs. The purpose of this review is to summarize the relevant literature on ACL loading mechanisms, ACL injury risk factors, and current ACL injury prevention programs for soccer players. Literature has shown that tibial anterior translation due to shear force at the proximal end of tibia is the primary ACL loading mechanism. No evidence has been found showing that knee valgus moment is the primary ACL loading mechanism. ACL loading mechanisms are largely ignored in previous studies on risk factors for ACL injury. Identified risk factors have little connections to ACL loading mechanisms. The results of studies on ACL injury prevention programs for soccer players are inconsistent. Current ACL injury prevention programs for soccer players are clinically ineffective due to low compliance. Future studies are urgently needed to identify risk factors for ACL injury in soccer that are connected to ACL loading mechanisms and have cause-and-effect relationships with injury rate, and to develop new prevention programs to improve compliance. Copyright 2014, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.","author":[{"family":"Dai","given":"Boyi"},{"family":"Mao","given":"Dewei"},{"family":"Garrett","given":"William E."},{"family":"Yu","given":"Bing"}],"citation-label":"1278040","container-title":"Journal of sport and health science","container-title-short":"J. Sport Health Sci.","id":"1278040","invisible":false,"issue":"4","issued":{"date-parts":[["2014","12"]]},"journalAbbreviation":"J. Sport Health Sci.","page":"299-306","suppress-author":false,"title":"Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and prevention programs","type":"article-journal","volume":"3"}]5 These effects are most pronounced when combined with an anterior shear force.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1016/j.jshs.2014.06.002","First":false,"Last":false,"abstract":"Anterior cruciate ligament (ACL) injuries are common in soccer. Understanding ACL loading mechanisms and risk factors for ACL injury is critical for designing effective prevention programs. The purpose of this review is to summarize the relevant literature on ACL loading mechanisms, ACL injury risk factors, and current ACL injury prevention programs for soccer players. Literature has shown that tibial anterior translation due to shear force at the proximal end of tibia is the primary ACL loading mechanism. No evidence has been found showing that knee valgus moment is the primary ACL loading mechanism. ACL loading mechanisms are largely ignored in previous studies on risk factors for ACL injury. Identified risk factors have little connections to ACL loading mechanisms. The results of studies on ACL injury prevention programs for soccer players are inconsistent. Current ACL injury prevention programs for soccer players are clinically ineffective due to low compliance. Future studies are urgently needed to identify risk factors for ACL injury in soccer that are connected to ACL loading mechanisms and have cause-and-effect relationships with injury rate, and to develop new prevention programs to improve compliance. Copyright 2014, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.","author":[{"family":"Dai","given":"Boyi"},{"family":"Mao","given":"Dewei"},{"family":"Garrett","given":"William E."},{"family":"Yu","given":"Bing"}],"citation-label":"1278040","container-title":"Journal of sport and health science","container-title-short":"J. Sport Health Sci.","id":"1278040","invisible":false,"issue":"4","issued":{"date-parts":[["2014","12"]]},"journalAbbreviation":"J. Sport Health Sci.","page":"299-306","suppress-author":false,"title":"Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and prevention programs","type":"article-journal","volume":"3"}]5 In vivo research has shown that the knee valgus stress only produced increased ACL length when the knee was near full extension, and valgus loading had no impact on ACL length with the knee in flexion.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1016/j.jshs.2014.06.002","First":false,"Last":false,"abstract":"Anterior cruciate ligament (ACL) injuries are common in soccer. Understanding ACL loading mechanisms and risk factors for ACL injury is critical for designing effective prevention programs. The purpose of this review is to summarize the relevant literature on ACL loading mechanisms, ACL injury risk factors, and current ACL injury prevention programs for soccer players. Literature has shown that tibial anterior translation due to shear force at the proximal end of tibia is the primary ACL loading mechanism. No evidence has been found showing that knee valgus moment is the primary ACL loading mechanism. ACL loading mechanisms are largely ignored in previous studies on risk factors for ACL injury. Identified risk factors have little connections to ACL loading mechanisms. The results of studies on ACL injury prevention programs for soccer players are inconsistent. Current ACL injury prevention programs for soccer players are clinically ineffective due to low compliance. Future studies are urgently needed to identify risk factors for ACL injury in soccer that are connected to ACL loading mechanisms and have cause-and-effect relationships with injury rate, and to develop new prevention programs to improve compliance. Copyright 2014, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.","author":[{"family":"Dai","given":"Boyi"},{"family":"Mao","given":"Dewei"},{"family":"Garrett","given":"William E."},{"family":"Yu","given":"Bing"}],"citation-label":"1278040","container-title":"Journal of sport and health science","container-title-short":"J. Sport Health Sci.","id":"1278040","invisible":false,"issue":"4","issued":{"date-parts":[["2014","12"]]},"journalAbbreviation":"J. Sport Health Sci.","page":"299-306","suppress-author":false,"title":"Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and prevention programs","type":"article-journal","volume":"3"}]5 Isolated internal rotation, valgus or varus produce little strain on the ACL.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1007/s00167-009-0813-1","First":false,"Last":false,"PMID":"19452139","author":[{"family":"Alentorn-Geli","given":"Eduard"},{"family":"Myer","given":"Gregory D"},{"family":"Silvers","given":"Holly J"},{"family":"Samitier","given":"Gonzalo"},{"family":"Romero","given":"Daniel"},{"family":"Lázaro-Haro","given":"Cristina"},{"family":"Cugat","given":"Ramón"}],"citation-label":"2595869","container-title":"Knee Surgery, Sports Traumatology, Arthroscopy","container-title-short":"Knee Surg. Sports Traumatol. Arthrosc.","id":"2595869","invisible":false,"issue":"7","issued":{"date-parts":[["2009","7"]]},"journalAbbreviation":"Knee Surg. Sports Traumatol. Arthrosc.","page":"705-729","suppress-author":false,"title":"Prevention of non-contact anterior cruciate ligament injuries in soccer players. Part 1: Mechanisms of injury and underlying risk factors.","type":"article-journal","volume":"17"}]1 Markolf et al. found that the in vitro ACL undergoes the highest amount of loading when an anterior shear force and valgus or varus moments are combined with internal tibial torque.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1002/jor.1100130618","First":false,"Last":false,"PMID":"8544031","abstract":"Injuries to the anterior cruciate ligament frequently occur under combined mechanisms of knee loading. This in vitro study was designed to measure levels of ligament force under dual combinations of individual loading states and to determine which combinations generated high force. Resultant force was recorded as the knee was extended passively from 90 degrees of flexion to 5 degrees of hyperextension under constant tibial loadings. The individual loading states were 100 N of anterior tibial force, 10 Nm of varus and valgus moment, and 10 Nm of internal and external tibial torque. Straight anterior tibial force was the most direct loading mechanisms; the mean ligament force was approximately equal to applied anterior tibial force near 30 degrees of flexion and to 150% of applied tibial force at full extension. The addition of internal tibial torque to a knee loaded by anterior tibial force produced dramatic increases of force at full extension and hyperextension. This loading combination produced the highest ligament forces recorded in the study and is the most dangerous in terms of potential injury to the ligament. In direct contrast, the addition of external tibial torque to a knee loaded by anterior tibial force decreased the force dramatically for flexed positions of the knee; at close to 90 degrees of flexion, the anterior cruciate ligament became completely unloaded. The addition of varus moment to a knee loaded by anterior tibial force increased the force in extension and hyperextension, whereas the addition of valgus moment increased the force at flexed positions. These states of combined loading also could present an increased risk for injury. Internal tibial torque is an important loading mechanism of the anterior cruciate ligament for an extended knee. The overall risk of injury to the ligament from varus or valgus moment applied in combination with internal tibial torque is similar to the risk from internal tibial torque alone. External tibial torque was a relatively unimportant mechanism for generating anterior cruciate ligament force.","author":[{"family":"Markolf","given":"K L"},{"family":"Burchfield","given":"D M"},{"family":"Shapiro","given":"M M"},{"family":"Shepard","given":"M F"},{"family":"Finerman","given":"G A"},{"family":"Slauterbeck","given":"J L"}],"citation-label":"4935762","container-title":"Journal of Orthopaedic Research","container-title-short":"J. Orthop. Res.","id":"4935762","invisible":false,"issue":"6","issued":{"date-parts":[["1995","11"]]},"journalAbbreviation":"J. Orthop. Res.","page":"930-935","suppress-author":false,"title":"Combined knee loading states that generate high anterior cruciate ligament forces.","type":"article-journal","volume":"13"}]9 External tibial torque had little influence on ACL stress, and may serve to unload the ACL.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1002/jor.1100130618","First":false,"Last":false,"PMID":"8544031","abstract":"Injuries to the anterior cruciate ligament frequently occur under combined mechanisms of knee loading. This in vitro study was designed to measure levels of ligament force under dual combinations of individual loading states and to determine which combinations generated high force. Resultant force was recorded as the knee was extended passively from 90 degrees of flexion to 5 degrees of hyperextension under constant tibial loadings. The individual loading states were 100 N of anterior tibial force, 10 Nm of varus and valgus moment, and 10 Nm of internal and external tibial torque. Straight anterior tibial force was the most direct loading mechanisms; the mean ligament force was approximately equal to applied anterior tibial force near 30 degrees of flexion and to 150% of applied tibial force at full extension. The addition of internal tibial torque to a knee loaded by anterior tibial force produced dramatic increases of force at full extension and hyperextension. This loading combination produced the highest ligament forces recorded in the study and is the most dangerous in terms of potential injury to the ligament. In direct contrast, the addition of external tibial torque to a knee loaded by anterior tibial force decreased the force dramatically for flexed positions of the knee; at close to 90 degrees of flexion, the anterior cruciate ligament became completely unloaded. The addition of varus moment to a knee loaded by anterior tibial force increased the force in extension and hyperextension, whereas the addition of valgus moment increased the force at flexed positions. These states of combined loading also could present an increased risk for injury. Internal tibial torque is an important loading mechanism of the anterior cruciate ligament for an extended knee. The overall risk of injury to the ligament from varus or valgus moment applied in combination with internal tibial torque is similar to the risk from internal tibial torque alone. External tibial torque was a relatively unimportant mechanism for generating anterior cruciate ligament force.","author":[{"family":"Markolf","given":"K L"},{"family":"Burchfield","given":"D M"},{"family":"Shapiro","given":"M M"},{"family":"Shepard","given":"M F"},{"family":"Finerman","given":"G A"},{"family":"Slauterbeck","given":"J L"}],"citation-label":"4935762","container-title":"Journal of Orthopaedic Research","container-title-short":"J. Orthop. Res.","id":"4935762","invisible":false,"issue":"6","issued":{"date-parts":[["1995","11"]]},"journalAbbreviation":"J. Orthop. Res.","page":"930-935","suppress-author":false,"title":"Combined knee loading states that generate high anterior cruciate ligament forces.","type":"article-journal","volume":"13"}]9 Levine et al. evaluated physiological loading of cadaveric ACLs.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/0363546512465167","First":false,"Last":false,"PMCID":"PMC3935824","PMID":"23144366","author":[{"family":"Levine","given":"Jason W"},{"family":"Kiapour","given":"Ata M"},{"family":"Quatman","given":"Carmen E"},{"family":"Wordeman","given":"Samuel C"},{"family":"Goel","given":"Vijay K"},{"family":"Hewett","given":"Timothy E"},{"family":"Demetropoulos","given":"Constantine K"}],"citation-label":"612468","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"612468","invisible":false,"issue":"2","issued":{"date-parts":[["2013","2"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"385-395","suppress-author":false,"title":"Clinically relevant injury patterns after an anterior cruciate ligament injury provide insight into injury mechanisms.","type":"article-journal","volume":"41"}]10 They found that a position of anterior tibial shear, knee abduction and tibial internal rotation led to the greatest risk of an ACL injury.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/0363546512465167","First":false,"Last":false,"PMCID":"PMC3935824","PMID":"23144366","author":[{"family":"Levine","given":"Jason W"},{"family":"Kiapour","given":"Ata M"},{"family":"Quatman","given":"Carmen E"},{"family":"Wordeman","given":"Samuel C"},{"family":"Goel","given":"Vijay K"},{"family":"Hewett","given":"Timothy E"},{"family":"Demetropoulos","given":"Constantine K"}],"citation-label":"612468","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"612468","invisible":false,"issue":"2","issued":{"date-parts":[["2013","2"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"385-395","suppress-author":false,"title":"Clinically relevant injury patterns after an anterior cruciate ligament injury provide insight into injury mechanisms.","type":"article-journal","volume":"41"}]10 Knee abduction was also associated with depression of the subchondral bone and tibial internal rotation was associated with damage to articular cartilage along the posterior lateral aspect of the tibial plateau.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/0363546512465167","First":false,"Last":false,"PMCID":"PMC3935824","PMID":"23144366","author":[{"family":"Levine","given":"Jason W"},{"family":"Kiapour","given":"Ata M"},{"family":"Quatman","given":"Carmen E"},{"family":"Wordeman","given":"Samuel C"},{"family":"Goel","given":"Vijay K"},{"family":"Hewett","given":"Timothy E"},{"family":"Demetropoulos","given":"Constantine K"}],"citation-label":"612468","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"612468","invisible":false,"issue":"2","issued":{"date-parts":[["2013","2"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"385-395","suppress-author":false,"title":"Clinically relevant injury patterns after an anterior cruciate ligament injury provide insight into injury mechanisms.","type":"article-journal","volume":"41"}]10 Soccer is a sport involving jumping, cutting, acceleration and deceleration thus the ACL is continually loaded in uniplanar and multi-planer dimensions. ACL loading can also occur from a compressive force along the longitudinal axis of the tibia. This relates the slope angle of the posterior tibial plateau.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1016/j.jshs.2014.06.002","First":false,"Last":false,"abstract":"Anterior cruciate ligament (ACL) injuries are common in soccer. Understanding ACL loading mechanisms and risk factors for ACL injury is critical for designing effective prevention programs. The purpose of this review is to summarize the relevant literature on ACL loading mechanisms, ACL injury risk factors, and current ACL injury prevention programs for soccer players. Literature has shown that tibial anterior translation due to shear force at the proximal end of tibia is the primary ACL loading mechanism. No evidence has been found showing that knee valgus moment is the primary ACL loading mechanism. ACL loading mechanisms are largely ignored in previous studies on risk factors for ACL injury. Identified risk factors have little connections to ACL loading mechanisms. The results of studies on ACL injury prevention programs for soccer players are inconsistent. Current ACL injury prevention programs for soccer players are clinically ineffective due to low compliance. Future studies are urgently needed to identify risk factors for ACL injury in soccer that are connected to ACL loading mechanisms and have cause-and-effect relationships with injury rate, and to develop new prevention programs to improve compliance. Copyright 2014, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.","author":[{"family":"Dai","given":"Boyi"},{"family":"Mao","given":"Dewei"},{"family":"Garrett","given":"William E."},{"family":"Yu","given":"Bing"}],"citation-label":"1278040","container-title":"Journal of sport and health science","container-title-short":"J. Sport Health Sci.","id":"1278040","invisible":false,"issue":"4","issued":{"date-parts":[["2014","12"]]},"journalAbbreviation":"J. Sport Health Sci.","page":"299-306","suppress-author":false,"title":"Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and prevention programs","type":"article-journal","volume":"3"}]5 A greater angle causes greater anterior shear force generation and increased load on the ACL.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1016/j.jshs.2014.06.002","First":false,"Last":false,"abstract":"Anterior cruciate ligament (ACL) injuries are common in soccer. Understanding ACL loading mechanisms and risk factors for ACL injury is critical for designing effective prevention programs. The purpose of this review is to summarize the relevant literature on ACL loading mechanisms, ACL injury risk factors, and current ACL injury prevention programs for soccer players. Literature has shown that tibial anterior translation due to shear force at the proximal end of tibia is the primary ACL loading mechanism. No evidence has been found showing that knee valgus moment is the primary ACL loading mechanism. ACL loading mechanisms are largely ignored in previous studies on risk factors for ACL injury. Identified risk factors have little connections to ACL loading mechanisms. The results of studies on ACL injury prevention programs for soccer players are inconsistent. Current ACL injury prevention programs for soccer players are clinically ineffective due to low compliance. Future studies are urgently needed to identify risk factors for ACL injury in soccer that are connected to ACL loading mechanisms and have cause-and-effect relationships with injury rate, and to develop new prevention programs to improve compliance. Copyright 2014, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.","author":[{"family":"Dai","given":"Boyi"},{"family":"Mao","given":"Dewei"},{"family":"Garrett","given":"William E."},{"family":"Yu","given":"Bing"}],"citation-label":"1278040","container-title":"Journal of sport and health science","container-title-short":"J. Sport Health Sci.","id":"1278040","invisible":false,"issue":"4","issued":{"date-parts":[["2014","12"]]},"journalAbbreviation":"J. Sport Health Sci.","page":"299-306","suppress-author":false,"title":"Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and prevention programs","type":"article-journal","volume":"3"}]5 This posterior slope angle may predispose an athlete to an ACL injury.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1016/j.jshs.2014.06.002","First":false,"Last":false,"abstract":"Anterior cruciate ligament (ACL) injuries are common in soccer. Understanding ACL loading mechanisms and risk factors for ACL injury is critical for designing effective prevention programs. The purpose of this review is to summarize the relevant literature on ACL loading mechanisms, ACL injury risk factors, and current ACL injury prevention programs for soccer players. Literature has shown that tibial anterior translation due to shear force at the proximal end of tibia is the primary ACL loading mechanism. No evidence has been found showing that knee valgus moment is the primary ACL loading mechanism. ACL loading mechanisms are largely ignored in previous studies on risk factors for ACL injury. Identified risk factors have little connections to ACL loading mechanisms. The results of studies on ACL injury prevention programs for soccer players are inconsistent. Current ACL injury prevention programs for soccer players are clinically ineffective due to low compliance. Future studies are urgently needed to identify risk factors for ACL injury in soccer that are connected to ACL loading mechanisms and have cause-and-effect relationships with injury rate, and to develop new prevention programs to improve compliance. Copyright 2014, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.","author":[{"family":"Dai","given":"Boyi"},{"family":"Mao","given":"Dewei"},{"family":"Garrett","given":"William E."},{"family":"Yu","given":"Bing"}],"citation-label":"1278040","container-title":"Journal of sport and health science","container-title-short":"J. Sport Health Sci.","id":"1278040","invisible":false,"issue":"4","issued":{"date-parts":[["2014","12"]]},"journalAbbreviation":"J. Sport Health Sci.","page":"299-306","suppress-author":false,"title":"Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and prevention programs","type":"article-journal","volume":"3"}]5 People who have sustained ACL injuries have greater tibial plateau slopes than an uninjured comparison.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1016/j.jshs.2014.06.002","First":false,"Last":false,"abstract":"Anterior cruciate ligament (ACL) injuries are common in soccer. Understanding ACL loading mechanisms and risk factors for ACL injury is critical for designing effective prevention programs. The purpose of this review is to summarize the relevant literature on ACL loading mechanisms, ACL injury risk factors, and current ACL injury prevention programs for soccer players. Literature has shown that tibial anterior translation due to shear force at the proximal end of tibia is the primary ACL loading mechanism. No evidence has been found showing that knee valgus moment is the primary ACL loading mechanism. ACL loading mechanisms are largely ignored in previous studies on risk factors for ACL injury. Identified risk factors have little connections to ACL loading mechanisms. The results of studies on ACL injury prevention programs for soccer players are inconsistent. Current ACL injury prevention programs for soccer players are clinically ineffective due to low compliance. Future studies are urgently needed to identify risk factors for ACL injury in soccer that are connected to ACL loading mechanisms and have cause-and-effect relationships with injury rate, and to develop new prevention programs to improve compliance. Copyright 2014, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.","author":[{"family":"Dai","given":"Boyi"},{"family":"Mao","given":"Dewei"},{"family":"Garrett","given":"William E."},{"family":"Yu","given":"Bing"}],"citation-label":"1278040","container-title":"Journal of sport and health science","container-title-short":"J. Sport Health Sci.","id":"1278040","invisible":false,"issue":"4","issued":{"date-parts":[["2014","12"]]},"journalAbbreviation":"J. Sport Health Sci.","page":"299-306","suppress-author":false,"title":"Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and prevention programs","type":"article-journal","volume":"3"}]5,ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/2325967116634074","First":false,"Last":false,"PMCID":"PMC4794976","PMID":"27047983","abstract":"BACKGROUND: There has been a substantial increase in the amount of systematic reviews and meta-analyses published on the anterior cruciate ligament (ACL). PURPOSE: To quantify the number of systematic reviews and meta-analyses published on the ACL in the past decade and to provide an overall summary of this literature. STUDY DESIGN: Systematic review; Level of evidence, 4. METHODS: A systematic review of all ACL-related systematic reviews and meta-analyses published between January 2004 and September 2014 was performed using PubMed, MEDLINE, and the Cochrane Database. Narrative reviews and non-English articles were excluded. RESULTS: A total of 1031 articles were found, of which 240 met the inclusion criteria. Included articles were summarized and divided into 17 topics: anatomy, epidemiology, prevention, associated injuries, diagnosis, operative versus nonoperative management, graft choice, surgical technique, fixation methods, computer-assisted surgery, platelet-rich plasma, rehabilitation, return to play, outcomes assessment, arthritis, complications, and miscellaneous. CONCLUSION: A summary of systematic reviews on the ACL can supply the surgeon with a single source for the most up-to-date synthesis of the literature.","author":[{"family":"Anderson","given":"Michael J"},{"family":"Browning","given":"William M"},{"family":"Urband","given":"Christopher E"},{"family":"Kluczynski","given":"Melissa A"},{"family":"Bisson","given":"Leslie J"}],"citation-label":"2062386","container-title":"Orthopaedic journal of sports medicine","container-title-short":"Orthop. J. Sports Med.","id":"2062386","invisible":false,"issue":"3","issued":{"date-parts":[["2016","3","15"]]},"journalAbbreviation":"Orthop. J. Sports Med.","page":"2325967116634074","suppress-author":false,"title":"A systematic summary of systematic reviews on the topic of the anterior cruciate ligament.","type":"article-journal","volume":"4"}]14Understanding the purpose of the ACL and factors that include ACL stress help with the understanding of common mechanisms of ACL injury. Very broadly, ACL injuries in soccer players can either be contact or non-contact injuries.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1007/s00167-009-0813-1","First":false,"Last":false,"PMID":"19452139","author":[{"family":"Alentorn-Geli","given":"Eduard"},{"family":"Myer","given":"Gregory D"},{"family":"Silvers","given":"Holly J"},{"family":"Samitier","given":"Gonzalo"},{"family":"Romero","given":"Daniel"},{"family":"Lázaro-Haro","given":"Cristina"},{"family":"Cugat","given":"Ramón"}],"citation-label":"2595869","container-title":"Knee Surgery, Sports Traumatology, Arthroscopy","container-title-short":"Knee Surg. Sports Traumatol. Arthrosc.","id":"2595869","invisible":false,"issue":"7","issued":{"date-parts":[["2009","7"]]},"journalAbbreviation":"Knee Surg. Sports Traumatol. Arthrosc.","page":"705-729","suppress-author":false,"title":"Prevention of non-contact anterior cruciate ligament injuries in soccer players. Part 1: Mechanisms of injury and underlying risk factors.","type":"article-journal","volume":"17"}]1 Most ACL tears occur without body-to-body contact.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1007/s00167-009-0813-1","First":false,"Last":false,"PMID":"19452139","author":[{"family":"Alentorn-Geli","given":"Eduard"},{"family":"Myer","given":"Gregory D"},{"family":"Silvers","given":"Holly J"},{"family":"Samitier","given":"Gonzalo"},{"family":"Romero","given":"Daniel"},{"family":"Lázaro-Haro","given":"Cristina"},{"family":"Cugat","given":"Ramón"}],"citation-label":"2595869","container-title":"Knee Surgery, Sports Traumatology, Arthroscopy","container-title-short":"Knee Surg. Sports Traumatol. Arthrosc.","id":"2595869","invisible":false,"issue":"7","issued":{"date-parts":[["2009","7"]]},"journalAbbreviation":"Knee Surg. Sports Traumatol. Arthrosc.","page":"705-729","suppress-author":false,"title":"Prevention of non-contact anterior cruciate ligament injuries in soccer players. Part 1: Mechanisms of injury and underlying risk factors.","type":"article-journal","volume":"17"}]1 70-84% of ACL injuries are non-contact.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1007/s00167-009-0813-1","First":false,"Last":false,"PMID":"19452139","author":[{"family":"Alentorn-Geli","given":"Eduard"},{"family":"Myer","given":"Gregory D"},{"family":"Silvers","given":"Holly J"},{"family":"Samitier","given":"Gonzalo"},{"family":"Romero","given":"Daniel"},{"family":"Lázaro-Haro","given":"Cristina"},{"family":"Cugat","given":"Ramón"}],"citation-label":"2595869","container-title":"Knee Surgery, Sports Traumatology, Arthroscopy","container-title-short":"Knee Surg. Sports Traumatol. Arthrosc.","id":"2595869","invisible":false,"issue":"7","issued":{"date-parts":[["2009","7"]]},"journalAbbreviation":"Knee Surg. Sports Traumatol. Arthrosc.","page":"705-729","suppress-author":false,"title":"Prevention of non-contact anterior cruciate ligament injuries in soccer players. Part 1: Mechanisms of injury and underlying risk factors.","type":"article-journal","volume":"17"}]1 Non-contact ACL injuries in soccer can occur during cutting and changes of direction with deceleration, landing a jump, pivoting with the foot planted.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1007/s00167-009-0813-1","First":false,"Last":false,"PMID":"19452139","author":[{"family":"Alentorn-Geli","given":"Eduard"},{"family":"Myer","given":"Gregory D"},{"family":"Silvers","given":"Holly J"},{"family":"Samitier","given":"Gonzalo"},{"family":"Romero","given":"Daniel"},{"family":"Lázaro-Haro","given":"Cristina"},{"family":"Cugat","given":"Ramón"}],"citation-label":"2595869","container-title":"Knee Surgery, Sports Traumatology, Arthroscopy","container-title-short":"Knee Surg. Sports Traumatol. Arthrosc.","id":"2595869","invisible":false,"issue":"7","issued":{"date-parts":[["2009","7"]]},"journalAbbreviation":"Knee Surg. Sports Traumatol. Arthrosc.","page":"705-729","suppress-author":false,"title":"Prevention of non-contact anterior cruciate ligament injuries in soccer players. Part 1: Mechanisms of injury and underlying risk factors.","type":"article-journal","volume":"17"}]1 These scenarios typically involve the knee near full extension (10-30 degrees of flexion) with or without varus or valgus force where the ACL is put under the greatest amount of stress.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1007/s00167-009-0813-1","First":false,"Last":false,"PMID":"19452139","author":[{"family":"Alentorn-Geli","given":"Eduard"},{"family":"Myer","given":"Gregory D"},{"family":"Silvers","given":"Holly J"},{"family":"Samitier","given":"Gonzalo"},{"family":"Romero","given":"Daniel"},{"family":"Lázaro-Haro","given":"Cristina"},{"family":"Cugat","given":"Ramón"}],"citation-label":"2595869","container-title":"Knee Surgery, Sports Traumatology, Arthroscopy","container-title-short":"Knee Surg. Sports Traumatol. Arthrosc.","id":"2595869","invisible":false,"issue":"7","issued":{"date-parts":[["2009","7"]]},"journalAbbreviation":"Knee Surg. Sports Traumatol. Arthrosc.","page":"705-729","suppress-author":false,"title":"Prevention of non-contact anterior cruciate ligament injuries in soccer players. Part 1: Mechanisms of injury and underlying risk factors.","type":"article-journal","volume":"17"}]1 This matches the proposed primary mechanism of ACL loading outlined above.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1016/j.jshs.2014.06.002","First":false,"Last":false,"abstract":"Anterior cruciate ligament (ACL) injuries are common in soccer. Understanding ACL loading mechanisms and risk factors for ACL injury is critical for designing effective prevention programs. The purpose of this review is to summarize the relevant literature on ACL loading mechanisms, ACL injury risk factors, and current ACL injury prevention programs for soccer players. Literature has shown that tibial anterior translation due to shear force at the proximal end of tibia is the primary ACL loading mechanism. No evidence has been found showing that knee valgus moment is the primary ACL loading mechanism. ACL loading mechanisms are largely ignored in previous studies on risk factors for ACL injury. Identified risk factors have little connections to ACL loading mechanisms. The results of studies on ACL injury prevention programs for soccer players are inconsistent. Current ACL injury prevention programs for soccer players are clinically ineffective due to low compliance. Future studies are urgently needed to identify risk factors for ACL injury in soccer that are connected to ACL loading mechanisms and have cause-and-effect relationships with injury rate, and to develop new prevention programs to improve compliance. Copyright 2014, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.","author":[{"family":"Dai","given":"Boyi"},{"family":"Mao","given":"Dewei"},{"family":"Garrett","given":"William E."},{"family":"Yu","given":"Bing"}],"citation-label":"1278040","container-title":"Journal of sport and health science","container-title-short":"J. Sport Health Sci.","id":"1278040","invisible":false,"issue":"4","issued":{"date-parts":[["2014","12"]]},"journalAbbreviation":"J. Sport Health Sci.","page":"299-306","suppress-author":false,"title":"Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and prevention programs","type":"article-journal","volume":"3"}]5 Cochrane et al. observed that over 90% of non-contact soccer ACL injuries occurred when the knee was in less than 30 degrees of flexion in a sample of 34 professional and amateur players.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1016/j.jsams.2006.05.015","First":false,"Last":false,"PMID":"16807104","abstract":"Anterior cruciate ligament (ACL) injuries are the most costly injuries in football at both professional and amateur levels (Orchard J, Seward H, McGivern J, Hood S. Intrinsic and extrinsic risk factors for anterior cruciate ligament injury in Australian footballers. Am J Sports Med 2001;29:196-200.). In this study video analysis of 34 ACL injuries in Australian football was performed to investigate the causes of these injuries. Factors that may have contributed to the cause of the injury were analysed, rated and reported. The factors analysed were: type of manoeuvre, direction the knee 'gave way', running speed, knee angle, cutting angle and if the player was accelerating or decelerating. The majority of the injuries analysed occurred in non-contact situations (56%). Of these 37% occurred during sidestepping manoeuvres, 32% in landing, 16% land and step, 10% stopping/slowing and 5% crossover cut manoeuvres. Ninety-two percent of the non-contact injuries occurred at extended knee angles of 30 degrees or less, which is also commonly known to place stress on the ACL and reduce the protective role of hamstrings. Over half (54%) of non-contact injuries occurred whilst decelerating. It would be expected that greater speed and angle cut too would increase the frequency of ACL injury. The results could not confirm this with most injuries occurring at running speeds of slow jogging to running and equal number of injuries occurred at cutting to angles of the ranges 15-45 degrees and 45-75 degrees. These results give greater understanding into potential causes or contributors of ACL injury and information to assist in the development of knee injury prevention programs.","author":[{"family":"Cochrane","given":"Jodie L"},{"family":"Lloyd","given":"David G"},{"family":"Buttfield","given":"Alec"},{"family":"Seward","given":"Hugh"},{"family":"McGivern","given":"Jeanne"}],"citation-label":"6055274","container-title":"Journal of science and medicine in sport / Sports Medicine Australia","container-title-short":"J. Sci. Med. Sport","id":"6055274","invisible":false,"issue":"2","issued":{"date-parts":[["2007","4"]]},"journalAbbreviation":"J. Sci. Med. Sport","page":"96-104","suppress-author":false,"title":"Characteristics of anterior cruciate ligament injuries in Australian football.","type":"article-journal","volume":"10"}]11 As outlined previously, this is the time when the hamstrings offer the least amount of anterior shear shielding and when the quadriceps produce the highest amount of anterior shear, and when patellar tendon tibia angle is greatest, creating a considerable amount of ACL stress.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1016/j.jshs.2014.06.002","First":false,"Last":false,"abstract":"Anterior cruciate ligament (ACL) injuries are common in soccer. Understanding ACL loading mechanisms and risk factors for ACL injury is critical for designing effective prevention programs. The purpose of this review is to summarize the relevant literature on ACL loading mechanisms, ACL injury risk factors, and current ACL injury prevention programs for soccer players. Literature has shown that tibial anterior translation due to shear force at the proximal end of tibia is the primary ACL loading mechanism. No evidence has been found showing that knee valgus moment is the primary ACL loading mechanism. ACL loading mechanisms are largely ignored in previous studies on risk factors for ACL injury. Identified risk factors have little connections to ACL loading mechanisms. The results of studies on ACL injury prevention programs for soccer players are inconsistent. Current ACL injury prevention programs for soccer players are clinically ineffective due to low compliance. Future studies are urgently needed to identify risk factors for ACL injury in soccer that are connected to ACL loading mechanisms and have cause-and-effect relationships with injury rate, and to develop new prevention programs to improve compliance. Copyright 2014, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.","author":[{"family":"Dai","given":"Boyi"},{"family":"Mao","given":"Dewei"},{"family":"Garrett","given":"William E."},{"family":"Yu","given":"Bing"}],"citation-label":"1278040","container-title":"Journal of sport and health science","container-title-short":"J. Sport Health Sci.","id":"1278040","invisible":false,"issue":"4","issued":{"date-parts":[["2014","12"]]},"journalAbbreviation":"J. Sport Health Sci.","page":"299-306","suppress-author":false,"title":"Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and prevention programs","type":"article-journal","volume":"3"}]5 The position of pivoting with the foot planted and the knee near full extension can cause a valgus/varus load with tibial internal rotation which is the position that Levine et al. identified as posing the most significant risk of ACL injury.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/0363546512465167","First":false,"Last":false,"PMCID":"PMC3935824","PMID":"23144366","author":[{"family":"Levine","given":"Jason W"},{"family":"Kiapour","given":"Ata M"},{"family":"Quatman","given":"Carmen E"},{"family":"Wordeman","given":"Samuel C"},{"family":"Goel","given":"Vijay K"},{"family":"Hewett","given":"Timothy E"},{"family":"Demetropoulos","given":"Constantine K"}],"citation-label":"612468","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"612468","invisible":false,"issue":"2","issued":{"date-parts":[["2013","2"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"385-395","suppress-author":false,"title":"Clinically relevant injury patterns after an anterior cruciate ligament injury provide insight into injury mechanisms.","type":"article-journal","volume":"41"}]10Cochrane et al. also found that 37% of non-contact ACL injuries occurred during a sidestepping movement, 32% during landing, 16% with a land and step, and 10% with a stopping or slowing movement.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1016/j.jsams.2006.05.015","First":false,"Last":false,"PMID":"16807104","abstract":"Anterior cruciate ligament (ACL) injuries are the most costly injuries in football at both professional and amateur levels (Orchard J, Seward H, McGivern J, Hood S. Intrinsic and extrinsic risk factors for anterior cruciate ligament injury in Australian footballers. Am J Sports Med 2001;29:196-200.). In this study video analysis of 34 ACL injuries in Australian football was performed to investigate the causes of these injuries. Factors that may have contributed to the cause of the injury were analysed, rated and reported. The factors analysed were: type of manoeuvre, direction the knee 'gave way', running speed, knee angle, cutting angle and if the player was accelerating or decelerating. The majority of the injuries analysed occurred in non-contact situations (56%). Of these 37% occurred during sidestepping manoeuvres, 32% in landing, 16% land and step, 10% stopping/slowing and 5% crossover cut manoeuvres. Ninety-two percent of the non-contact injuries occurred at extended knee angles of 30 degrees or less, which is also commonly known to place stress on the ACL and reduce the protective role of hamstrings. Over half (54%) of non-contact injuries occurred whilst decelerating. It would be expected that greater speed and angle cut too would increase the frequency of ACL injury. The results could not confirm this with most injuries occurring at running speeds of slow jogging to running and equal number of injuries occurred at cutting to angles of the ranges 15-45 degrees and 45-75 degrees. These results give greater understanding into potential causes or contributors of ACL injury and information to assist in the development of knee injury prevention programs.","author":[{"family":"Cochrane","given":"Jodie L"},{"family":"Lloyd","given":"David G"},{"family":"Buttfield","given":"Alec"},{"family":"Seward","given":"Hugh"},{"family":"McGivern","given":"Jeanne"}],"citation-label":"6055274","container-title":"Journal of science and medicine in sport / Sports Medicine Australia","container-title-short":"J. Sci. Med. Sport","id":"6055274","invisible":false,"issue":"2","issued":{"date-parts":[["2007","4"]]},"journalAbbreviation":"J. Sci. Med. Sport","page":"96-104","suppress-author":false,"title":"Characteristics of anterior cruciate ligament injuries in Australian football.","type":"article-journal","volume":"10"}]11 Most of these occurred when the athlete was decelerating.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1016/j.jsams.2006.05.015","First":false,"Last":false,"PMID":"16807104","abstract":"Anterior cruciate ligament (ACL) injuries are the most costly injuries in football at both professional and amateur levels (Orchard J, Seward H, McGivern J, Hood S. Intrinsic and extrinsic risk factors for anterior cruciate ligament injury in Australian footballers. Am J Sports Med 2001;29:196-200.). In this study video analysis of 34 ACL injuries in Australian football was performed to investigate the causes of these injuries. Factors that may have contributed to the cause of the injury were analysed, rated and reported. The factors analysed were: type of manoeuvre, direction the knee 'gave way', running speed, knee angle, cutting angle and if the player was accelerating or decelerating. The majority of the injuries analysed occurred in non-contact situations (56%). Of these 37% occurred during sidestepping manoeuvres, 32% in landing, 16% land and step, 10% stopping/slowing and 5% crossover cut manoeuvres. Ninety-two percent of the non-contact injuries occurred at extended knee angles of 30 degrees or less, which is also commonly known to place stress on the ACL and reduce the protective role of hamstrings. Over half (54%) of non-contact injuries occurred whilst decelerating. It would be expected that greater speed and angle cut too would increase the frequency of ACL injury. The results could not confirm this with most injuries occurring at running speeds of slow jogging to running and equal number of injuries occurred at cutting to angles of the ranges 15-45 degrees and 45-75 degrees. These results give greater understanding into potential causes or contributors of ACL injury and information to assist in the development of knee injury prevention programs.","author":[{"family":"Cochrane","given":"Jodie L"},{"family":"Lloyd","given":"David G"},{"family":"Buttfield","given":"Alec"},{"family":"Seward","given":"Hugh"},{"family":"McGivern","given":"Jeanne"}],"citation-label":"6055274","container-title":"Journal of science and medicine in sport / Sports Medicine Australia","container-title-short":"J. Sci. Med. Sport","id":"6055274","invisible":false,"issue":"2","issued":{"date-parts":[["2007","4"]]},"journalAbbreviation":"J. Sci. Med. Sport","page":"96-104","suppress-author":false,"title":"Characteristics of anterior cruciate ligament injuries in Australian football.","type":"article-journal","volume":"10"}]11 During deceleration, a high amount of tibial displacement is associated with eccentric quadriceps contraction near full knee extension.ADDIN F1000_CSL_CITATION<~#@#~>[{"First":false,"Last":false,"PMID":"10875418","abstract":"This study examined the mechanisms of anterior cruciate ligament (ACL) injury. In the first part of the study, using a comprehensive, standardized questionnaire, 89 athletes (100 knees) were interviewed about the events surrounding their ACL injury. A noncontact mechanism was reported in 71 (72%) knees and a contact injury in 28 (28%) knees; one patient was unsure if there was any contact. Most of the injuries were sustained at footstrike with the knee close to full extension. Noncontact mechanisms were classified as sudden deceleration prior to a change of direction or landing motion, while contact injuries occurred as a result of valgus collapse of the knee. Hamstring flexibility parameters revealed a statistically higher level of laxity in the injured athletes compared with a matched group of 28 controls. In the second part of the study, videotapes of 27 separate ACL disruptions were reviewed and confirmed that most noncontact injuries occur with the knee close to extension during a sharp deceleration or landing maneuver. Because the knee is in a position to allow the extensor mechanism to strain the ACL and maximum, eccentric muscle force conditions usually apply, the quadriceps may play an important role in ACL disruption. Passive protection of the ACL by the hamstring muscles may be reduced in patients with above-average flexibility.","author":[{"family":"Boden","given":"B P"},{"family":"Dean","given":"G S"},{"family":"Feagin","given":"J A"},{"family":"Garrett","given":"W E"}],"citation-label":"3827539","container-title":"Orthopedics","container-title-short":"Orthopedics","id":"3827539","invisible":false,"issue":"6","issued":{"date-parts":[["2000","6"]]},"journalAbbreviation":"Orthopedics","page":"573-578","suppress-author":false,"title":"Mechanisms of anterior cruciate ligament injury.","type":"article-journal","volume":"23"}]7 Walden et al. used video analysis to study the mechanisms of ACL injuries in 39 professional soccer players.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bjsports-2014-094573","First":false,"Last":false,"PMCID":"PMC4680158","PMID":"25907183","abstract":"BACKGROUND: Current knowledge on anterior cruciate ligament (ACL) injury mechanisms in male football players is limited. AIM: To describe ACL injury mechanisms in male professional football players using systematic video analysis. METHODS: We assessed videos from 39 complete ACL tears recorded via prospective professional football injury surveillance between 2001 and 2011. Five analysts independently reviewed all videos to estimate the time of initial foot contact with the ground and the time of ACL tear. We then analysed all videos according to a structured format describing the injury circumstances and lower limb joint biomechanics. RESULTS: Twenty-five injuries were non-contact, eight indirect contact and six direct contact injuries. We identified three main categories of non-contact and indirect contact injury situations: (1) pressing (n=11), (2) re-gaining balance after kicking (n=5) and (3) landing after heading (n=5). The fourth main injury situation was direct contact with the injured leg or knee (n=6). Knee valgus was frequently seen in the main categories of non-contact and indirect contact playing situations (n=11), but a dynamic valgus collapse was infrequent (n=3). This was in contrast to the tackling-induced direct contact situations where a knee valgus collapse occurred in all cases (n=3). CONCLUSIONS: Eighty-five per cent of the ACL injuries in male professional football players resulted from non-contact or indirect contact mechanisms. The most common playing situation leading to injury was pressing followed by kicking and heading. Knee valgus was frequently seen regardless of the playing situation, but a dynamic valgus collapse was rare. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to ","author":[{"family":"Waldén","given":"Markus"},{"family":"Krosshaug","given":"Tron"},{"family":"Bj?rneboe","given":"John"},{"family":"Andersen","given":"Thor Einar"},{"family":"Faul","given":"Oliver"},{"family":"H?gglund","given":"Martin"}],"citation-label":"1129936","container-title":"British Journal of Sports Medicine","container-title-short":"Br. J. Sports Med.","id":"1129936","invisible":false,"issue":"22","issued":{"date-parts":[["2015","11"]]},"journalAbbreviation":"Br. J. Sports Med.","page":"1452-1460","suppress-author":false,"title":"Three distinct mechanisms predominate in non-contact anterior cruciate ligament injuries in male professional football players: a systematic video analysis of 39 cases.","type":"article-journal","volume":"49"}]12 They observed three predominant mechanisms of non-contact ACL injuries: regaining balance following a kick, landing from a jump, and pressing defensively.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bjsports-2014-094573","First":false,"Last":false,"PMCID":"PMC4680158","PMID":"25907183","abstract":"BACKGROUND: Current knowledge on anterior cruciate ligament (ACL) injury mechanisms in male football players is limited. AIM: To describe ACL injury mechanisms in male professional football players using systematic video analysis. METHODS: We assessed videos from 39 complete ACL tears recorded via prospective professional football injury surveillance between 2001 and 2011. Five analysts independently reviewed all videos to estimate the time of initial foot contact with the ground and the time of ACL tear. We then analysed all videos according to a structured format describing the injury circumstances and lower limb joint biomechanics. RESULTS: Twenty-five injuries were non-contact, eight indirect contact and six direct contact injuries. We identified three main categories of non-contact and indirect contact injury situations: (1) pressing (n=11), (2) re-gaining balance after kicking (n=5) and (3) landing after heading (n=5). The fourth main injury situation was direct contact with the injured leg or knee (n=6). Knee valgus was frequently seen in the main categories of non-contact and indirect contact playing situations (n=11), but a dynamic valgus collapse was infrequent (n=3). This was in contrast to the tackling-induced direct contact situations where a knee valgus collapse occurred in all cases (n=3). CONCLUSIONS: Eighty-five per cent of the ACL injuries in male professional football players resulted from non-contact or indirect contact mechanisms. The most common playing situation leading to injury was pressing followed by kicking and heading. Knee valgus was frequently seen regardless of the playing situation, but a dynamic valgus collapse was rare. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to ","author":[{"family":"Waldén","given":"Markus"},{"family":"Krosshaug","given":"Tron"},{"family":"Bj?rneboe","given":"John"},{"family":"Andersen","given":"Thor Einar"},{"family":"Faul","given":"Oliver"},{"family":"H?gglund","given":"Martin"}],"citation-label":"1129936","container-title":"British Journal of Sports Medicine","container-title-short":"Br. J. Sports Med.","id":"1129936","invisible":false,"issue":"22","issued":{"date-parts":[["2015","11"]]},"journalAbbreviation":"Br. J. Sports Med.","page":"1452-1460","suppress-author":false,"title":"Three distinct mechanisms predominate in non-contact anterior cruciate ligament injuries in male professional football players: a systematic video analysis of 39 cases.","type":"article-journal","volume":"49"}]12 Defensive pressing involves a reactive sidestep to attempt to obtain the ball from the opponent with a cutting angle between 30 and 90 degrees and knee flexion less than 20 degrees.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bjsports-2014-094573","First":false,"Last":false,"PMCID":"PMC4680158","PMID":"25907183","abstract":"BACKGROUND: Current knowledge on anterior cruciate ligament (ACL) injury mechanisms in male football players is limited. AIM: To describe ACL injury mechanisms in male professional football players using systematic video analysis. METHODS: We assessed videos from 39 complete ACL tears recorded via prospective professional football injury surveillance between 2001 and 2011. Five analysts independently reviewed all videos to estimate the time of initial foot contact with the ground and the time of ACL tear. We then analysed all videos according to a structured format describing the injury circumstances and lower limb joint biomechanics. RESULTS: Twenty-five injuries were non-contact, eight indirect contact and six direct contact injuries. We identified three main categories of non-contact and indirect contact injury situations: (1) pressing (n=11), (2) re-gaining balance after kicking (n=5) and (3) landing after heading (n=5). The fourth main injury situation was direct contact with the injured leg or knee (n=6). Knee valgus was frequently seen in the main categories of non-contact and indirect contact playing situations (n=11), but a dynamic valgus collapse was infrequent (n=3). This was in contrast to the tackling-induced direct contact situations where a knee valgus collapse occurred in all cases (n=3). CONCLUSIONS: Eighty-five per cent of the ACL injuries in male professional football players resulted from non-contact or indirect contact mechanisms. The most common playing situation leading to injury was pressing followed by kicking and heading. Knee valgus was frequently seen regardless of the playing situation, but a dynamic valgus collapse was rare. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to ","author":[{"family":"Waldén","given":"Markus"},{"family":"Krosshaug","given":"Tron"},{"family":"Bj?rneboe","given":"John"},{"family":"Andersen","given":"Thor Einar"},{"family":"Faul","given":"Oliver"},{"family":"H?gglund","given":"Martin"}],"citation-label":"1129936","container-title":"British Journal of Sports Medicine","container-title-short":"Br. J. Sports Med.","id":"1129936","invisible":false,"issue":"22","issued":{"date-parts":[["2015","11"]]},"journalAbbreviation":"Br. J. Sports Med.","page":"1452-1460","suppress-author":false,"title":"Three distinct mechanisms predominate in non-contact anterior cruciate ligament injuries in male professional football players: a systematic video analysis of 39 cases.","type":"article-journal","volume":"49"}]12 This lunge to get the ball also typically involved a valgus load on the plant foot.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bjsports-2014-094573","First":false,"Last":false,"PMCID":"PMC4680158","PMID":"25907183","abstract":"BACKGROUND: Current knowledge on anterior cruciate ligament (ACL) injury mechanisms in male football players is limited. AIM: To describe ACL injury mechanisms in male professional football players using systematic video analysis. METHODS: We assessed videos from 39 complete ACL tears recorded via prospective professional football injury surveillance between 2001 and 2011. Five analysts independently reviewed all videos to estimate the time of initial foot contact with the ground and the time of ACL tear. We then analysed all videos according to a structured format describing the injury circumstances and lower limb joint biomechanics. RESULTS: Twenty-five injuries were non-contact, eight indirect contact and six direct contact injuries. We identified three main categories of non-contact and indirect contact injury situations: (1) pressing (n=11), (2) re-gaining balance after kicking (n=5) and (3) landing after heading (n=5). The fourth main injury situation was direct contact with the injured leg or knee (n=6). Knee valgus was frequently seen in the main categories of non-contact and indirect contact playing situations (n=11), but a dynamic valgus collapse was infrequent (n=3). This was in contrast to the tackling-induced direct contact situations where a knee valgus collapse occurred in all cases (n=3). CONCLUSIONS: Eighty-five per cent of the ACL injuries in male professional football players resulted from non-contact or indirect contact mechanisms. The most common playing situation leading to injury was pressing followed by kicking and heading. Knee valgus was frequently seen regardless of the playing situation, but a dynamic valgus collapse was rare. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to ","author":[{"family":"Waldén","given":"Markus"},{"family":"Krosshaug","given":"Tron"},{"family":"Bj?rneboe","given":"John"},{"family":"Andersen","given":"Thor Einar"},{"family":"Faul","given":"Oliver"},{"family":"H?gglund","given":"Martin"}],"citation-label":"1129936","container-title":"British Journal of Sports Medicine","container-title-short":"Br. J. Sports Med.","id":"1129936","invisible":false,"issue":"22","issued":{"date-parts":[["2015","11"]]},"journalAbbreviation":"Br. J. Sports Med.","page":"1452-1460","suppress-author":false,"title":"Three distinct mechanisms predominate in non-contact anterior cruciate ligament injuries in male professional football players: a systematic video analysis of 39 cases.","type":"article-journal","volume":"49"}]12 This position is depicted in Appendix 4. Both pressing and regaining balance after kicking involved the hip abduction, minimal knee and hip flexion.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bjsports-2014-094573","First":false,"Last":false,"PMCID":"PMC4680158","PMID":"25907183","abstract":"BACKGROUND: Current knowledge on anterior cruciate ligament (ACL) injury mechanisms in male football players is limited. AIM: To describe ACL injury mechanisms in male professional football players using systematic video analysis. METHODS: We assessed videos from 39 complete ACL tears recorded via prospective professional football injury surveillance between 2001 and 2011. Five analysts independently reviewed all videos to estimate the time of initial foot contact with the ground and the time of ACL tear. We then analysed all videos according to a structured format describing the injury circumstances and lower limb joint biomechanics. RESULTS: Twenty-five injuries were non-contact, eight indirect contact and six direct contact injuries. We identified three main categories of non-contact and indirect contact injury situations: (1) pressing (n=11), (2) re-gaining balance after kicking (n=5) and (3) landing after heading (n=5). The fourth main injury situation was direct contact with the injured leg or knee (n=6). Knee valgus was frequently seen in the main categories of non-contact and indirect contact playing situations (n=11), but a dynamic valgus collapse was infrequent (n=3). This was in contrast to the tackling-induced direct contact situations where a knee valgus collapse occurred in all cases (n=3). CONCLUSIONS: Eighty-five per cent of the ACL injuries in male professional football players resulted from non-contact or indirect contact mechanisms. The most common playing situation leading to injury was pressing followed by kicking and heading. Knee valgus was frequently seen regardless of the playing situation, but a dynamic valgus collapse was rare. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to ","author":[{"family":"Waldén","given":"Markus"},{"family":"Krosshaug","given":"Tron"},{"family":"Bj?rneboe","given":"John"},{"family":"Andersen","given":"Thor Einar"},{"family":"Faul","given":"Oliver"},{"family":"H?gglund","given":"Martin"}],"citation-label":"1129936","container-title":"British Journal of Sports Medicine","container-title-short":"Br. J. Sports Med.","id":"1129936","invisible":false,"issue":"22","issued":{"date-parts":[["2015","11"]]},"journalAbbreviation":"Br. J. Sports Med.","page":"1452-1460","suppress-author":false,"title":"Three distinct mechanisms predominate in non-contact anterior cruciate ligament injuries in male professional football players: a systematic video analysis of 39 cases.","type":"article-journal","volume":"49"}]12 Grassi et al. identified this position of hip abduction, minimal knee flexion and valgus stress as the most common mechanism of ACL injury among a sample of 34 male professional soccer players.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1007/s00590-017-1905-0","First":false,"Last":false,"PMID":"28124130","abstract":"BACKGROUND: Soccer is considered the most popular sport in the world concerning both audience and athlete participation, and the incidence of ACL injury in this sport is high. The understanding of injury situations and mechanisms could be useful as substratum for preventive actions. PURPOSE: To conduct a video analysis evaluating the situations and mechanisms of ACL injury in a homogeneous population of professional male soccer players, through a search entirely performed on the Web site focusing on the most recent years. METHODS: A video analysis was conducted obtaining videos of ACL injury in professional male soccer players from the Web site YouTube. Details regarding injured players, events and situations were obtained. The mechanism of injury was defined on the basis of the action, duel type, contact or non-contact injury, and on the hip, knee and foot position. RESULTS: Thirty-four videos were analyzed, mostly from the 2014-2015 season. Injuries occurred mostly in the first 9?min of the match (26%), in the penalty area (32%) or near the side-lines (44%), and in non-rainy conditions (97%). Non-contact injuries occurred in 44% of cases, while indirect injuries occurred in 65%, mostly during pressing, dribbling or tackling. The most recurrent mechanism was with an abducted and flexed hip, with knee at first degrees of flexion and under valgus stress. CONCLUSIONS: Through a YouTube-based video analysis, it was possible to delineate recurrent temporal, spatial and mechanical characteristics of ACL injury in male professional soccer players. LEVEL OF EVIDENCE: Level IV, case series.","author":[{"family":"Grassi","given":"Alberto"},{"family":"Smiley","given":"Stephen Paul"},{"family":"Roberti di Sarsina","given":"Tommaso"},{"family":"Signorelli","given":"Cecilia"},{"family":"Marcheggiani Muccioli","given":"Giulio Maria"},{"family":"Bondi","given":"Alice"},{"family":"Romagnoli","given":"Matteo"},{"family":"Agostini","given":"Alessandra"},{"family":"Zaffagnini","given":"Stefano"}],"citation-label":"6055981","container-title":"European journal of orthopaedic surgery & traumatology : orthopedie traumatologie","container-title-short":"Eur. J. Orthop. Surg. Traumatol.","id":"6055981","invisible":false,"issue":"7","issued":{"date-parts":[["2017","10"]]},"journalAbbreviation":"Eur. J. Orthop. Surg. Traumatol.","page":"967-981","suppress-author":false,"title":"Mechanisms and situations of anterior cruciate ligament injuries in professional male soccer players: a YouTube-based video analysis.","type":"article-journal","volume":"27"}]13 Similarly, Grassi et al. found that most of the non-contact injuries occurred when the player was either pressing, dribbling or tackling.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1007/s00590-017-1905-0","First":false,"Last":false,"PMID":"28124130","abstract":"BACKGROUND: Soccer is considered the most popular sport in the world concerning both audience and athlete participation, and the incidence of ACL injury in this sport is high. The understanding of injury situations and mechanisms could be useful as substratum for preventive actions. PURPOSE: To conduct a video analysis evaluating the situations and mechanisms of ACL injury in a homogeneous population of professional male soccer players, through a search entirely performed on the Web site focusing on the most recent years. METHODS: A video analysis was conducted obtaining videos of ACL injury in professional male soccer players from the Web site YouTube. Details regarding injured players, events and situations were obtained. The mechanism of injury was defined on the basis of the action, duel type, contact or non-contact injury, and on the hip, knee and foot position. RESULTS: Thirty-four videos were analyzed, mostly from the 2014-2015 season. Injuries occurred mostly in the first 9?min of the match (26%), in the penalty area (32%) or near the side-lines (44%), and in non-rainy conditions (97%). Non-contact injuries occurred in 44% of cases, while indirect injuries occurred in 65%, mostly during pressing, dribbling or tackling. The most recurrent mechanism was with an abducted and flexed hip, with knee at first degrees of flexion and under valgus stress. CONCLUSIONS: Through a YouTube-based video analysis, it was possible to delineate recurrent temporal, spatial and mechanical characteristics of ACL injury in male professional soccer players. LEVEL OF EVIDENCE: Level IV, case series.","author":[{"family":"Grassi","given":"Alberto"},{"family":"Smiley","given":"Stephen Paul"},{"family":"Roberti di Sarsina","given":"Tommaso"},{"family":"Signorelli","given":"Cecilia"},{"family":"Marcheggiani Muccioli","given":"Giulio Maria"},{"family":"Bondi","given":"Alice"},{"family":"Romagnoli","given":"Matteo"},{"family":"Agostini","given":"Alessandra"},{"family":"Zaffagnini","given":"Stefano"}],"citation-label":"6055981","container-title":"European journal of orthopaedic surgery & traumatology : orthopedie traumatologie","container-title-short":"Eur. J. Orthop. Surg. Traumatol.","id":"6055981","invisible":false,"issue":"7","issued":{"date-parts":[["2017","10"]]},"journalAbbreviation":"Eur. J. Orthop. Surg. Traumatol.","page":"967-981","suppress-author":false,"title":"Mechanisms and situations of anterior cruciate ligament injuries in professional male soccer players: a YouTube-based video analysis.","type":"article-journal","volume":"27"}]13 Walden et al. also observed that 30 of the 39 injuries occurred while the player was making a defensive effort.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bjsports-2014-094573","First":false,"Last":false,"PMCID":"PMC4680158","PMID":"25907183","abstract":"BACKGROUND: Current knowledge on anterior cruciate ligament (ACL) injury mechanisms in male football players is limited. AIM: To describe ACL injury mechanisms in male professional football players using systematic video analysis. METHODS: We assessed videos from 39 complete ACL tears recorded via prospective professional football injury surveillance between 2001 and 2011. Five analysts independently reviewed all videos to estimate the time of initial foot contact with the ground and the time of ACL tear. We then analysed all videos according to a structured format describing the injury circumstances and lower limb joint biomechanics. RESULTS: Twenty-five injuries were non-contact, eight indirect contact and six direct contact injuries. We identified three main categories of non-contact and indirect contact injury situations: (1) pressing (n=11), (2) re-gaining balance after kicking (n=5) and (3) landing after heading (n=5). The fourth main injury situation was direct contact with the injured leg or knee (n=6). Knee valgus was frequently seen in the main categories of non-contact and indirect contact playing situations (n=11), but a dynamic valgus collapse was infrequent (n=3). This was in contrast to the tackling-induced direct contact situations where a knee valgus collapse occurred in all cases (n=3). CONCLUSIONS: Eighty-five per cent of the ACL injuries in male professional football players resulted from non-contact or indirect contact mechanisms. The most common playing situation leading to injury was pressing followed by kicking and heading. Knee valgus was frequently seen regardless of the playing situation, but a dynamic valgus collapse was rare. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to ","author":[{"family":"Waldén","given":"Markus"},{"family":"Krosshaug","given":"Tron"},{"family":"Bj?rneboe","given":"John"},{"family":"Andersen","given":"Thor Einar"},{"family":"Faul","given":"Oliver"},{"family":"H?gglund","given":"Martin"}],"citation-label":"1129936","container-title":"British Journal of Sports Medicine","container-title-short":"Br. J. Sports Med.","id":"1129936","invisible":false,"issue":"22","issued":{"date-parts":[["2015","11"]]},"journalAbbreviation":"Br. J. Sports Med.","page":"1452-1460","suppress-author":false,"title":"Three distinct mechanisms predominate in non-contact anterior cruciate ligament injuries in male professional football players: a systematic video analysis of 39 cases.","type":"article-journal","volume":"49"}]12 Defense is typically correlated with unplanned movement tasks. Unanticipated movements have been associated with an increased risk of ACL injury.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/2325967116634074","First":false,"Last":false,"PMCID":"PMC4794976","PMID":"27047983","abstract":"BACKGROUND: There has been a substantial increase in the amount of systematic reviews and meta-analyses published on the anterior cruciate ligament (ACL). PURPOSE: To quantify the number of systematic reviews and meta-analyses published on the ACL in the past decade and to provide an overall summary of this literature. STUDY DESIGN: Systematic review; Level of evidence, 4. METHODS: A systematic review of all ACL-related systematic reviews and meta-analyses published between January 2004 and September 2014 was performed using PubMed, MEDLINE, and the Cochrane Database. Narrative reviews and non-English articles were excluded. RESULTS: A total of 1031 articles were found, of which 240 met the inclusion criteria. Included articles were summarized and divided into 17 topics: anatomy, epidemiology, prevention, associated injuries, diagnosis, operative versus nonoperative management, graft choice, surgical technique, fixation methods, computer-assisted surgery, platelet-rich plasma, rehabilitation, return to play, outcomes assessment, arthritis, complications, and miscellaneous. CONCLUSION: A summary of systematic reviews on the ACL can supply the surgeon with a single source for the most up-to-date synthesis of the literature.","author":[{"family":"Anderson","given":"Michael J"},{"family":"Browning","given":"William M"},{"family":"Urband","given":"Christopher E"},{"family":"Kluczynski","given":"Melissa A"},{"family":"Bisson","given":"Leslie J"}],"citation-label":"2062386","container-title":"Orthopaedic journal of sports medicine","container-title-short":"Orthop. J. Sports Med.","id":"2062386","invisible":false,"issue":"3","issued":{"date-parts":[["2016","3","15"]]},"journalAbbreviation":"Orthop. J. Sports Med.","page":"2325967116634074","suppress-author":false,"title":"A systematic summary of systematic reviews on the topic of the anterior cruciate ligament.","type":"article-journal","volume":"4"}]14 Most of the non-contact injuries observed by Walden et al. involved knee valgus but dynamic valgus collapse rarely occurred. Also, the majority of the injuries occurred in situations of single leg loading.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bjsports-2014-094573","First":false,"Last":false,"PMCID":"PMC4680158","PMID":"25907183","abstract":"BACKGROUND: Current knowledge on anterior cruciate ligament (ACL) injury mechanisms in male football players is limited. AIM: To describe ACL injury mechanisms in male professional football players using systematic video analysis. METHODS: We assessed videos from 39 complete ACL tears recorded via prospective professional football injury surveillance between 2001 and 2011. Five analysts independently reviewed all videos to estimate the time of initial foot contact with the ground and the time of ACL tear. We then analysed all videos according to a structured format describing the injury circumstances and lower limb joint biomechanics. RESULTS: Twenty-five injuries were non-contact, eight indirect contact and six direct contact injuries. We identified three main categories of non-contact and indirect contact injury situations: (1) pressing (n=11), (2) re-gaining balance after kicking (n=5) and (3) landing after heading (n=5). The fourth main injury situation was direct contact with the injured leg or knee (n=6). Knee valgus was frequently seen in the main categories of non-contact and indirect contact playing situations (n=11), but a dynamic valgus collapse was infrequent (n=3). This was in contrast to the tackling-induced direct contact situations where a knee valgus collapse occurred in all cases (n=3). CONCLUSIONS: Eighty-five per cent of the ACL injuries in male professional football players resulted from non-contact or indirect contact mechanisms. The most common playing situation leading to injury was pressing followed by kicking and heading. Knee valgus was frequently seen regardless of the playing situation, but a dynamic valgus collapse was rare. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to ","author":[{"family":"Waldén","given":"Markus"},{"family":"Krosshaug","given":"Tron"},{"family":"Bj?rneboe","given":"John"},{"family":"Andersen","given":"Thor Einar"},{"family":"Faul","given":"Oliver"},{"family":"H?gglund","given":"Martin"}],"citation-label":"1129936","container-title":"British Journal of Sports Medicine","container-title-short":"Br. J. Sports Med.","id":"1129936","invisible":false,"issue":"22","issued":{"date-parts":[["2015","11"]]},"journalAbbreviation":"Br. J. Sports Med.","page":"1452-1460","suppress-author":false,"title":"Three distinct mechanisms predominate in non-contact anterior cruciate ligament injuries in male professional football players: a systematic video analysis of 39 cases.","type":"article-journal","volume":"49"}]12 Many activities in soccer involve landing a jump and decelerating, which both require eccentric quadriceps contraction in which the ACL needs to resist anterior tibial translation.ADDIN F1000_CSL_CITATION<~#@#~>[{"First":false,"Last":false,"PMID":"10875418","abstract":"This study examined the mechanisms of anterior cruciate ligament (ACL) injury. In the first part of the study, using a comprehensive, standardized questionnaire, 89 athletes (100 knees) were interviewed about the events surrounding their ACL injury. A noncontact mechanism was reported in 71 (72%) knees and a contact injury in 28 (28%) knees; one patient was unsure if there was any contact. Most of the injuries were sustained at footstrike with the knee close to full extension. Noncontact mechanisms were classified as sudden deceleration prior to a change of direction or landing motion, while contact injuries occurred as a result of valgus collapse of the knee. Hamstring flexibility parameters revealed a statistically higher level of laxity in the injured athletes compared with a matched group of 28 controls. In the second part of the study, videotapes of 27 separate ACL disruptions were reviewed and confirmed that most noncontact injuries occur with the knee close to extension during a sharp deceleration or landing maneuver. Because the knee is in a position to allow the extensor mechanism to strain the ACL and maximum, eccentric muscle force conditions usually apply, the quadriceps may play an important role in ACL disruption. Passive protection of the ACL by the hamstring muscles may be reduced in patients with above-average flexibility.","author":[{"family":"Boden","given":"B P"},{"family":"Dean","given":"G S"},{"family":"Feagin","given":"J A"},{"family":"Garrett","given":"W E"}],"citation-label":"3827539","container-title":"Orthopedics","container-title-short":"Orthopedics","id":"3827539","invisible":false,"issue":"6","issued":{"date-parts":[["2000","6"]]},"journalAbbreviation":"Orthopedics","page":"573-578","suppress-author":false,"title":"Mechanisms of anterior cruciate ligament injury.","type":"article-journal","volume":"23"}]7 Direct contact injuries are also another common mechanism of ACL injuries among soccer players.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bjsports-2014-094573","First":false,"Last":false,"PMCID":"PMC4680158","PMID":"25907183","abstract":"BACKGROUND: Current knowledge on anterior cruciate ligament (ACL) injury mechanisms in male football players is limited. AIM: To describe ACL injury mechanisms in male professional football players using systematic video analysis. METHODS: We assessed videos from 39 complete ACL tears recorded via prospective professional football injury surveillance between 2001 and 2011. Five analysts independently reviewed all videos to estimate the time of initial foot contact with the ground and the time of ACL tear. We then analysed all videos according to a structured format describing the injury circumstances and lower limb joint biomechanics. RESULTS: Twenty-five injuries were non-contact, eight indirect contact and six direct contact injuries. We identified three main categories of non-contact and indirect contact injury situations: (1) pressing (n=11), (2) re-gaining balance after kicking (n=5) and (3) landing after heading (n=5). The fourth main injury situation was direct contact with the injured leg or knee (n=6). Knee valgus was frequently seen in the main categories of non-contact and indirect contact playing situations (n=11), but a dynamic valgus collapse was infrequent (n=3). This was in contrast to the tackling-induced direct contact situations where a knee valgus collapse occurred in all cases (n=3). CONCLUSIONS: Eighty-five per cent of the ACL injuries in male professional football players resulted from non-contact or indirect contact mechanisms. The most common playing situation leading to injury was pressing followed by kicking and heading. Knee valgus was frequently seen regardless of the playing situation, but a dynamic valgus collapse was rare. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to ","author":[{"family":"Waldén","given":"Markus"},{"family":"Krosshaug","given":"Tron"},{"family":"Bj?rneboe","given":"John"},{"family":"Andersen","given":"Thor Einar"},{"family":"Faul","given":"Oliver"},{"family":"H?gglund","given":"Martin"}],"citation-label":"1129936","container-title":"British Journal of Sports Medicine","container-title-short":"Br. J. Sports Med.","id":"1129936","invisible":false,"issue":"22","issued":{"date-parts":[["2015","11"]]},"journalAbbreviation":"Br. J. Sports Med.","page":"1452-1460","suppress-author":false,"title":"Three distinct mechanisms predominate in non-contact anterior cruciate ligament injuries in male professional football players: a systematic video analysis of 39 cases.","type":"article-journal","volume":"49"}]12 The mechanism associated with contact ACL injuries are variable.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bjsports-2014-094573","First":false,"Last":false,"PMCID":"PMC4680158","PMID":"25907183","abstract":"BACKGROUND: Current knowledge on anterior cruciate ligament (ACL) injury mechanisms in male football players is limited. AIM: To describe ACL injury mechanisms in male professional football players using systematic video analysis. METHODS: We assessed videos from 39 complete ACL tears recorded via prospective professional football injury surveillance between 2001 and 2011. Five analysts independently reviewed all videos to estimate the time of initial foot contact with the ground and the time of ACL tear. We then analysed all videos according to a structured format describing the injury circumstances and lower limb joint biomechanics. RESULTS: Twenty-five injuries were non-contact, eight indirect contact and six direct contact injuries. We identified three main categories of non-contact and indirect contact injury situations: (1) pressing (n=11), (2) re-gaining balance after kicking (n=5) and (3) landing after heading (n=5). The fourth main injury situation was direct contact with the injured leg or knee (n=6). Knee valgus was frequently seen in the main categories of non-contact and indirect contact playing situations (n=11), but a dynamic valgus collapse was infrequent (n=3). This was in contrast to the tackling-induced direct contact situations where a knee valgus collapse occurred in all cases (n=3). CONCLUSIONS: Eighty-five per cent of the ACL injuries in male professional football players resulted from non-contact or indirect contact mechanisms. The most common playing situation leading to injury was pressing followed by kicking and heading. Knee valgus was frequently seen regardless of the playing situation, but a dynamic valgus collapse was rare. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to ","author":[{"family":"Waldén","given":"Markus"},{"family":"Krosshaug","given":"Tron"},{"family":"Bj?rneboe","given":"John"},{"family":"Andersen","given":"Thor Einar"},{"family":"Faul","given":"Oliver"},{"family":"H?gglund","given":"Martin"}],"citation-label":"1129936","container-title":"British Journal of Sports Medicine","container-title-short":"Br. J. Sports Med.","id":"1129936","invisible":false,"issue":"22","issued":{"date-parts":[["2015","11"]]},"journalAbbreviation":"Br. J. Sports Med.","page":"1452-1460","suppress-author":false,"title":"Three distinct mechanisms predominate in non-contact anterior cruciate ligament injuries in male professional football players: a systematic video analysis of 39 cases.","type":"article-journal","volume":"49"}]12 Walden et al. identified that all direct injuries resulted from either tackling or accidental collisions.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bjsports-2014-094573","First":false,"Last":false,"PMCID":"PMC4680158","PMID":"25907183","abstract":"BACKGROUND: Current knowledge on anterior cruciate ligament (ACL) injury mechanisms in male football players is limited. AIM: To describe ACL injury mechanisms in male professional football players using systematic video analysis. METHODS: We assessed videos from 39 complete ACL tears recorded via prospective professional football injury surveillance between 2001 and 2011. Five analysts independently reviewed all videos to estimate the time of initial foot contact with the ground and the time of ACL tear. We then analysed all videos according to a structured format describing the injury circumstances and lower limb joint biomechanics. RESULTS: Twenty-five injuries were non-contact, eight indirect contact and six direct contact injuries. We identified three main categories of non-contact and indirect contact injury situations: (1) pressing (n=11), (2) re-gaining balance after kicking (n=5) and (3) landing after heading (n=5). The fourth main injury situation was direct contact with the injured leg or knee (n=6). Knee valgus was frequently seen in the main categories of non-contact and indirect contact playing situations (n=11), but a dynamic valgus collapse was infrequent (n=3). This was in contrast to the tackling-induced direct contact situations where a knee valgus collapse occurred in all cases (n=3). CONCLUSIONS: Eighty-five per cent of the ACL injuries in male professional football players resulted from non-contact or indirect contact mechanisms. The most common playing situation leading to injury was pressing followed by kicking and heading. Knee valgus was frequently seen regardless of the playing situation, but a dynamic valgus collapse was rare. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to ","author":[{"family":"Waldén","given":"Markus"},{"family":"Krosshaug","given":"Tron"},{"family":"Bj?rneboe","given":"John"},{"family":"Andersen","given":"Thor Einar"},{"family":"Faul","given":"Oliver"},{"family":"H?gglund","given":"Martin"}],"citation-label":"1129936","container-title":"British Journal of Sports Medicine","container-title-short":"Br. J. Sports Med.","id":"1129936","invisible":false,"issue":"22","issued":{"date-parts":[["2015","11"]]},"journalAbbreviation":"Br. J. Sports Med.","page":"1452-1460","suppress-author":false,"title":"Three distinct mechanisms predominate in non-contact anterior cruciate ligament injuries in male professional football players: a systematic video analysis of 39 cases.","type":"article-journal","volume":"49"}]12 During direct tackling scenarios, the tackles were either from behind which drove the knee into a forceful valgus collapse or a collision injury.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bjsports-2014-094573","First":false,"Last":false,"PMCID":"PMC4680158","PMID":"25907183","abstract":"BACKGROUND: Current knowledge on anterior cruciate ligament (ACL) injury mechanisms in male football players is limited. AIM: To describe ACL injury mechanisms in male professional football players using systematic video analysis. METHODS: We assessed videos from 39 complete ACL tears recorded via prospective professional football injury surveillance between 2001 and 2011. Five analysts independently reviewed all videos to estimate the time of initial foot contact with the ground and the time of ACL tear. We then analysed all videos according to a structured format describing the injury circumstances and lower limb joint biomechanics. RESULTS: Twenty-five injuries were non-contact, eight indirect contact and six direct contact injuries. We identified three main categories of non-contact and indirect contact injury situations: (1) pressing (n=11), (2) re-gaining balance after kicking (n=5) and (3) landing after heading (n=5). The fourth main injury situation was direct contact with the injured leg or knee (n=6). Knee valgus was frequently seen in the main categories of non-contact and indirect contact playing situations (n=11), but a dynamic valgus collapse was infrequent (n=3). This was in contrast to the tackling-induced direct contact situations where a knee valgus collapse occurred in all cases (n=3). CONCLUSIONS: Eighty-five per cent of the ACL injuries in male professional football players resulted from non-contact or indirect contact mechanisms. The most common playing situation leading to injury was pressing followed by kicking and heading. Knee valgus was frequently seen regardless of the playing situation, but a dynamic valgus collapse was rare. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to ","author":[{"family":"Waldén","given":"Markus"},{"family":"Krosshaug","given":"Tron"},{"family":"Bj?rneboe","given":"John"},{"family":"Andersen","given":"Thor Einar"},{"family":"Faul","given":"Oliver"},{"family":"H?gglund","given":"Martin"}],"citation-label":"1129936","container-title":"British Journal of Sports Medicine","container-title-short":"Br. J. Sports Med.","id":"1129936","invisible":false,"issue":"22","issued":{"date-parts":[["2015","11"]]},"journalAbbreviation":"Br. J. Sports Med.","page":"1452-1460","suppress-author":false,"title":"Three distinct mechanisms predominate in non-contact anterior cruciate ligament injuries in male professional football players: a systematic video analysis of 39 cases.","type":"article-journal","volume":"49"}]12Many potential risk factors may make someone more susceptible to an ACL injury. These include environmental factors, anatomic factors, hormonal and sex factors, neuromuscular control, and biomechanical factors.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1007/s00167-009-0813-1","First":false,"Last":false,"PMID":"19452139","author":[{"family":"Alentorn-Geli","given":"Eduard"},{"family":"Myer","given":"Gregory D"},{"family":"Silvers","given":"Holly J"},{"family":"Samitier","given":"Gonzalo"},{"family":"Romero","given":"Daniel"},{"family":"Lázaro-Haro","given":"Cristina"},{"family":"Cugat","given":"Ramón"}],"citation-label":"2595869","container-title":"Knee Surgery, Sports Traumatology, Arthroscopy","container-title-short":"Knee Surg. Sports Traumatol. Arthrosc.","id":"2595869","invisible":false,"issue":"7","issued":{"date-parts":[["2009","7"]]},"journalAbbreviation":"Knee Surg. Sports Traumatol. Arthrosc.","page":"705-729","suppress-author":false,"title":"Prevention of non-contact anterior cruciate ligament injuries in soccer players. Part 1: Mechanisms of injury and underlying risk factors.","type":"article-journal","volume":"17"}]1 A few of these will be briefly explored below.Environmental factors include the sport, the playing surface, the weather, and the footwear. In soccer, a few studies observed higher incidences of ACL injuries on natural grass fields when the conditions are dry.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1007/s00167-009-0813-1","First":false,"Last":false,"PMID":"19452139","author":[{"family":"Alentorn-Geli","given":"Eduard"},{"family":"Myer","given":"Gregory D"},{"family":"Silvers","given":"Holly J"},{"family":"Samitier","given":"Gonzalo"},{"family":"Romero","given":"Daniel"},{"family":"Lázaro-Haro","given":"Cristina"},{"family":"Cugat","given":"Ramón"}],"citation-label":"2595869","container-title":"Knee Surgery, Sports Traumatology, Arthroscopy","container-title-short":"Knee Surg. Sports Traumatol. Arthrosc.","id":"2595869","invisible":false,"issue":"7","issued":{"date-parts":[["2009","7"]]},"journalAbbreviation":"Knee Surg. Sports Traumatol. Arthrosc.","page":"705-729","suppress-author":false,"title":"Prevention of non-contact anterior cruciate ligament injuries in soccer players. Part 1: Mechanisms of injury and underlying risk factors.","type":"article-journal","volume":"17"}]1 This elevated risk of an ACL injury in dry conditions may be explained by the increased friction between the grass surface and cleats which could lead to a higher torque imposed during cutting or decelerating.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1007/s00167-009-0813-1","First":false,"Last":false,"PMID":"19452139","author":[{"family":"Alentorn-Geli","given":"Eduard"},{"family":"Myer","given":"Gregory D"},{"family":"Silvers","given":"Holly J"},{"family":"Samitier","given":"Gonzalo"},{"family":"Romero","given":"Daniel"},{"family":"Lázaro-Haro","given":"Cristina"},{"family":"Cugat","given":"Ramón"}],"citation-label":"2595869","container-title":"Knee Surgery, Sports Traumatology, Arthroscopy","container-title-short":"Knee Surg. Sports Traumatol. Arthrosc.","id":"2595869","invisible":false,"issue":"7","issued":{"date-parts":[["2009","7"]]},"journalAbbreviation":"Knee Surg. Sports Traumatol. Arthrosc.","page":"705-729","suppress-author":false,"title":"Prevention of non-contact anterior cruciate ligament injuries in soccer players. Part 1: Mechanisms of injury and underlying risk factors.","type":"article-journal","volume":"17"}]1 This concept of friction between the shoe and the playing surface is further supported by the fact that ryegrass is associated with a lower incidence of ACL tears during soccer practice versus Bermuda grass which is thicker with greater traction.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1007/s00167-009-0813-1","First":false,"Last":false,"PMID":"19452139","author":[{"family":"Alentorn-Geli","given":"Eduard"},{"family":"Myer","given":"Gregory D"},{"family":"Silvers","given":"Holly J"},{"family":"Samitier","given":"Gonzalo"},{"family":"Romero","given":"Daniel"},{"family":"Lázaro-Haro","given":"Cristina"},{"family":"Cugat","given":"Ramón"}],"citation-label":"2595869","container-title":"Knee Surgery, Sports Traumatology, Arthroscopy","container-title-short":"Knee Surg. Sports Traumatol. Arthrosc.","id":"2595869","invisible":false,"issue":"7","issued":{"date-parts":[["2009","7"]]},"journalAbbreviation":"Knee Surg. Sports Traumatol. Arthrosc.","page":"705-729","suppress-author":false,"title":"Prevention of non-contact anterior cruciate ligament injuries in soccer players. Part 1: Mechanisms of injury and underlying risk factors.","type":"article-journal","volume":"17"}]1 No conclusive findings exist regarding the risk of an ACL injury on turf versus on authentic grass for male or female soccer players.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1007/s00167-009-0813-1","First":false,"Last":false,"PMID":"19452139","author":[{"family":"Alentorn-Geli","given":"Eduard"},{"family":"Myer","given":"Gregory D"},{"family":"Silvers","given":"Holly J"},{"family":"Samitier","given":"Gonzalo"},{"family":"Romero","given":"Daniel"},{"family":"Lázaro-Haro","given":"Cristina"},{"family":"Cugat","given":"Ramón"}],"citation-label":"2595869","container-title":"Knee Surgery, Sports Traumatology, Arthroscopy","container-title-short":"Knee Surg. Sports Traumatol. Arthrosc.","id":"2595869","invisible":false,"issue":"7","issued":{"date-parts":[["2009","7"]]},"journalAbbreviation":"Knee Surg. Sports Traumatol. Arthrosc.","page":"705-729","suppress-author":false,"title":"Prevention of non-contact anterior cruciate ligament injuries in soccer players. Part 1: Mechanisms of injury and underlying risk factors.","type":"article-journal","volume":"17"}]1Female soccer players are at a two to three times elevated risk of an ACL injury versus males across ages.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/0363546516648439","First":false,"Last":false,"PMID":"27261476","abstract":"BACKGROUND: Female soccer players have a well-known risk for anterior cruciate ligament (ACL) injury, but few studies have reported on second ACL injuries in this population. PURPOSE: To (1) report the rates of subsequent ACL injury (ipsilateral graft rupture or contralateral tear) in competitive female soccer players, (2) compare these rates with those of other female athletes of similar competitive level, (3) determine risk factors for second ACL injury, and (4) report clinical outcome scores in this population. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: The medical records at a single institution were reviewed for female patients who were injured during a competitive athletic event and treated with primary ACL reconstruction (ACLR) between 1998 and 2013. Patients were followed for a mean of 68.8 months postoperatively (range, 24-115.2 months). Clinical outcome was obtained via Lysholm and International Knee Documentation Committee (IKDC) scores. Soccer players were matched 1:1 to non-soccer athletes for age, activity level, and graft type. RESULTS: A total of 180 female ACLR patients with a mean ± SD age of 19.6 ± 6.9 years met the study inclusion and exclusion criteria (90 soccer players and 90 non-soccer players). Soccer players sustained more second ACL injuries, including both graft failures (11% vs 1%; P < .01) and contralateral ACL tears (17% vs 4%; P < .01), compared with non-soccer players. Of the 67 patients who returned to soccer after ACLR (mean age, 17.5 years; range, 13-27 years), significantly more had graft tears compared with those who did not return to soccer (15% vs 0%, respectively; P = .04); however, the difference in contralateral ACL tears (19% for returning players vs 9% for those who did not return; P = .34) was not significant. Relatively older age (odds ratio, 1.5 per year; P = .03) was a significant risk factor for ACL graft tear but not for contralateral ACL injury. Both groups had similar mean Lysholm (96 vs 95) and IKDC scores (95 vs 96) at final follow-up. CONCLUSION: Twenty-eight percent of all female soccer players and 34% of those players who returned to soccer had a second ACL tear. Soccer players had an increased rate of both graft tear and contralateral ACL injury compared with similar non-soccer athletes. Older age and return to soccer were significant risk factors for graft rupture. ? 2016 The Author(s).","author":[{"family":"Allen","given":"Melissa M"},{"family":"Pareek","given":"Ayoosh"},{"family":"Krych","given":"Aaron J"},{"family":"Hewett","given":"Timothy E"},{"family":"Levy","given":"Bruce A"},{"family":"Stuart","given":"Michael J"},{"family":"Dahm","given":"Diane L"}],"citation-label":"6053540","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"6053540","invisible":false,"issue":"10","issued":{"date-parts":[["2016","6","3"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"2492-2498","suppress-author":false,"title":"Are female soccer players at an increased risk of second anterior cruciate ligament injury compared with their athletic peers?","type":"article-journal","volume":"44"}]4,ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1007/s00167-010-1172-7","First":false,"Last":false,"PMID":"20532868","abstract":"Football (soccer), the most popular sport worldwide, is associated with a high injury risk, and the knee joint is often affected. Several studies have found female players to be more susceptible to knee injury, anterior cruciate ligament (ACL) injury in particular, compared to their male counterparts. There is, however, some controversy regarding the magnitude of this risk increase and a few studies have found no differences. The influence of age and activity type on gender-related differences in injury risk is only scarcely investigated. In this paper, the literature reporting gender-specific ACL injury risk in football is reviewed. A literature search yielded 33 relevant articles that were included for review. These show that female players have a 2-3 times higher ACL injury risk compared to their male counterparts. Females also tend to sustain their ACL injury at a younger age than males, and a limiting factor in the existing literature is that age is not adjusted for in comparisons of ACL injury risk between genders. Furthermore, the risk increase in females is primarily evident during match play, but type of exposure is also rarely adjusted for. Finally, the studies included in this review share important methodological limitations that are discussed as a starting point for future research in the field.","author":[{"family":"Waldén","given":"Markus"},{"family":"H?gglund","given":"Martin"},{"family":"Werner","given":"Jonas"},{"family":"Ekstrand","given":"Jan"}],"citation-label":"1278031","container-title":"Knee Surgery, Sports Traumatology, Arthroscopy","container-title-short":"Knee Surg. Sports Traumatol. Arthrosc.","id":"1278031","invisible":false,"issue":"1","issued":{"date-parts":[["2011","1"]]},"journalAbbreviation":"Knee Surg. Sports Traumatol. Arthrosc.","page":"3-10","suppress-author":false,"title":"The epidemiology of anterior cruciate ligament injury in football (soccer): a review of the literature from a gender-related perspective.","type":"article-journal","volume":"19"}]15 Some estimates have shown that high-level female soccer players may have up to seven times the risk of sustaining an ACL injury versus a male player of the same ability level.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/0363546516648439","First":false,"Last":false,"PMID":"27261476","abstract":"BACKGROUND: Female soccer players have a well-known risk for anterior cruciate ligament (ACL) injury, but few studies have reported on second ACL injuries in this population. PURPOSE: To (1) report the rates of subsequent ACL injury (ipsilateral graft rupture or contralateral tear) in competitive female soccer players, (2) compare these rates with those of other female athletes of similar competitive level, (3) determine risk factors for second ACL injury, and (4) report clinical outcome scores in this population. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: The medical records at a single institution were reviewed for female patients who were injured during a competitive athletic event and treated with primary ACL reconstruction (ACLR) between 1998 and 2013. Patients were followed for a mean of 68.8 months postoperatively (range, 24-115.2 months). Clinical outcome was obtained via Lysholm and International Knee Documentation Committee (IKDC) scores. Soccer players were matched 1:1 to non-soccer athletes for age, activity level, and graft type. RESULTS: A total of 180 female ACLR patients with a mean ± SD age of 19.6 ± 6.9 years met the study inclusion and exclusion criteria (90 soccer players and 90 non-soccer players). Soccer players sustained more second ACL injuries, including both graft failures (11% vs 1%; P < .01) and contralateral ACL tears (17% vs 4%; P < .01), compared with non-soccer players. Of the 67 patients who returned to soccer after ACLR (mean age, 17.5 years; range, 13-27 years), significantly more had graft tears compared with those who did not return to soccer (15% vs 0%, respectively; P = .04); however, the difference in contralateral ACL tears (19% for returning players vs 9% for those who did not return; P = .34) was not significant. Relatively older age (odds ratio, 1.5 per year; P = .03) was a significant risk factor for ACL graft tear but not for contralateral ACL injury. Both groups had similar mean Lysholm (96 vs 95) and IKDC scores (95 vs 96) at final follow-up. CONCLUSION: Twenty-eight percent of all female soccer players and 34% of those players who returned to soccer had a second ACL tear. Soccer players had an increased rate of both graft tear and contralateral ACL injury compared with similar non-soccer athletes. Older age and return to soccer were significant risk factors for graft rupture. ? 2016 The Author(s).","author":[{"family":"Allen","given":"Melissa M"},{"family":"Pareek","given":"Ayoosh"},{"family":"Krych","given":"Aaron J"},{"family":"Hewett","given":"Timothy E"},{"family":"Levy","given":"Bruce A"},{"family":"Stuart","given":"Michael J"},{"family":"Dahm","given":"Diane L"}],"citation-label":"6053540","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"6053540","invisible":false,"issue":"10","issued":{"date-parts":[["2016","6","3"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"2492-2498","suppress-author":false,"title":"Are female soccer players at an increased risk of second anterior cruciate ligament injury compared with their athletic peers?","type":"article-journal","volume":"44"}]4 Numerous factors have been suggested to increase the risk of ACL injuries in females.ADDIN F1000_CSL_CITATION<~#@#~>[{"First":false,"Last":false,"PMID":"10875418","abstract":"This study examined the mechanisms of anterior cruciate ligament (ACL) injury. In the first part of the study, using a comprehensive, standardized questionnaire, 89 athletes (100 knees) were interviewed about the events surrounding their ACL injury. A noncontact mechanism was reported in 71 (72%) knees and a contact injury in 28 (28%) knees; one patient was unsure if there was any contact. Most of the injuries were sustained at footstrike with the knee close to full extension. Noncontact mechanisms were classified as sudden deceleration prior to a change of direction or landing motion, while contact injuries occurred as a result of valgus collapse of the knee. Hamstring flexibility parameters revealed a statistically higher level of laxity in the injured athletes compared with a matched group of 28 controls. In the second part of the study, videotapes of 27 separate ACL disruptions were reviewed and confirmed that most noncontact injuries occur with the knee close to extension during a sharp deceleration or landing maneuver. Because the knee is in a position to allow the extensor mechanism to strain the ACL and maximum, eccentric muscle force conditions usually apply, the quadriceps may play an important role in ACL disruption. Passive protection of the ACL by the hamstring muscles may be reduced in patients with above-average flexibility.","author":[{"family":"Boden","given":"B P"},{"family":"Dean","given":"G S"},{"family":"Feagin","given":"J A"},{"family":"Garrett","given":"W E"}],"citation-label":"3827539","container-title":"Orthopedics","container-title-short":"Orthopedics","id":"3827539","invisible":false,"issue":"6","issued":{"date-parts":[["2000","6"]]},"journalAbbreviation":"Orthopedics","page":"573-578","suppress-author":false,"title":"Mechanisms of anterior cruciate ligament injury.","type":"article-journal","volume":"23"}]7 Some of the proposed differences may be explained by anatomy. One factor that has been identified is the difference in pelvic structure and a possible increased Q angle, leading to increased genu valgus in females.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/03635465990270060301","First":false,"Last":false,"PMID":"10569353","abstract":"To prospectively evaluate the effect of neuromuscular training on the incidence of knee injury in female athletes, we monitored two groups of female athletes, one trained before sports participation and the other not trained, and a group of untrained male athletes throughout the high school soccer, volleyball, and basketball seasons. Weekly reports included the number of practice and competition exposures and mechanism of injury. There were 14 serious knee injuries in the 1263 athletes tracked through the study. Ten of 463 untrained female athletes sustained serious knee injuries (8 noncontact), 2 of 366 trained female athletes sustained serious knee injuries (0 noncontact), and 2 of 434 male athletes sustained serious knee injuries (1 noncontact). The knee injury incidence per 1000 athlete-exposures was 0.43 in untrained female athletes, 0.12 in trained female athletes, and 0.09 in male athletes (P = 0.02, chi-square analysis). Untrained female athletes had a 3.6 times higher incidence of knee injury than trained female athletes (P = 0.05) and 4.8 times higher than male athletes (P = 0.03). The incidence of knee injury in trained female athletes was not significantly different from that in untrained male athletes (P = 0.86). The difference in the incidence of noncontact injuries between the female groups was also significant (P = 0.01). This prospective study demonstrated a decreased incidence of knee injury in female athletes after a specific plyometric training program.","author":[{"family":"Hewett","given":"T E"},{"family":"Lindenfeld","given":"T N"},{"family":"Riccobene","given":"J V"},{"family":"Noyes","given":"F R"}],"citation-label":"3625077","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"3625077","invisible":false,"issue":"6","issued":{"date-parts":[["1999","12"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"699-706","suppress-author":false,"title":"The effect of neuromuscular training on the incidence of knee injury in female athletes. A prospective study.","type":"article-journal","volume":"27"}]16 Women have a slightly higher patellar tendon tibia angle near full knee extension, secondary to increased anterior-posterior dimension of the proximal tibia, which leads to increased tibiofemoral shear stress as the knee moves into knee extension, increasing strain on the ACL.ADDIN F1000_CSL_CITATION<~#@#~>[{"First":false,"Last":false,"PMID":"10875418","abstract":"This study examined the mechanisms of anterior cruciate ligament (ACL) injury. In the first part of the study, using a comprehensive, standardized questionnaire, 89 athletes (100 knees) were interviewed about the events surrounding their ACL injury. A noncontact mechanism was reported in 71 (72%) knees and a contact injury in 28 (28%) knees; one patient was unsure if there was any contact. Most of the injuries were sustained at footstrike with the knee close to full extension. Noncontact mechanisms were classified as sudden deceleration prior to a change of direction or landing motion, while contact injuries occurred as a result of valgus collapse of the knee. Hamstring flexibility parameters revealed a statistically higher level of laxity in the injured athletes compared with a matched group of 28 controls. In the second part of the study, videotapes of 27 separate ACL disruptions were reviewed and confirmed that most noncontact injuries occur with the knee close to extension during a sharp deceleration or landing maneuver. Because the knee is in a position to allow the extensor mechanism to strain the ACL and maximum, eccentric muscle force conditions usually apply, the quadriceps may play an important role in ACL disruption. Passive protection of the ACL by the hamstring muscles may be reduced in patients with above-average flexibility.","author":[{"family":"Boden","given":"B P"},{"family":"Dean","given":"G S"},{"family":"Feagin","given":"J A"},{"family":"Garrett","given":"W E"}],"citation-label":"3827539","container-title":"Orthopedics","container-title-short":"Orthopedics","id":"3827539","invisible":false,"issue":"6","issued":{"date-parts":[["2000","6"]]},"journalAbbreviation":"Orthopedics","page":"573-578","suppress-author":false,"title":"Mechanisms of anterior cruciate ligament injury.","type":"article-journal","volume":"23"}]7 This is especially problematic for female athletes who have a more upright style of play.ADDIN F1000_CSL_CITATION<~#@#~>[{"First":false,"Last":false,"PMID":"10875418","abstract":"This study examined the mechanisms of anterior cruciate ligament (ACL) injury. In the first part of the study, using a comprehensive, standardized questionnaire, 89 athletes (100 knees) were interviewed about the events surrounding their ACL injury. A noncontact mechanism was reported in 71 (72%) knees and a contact injury in 28 (28%) knees; one patient was unsure if there was any contact. Most of the injuries were sustained at footstrike with the knee close to full extension. Noncontact mechanisms were classified as sudden deceleration prior to a change of direction or landing motion, while contact injuries occurred as a result of valgus collapse of the knee. Hamstring flexibility parameters revealed a statistically higher level of laxity in the injured athletes compared with a matched group of 28 controls. In the second part of the study, videotapes of 27 separate ACL disruptions were reviewed and confirmed that most noncontact injuries occur with the knee close to extension during a sharp deceleration or landing maneuver. Because the knee is in a position to allow the extensor mechanism to strain the ACL and maximum, eccentric muscle force conditions usually apply, the quadriceps may play an important role in ACL disruption. Passive protection of the ACL by the hamstring muscles may be reduced in patients with above-average flexibility.","author":[{"family":"Boden","given":"B P"},{"family":"Dean","given":"G S"},{"family":"Feagin","given":"J A"},{"family":"Garrett","given":"W E"}],"citation-label":"3827539","container-title":"Orthopedics","container-title-short":"Orthopedics","id":"3827539","invisible":false,"issue":"6","issued":{"date-parts":[["2000","6"]]},"journalAbbreviation":"Orthopedics","page":"573-578","suppress-author":false,"title":"Mechanisms of anterior cruciate ligament injury.","type":"article-journal","volume":"23"}]7 Estrogen is correlated with increased joint laxity, thus increased risk of ligamentous injury.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/03635465990270060301","First":false,"Last":false,"PMID":"10569353","abstract":"To prospectively evaluate the effect of neuromuscular training on the incidence of knee injury in female athletes, we monitored two groups of female athletes, one trained before sports participation and the other not trained, and a group of untrained male athletes throughout the high school soccer, volleyball, and basketball seasons. Weekly reports included the number of practice and competition exposures and mechanism of injury. There were 14 serious knee injuries in the 1263 athletes tracked through the study. Ten of 463 untrained female athletes sustained serious knee injuries (8 noncontact), 2 of 366 trained female athletes sustained serious knee injuries (0 noncontact), and 2 of 434 male athletes sustained serious knee injuries (1 noncontact). The knee injury incidence per 1000 athlete-exposures was 0.43 in untrained female athletes, 0.12 in trained female athletes, and 0.09 in male athletes (P = 0.02, chi-square analysis). Untrained female athletes had a 3.6 times higher incidence of knee injury than trained female athletes (P = 0.05) and 4.8 times higher than male athletes (P = 0.03). The incidence of knee injury in trained female athletes was not significantly different from that in untrained male athletes (P = 0.86). The difference in the incidence of noncontact injuries between the female groups was also significant (P = 0.01). This prospective study demonstrated a decreased incidence of knee injury in female athletes after a specific plyometric training program.","author":[{"family":"Hewett","given":"T E"},{"family":"Lindenfeld","given":"T N"},{"family":"Riccobene","given":"J V"},{"family":"Noyes","given":"F R"}],"citation-label":"3625077","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"3625077","invisible":false,"issue":"6","issued":{"date-parts":[["1999","12"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"699-706","suppress-author":false,"title":"The effect of neuromuscular training on the incidence of knee injury in female athletes. A prospective study.","type":"article-journal","volume":"27"}]16 However, these anatomic and hormonal differences do not fully explain the discrepancy between sex-related ACL injury rates.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/03635465990270060301","First":false,"Last":false,"PMID":"10569353","abstract":"To prospectively evaluate the effect of neuromuscular training on the incidence of knee injury in female athletes, we monitored two groups of female athletes, one trained before sports participation and the other not trained, and a group of untrained male athletes throughout the high school soccer, volleyball, and basketball seasons. Weekly reports included the number of practice and competition exposures and mechanism of injury. There were 14 serious knee injuries in the 1263 athletes tracked through the study. Ten of 463 untrained female athletes sustained serious knee injuries (8 noncontact), 2 of 366 trained female athletes sustained serious knee injuries (0 noncontact), and 2 of 434 male athletes sustained serious knee injuries (1 noncontact). The knee injury incidence per 1000 athlete-exposures was 0.43 in untrained female athletes, 0.12 in trained female athletes, and 0.09 in male athletes (P = 0.02, chi-square analysis). Untrained female athletes had a 3.6 times higher incidence of knee injury than trained female athletes (P = 0.05) and 4.8 times higher than male athletes (P = 0.03). The incidence of knee injury in trained female athletes was not significantly different from that in untrained male athletes (P = 0.86). The difference in the incidence of noncontact injuries between the female groups was also significant (P = 0.01). This prospective study demonstrated a decreased incidence of knee injury in female athletes after a specific plyometric training program.","author":[{"family":"Hewett","given":"T E"},{"family":"Lindenfeld","given":"T N"},{"family":"Riccobene","given":"J V"},{"family":"Noyes","given":"F R"}],"citation-label":"3625077","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"3625077","invisible":false,"issue":"6","issued":{"date-parts":[["1999","12"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"699-706","suppress-author":false,"title":"The effect of neuromuscular training on the incidence of knee injury in female athletes. A prospective study.","type":"article-journal","volume":"27"}]16 Other factors may be related to muscle strength imbalance and movement patterns.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/03635465990270060301","First":false,"Last":false,"PMID":"10569353","abstract":"To prospectively evaluate the effect of neuromuscular training on the incidence of knee injury in female athletes, we monitored two groups of female athletes, one trained before sports participation and the other not trained, and a group of untrained male athletes throughout the high school soccer, volleyball, and basketball seasons. Weekly reports included the number of practice and competition exposures and mechanism of injury. There were 14 serious knee injuries in the 1263 athletes tracked through the study. Ten of 463 untrained female athletes sustained serious knee injuries (8 noncontact), 2 of 366 trained female athletes sustained serious knee injuries (0 noncontact), and 2 of 434 male athletes sustained serious knee injuries (1 noncontact). The knee injury incidence per 1000 athlete-exposures was 0.43 in untrained female athletes, 0.12 in trained female athletes, and 0.09 in male athletes (P = 0.02, chi-square analysis). Untrained female athletes had a 3.6 times higher incidence of knee injury than trained female athletes (P = 0.05) and 4.8 times higher than male athletes (P = 0.03). The incidence of knee injury in trained female athletes was not significantly different from that in untrained male athletes (P = 0.86). The difference in the incidence of noncontact injuries between the female groups was also significant (P = 0.01). This prospective study demonstrated a decreased incidence of knee injury in female athletes after a specific plyometric training program.","author":[{"family":"Hewett","given":"T E"},{"family":"Lindenfeld","given":"T N"},{"family":"Riccobene","given":"J V"},{"family":"Noyes","given":"F R"}],"citation-label":"3625077","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"3625077","invisible":false,"issue":"6","issued":{"date-parts":[["1999","12"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"699-706","suppress-author":false,"title":"The effect of neuromuscular training on the incidence of knee injury in female athletes. A prospective study.","type":"article-journal","volume":"27"}]16 In comparison to males, females athletes may rely more on quadriceps muscles than on hamstrings.ADDIN F1000_CSL_CITATION<~#@#~>[{"First":false,"Last":false,"PMID":"10875418","abstract":"This study examined the mechanisms of anterior cruciate ligament (ACL) injury. In the first part of the study, using a comprehensive, standardized questionnaire, 89 athletes (100 knees) were interviewed about the events surrounding their ACL injury. A noncontact mechanism was reported in 71 (72%) knees and a contact injury in 28 (28%) knees; one patient was unsure if there was any contact. Most of the injuries were sustained at footstrike with the knee close to full extension. Noncontact mechanisms were classified as sudden deceleration prior to a change of direction or landing motion, while contact injuries occurred as a result of valgus collapse of the knee. Hamstring flexibility parameters revealed a statistically higher level of laxity in the injured athletes compared with a matched group of 28 controls. In the second part of the study, videotapes of 27 separate ACL disruptions were reviewed and confirmed that most noncontact injuries occur with the knee close to extension during a sharp deceleration or landing maneuver. Because the knee is in a position to allow the extensor mechanism to strain the ACL and maximum, eccentric muscle force conditions usually apply, the quadriceps may play an important role in ACL disruption. Passive protection of the ACL by the hamstring muscles may be reduced in patients with above-average flexibility.","author":[{"family":"Boden","given":"B P"},{"family":"Dean","given":"G S"},{"family":"Feagin","given":"J A"},{"family":"Garrett","given":"W E"}],"citation-label":"3827539","container-title":"Orthopedics","container-title-short":"Orthopedics","id":"3827539","invisible":false,"issue":"6","issued":{"date-parts":[["2000","6"]]},"journalAbbreviation":"Orthopedics","page":"573-578","suppress-author":false,"title":"Mechanisms of anterior cruciate ligament injury.","type":"article-journal","volume":"23"}]7 Male athletes land from a jump with three times the knee flexor moment.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/03635465990270060301","First":false,"Last":false,"PMID":"10569353","abstract":"To prospectively evaluate the effect of neuromuscular training on the incidence of knee injury in female athletes, we monitored two groups of female athletes, one trained before sports participation and the other not trained, and a group of untrained male athletes throughout the high school soccer, volleyball, and basketball seasons. Weekly reports included the number of practice and competition exposures and mechanism of injury. There were 14 serious knee injuries in the 1263 athletes tracked through the study. Ten of 463 untrained female athletes sustained serious knee injuries (8 noncontact), 2 of 366 trained female athletes sustained serious knee injuries (0 noncontact), and 2 of 434 male athletes sustained serious knee injuries (1 noncontact). The knee injury incidence per 1000 athlete-exposures was 0.43 in untrained female athletes, 0.12 in trained female athletes, and 0.09 in male athletes (P = 0.02, chi-square analysis). Untrained female athletes had a 3.6 times higher incidence of knee injury than trained female athletes (P = 0.05) and 4.8 times higher than male athletes (P = 0.03). The incidence of knee injury in trained female athletes was not significantly different from that in untrained male athletes (P = 0.86). The difference in the incidence of noncontact injuries between the female groups was also significant (P = 0.01). This prospective study demonstrated a decreased incidence of knee injury in female athletes after a specific plyometric training program.","author":[{"family":"Hewett","given":"T E"},{"family":"Lindenfeld","given":"T N"},{"family":"Riccobene","given":"J V"},{"family":"Noyes","given":"F R"}],"citation-label":"3625077","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"3625077","invisible":false,"issue":"6","issued":{"date-parts":[["1999","12"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"699-706","suppress-author":false,"title":"The effect of neuromuscular training on the incidence of knee injury in female athletes. A prospective study.","type":"article-journal","volume":"27"}]16 A systematic review by Carson and Ford found that females land with increased knee abduction versus males, placing the knee in valgus.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/1941738111410180","First":false,"Last":false,"PMCID":"PMC3445198","PMID":"23016030","abstract":"BACKGROUND: Females suffer injuries to the anterior cruciate ligament at rates significantly higher than males. Frontal plane knee motion and load have been identified as major risk factors for anterior cruciate ligament injury and in turn have been examined extensively.\n \n \nMETHODS: A systematic review of MEDLINE, CINHAL, and SportDISCUS was performed (1982-June 2010). Criteria for inclusion were the use of 3-dimensional analyses of frontal plane knee motion and moments during landing between males and females.\n \n \nRESULTS: Twenty-seven studies met the inclusion criteria and were reviewed. Sixty-three percent of included studies identified sex differences in knee abduction when landing across a variety of landing conditions.\n \n \nCONCLUSIONS: Females appear to land with increased knee abduction motion compared with males in most biomechanics studies.","author":[{"family":"Carson","given":"Daniel W"},{"family":"Ford","given":"Kevin R"}],"citation-label":"1130005","container-title":"Sports health","container-title-short":"Sports Health","id":"1130005","invisible":false,"issue":"4","issued":{"date-parts":[["2011","7"]]},"journalAbbreviation":"Sports Health","page":"373-382","suppress-author":false,"title":"Sex differences in knee abduction during landing: a systematic review.","type":"article-journal","volume":"3"}]17 This difference is sustained across various landing movements such as single leg hop, drop landing, and vertical jumps, that are all common in high-risk sports.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/1941738111410180","First":false,"Last":false,"PMCID":"PMC3445198","PMID":"23016030","abstract":"BACKGROUND: Females suffer injuries to the anterior cruciate ligament at rates significantly higher than males. Frontal plane knee motion and load have been identified as major risk factors for anterior cruciate ligament injury and in turn have been examined extensively.\n \n \nMETHODS: A systematic review of MEDLINE, CINHAL, and SportDISCUS was performed (1982-June 2010). Criteria for inclusion were the use of 3-dimensional analyses of frontal plane knee motion and moments during landing between males and females.\n \n \nRESULTS: Twenty-seven studies met the inclusion criteria and were reviewed. Sixty-three percent of included studies identified sex differences in knee abduction when landing across a variety of landing conditions.\n \n \nCONCLUSIONS: Females appear to land with increased knee abduction motion compared with males in most biomechanics studies.","author":[{"family":"Carson","given":"Daniel W"},{"family":"Ford","given":"Kevin R"}],"citation-label":"1130005","container-title":"Sports health","container-title-short":"Sports Health","id":"1130005","invisible":false,"issue":"4","issued":{"date-parts":[["2011","7"]]},"journalAbbreviation":"Sports Health","page":"373-382","suppress-author":false,"title":"Sex differences in knee abduction during landing: a systematic review.","type":"article-journal","volume":"3"}]17 These landing mechanics may place the ACL at greater risk of injury.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/1941738111410180","First":false,"Last":false,"PMCID":"PMC3445198","PMID":"23016030","abstract":"BACKGROUND: Females suffer injuries to the anterior cruciate ligament at rates significantly higher than males. Frontal plane knee motion and load have been identified as major risk factors for anterior cruciate ligament injury and in turn have been examined extensively.\n \n \nMETHODS: A systematic review of MEDLINE, CINHAL, and SportDISCUS was performed (1982-June 2010). Criteria for inclusion were the use of 3-dimensional analyses of frontal plane knee motion and moments during landing between males and females.\n \n \nRESULTS: Twenty-seven studies met the inclusion criteria and were reviewed. Sixty-three percent of included studies identified sex differences in knee abduction when landing across a variety of landing conditions.\n \n \nCONCLUSIONS: Females appear to land with increased knee abduction motion compared with males in most biomechanics studies.","author":[{"family":"Carson","given":"Daniel W"},{"family":"Ford","given":"Kevin R"}],"citation-label":"1130005","container-title":"Sports health","container-title-short":"Sports Health","id":"1130005","invisible":false,"issue":"4","issued":{"date-parts":[["2011","7"]]},"journalAbbreviation":"Sports Health","page":"373-382","suppress-author":false,"title":"Sex differences in knee abduction during landing: a systematic review.","type":"article-journal","volume":"3"}]17 While changing anatomy and hormonal factors may not be feasible to address through an injury prevention program, programs focused on proper landing mechanics with increased knee flexion and decreased knee valgus may be especially beneficial for female athletes.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/1941738111410180","First":false,"Last":false,"PMCID":"PMC3445198","PMID":"23016030","abstract":"BACKGROUND: Females suffer injuries to the anterior cruciate ligament at rates significantly higher than males. Frontal plane knee motion and load have been identified as major risk factors for anterior cruciate ligament injury and in turn have been examined extensively.\n \n \nMETHODS: A systematic review of MEDLINE, CINHAL, and SportDISCUS was performed (1982-June 2010). Criteria for inclusion were the use of 3-dimensional analyses of frontal plane knee motion and moments during landing between males and females.\n \n \nRESULTS: Twenty-seven studies met the inclusion criteria and were reviewed. Sixty-three percent of included studies identified sex differences in knee abduction when landing across a variety of landing conditions.\n \n \nCONCLUSIONS: Females appear to land with increased knee abduction motion compared with males in most biomechanics studies.","author":[{"family":"Carson","given":"Daniel W"},{"family":"Ford","given":"Kevin R"}],"citation-label":"1130005","container-title":"Sports health","container-title-short":"Sports Health","id":"1130005","invisible":false,"issue":"4","issued":{"date-parts":[["2011","7"]]},"journalAbbreviation":"Sports Health","page":"373-382","suppress-author":false,"title":"Sex differences in knee abduction during landing: a systematic review.","type":"article-journal","volume":"3"}]17In summary, the risk factors and common mechanisms of injury for ACL injuries are complex and multifaceted. For soccer players, poor landing or cutting mechanics such as landing with minimal knee flexion and hip abduction may increase the stress placed on the ACL, thus increasing one’s risk for injuries. Sex difference in landing and cutting mechanics may partially explain the sex differences that exist regarding the risk of sustaining an ACL injury including both anatomic and movement pattern factors. Many non-contact ACL injuries have been attributed to a neuromuscular control deficit that occurs during dynamic movements.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1302/2046-3758.32.2000241","First":false,"Last":false,"PMCID":"PMC3922117","PMID":"24497504","abstract":"Injury to the anterior cruciate ligament (ACL) is one of the most devastating and frequent injuries of the knee. Surgical reconstruction is the current standard of care for treatment of ACL injuries in active patients. The widespread adoption of ACL reconstruction over primary repair was based on early perception of the limited healing capacity of the ACL. Although the majority of ACL reconstruction surgeries successfully restore gross joint stability, post-traumatic osteoarthritis is commonplace following these injuries, even with ACL reconstruction. The development of new techniques to limit the long-term clinical sequelae associated with ACL reconstruction has been the main focus of research over the past decades. The improved knowledge of healing, along with recent advances in tissue engineering and regenerative medicine, has resulted in the discovery of novel biologically augmented ACL-repair techniques that have satisfactory outcomes in preclinical studies. This instructional review provides a summary of the latest advances made in ACL repair. Cite this article: Bone Joint Res 2014;3:20-31.","author":[{"family":"Kiapour","given":"A M"},{"family":"Murray","given":"M M"}],"citation-label":"6083246","container-title":"Bone & joint research","container-title-short":"Bone Joint Res.","id":"6083246","invisible":false,"issue":"2","issued":{"date-parts":[["2014","2","4"]]},"journalAbbreviation":"Bone Joint Res.","page":"20-31","suppress-author":false,"title":"Basic science of anterior cruciate ligament injury and repair.","type":"article-journal","volume":"3"}]18 These deficits lead to increased joint loads and increased stress placed on the ACL.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1302/2046-3758.32.2000241","First":false,"Last":false,"PMCID":"PMC3922117","PMID":"24497504","abstract":"Injury to the anterior cruciate ligament (ACL) is one of the most devastating and frequent injuries of the knee. Surgical reconstruction is the current standard of care for treatment of ACL injuries in active patients. The widespread adoption of ACL reconstruction over primary repair was based on early perception of the limited healing capacity of the ACL. Although the majority of ACL reconstruction surgeries successfully restore gross joint stability, post-traumatic osteoarthritis is commonplace following these injuries, even with ACL reconstruction. The development of new techniques to limit the long-term clinical sequelae associated with ACL reconstruction has been the main focus of research over the past decades. The improved knowledge of healing, along with recent advances in tissue engineering and regenerative medicine, has resulted in the discovery of novel biologically augmented ACL-repair techniques that have satisfactory outcomes in preclinical studies. This instructional review provides a summary of the latest advances made in ACL repair. Cite this article: Bone Joint Res 2014;3:20-31.","author":[{"family":"Kiapour","given":"A M"},{"family":"Murray","given":"M M"}],"citation-label":"6083246","container-title":"Bone & joint research","container-title-short":"Bone Joint Res.","id":"6083246","invisible":false,"issue":"2","issued":{"date-parts":[["2014","2","4"]]},"journalAbbreviation":"Bone Joint Res.","page":"20-31","suppress-author":false,"title":"Basic science of anterior cruciate ligament injury and repair.","type":"article-journal","volume":"3"}]18 Hamstring to quadriceps strength ratio is often reported when evaluating the risk of ACL injuries.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1519/JSC.0b013e3181e501a6","First":false,"Last":false,"PMID":"21701286","abstract":"Knee joint injuries are a serious issue in soccer. The ability to protect the knee from injury depends largely on the strength of the hamstring relatively to the quadriceps, that is, a low hamstring/quadriceps (H/Q) strength ratio is suggested as a risk factor. Although maximal muscle strength (MVC) has often been used to evaluate the H/Q ratio, the ability to rapidly develop force (rate of force development [RFD]) is more relevant in relation to fast dynamic movements. The aim of this study was to introduce and investigate a rapid RFD H/Q strength ratio compared with the traditional MVC H/Q strength ratio in elite soccer players. Twenty-three elite soccer players (11 women, 12 men) performed maximal voluntary static contraction for the hamstring and quadriceps in an isokinetic dynamometer, from which the maximal muscles strength (MVC) and RFD were extracted. Test-retest reliability for the RFD H/Q ratio was high (intraclass correlation coefficient = 0.664-0.933). The initial contraction phase up to 50 milliseconds from the onset of contraction showed a low RFD H/Q ratio compared to the MVC H/Q ratio (p < 0.001). These results suggest a reduced potential for knee joint stabilization during the very initial phase of muscle contraction. Two female players-both with a markedly low RFD H/Q ratio, but a normal MVC H/Q ratio, compared with the group mean-sustained ACL rupture at a later occasion. The high reliability of the new RFD H/Q strength ratio indicates that the method is a relevant tool in standardized clinical evaluation of the knee joint agonist-antagonist relationship.","author":[{"family":"Zebis","given":"Mette K"},{"family":"Andersen","given":"Lars L"},{"family":"Ellingsgaard","given":"Helga"},{"family":"Aagaard","given":"Per"}],"citation-label":"3625069","container-title":"Journal of Strength and Conditioning Research","container-title-short":"J. Strength Cond. Res.","id":"3625069","invisible":false,"issue":"7","issued":{"date-parts":[["2011","7"]]},"journalAbbreviation":"J. Strength Cond. Res.","page":"1989-1993","suppress-author":false,"title":"Rapid hamstring/quadriceps force capacity in male vs. female elite soccer players.","type":"article-journal","volume":"25"}]19 Hamstrings can serve a dynamic stabilizer to help protect the ACL strain by providing a posterior force on the tibia.ADDIN F1000_CSL_CITATION<~#@#~>[{"First":false,"Last":false,"PMID":"10875418","abstract":"This study examined the mechanisms of anterior cruciate ligament (ACL) injury. In the first part of the study, using a comprehensive, standardized questionnaire, 89 athletes (100 knees) were interviewed about the events surrounding their ACL injury. A noncontact mechanism was reported in 71 (72%) knees and a contact injury in 28 (28%) knees; one patient was unsure if there was any contact. Most of the injuries were sustained at footstrike with the knee close to full extension. Noncontact mechanisms were classified as sudden deceleration prior to a change of direction or landing motion, while contact injuries occurred as a result of valgus collapse of the knee. Hamstring flexibility parameters revealed a statistically higher level of laxity in the injured athletes compared with a matched group of 28 controls. In the second part of the study, videotapes of 27 separate ACL disruptions were reviewed and confirmed that most noncontact injuries occur with the knee close to extension during a sharp deceleration or landing maneuver. Because the knee is in a position to allow the extensor mechanism to strain the ACL and maximum, eccentric muscle force conditions usually apply, the quadriceps may play an important role in ACL disruption. Passive protection of the ACL by the hamstring muscles may be reduced in patients with above-average flexibility.","author":[{"family":"Boden","given":"B P"},{"family":"Dean","given":"G S"},{"family":"Feagin","given":"J A"},{"family":"Garrett","given":"W E"}],"citation-label":"3827539","container-title":"Orthopedics","container-title-short":"Orthopedics","id":"3827539","invisible":false,"issue":"6","issued":{"date-parts":[["2000","6"]]},"journalAbbreviation":"Orthopedics","page":"573-578","suppress-author":false,"title":"Mechanisms of anterior cruciate ligament injury.","type":"article-journal","volume":"23"}]7 The ability to rapidly develop hamstring force during dynamic movements, such as cutting in soccer can be important for stress shielding the ACL.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1519/JSC.0b013e3181e501a6","First":false,"Last":false,"PMID":"21701286","abstract":"Knee joint injuries are a serious issue in soccer. The ability to protect the knee from injury depends largely on the strength of the hamstring relatively to the quadriceps, that is, a low hamstring/quadriceps (H/Q) strength ratio is suggested as a risk factor. Although maximal muscle strength (MVC) has often been used to evaluate the H/Q ratio, the ability to rapidly develop force (rate of force development [RFD]) is more relevant in relation to fast dynamic movements. The aim of this study was to introduce and investigate a rapid RFD H/Q strength ratio compared with the traditional MVC H/Q strength ratio in elite soccer players. Twenty-three elite soccer players (11 women, 12 men) performed maximal voluntary static contraction for the hamstring and quadriceps in an isokinetic dynamometer, from which the maximal muscles strength (MVC) and RFD were extracted. Test-retest reliability for the RFD H/Q ratio was high (intraclass correlation coefficient = 0.664-0.933). The initial contraction phase up to 50 milliseconds from the onset of contraction showed a low RFD H/Q ratio compared to the MVC H/Q ratio (p < 0.001). These results suggest a reduced potential for knee joint stabilization during the very initial phase of muscle contraction. Two female players-both with a markedly low RFD H/Q ratio, but a normal MVC H/Q ratio, compared with the group mean-sustained ACL rupture at a later occasion. The high reliability of the new RFD H/Q strength ratio indicates that the method is a relevant tool in standardized clinical evaluation of the knee joint agonist-antagonist relationship.","author":[{"family":"Zebis","given":"Mette K"},{"family":"Andersen","given":"Lars L"},{"family":"Ellingsgaard","given":"Helga"},{"family":"Aagaard","given":"Per"}],"citation-label":"3625069","container-title":"Journal of Strength and Conditioning Research","container-title-short":"J. Strength Cond. Res.","id":"3625069","invisible":false,"issue":"7","issued":{"date-parts":[["2011","7"]]},"journalAbbreviation":"J. Strength Cond. Res.","page":"1989-1993","suppress-author":false,"title":"Rapid hamstring/quadriceps force capacity in male vs. female elite soccer players.","type":"article-journal","volume":"25"}]19 Interventions aimed at improving knee and landing mechanics, increase neuromuscular control at the knee joint and strengthening hamstrings may theoretically reduce one’s risk of sustaining an ACL injury, especially if many of the modifiable risk factors are present. Injury prevention programs: Several injury prevention programs aim to reduce the incidence of knee and ACL related injuries. According to a recently published Clinical Practice Guideline by Arundale et al., all soccer players should perform exercise focused injury prevention programs to reduce the risk of significant knee injuries, including ACL injuries.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.2519/jospt.2018.0303","First":false,"Last":false,"PMID":"30170521","abstract":"The Academy of Orthopaedic Physical Therapy and the American Academy of Sports Physical Therapy have an ongoing effort to create evidence-based clinical practice guidelines (CPGs) for orthopaedic and sports physical therapy management and prevention of musculoskeletal impairments described in the World Health Organization's International Classification of Functioning, Disability and Health (ICF). This particular guideline focuses on the exercise-based prevention of knee injuries. J Orthop Sports Phys Ther. 2018;48(9):A1-A42. doi:10.2519/jospt.2018.0303.","author":[{"family":"Arundale","given":"Amelia J H"},{"family":"Bizzini","given":"Mario"},{"family":"Giordano","given":"Airelle"},{"family":"Hewett","given":"Timothy E"},{"family":"Logerstedt","given":"David S"},{"family":"Mandelbaum","given":"Bert"},{"family":"Scalzitti","given":"David A"},{"family":"Silvers-Granelli","given":"Holly"},{"family":"Snyder-Mackler","given":"Lynn"}],"citation-label":"6006049","container-title":"The Journal of Orthopaedic and Sports Physical Therapy","container-title-short":"J. Orthop. Sports Phys. Ther.","id":"6006049","invisible":false,"issue":"9","issued":{"date-parts":[["2018","9"]]},"journalAbbreviation":"J. Orthop. Sports Phys. Ther.","page":"A1-A42","suppress-author":false,"title":"Exercise-Based Knee and Anterior Cruciate Ligament Injury Prevention.","type":"article-journal","volume":"48"}]20 They recommend the utilization of two specific training program, the Sportsmetrics protocol or the protocol utilized by Caraffa et al.ADDIN F1000_CSL_CITATION<~#@#~>[{"First":false,"Last":false,"PMID":"8963746","abstract":"Proprioceptive training has been shown to reduce the incidence of ankle sprains in different sports. It can also improve rehabilitation after anterior cruciate ligament (ACL) injuries whether treated operatively or nonoperatively. Since ACL injuries lead to long absence from sports and are one of the main causes of permanent sports disability, it is essential to try to prevent them. In a prospective controlled study of 600 soccer players in 40 semiprofessional or amateur teams, we studied the possible preventive effect of a gradually increasing proprioceptive training on four different types of wobble-boards during three soccer seasons. Three hundred players were instructed to train 20 min per day with 5 different phases of increasing difficulty. The first phase consisted of balance training without any balance board; phase 2 of training on a rectangular balance board; phase 3 of training on a round board; phase 4 of training on a combined round and rectangular board; phase 5 of training on a so-called BABS board. A control group of 300 players from other, comparable teams trained \"normally\" and received no special balance training. Both groups were observed for three whole soccer seasons, and possible ACL lesions were diagnosed by clinical examination, KT-1000 measurements, magnetic resonance imaging or computed tomography, and arthroscopy. We found an incidence of 1.15 ACL injuries per team per year in the proprioceptively trained group (P < 0.001). Proprioceptive training can thus significantly reduce the incidence of ACL injuries in soccer players.","author":[{"family":"Caraffa","given":"A"},{"family":"Cerulli","given":"G"},{"family":"Projetti","given":"M"},{"family":"Aisa","given":"G"},{"family":"Rizzo","given":"A"}],"citation-label":"6072844","container-title":"Knee Surgery, Sports Traumatology, Arthroscopy","container-title-short":"Knee Surg. Sports Traumatol. Arthrosc.","id":"6072844","invisible":false,"issue":"1","issued":{"date-parts":[["1996"]]},"journalAbbreviation":"Knee Surg. Sports Traumatol. Arthrosc.","page":"19-21","suppress-author":false,"title":"Prevention of anterior cruciate ligament injuries in soccer. A prospective controlled study of proprioceptive training.","type":"article-journal","volume":"4"}]21, to reduce the risk for ACL injuries among soccer players.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.2519/jospt.2018.0303","First":false,"Last":false,"PMID":"30170521","abstract":"The Academy of Orthopaedic Physical Therapy and the American Academy of Sports Physical Therapy have an ongoing effort to create evidence-based clinical practice guidelines (CPGs) for orthopaedic and sports physical therapy management and prevention of musculoskeletal impairments described in the World Health Organization's International Classification of Functioning, Disability and Health (ICF). This particular guideline focuses on the exercise-based prevention of knee injuries. J Orthop Sports Phys Ther. 2018;48(9):A1-A42. doi:10.2519/jospt.2018.0303.","author":[{"family":"Arundale","given":"Amelia J H"},{"family":"Bizzini","given":"Mario"},{"family":"Giordano","given":"Airelle"},{"family":"Hewett","given":"Timothy E"},{"family":"Logerstedt","given":"David S"},{"family":"Mandelbaum","given":"Bert"},{"family":"Scalzitti","given":"David A"},{"family":"Silvers-Granelli","given":"Holly"},{"family":"Snyder-Mackler","given":"Lynn"}],"citation-label":"6006049","container-title":"The Journal of Orthopaedic and Sports Physical Therapy","container-title-short":"J. Orthop. Sports Phys. Ther.","id":"6006049","invisible":false,"issue":"9","issued":{"date-parts":[["2018","9"]]},"journalAbbreviation":"J. Orthop. Sports Phys. Ther.","page":"A1-A42","suppress-author":false,"title":"Exercise-Based Knee and Anterior Cruciate Ligament Injury Prevention.","type":"article-journal","volume":"48"}]20Caraffa et al. utilized proprioceptive training as an intervention to reduce ACL injuries among soccer players.ADDIN F1000_CSL_CITATION<~#@#~>[{"First":false,"Last":false,"PMID":"8963746","abstract":"Proprioceptive training has been shown to reduce the incidence of ankle sprains in different sports. It can also improve rehabilitation after anterior cruciate ligament (ACL) injuries whether treated operatively or nonoperatively. Since ACL injuries lead to long absence from sports and are one of the main causes of permanent sports disability, it is essential to try to prevent them. In a prospective controlled study of 600 soccer players in 40 semiprofessional or amateur teams, we studied the possible preventive effect of a gradually increasing proprioceptive training on four different types of wobble-boards during three soccer seasons. Three hundred players were instructed to train 20 min per day with 5 different phases of increasing difficulty. The first phase consisted of balance training without any balance board; phase 2 of training on a rectangular balance board; phase 3 of training on a round board; phase 4 of training on a combined round and rectangular board; phase 5 of training on a so-called BABS board. A control group of 300 players from other, comparable teams trained \"normally\" and received no special balance training. Both groups were observed for three whole soccer seasons, and possible ACL lesions were diagnosed by clinical examination, KT-1000 measurements, magnetic resonance imaging or computed tomography, and arthroscopy. We found an incidence of 1.15 ACL injuries per team per year in the proprioceptively trained group (P < 0.001). Proprioceptive training can thus significantly reduce the incidence of ACL injuries in soccer players.","author":[{"family":"Caraffa","given":"A"},{"family":"Cerulli","given":"G"},{"family":"Projetti","given":"M"},{"family":"Aisa","given":"G"},{"family":"Rizzo","given":"A"}],"citation-label":"6072844","container-title":"Knee Surgery, Sports Traumatology, Arthroscopy","container-title-short":"Knee Surg. Sports Traumatol. Arthrosc.","id":"6072844","invisible":false,"issue":"1","issued":{"date-parts":[["1996"]]},"journalAbbreviation":"Knee Surg. Sports Traumatol. Arthrosc.","page":"19-21","suppress-author":false,"title":"Prevention of anterior cruciate ligament injuries in soccer. A prospective controlled study of proprioceptive training.","type":"article-journal","volume":"4"}]21 Caraffa et al. hypothesized that since proprioceptive training has been shown to reduce the risk of ankle injuries and is a component of ACL rehabilitation, it may serve as an intervention to decrease the risk of ACL injuries among soccer players.ADDIN F1000_CSL_CITATION<~#@#~>[{"First":false,"Last":false,"PMID":"8963746","abstract":"Proprioceptive training has been shown to reduce the incidence of ankle sprains in different sports. It can also improve rehabilitation after anterior cruciate ligament (ACL) injuries whether treated operatively or nonoperatively. Since ACL injuries lead to long absence from sports and are one of the main causes of permanent sports disability, it is essential to try to prevent them. In a prospective controlled study of 600 soccer players in 40 semiprofessional or amateur teams, we studied the possible preventive effect of a gradually increasing proprioceptive training on four different types of wobble-boards during three soccer seasons. Three hundred players were instructed to train 20 min per day with 5 different phases of increasing difficulty. The first phase consisted of balance training without any balance board; phase 2 of training on a rectangular balance board; phase 3 of training on a round board; phase 4 of training on a combined round and rectangular board; phase 5 of training on a so-called BABS board. A control group of 300 players from other, comparable teams trained \"normally\" and received no special balance training. Both groups were observed for three whole soccer seasons, and possible ACL lesions were diagnosed by clinical examination, KT-1000 measurements, magnetic resonance imaging or computed tomography, and arthroscopy. We found an incidence of 1.15 ACL injuries per team per year in the proprioceptively trained group (P < 0.001). Proprioceptive training can thus significantly reduce the incidence of ACL injuries in soccer players.","author":[{"family":"Caraffa","given":"A"},{"family":"Cerulli","given":"G"},{"family":"Projetti","given":"M"},{"family":"Aisa","given":"G"},{"family":"Rizzo","given":"A"}],"citation-label":"6072844","container-title":"Knee Surgery, Sports Traumatology, Arthroscopy","container-title-short":"Knee Surg. Sports Traumatol. Arthrosc.","id":"6072844","invisible":false,"issue":"1","issued":{"date-parts":[["1996"]]},"journalAbbreviation":"Knee Surg. Sports Traumatol. Arthrosc.","page":"19-21","suppress-author":false,"title":"Prevention of anterior cruciate ligament injuries in soccer. A prospective controlled study of proprioceptive training.","type":"article-journal","volume":"4"}]21 Their specific protocol is included below (appendix 5).ADDIN F1000_CSL_CITATION<~#@#~>[{"First":false,"Last":false,"PMID":"8963746","abstract":"Proprioceptive training has been shown to reduce the incidence of ankle sprains in different sports. It can also improve rehabilitation after anterior cruciate ligament (ACL) injuries whether treated operatively or nonoperatively. Since ACL injuries lead to long absence from sports and are one of the main causes of permanent sports disability, it is essential to try to prevent them. In a prospective controlled study of 600 soccer players in 40 semiprofessional or amateur teams, we studied the possible preventive effect of a gradually increasing proprioceptive training on four different types of wobble-boards during three soccer seasons. Three hundred players were instructed to train 20 min per day with 5 different phases of increasing difficulty. The first phase consisted of balance training without any balance board; phase 2 of training on a rectangular balance board; phase 3 of training on a round board; phase 4 of training on a combined round and rectangular board; phase 5 of training on a so-called BABS board. A control group of 300 players from other, comparable teams trained \"normally\" and received no special balance training. Both groups were observed for three whole soccer seasons, and possible ACL lesions were diagnosed by clinical examination, KT-1000 measurements, magnetic resonance imaging or computed tomography, and arthroscopy. We found an incidence of 1.15 ACL injuries per team per year in the proprioceptively trained group (P < 0.001). Proprioceptive training can thus significantly reduce the incidence of ACL injuries in soccer players.","author":[{"family":"Caraffa","given":"A"},{"family":"Cerulli","given":"G"},{"family":"Projetti","given":"M"},{"family":"Aisa","given":"G"},{"family":"Rizzo","given":"A"}],"citation-label":"6072844","container-title":"Knee Surgery, Sports Traumatology, Arthroscopy","container-title-short":"Knee Surg. Sports Traumatol. Arthrosc.","id":"6072844","invisible":false,"issue":"1","issued":{"date-parts":[["1996"]]},"journalAbbreviation":"Knee Surg. Sports Traumatol. Arthrosc.","page":"19-21","suppress-author":false,"title":"Prevention of anterior cruciate ligament injuries in soccer. A prospective controlled study of proprioceptive training.","type":"article-journal","volume":"4"}]21 The Caffaffa et al. protocol included a multiphase training where athletes performed balance training 20 minutes a day.ADDIN F1000_CSL_CITATION<~#@#~>[{"First":false,"Last":false,"PMID":"8963746","abstract":"Proprioceptive training has been shown to reduce the incidence of ankle sprains in different sports. It can also improve rehabilitation after anterior cruciate ligament (ACL) injuries whether treated operatively or nonoperatively. Since ACL injuries lead to long absence from sports and are one of the main causes of permanent sports disability, it is essential to try to prevent them. In a prospective controlled study of 600 soccer players in 40 semiprofessional or amateur teams, we studied the possible preventive effect of a gradually increasing proprioceptive training on four different types of wobble-boards during three soccer seasons. Three hundred players were instructed to train 20 min per day with 5 different phases of increasing difficulty. The first phase consisted of balance training without any balance board; phase 2 of training on a rectangular balance board; phase 3 of training on a round board; phase 4 of training on a combined round and rectangular board; phase 5 of training on a so-called BABS board. A control group of 300 players from other, comparable teams trained \"normally\" and received no special balance training. Both groups were observed for three whole soccer seasons, and possible ACL lesions were diagnosed by clinical examination, KT-1000 measurements, magnetic resonance imaging or computed tomography, and arthroscopy. We found an incidence of 1.15 ACL injuries per team per year in the proprioceptively trained group (P < 0.001). Proprioceptive training can thus significantly reduce the incidence of ACL injuries in soccer players.","author":[{"family":"Caraffa","given":"A"},{"family":"Cerulli","given":"G"},{"family":"Projetti","given":"M"},{"family":"Aisa","given":"G"},{"family":"Rizzo","given":"A"}],"citation-label":"6072844","container-title":"Knee Surgery, Sports Traumatology, Arthroscopy","container-title-short":"Knee Surg. Sports Traumatol. Arthrosc.","id":"6072844","invisible":false,"issue":"1","issued":{"date-parts":[["1996"]]},"journalAbbreviation":"Knee Surg. Sports Traumatol. Arthrosc.","page":"19-21","suppress-author":false,"title":"Prevention of anterior cruciate ligament injuries in soccer. A prospective controlled study of proprioceptive training.","type":"article-journal","volume":"4"}]21 The protocol consists of the performance of single leg stance for 2.5 minutes, four times a day. The difficulty of the stance exercise increases utilizing various balance boards in phases 2-5.ADDIN F1000_CSL_CITATION<~#@#~>[{"First":false,"Last":false,"PMID":"8963746","abstract":"Proprioceptive training has been shown to reduce the incidence of ankle sprains in different sports. It can also improve rehabilitation after anterior cruciate ligament (ACL) injuries whether treated operatively or nonoperatively. Since ACL injuries lead to long absence from sports and are one of the main causes of permanent sports disability, it is essential to try to prevent them. In a prospective controlled study of 600 soccer players in 40 semiprofessional or amateur teams, we studied the possible preventive effect of a gradually increasing proprioceptive training on four different types of wobble-boards during three soccer seasons. Three hundred players were instructed to train 20 min per day with 5 different phases of increasing difficulty. The first phase consisted of balance training without any balance board; phase 2 of training on a rectangular balance board; phase 3 of training on a round board; phase 4 of training on a combined round and rectangular board; phase 5 of training on a so-called BABS board. A control group of 300 players from other, comparable teams trained \"normally\" and received no special balance training. Both groups were observed for three whole soccer seasons, and possible ACL lesions were diagnosed by clinical examination, KT-1000 measurements, magnetic resonance imaging or computed tomography, and arthroscopy. We found an incidence of 1.15 ACL injuries per team per year in the proprioceptively trained group (P < 0.001). Proprioceptive training can thus significantly reduce the incidence of ACL injuries in soccer players.","author":[{"family":"Caraffa","given":"A"},{"family":"Cerulli","given":"G"},{"family":"Projetti","given":"M"},{"family":"Aisa","given":"G"},{"family":"Rizzo","given":"A"}],"citation-label":"6072844","container-title":"Knee Surgery, Sports Traumatology, Arthroscopy","container-title-short":"Knee Surg. Sports Traumatol. Arthrosc.","id":"6072844","invisible":false,"issue":"1","issued":{"date-parts":[["1996"]]},"journalAbbreviation":"Knee Surg. Sports Traumatol. Arthrosc.","page":"19-21","suppress-author":false,"title":"Prevention of anterior cruciate ligament injuries in soccer. A prospective controlled study of proprioceptive training.","type":"article-journal","volume":"4"}]21 Caraffa et al. employed this proprioceptive training program in a prospective cluster controlled study of 40 soccer teams, 600 players total to determine its impact on the incidence of ACL injuries.ADDIN F1000_CSL_CITATION<~#@#~>[{"First":false,"Last":false,"PMID":"8963746","abstract":"Proprioceptive training has been shown to reduce the incidence of ankle sprains in different sports. It can also improve rehabilitation after anterior cruciate ligament (ACL) injuries whether treated operatively or nonoperatively. Since ACL injuries lead to long absence from sports and are one of the main causes of permanent sports disability, it is essential to try to prevent them. In a prospective controlled study of 600 soccer players in 40 semiprofessional or amateur teams, we studied the possible preventive effect of a gradually increasing proprioceptive training on four different types of wobble-boards during three soccer seasons. Three hundred players were instructed to train 20 min per day with 5 different phases of increasing difficulty. The first phase consisted of balance training without any balance board; phase 2 of training on a rectangular balance board; phase 3 of training on a round board; phase 4 of training on a combined round and rectangular board; phase 5 of training on a so-called BABS board. A control group of 300 players from other, comparable teams trained \"normally\" and received no special balance training. Both groups were observed for three whole soccer seasons, and possible ACL lesions were diagnosed by clinical examination, KT-1000 measurements, magnetic resonance imaging or computed tomography, and arthroscopy. We found an incidence of 1.15 ACL injuries per team per year in the proprioceptively trained group (P < 0.001). Proprioceptive training can thus significantly reduce the incidence of ACL injuries in soccer players.","author":[{"family":"Caraffa","given":"A"},{"family":"Cerulli","given":"G"},{"family":"Projetti","given":"M"},{"family":"Aisa","given":"G"},{"family":"Rizzo","given":"A"}],"citation-label":"6072844","container-title":"Knee Surgery, Sports Traumatology, Arthroscopy","container-title-short":"Knee Surg. Sports Traumatol. Arthrosc.","id":"6072844","invisible":false,"issue":"1","issued":{"date-parts":[["1996"]]},"journalAbbreviation":"Knee Surg. Sports Traumatol. Arthrosc.","page":"19-21","suppress-author":false,"title":"Prevention of anterior cruciate ligament injuries in soccer. A prospective controlled study of proprioceptive training.","type":"article-journal","volume":"4"}]21 They found that their intervention protocol led to a statistically significant reduction in the number of ACL injuries per team during a single soccer season versus a control (0.15 injuries per team/season versus 1.15 injuries per team/season respectively).ADDIN F1000_CSL_CITATION<~#@#~>[{"First":false,"Last":false,"PMID":"8963746","abstract":"Proprioceptive training has been shown to reduce the incidence of ankle sprains in different sports. It can also improve rehabilitation after anterior cruciate ligament (ACL) injuries whether treated operatively or nonoperatively. Since ACL injuries lead to long absence from sports and are one of the main causes of permanent sports disability, it is essential to try to prevent them. In a prospective controlled study of 600 soccer players in 40 semiprofessional or amateur teams, we studied the possible preventive effect of a gradually increasing proprioceptive training on four different types of wobble-boards during three soccer seasons. Three hundred players were instructed to train 20 min per day with 5 different phases of increasing difficulty. The first phase consisted of balance training without any balance board; phase 2 of training on a rectangular balance board; phase 3 of training on a round board; phase 4 of training on a combined round and rectangular board; phase 5 of training on a so-called BABS board. A control group of 300 players from other, comparable teams trained \"normally\" and received no special balance training. Both groups were observed for three whole soccer seasons, and possible ACL lesions were diagnosed by clinical examination, KT-1000 measurements, magnetic resonance imaging or computed tomography, and arthroscopy. We found an incidence of 1.15 ACL injuries per team per year in the proprioceptively trained group (P < 0.001). Proprioceptive training can thus significantly reduce the incidence of ACL injuries in soccer players.","author":[{"family":"Caraffa","given":"A"},{"family":"Cerulli","given":"G"},{"family":"Projetti","given":"M"},{"family":"Aisa","given":"G"},{"family":"Rizzo","given":"A"}],"citation-label":"6072844","container-title":"Knee Surgery, Sports Traumatology, Arthroscopy","container-title-short":"Knee Surg. Sports Traumatol. Arthrosc.","id":"6072844","invisible":false,"issue":"1","issued":{"date-parts":[["1996"]]},"journalAbbreviation":"Knee Surg. Sports Traumatol. Arthrosc.","page":"19-21","suppress-author":false,"title":"Prevention of anterior cruciate ligament injuries in soccer. A prospective controlled study of proprioceptive training.","type":"article-journal","volume":"4"}]21 Hewett et al. proposed that given the high incidence of noncontact ACL injuries that occur during landing from a jump, especially in female athletes, an ACL injury intervention program should focus on jump training.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/03635465990270060301","First":false,"Last":false,"PMID":"10569353","abstract":"To prospectively evaluate the effect of neuromuscular training on the incidence of knee injury in female athletes, we monitored two groups of female athletes, one trained before sports participation and the other not trained, and a group of untrained male athletes throughout the high school soccer, volleyball, and basketball seasons. Weekly reports included the number of practice and competition exposures and mechanism of injury. There were 14 serious knee injuries in the 1263 athletes tracked through the study. Ten of 463 untrained female athletes sustained serious knee injuries (8 noncontact), 2 of 366 trained female athletes sustained serious knee injuries (0 noncontact), and 2 of 434 male athletes sustained serious knee injuries (1 noncontact). The knee injury incidence per 1000 athlete-exposures was 0.43 in untrained female athletes, 0.12 in trained female athletes, and 0.09 in male athletes (P = 0.02, chi-square analysis). Untrained female athletes had a 3.6 times higher incidence of knee injury than trained female athletes (P = 0.05) and 4.8 times higher than male athletes (P = 0.03). The incidence of knee injury in trained female athletes was not significantly different from that in untrained male athletes (P = 0.86). The difference in the incidence of noncontact injuries between the female groups was also significant (P = 0.01). This prospective study demonstrated a decreased incidence of knee injury in female athletes after a specific plyometric training program.","author":[{"family":"Hewett","given":"T E"},{"family":"Lindenfeld","given":"T N"},{"family":"Riccobene","given":"J V"},{"family":"Noyes","given":"F R"}],"citation-label":"3625077","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"3625077","invisible":false,"issue":"6","issued":{"date-parts":[["1999","12"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"699-706","suppress-author":false,"title":"The effect of neuromuscular training on the incidence of knee injury in female athletes. A prospective study.","type":"article-journal","volume":"27"}]16 Further, strengthening the muscular surrounding the knee may help reduce the risk of knee injuries.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/03635465990270060301","First":false,"Last":false,"PMID":"10569353","abstract":"To prospectively evaluate the effect of neuromuscular training on the incidence of knee injury in female athletes, we monitored two groups of female athletes, one trained before sports participation and the other not trained, and a group of untrained male athletes throughout the high school soccer, volleyball, and basketball seasons. Weekly reports included the number of practice and competition exposures and mechanism of injury. There were 14 serious knee injuries in the 1263 athletes tracked through the study. Ten of 463 untrained female athletes sustained serious knee injuries (8 noncontact), 2 of 366 trained female athletes sustained serious knee injuries (0 noncontact), and 2 of 434 male athletes sustained serious knee injuries (1 noncontact). The knee injury incidence per 1000 athlete-exposures was 0.43 in untrained female athletes, 0.12 in trained female athletes, and 0.09 in male athletes (P = 0.02, chi-square analysis). Untrained female athletes had a 3.6 times higher incidence of knee injury than trained female athletes (P = 0.05) and 4.8 times higher than male athletes (P = 0.03). The incidence of knee injury in trained female athletes was not significantly different from that in untrained male athletes (P = 0.86). The difference in the incidence of noncontact injuries between the female groups was also significant (P = 0.01). This prospective study demonstrated a decreased incidence of knee injury in female athletes after a specific plyometric training program.","author":[{"family":"Hewett","given":"T E"},{"family":"Lindenfeld","given":"T N"},{"family":"Riccobene","given":"J V"},{"family":"Noyes","given":"F R"}],"citation-label":"3625077","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"3625077","invisible":false,"issue":"6","issued":{"date-parts":[["1999","12"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"699-706","suppress-author":false,"title":"The effect of neuromuscular training on the incidence of knee injury in female athletes. A prospective study.","type":"article-journal","volume":"27"}]16 This hypothesis is tested through the Sportsmetrics prevention program. The Sportsmetrics prevention program includes flexibility, running, strength, core stability and plyometrics.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/03635465990270060301","First":false,"Last":false,"PMID":"10569353","abstract":"To prospectively evaluate the effect of neuromuscular training on the incidence of knee injury in female athletes, we monitored two groups of female athletes, one trained before sports participation and the other not trained, and a group of untrained male athletes throughout the high school soccer, volleyball, and basketball seasons. Weekly reports included the number of practice and competition exposures and mechanism of injury. There were 14 serious knee injuries in the 1263 athletes tracked through the study. Ten of 463 untrained female athletes sustained serious knee injuries (8 noncontact), 2 of 366 trained female athletes sustained serious knee injuries (0 noncontact), and 2 of 434 male athletes sustained serious knee injuries (1 noncontact). The knee injury incidence per 1000 athlete-exposures was 0.43 in untrained female athletes, 0.12 in trained female athletes, and 0.09 in male athletes (P = 0.02, chi-square analysis). Untrained female athletes had a 3.6 times higher incidence of knee injury than trained female athletes (P = 0.05) and 4.8 times higher than male athletes (P = 0.03). The incidence of knee injury in trained female athletes was not significantly different from that in untrained male athletes (P = 0.86). The difference in the incidence of noncontact injuries between the female groups was also significant (P = 0.01). This prospective study demonstrated a decreased incidence of knee injury in female athletes after a specific plyometric training program.","author":[{"family":"Hewett","given":"T E"},{"family":"Lindenfeld","given":"T N"},{"family":"Riccobene","given":"J V"},{"family":"Noyes","given":"F R"}],"citation-label":"3625077","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"3625077","invisible":false,"issue":"6","issued":{"date-parts":[["1999","12"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"699-706","suppress-author":false,"title":"The effect of neuromuscular training on the incidence of knee injury in female athletes. A prospective study.","type":"article-journal","volume":"27"}]16 The protocol includes several jumping exercises with a focus on landing technique in addition to full body strengthening and stretching. It consists of 3 phases, each lasting two weeks.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/03635465990270060301","First":false,"Last":false,"PMID":"10569353","abstract":"To prospectively evaluate the effect of neuromuscular training on the incidence of knee injury in female athletes, we monitored two groups of female athletes, one trained before sports participation and the other not trained, and a group of untrained male athletes throughout the high school soccer, volleyball, and basketball seasons. Weekly reports included the number of practice and competition exposures and mechanism of injury. There were 14 serious knee injuries in the 1263 athletes tracked through the study. Ten of 463 untrained female athletes sustained serious knee injuries (8 noncontact), 2 of 366 trained female athletes sustained serious knee injuries (0 noncontact), and 2 of 434 male athletes sustained serious knee injuries (1 noncontact). The knee injury incidence per 1000 athlete-exposures was 0.43 in untrained female athletes, 0.12 in trained female athletes, and 0.09 in male athletes (P = 0.02, chi-square analysis). Untrained female athletes had a 3.6 times higher incidence of knee injury than trained female athletes (P = 0.05) and 4.8 times higher than male athletes (P = 0.03). The incidence of knee injury in trained female athletes was not significantly different from that in untrained male athletes (P = 0.86). The difference in the incidence of noncontact injuries between the female groups was also significant (P = 0.01). This prospective study demonstrated a decreased incidence of knee injury in female athletes after a specific plyometric training program.","author":[{"family":"Hewett","given":"T E"},{"family":"Lindenfeld","given":"T N"},{"family":"Riccobene","given":"J V"},{"family":"Noyes","given":"F R"}],"citation-label":"3625077","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"3625077","invisible":false,"issue":"6","issued":{"date-parts":[["1999","12"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"699-706","suppress-author":false,"title":"The effect of neuromuscular training on the incidence of knee injury in female athletes. A prospective study.","type":"article-journal","volume":"27"}]16 The number of reps of each exercise increases between the first and second week in each phase.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/03635465990270060301","First":false,"Last":false,"PMID":"10569353","abstract":"To prospectively evaluate the effect of neuromuscular training on the incidence of knee injury in female athletes, we monitored two groups of female athletes, one trained before sports participation and the other not trained, and a group of untrained male athletes throughout the high school soccer, volleyball, and basketball seasons. Weekly reports included the number of practice and competition exposures and mechanism of injury. There were 14 serious knee injuries in the 1263 athletes tracked through the study. Ten of 463 untrained female athletes sustained serious knee injuries (8 noncontact), 2 of 366 trained female athletes sustained serious knee injuries (0 noncontact), and 2 of 434 male athletes sustained serious knee injuries (1 noncontact). The knee injury incidence per 1000 athlete-exposures was 0.43 in untrained female athletes, 0.12 in trained female athletes, and 0.09 in male athletes (P = 0.02, chi-square analysis). Untrained female athletes had a 3.6 times higher incidence of knee injury than trained female athletes (P = 0.05) and 4.8 times higher than male athletes (P = 0.03). The incidence of knee injury in trained female athletes was not significantly different from that in untrained male athletes (P = 0.86). The difference in the incidence of noncontact injuries between the female groups was also significant (P = 0.01). This prospective study demonstrated a decreased incidence of knee injury in female athletes after a specific plyometric training program.","author":[{"family":"Hewett","given":"T E"},{"family":"Lindenfeld","given":"T N"},{"family":"Riccobene","given":"J V"},{"family":"Noyes","given":"F R"}],"citation-label":"3625077","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"3625077","invisible":false,"issue":"6","issued":{"date-parts":[["1999","12"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"699-706","suppress-author":false,"title":"The effect of neuromuscular training on the incidence of knee injury in female athletes. A prospective study.","type":"article-journal","volume":"27"}]16 The Sportsmetrics protocol is outlined in more detail in Appendix 6. This program has been shown to decrease hip abduction/adduction moments, thus reducing the peak landing force.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/03635465990270060301","First":false,"Last":false,"PMID":"10569353","abstract":"To prospectively evaluate the effect of neuromuscular training on the incidence of knee injury in female athletes, we monitored two groups of female athletes, one trained before sports participation and the other not trained, and a group of untrained male athletes throughout the high school soccer, volleyball, and basketball seasons. Weekly reports included the number of practice and competition exposures and mechanism of injury. There were 14 serious knee injuries in the 1263 athletes tracked through the study. Ten of 463 untrained female athletes sustained serious knee injuries (8 noncontact), 2 of 366 trained female athletes sustained serious knee injuries (0 noncontact), and 2 of 434 male athletes sustained serious knee injuries (1 noncontact). The knee injury incidence per 1000 athlete-exposures was 0.43 in untrained female athletes, 0.12 in trained female athletes, and 0.09 in male athletes (P = 0.02, chi-square analysis). Untrained female athletes had a 3.6 times higher incidence of knee injury than trained female athletes (P = 0.05) and 4.8 times higher than male athletes (P = 0.03). The incidence of knee injury in trained female athletes was not significantly different from that in untrained male athletes (P = 0.86). The difference in the incidence of noncontact injuries between the female groups was also significant (P = 0.01). This prospective study demonstrated a decreased incidence of knee injury in female athletes after a specific plyometric training program.","author":[{"family":"Hewett","given":"T E"},{"family":"Lindenfeld","given":"T N"},{"family":"Riccobene","given":"J V"},{"family":"Noyes","given":"F R"}],"citation-label":"3625077","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"3625077","invisible":false,"issue":"6","issued":{"date-parts":[["1999","12"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"699-706","suppress-author":false,"title":"The effect of neuromuscular training on the incidence of knee injury in female athletes. A prospective study.","type":"article-journal","volume":"27"}]16 It has also led to increases hamstring strength, and reductions in the hamstring to quad torque ratios and muscle imbalance.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/03635465990270060301","First":false,"Last":false,"PMID":"10569353","abstract":"To prospectively evaluate the effect of neuromuscular training on the incidence of knee injury in female athletes, we monitored two groups of female athletes, one trained before sports participation and the other not trained, and a group of untrained male athletes throughout the high school soccer, volleyball, and basketball seasons. Weekly reports included the number of practice and competition exposures and mechanism of injury. There were 14 serious knee injuries in the 1263 athletes tracked through the study. Ten of 463 untrained female athletes sustained serious knee injuries (8 noncontact), 2 of 366 trained female athletes sustained serious knee injuries (0 noncontact), and 2 of 434 male athletes sustained serious knee injuries (1 noncontact). The knee injury incidence per 1000 athlete-exposures was 0.43 in untrained female athletes, 0.12 in trained female athletes, and 0.09 in male athletes (P = 0.02, chi-square analysis). Untrained female athletes had a 3.6 times higher incidence of knee injury than trained female athletes (P = 0.05) and 4.8 times higher than male athletes (P = 0.03). The incidence of knee injury in trained female athletes was not significantly different from that in untrained male athletes (P = 0.86). The difference in the incidence of noncontact injuries between the female groups was also significant (P = 0.01). This prospective study demonstrated a decreased incidence of knee injury in female athletes after a specific plyometric training program.","author":[{"family":"Hewett","given":"T E"},{"family":"Lindenfeld","given":"T N"},{"family":"Riccobene","given":"J V"},{"family":"Noyes","given":"F R"}],"citation-label":"3625077","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"3625077","invisible":false,"issue":"6","issued":{"date-parts":[["1999","12"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"699-706","suppress-author":false,"title":"The effect of neuromuscular training on the incidence of knee injury in female athletes. A prospective study.","type":"article-journal","volume":"27"}]16 Both of these factors are implicated in ACL injuries. Hewett et al. hypothesized that this Sportsmetrics prevention program could reduce the incidence of ACL injuries, especially in female athletes.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/03635465990270060301","First":false,"Last":false,"PMID":"10569353","abstract":"To prospectively evaluate the effect of neuromuscular training on the incidence of knee injury in female athletes, we monitored two groups of female athletes, one trained before sports participation and the other not trained, and a group of untrained male athletes throughout the high school soccer, volleyball, and basketball seasons. Weekly reports included the number of practice and competition exposures and mechanism of injury. There were 14 serious knee injuries in the 1263 athletes tracked through the study. Ten of 463 untrained female athletes sustained serious knee injuries (8 noncontact), 2 of 366 trained female athletes sustained serious knee injuries (0 noncontact), and 2 of 434 male athletes sustained serious knee injuries (1 noncontact). The knee injury incidence per 1000 athlete-exposures was 0.43 in untrained female athletes, 0.12 in trained female athletes, and 0.09 in male athletes (P = 0.02, chi-square analysis). Untrained female athletes had a 3.6 times higher incidence of knee injury than trained female athletes (P = 0.05) and 4.8 times higher than male athletes (P = 0.03). The incidence of knee injury in trained female athletes was not significantly different from that in untrained male athletes (P = 0.86). The difference in the incidence of noncontact injuries between the female groups was also significant (P = 0.01). This prospective study demonstrated a decreased incidence of knee injury in female athletes after a specific plyometric training program.","author":[{"family":"Hewett","given":"T E"},{"family":"Lindenfeld","given":"T N"},{"family":"Riccobene","given":"J V"},{"family":"Noyes","given":"F R"}],"citation-label":"3625077","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"3625077","invisible":false,"issue":"6","issued":{"date-parts":[["1999","12"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"699-706","suppress-author":false,"title":"The effect of neuromuscular training on the incidence of knee injury in female athletes. A prospective study.","type":"article-journal","volume":"27"}]16 Hewett et al. conducted a cohort study of 1263 female athletes (soccer, basketball and volleyball players) who performed the Sportsmetrics training program 3 days a week (60-90 minutes to complete) as part of a team for 6 weeks.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/03635465990270060301","First":false,"Last":false,"PMID":"10569353","abstract":"To prospectively evaluate the effect of neuromuscular training on the incidence of knee injury in female athletes, we monitored two groups of female athletes, one trained before sports participation and the other not trained, and a group of untrained male athletes throughout the high school soccer, volleyball, and basketball seasons. Weekly reports included the number of practice and competition exposures and mechanism of injury. There were 14 serious knee injuries in the 1263 athletes tracked through the study. Ten of 463 untrained female athletes sustained serious knee injuries (8 noncontact), 2 of 366 trained female athletes sustained serious knee injuries (0 noncontact), and 2 of 434 male athletes sustained serious knee injuries (1 noncontact). The knee injury incidence per 1000 athlete-exposures was 0.43 in untrained female athletes, 0.12 in trained female athletes, and 0.09 in male athletes (P = 0.02, chi-square analysis). Untrained female athletes had a 3.6 times higher incidence of knee injury than trained female athletes (P = 0.05) and 4.8 times higher than male athletes (P = 0.03). The incidence of knee injury in trained female athletes was not significantly different from that in untrained male athletes (P = 0.86). The difference in the incidence of noncontact injuries between the female groups was also significant (P = 0.01). This prospective study demonstrated a decreased incidence of knee injury in female athletes after a specific plyometric training program.","author":[{"family":"Hewett","given":"T E"},{"family":"Lindenfeld","given":"T N"},{"family":"Riccobene","given":"J V"},{"family":"Noyes","given":"F R"}],"citation-label":"3625077","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"3625077","invisible":false,"issue":"6","issued":{"date-parts":[["1999","12"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"699-706","suppress-author":false,"title":"The effect of neuromuscular training on the incidence of knee injury in female athletes. A prospective study.","type":"article-journal","volume":"27"}]16 They measured the incidence of ACL injuries in the female intervention group versus a control of untrained females and a control of untrained male athletes.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/03635465990270060301","First":false,"Last":false,"PMID":"10569353","abstract":"To prospectively evaluate the effect of neuromuscular training on the incidence of knee injury in female athletes, we monitored two groups of female athletes, one trained before sports participation and the other not trained, and a group of untrained male athletes throughout the high school soccer, volleyball, and basketball seasons. Weekly reports included the number of practice and competition exposures and mechanism of injury. There were 14 serious knee injuries in the 1263 athletes tracked through the study. Ten of 463 untrained female athletes sustained serious knee injuries (8 noncontact), 2 of 366 trained female athletes sustained serious knee injuries (0 noncontact), and 2 of 434 male athletes sustained serious knee injuries (1 noncontact). The knee injury incidence per 1000 athlete-exposures was 0.43 in untrained female athletes, 0.12 in trained female athletes, and 0.09 in male athletes (P = 0.02, chi-square analysis). Untrained female athletes had a 3.6 times higher incidence of knee injury than trained female athletes (P = 0.05) and 4.8 times higher than male athletes (P = 0.03). The incidence of knee injury in trained female athletes was not significantly different from that in untrained male athletes (P = 0.86). The difference in the incidence of noncontact injuries between the female groups was also significant (P = 0.01). This prospective study demonstrated a decreased incidence of knee injury in female athletes after a specific plyometric training program.","author":[{"family":"Hewett","given":"T E"},{"family":"Lindenfeld","given":"T N"},{"family":"Riccobene","given":"J V"},{"family":"Noyes","given":"F R"}],"citation-label":"3625077","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"3625077","invisible":false,"issue":"6","issued":{"date-parts":[["1999","12"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"699-706","suppress-author":false,"title":"The effect of neuromuscular training on the incidence of knee injury in female athletes. A prospective study.","type":"article-journal","volume":"27"}]16 They found that women who underwent the Sportsmetrics protocol had a significantly lower rate of knee injuries versus untrained females (incidence of 0.12/1,000 athletic exposures versus 0.43/1,000 athletic exposures respectively).ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/03635465990270060301","First":false,"Last":false,"PMID":"10569353","abstract":"To prospectively evaluate the effect of neuromuscular training on the incidence of knee injury in female athletes, we monitored two groups of female athletes, one trained before sports participation and the other not trained, and a group of untrained male athletes throughout the high school soccer, volleyball, and basketball seasons. Weekly reports included the number of practice and competition exposures and mechanism of injury. There were 14 serious knee injuries in the 1263 athletes tracked through the study. Ten of 463 untrained female athletes sustained serious knee injuries (8 noncontact), 2 of 366 trained female athletes sustained serious knee injuries (0 noncontact), and 2 of 434 male athletes sustained serious knee injuries (1 noncontact). The knee injury incidence per 1000 athlete-exposures was 0.43 in untrained female athletes, 0.12 in trained female athletes, and 0.09 in male athletes (P = 0.02, chi-square analysis). Untrained female athletes had a 3.6 times higher incidence of knee injury than trained female athletes (P = 0.05) and 4.8 times higher than male athletes (P = 0.03). The incidence of knee injury in trained female athletes was not significantly different from that in untrained male athletes (P = 0.86). The difference in the incidence of noncontact injuries between the female groups was also significant (P = 0.01). This prospective study demonstrated a decreased incidence of knee injury in female athletes after a specific plyometric training program.","author":[{"family":"Hewett","given":"T E"},{"family":"Lindenfeld","given":"T N"},{"family":"Riccobene","given":"J V"},{"family":"Noyes","given":"F R"}],"citation-label":"3625077","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"3625077","invisible":false,"issue":"6","issued":{"date-parts":[["1999","12"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"699-706","suppress-author":false,"title":"The effect of neuromuscular training on the incidence of knee injury in female athletes. A prospective study.","type":"article-journal","volume":"27"}]16 Among soccer players, there were zero serious knee injuries (n=97) in the trained group and an incidence of 0.56/1000 athletic exposures in the untrained female group (n=193).ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/03635465990270060301","First":false,"Last":false,"PMID":"10569353","abstract":"To prospectively evaluate the effect of neuromuscular training on the incidence of knee injury in female athletes, we monitored two groups of female athletes, one trained before sports participation and the other not trained, and a group of untrained male athletes throughout the high school soccer, volleyball, and basketball seasons. Weekly reports included the number of practice and competition exposures and mechanism of injury. There were 14 serious knee injuries in the 1263 athletes tracked through the study. Ten of 463 untrained female athletes sustained serious knee injuries (8 noncontact), 2 of 366 trained female athletes sustained serious knee injuries (0 noncontact), and 2 of 434 male athletes sustained serious knee injuries (1 noncontact). The knee injury incidence per 1000 athlete-exposures was 0.43 in untrained female athletes, 0.12 in trained female athletes, and 0.09 in male athletes (P = 0.02, chi-square analysis). Untrained female athletes had a 3.6 times higher incidence of knee injury than trained female athletes (P = 0.05) and 4.8 times higher than male athletes (P = 0.03). The incidence of knee injury in trained female athletes was not significantly different from that in untrained male athletes (P = 0.86). The difference in the incidence of noncontact injuries between the female groups was also significant (P = 0.01). This prospective study demonstrated a decreased incidence of knee injury in female athletes after a specific plyometric training program.","author":[{"family":"Hewett","given":"T E"},{"family":"Lindenfeld","given":"T N"},{"family":"Riccobene","given":"J V"},{"family":"Noyes","given":"F R"}],"citation-label":"3625077","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"3625077","invisible":false,"issue":"6","issued":{"date-parts":[["1999","12"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"699-706","suppress-author":false,"title":"The effect of neuromuscular training on the incidence of knee injury in female athletes. A prospective study.","type":"article-journal","volume":"27"}]16 This study provides preliminary evidence into the efficacy of a comprehensive strength, flexibility and landing mechanics retraining exercise program in the reduction of ACL injuries specific to the soccer athletes.Kn?kontroll, 2015, developed a similar program to the Sportsmetrics protocol. The Kn?kontroll program is a neuromuscular warm-up program that consists of exercises related to knee strengthening, and core stability.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bmj.e3042","First":false,"Last":false,"PMCID":"PMC3342926","PMID":"22556050","abstract":"OBJECTIVE: To evaluate the effectiveness of neuromuscular training in reducing the rate of acute knee injury in adolescent female football players.\n \n \nDESIGN: Stratified cluster randomised controlled trial with clubs as the unit of randomisation.\n \n \nSETTING: 230 Swedish football clubs (121 in the intervention group, 109 in the control group) were followed for one season (2009, seven months).\n \n \nPARTICIPANTS: 4564 players aged 12-17 years (2479 in the intervention group, 2085 in the control group) completed the study.\n \n \nINTERVENTION: 15 minute neuromuscular warm-up programme (targeting core stability, balance, and proper knee alignment) to be carried out twice a week throughout the season.\n \n \nMAIN OUTCOME MEASURES: The primary outcome was rate of anterior cruciate ligament injury; secondary outcomes were rates of severe knee injury (>4 weeks' absence) and any acute knee injury.\n \n \nRESULTS: Seven players (0.28%) in the intervention group, and 14 (0.67%) in the control group had an anterior cruciate ligament injury. By Cox regression analysis according to intention to treat, a 64% reduction in the rate of anterior cruciate ligament injury was seen in the intervention group (rate ratio 0.36, 95% confidence interval 0.15 to 0.85). The absolute rate difference was -0.07 (95% confidence interval -0.13 to 0.001) per 1000 playing hours in favour of the intervention group. No significant rate reductions were seen for secondary outcomes.\n \n \nCONCLUSIONS: A neuromuscular warm-up programme significantly reduced the rate of anterior cruciate ligament injury in adolescent female football players. However, the absolute rate difference did not reach statistical significance, possibly owing to the small number of events.\n \n \nTRIAL REGISTRATION: Clinical trials NCT00894595.","author":[{"family":"Waldén","given":"Markus"},{"family":"Atroshi","given":"Isam"},{"family":"Magnusson","given":"Henrik"},{"family":"Wagner","given":"Philippe"},{"family":"H?gglund","given":"Martin"}],"citation-label":"1129629","container-title":"BMJ (Clinical Research Ed.)","container-title-short":"BMJ","id":"1129629","invisible":false,"issued":{"date-parts":[["2012","5","3"]]},"journalAbbreviation":"BMJ","page":"e3042","suppress-author":false,"title":"Prevention of acute knee injuries in adolescent female football players: cluster randomised controlled trial.","type":"article-journal","volume":"344"}]22 The Kn?kontroll program focuses on proper landing/jumping, squatting and lunging techniques.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bmj.e3042","First":false,"Last":false,"PMCID":"PMC3342926","PMID":"22556050","abstract":"OBJECTIVE: To evaluate the effectiveness of neuromuscular training in reducing the rate of acute knee injury in adolescent female football players.\n \n \nDESIGN: Stratified cluster randomised controlled trial with clubs as the unit of randomisation.\n \n \nSETTING: 230 Swedish football clubs (121 in the intervention group, 109 in the control group) were followed for one season (2009, seven months).\n \n \nPARTICIPANTS: 4564 players aged 12-17 years (2479 in the intervention group, 2085 in the control group) completed the study.\n \n \nINTERVENTION: 15 minute neuromuscular warm-up programme (targeting core stability, balance, and proper knee alignment) to be carried out twice a week throughout the season.\n \n \nMAIN OUTCOME MEASURES: The primary outcome was rate of anterior cruciate ligament injury; secondary outcomes were rates of severe knee injury (>4 weeks' absence) and any acute knee injury.\n \n \nRESULTS: Seven players (0.28%) in the intervention group, and 14 (0.67%) in the control group had an anterior cruciate ligament injury. By Cox regression analysis according to intention to treat, a 64% reduction in the rate of anterior cruciate ligament injury was seen in the intervention group (rate ratio 0.36, 95% confidence interval 0.15 to 0.85). The absolute rate difference was -0.07 (95% confidence interval -0.13 to 0.001) per 1000 playing hours in favour of the intervention group. No significant rate reductions were seen for secondary outcomes.\n \n \nCONCLUSIONS: A neuromuscular warm-up programme significantly reduced the rate of anterior cruciate ligament injury in adolescent female football players. However, the absolute rate difference did not reach statistical significance, possibly owing to the small number of events.\n \n \nTRIAL REGISTRATION: Clinical trials NCT00894595.","author":[{"family":"Waldén","given":"Markus"},{"family":"Atroshi","given":"Isam"},{"family":"Magnusson","given":"Henrik"},{"family":"Wagner","given":"Philippe"},{"family":"H?gglund","given":"Martin"}],"citation-label":"1129629","container-title":"BMJ (Clinical Research Ed.)","container-title-short":"BMJ","id":"1129629","invisible":false,"issued":{"date-parts":[["2012","5","3"]]},"journalAbbreviation":"BMJ","page":"e3042","suppress-author":false,"title":"Prevention of acute knee injuries in adolescent female football players: cluster randomised controlled trial.","type":"article-journal","volume":"344"}]22 The program aims to reduce dynamic knee valgus during play. Walden et al. evaluated the efficacy of the Kn?kontroll program over the course of a season in 309 club teams found that this neuromuscular training program led to a reduction in overall ACL injury incidence rate of 64% in female soccer players (RR: 0.36, 95% CI: 0.15-0.85).ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bmj.e3042","First":false,"Last":false,"PMCID":"PMC3342926","PMID":"22556050","abstract":"OBJECTIVE: To evaluate the effectiveness of neuromuscular training in reducing the rate of acute knee injury in adolescent female football players.\n \n \nDESIGN: Stratified cluster randomised controlled trial with clubs as the unit of randomisation.\n \n \nSETTING: 230 Swedish football clubs (121 in the intervention group, 109 in the control group) were followed for one season (2009, seven months).\n \n \nPARTICIPANTS: 4564 players aged 12-17 years (2479 in the intervention group, 2085 in the control group) completed the study.\n \n \nINTERVENTION: 15 minute neuromuscular warm-up programme (targeting core stability, balance, and proper knee alignment) to be carried out twice a week throughout the season.\n \n \nMAIN OUTCOME MEASURES: The primary outcome was rate of anterior cruciate ligament injury; secondary outcomes were rates of severe knee injury (>4 weeks' absence) and any acute knee injury.\n \n \nRESULTS: Seven players (0.28%) in the intervention group, and 14 (0.67%) in the control group had an anterior cruciate ligament injury. By Cox regression analysis according to intention to treat, a 64% reduction in the rate of anterior cruciate ligament injury was seen in the intervention group (rate ratio 0.36, 95% confidence interval 0.15 to 0.85). The absolute rate difference was -0.07 (95% confidence interval -0.13 to 0.001) per 1000 playing hours in favour of the intervention group. No significant rate reductions were seen for secondary outcomes.\n \n \nCONCLUSIONS: A neuromuscular warm-up programme significantly reduced the rate of anterior cruciate ligament injury in adolescent female football players. However, the absolute rate difference did not reach statistical significance, possibly owing to the small number of events.\n \n \nTRIAL REGISTRATION: Clinical trials NCT00894595.","author":[{"family":"Waldén","given":"Markus"},{"family":"Atroshi","given":"Isam"},{"family":"Magnusson","given":"Henrik"},{"family":"Wagner","given":"Philippe"},{"family":"H?gglund","given":"Martin"}],"citation-label":"1129629","container-title":"BMJ (Clinical Research Ed.)","container-title-short":"BMJ","id":"1129629","invisible":false,"issued":{"date-parts":[["2012","5","3"]]},"journalAbbreviation":"BMJ","page":"e3042","suppress-author":false,"title":"Prevention of acute knee injuries in adolescent female football players: cluster randomised controlled trial.","type":"article-journal","volume":"344"}]22 Both greater compliance and the performance of the intervention more than one time a week were associated with better outcomes.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bmj.e3042","First":false,"Last":false,"PMCID":"PMC3342926","PMID":"22556050","abstract":"OBJECTIVE: To evaluate the effectiveness of neuromuscular training in reducing the rate of acute knee injury in adolescent female football players.\n \n \nDESIGN: Stratified cluster randomised controlled trial with clubs as the unit of randomisation.\n \n \nSETTING: 230 Swedish football clubs (121 in the intervention group, 109 in the control group) were followed for one season (2009, seven months).\n \n \nPARTICIPANTS: 4564 players aged 12-17 years (2479 in the intervention group, 2085 in the control group) completed the study.\n \n \nINTERVENTION: 15 minute neuromuscular warm-up programme (targeting core stability, balance, and proper knee alignment) to be carried out twice a week throughout the season.\n \n \nMAIN OUTCOME MEASURES: The primary outcome was rate of anterior cruciate ligament injury; secondary outcomes were rates of severe knee injury (>4 weeks' absence) and any acute knee injury.\n \n \nRESULTS: Seven players (0.28%) in the intervention group, and 14 (0.67%) in the control group had an anterior cruciate ligament injury. By Cox regression analysis according to intention to treat, a 64% reduction in the rate of anterior cruciate ligament injury was seen in the intervention group (rate ratio 0.36, 95% confidence interval 0.15 to 0.85). The absolute rate difference was -0.07 (95% confidence interval -0.13 to 0.001) per 1000 playing hours in favour of the intervention group. No significant rate reductions were seen for secondary outcomes.\n \n \nCONCLUSIONS: A neuromuscular warm-up programme significantly reduced the rate of anterior cruciate ligament injury in adolescent female football players. However, the absolute rate difference did not reach statistical significance, possibly owing to the small number of events.\n \n \nTRIAL REGISTRATION: Clinical trials NCT00894595.","author":[{"family":"Waldén","given":"Markus"},{"family":"Atroshi","given":"Isam"},{"family":"Magnusson","given":"Henrik"},{"family":"Wagner","given":"Philippe"},{"family":"H?gglund","given":"Martin"}],"citation-label":"1129629","container-title":"BMJ (Clinical Research Ed.)","container-title-short":"BMJ","id":"1129629","invisible":false,"issued":{"date-parts":[["2012","5","3"]]},"journalAbbreviation":"BMJ","page":"e3042","suppress-author":false,"title":"Prevention of acute knee injuries in adolescent female football players: cluster randomised controlled trial.","type":"article-journal","volume":"344"}]22 The absolute rate difference between the intervention and the control did not reach clinical significance given the relatively rare rate of occurrence of ACL injuries among the sample (7 players in the intervention and 14 in the control).ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bmj.e3042","First":false,"Last":false,"PMCID":"PMC3342926","PMID":"22556050","abstract":"OBJECTIVE: To evaluate the effectiveness of neuromuscular training in reducing the rate of acute knee injury in adolescent female football players.\n \n \nDESIGN: Stratified cluster randomised controlled trial with clubs as the unit of randomisation.\n \n \nSETTING: 230 Swedish football clubs (121 in the intervention group, 109 in the control group) were followed for one season (2009, seven months).\n \n \nPARTICIPANTS: 4564 players aged 12-17 years (2479 in the intervention group, 2085 in the control group) completed the study.\n \n \nINTERVENTION: 15 minute neuromuscular warm-up programme (targeting core stability, balance, and proper knee alignment) to be carried out twice a week throughout the season.\n \n \nMAIN OUTCOME MEASURES: The primary outcome was rate of anterior cruciate ligament injury; secondary outcomes were rates of severe knee injury (>4 weeks' absence) and any acute knee injury.\n \n \nRESULTS: Seven players (0.28%) in the intervention group, and 14 (0.67%) in the control group had an anterior cruciate ligament injury. By Cox regression analysis according to intention to treat, a 64% reduction in the rate of anterior cruciate ligament injury was seen in the intervention group (rate ratio 0.36, 95% confidence interval 0.15 to 0.85). The absolute rate difference was -0.07 (95% confidence interval -0.13 to 0.001) per 1000 playing hours in favour of the intervention group. No significant rate reductions were seen for secondary outcomes.\n \n \nCONCLUSIONS: A neuromuscular warm-up programme significantly reduced the rate of anterior cruciate ligament injury in adolescent female football players. However, the absolute rate difference did not reach statistical significance, possibly owing to the small number of events.\n \n \nTRIAL REGISTRATION: Clinical trials NCT00894595.","author":[{"family":"Waldén","given":"Markus"},{"family":"Atroshi","given":"Isam"},{"family":"Magnusson","given":"Henrik"},{"family":"Wagner","given":"Philippe"},{"family":"H?gglund","given":"Martin"}],"citation-label":"1129629","container-title":"BMJ (Clinical Research Ed.)","container-title-short":"BMJ","id":"1129629","invisible":false,"issued":{"date-parts":[["2012","5","3"]]},"journalAbbreviation":"BMJ","page":"e3042","suppress-author":false,"title":"Prevention of acute knee injuries in adolescent female football players: cluster randomised controlled trial.","type":"article-journal","volume":"344"}]22 More research with a large sample size and over an extended period if time is indicated to determine the actual of the Kn?kontroll program, if there is one, specifically in the reduction of ACL injuries. Another injury prevention program that may have relevance in terms of reduction of ACL injuries among soccer players is the FIFA 11+ intervention program.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bjsports-2016-097066","First":false,"Last":false,"PMID":"28087568","abstract":"OBJECTIVE: To investigate the effect of FIFA injury prevention programmes in football (FIFA 11 and FIFA 11+). DESIGN: Systematic review and meta-analysis. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Randomised controlled trials comparing the FIFA injury prevention programmes with a control (no or sham intervention) among football players. DATA SOURCES: MEDLINE via PubMed, EMBASE via OVID, CINAHL via Ebsco, Web of Science, SportDiscus and Cochrane Central Register of Controlled Trials, from 2004 to 14 March 2016. RESULTS: 6 cluster-randomised controlled trials had assessed the effect of FIFA injury prevention programmes compared with controls on the overall football injury incidence in recreational/subelite football. These studies included 2 specific exercise-based injury prevention programmes: FIFA 11 (2 studies) and FIFA 11+ (4 studies). The primary analysis showed a reduction in the overall injury risk ratio of 0.75 (95% CI 0.57 to 0.98), p=0.04, in favour of the FIFA injury prevention programmes. Secondary analyses revealed that when pooling the 4 studies applying the FIFA 11+ prevention programme, a reduction in the overall injury risk ratio (incidence rate ratio (IRR) 0.61; 95% CI 0.48 to 0.77, p< 0.001) was present in favour of the FIFA 11+ prevention programme. No reduction was present when pooling the 2 studies including the FIFA 11 prevention programme (IRR 0.99; 95% CI 0.80 to 1.23, p=0.940). CONCLUSIONS: An injury-preventing effect of the FIFA injury prevention programmes compared with controls was shown in football. This effect was induced by the FIFA 11+ prevention programme which has a substantial injury-preventing effect by reducing football injuries by 39%, whereas a preventive effect of the FIFA 11 prevention programme could not be documented. TRIAL REGISTRATION NUMBER: PROSPERO CRD42015024120. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to .","author":[{"family":"Thorborg","given":"Kristian"},{"family":"Krommes","given":"Kasper Kühn"},{"family":"Esteve","given":"Ernest"},{"family":"Clausen","given":"Mikkel Bek"},{"family":"Bartels","given":"Else Marie"},{"family":"Rathleff","given":"Michael Skovdal"}],"citation-label":"5824173","container-title":"British Journal of Sports Medicine","container-title-short":"Br. J. Sports Med.","id":"5824173","invisible":false,"issue":"7","issued":{"date-parts":[["2017","4"]]},"journalAbbreviation":"Br. J. Sports Med.","page":"562-571","suppress-author":false,"title":"Effect of specific exercise-based football injury prevention programmes on the overall injury rate in football: a systematic review and meta-analysis of the FIFA 11 and 11+ programmes.","type":"article-journal","volume":"51"}]23 The FIFA 11+ is a program designed by the FIFA Medical Assessment and Research Centre (F-MARC) specifically for soccer players as a warm-up session which includes strengthening, balance, and jumping exercises.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bjsports-2016-097066","First":false,"Last":false,"PMID":"28087568","abstract":"OBJECTIVE: To investigate the effect of FIFA injury prevention programmes in football (FIFA 11 and FIFA 11+). DESIGN: Systematic review and meta-analysis. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Randomised controlled trials comparing the FIFA injury prevention programmes with a control (no or sham intervention) among football players. DATA SOURCES: MEDLINE via PubMed, EMBASE via OVID, CINAHL via Ebsco, Web of Science, SportDiscus and Cochrane Central Register of Controlled Trials, from 2004 to 14 March 2016. RESULTS: 6 cluster-randomised controlled trials had assessed the effect of FIFA injury prevention programmes compared with controls on the overall football injury incidence in recreational/subelite football. These studies included 2 specific exercise-based injury prevention programmes: FIFA 11 (2 studies) and FIFA 11+ (4 studies). The primary analysis showed a reduction in the overall injury risk ratio of 0.75 (95% CI 0.57 to 0.98), p=0.04, in favour of the FIFA injury prevention programmes. Secondary analyses revealed that when pooling the 4 studies applying the FIFA 11+ prevention programme, a reduction in the overall injury risk ratio (incidence rate ratio (IRR) 0.61; 95% CI 0.48 to 0.77, p< 0.001) was present in favour of the FIFA 11+ prevention programme. No reduction was present when pooling the 2 studies including the FIFA 11 prevention programme (IRR 0.99; 95% CI 0.80 to 1.23, p=0.940). CONCLUSIONS: An injury-preventing effect of the FIFA injury prevention programmes compared with controls was shown in football. This effect was induced by the FIFA 11+ prevention programme which has a substantial injury-preventing effect by reducing football injuries by 39%, whereas a preventive effect of the FIFA 11 prevention programme could not be documented. TRIAL REGISTRATION NUMBER: PROSPERO CRD42015024120. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to .","author":[{"family":"Thorborg","given":"Kristian"},{"family":"Krommes","given":"Kasper Kühn"},{"family":"Esteve","given":"Ernest"},{"family":"Clausen","given":"Mikkel Bek"},{"family":"Bartels","given":"Else Marie"},{"family":"Rathleff","given":"Michael Skovdal"}],"citation-label":"5824173","container-title":"British Journal of Sports Medicine","container-title-short":"Br. J. Sports Med.","id":"5824173","invisible":false,"issue":"7","issued":{"date-parts":[["2017","4"]]},"journalAbbreviation":"Br. J. Sports Med.","page":"562-571","suppress-author":false,"title":"Effect of specific exercise-based football injury prevention programmes on the overall injury rate in football: a systematic review and meta-analysis of the FIFA 11 and 11+ programmes.","type":"article-journal","volume":"51"}]23 The primary goal of the program is to prevent soccer-related injuries. The FIFA 11+ prevention program includes running drills, strength, plyometrics and balance exercises. The program is intended to be performed at least twice a week.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bjsports-2016-097066","First":false,"Last":false,"PMID":"28087568","abstract":"OBJECTIVE: To investigate the effect of FIFA injury prevention programmes in football (FIFA 11 and FIFA 11+). DESIGN: Systematic review and meta-analysis. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Randomised controlled trials comparing the FIFA injury prevention programmes with a control (no or sham intervention) among football players. DATA SOURCES: MEDLINE via PubMed, EMBASE via OVID, CINAHL via Ebsco, Web of Science, SportDiscus and Cochrane Central Register of Controlled Trials, from 2004 to 14 March 2016. RESULTS: 6 cluster-randomised controlled trials had assessed the effect of FIFA injury prevention programmes compared with controls on the overall football injury incidence in recreational/subelite football. These studies included 2 specific exercise-based injury prevention programmes: FIFA 11 (2 studies) and FIFA 11+ (4 studies). The primary analysis showed a reduction in the overall injury risk ratio of 0.75 (95% CI 0.57 to 0.98), p=0.04, in favour of the FIFA injury prevention programmes. Secondary analyses revealed that when pooling the 4 studies applying the FIFA 11+ prevention programme, a reduction in the overall injury risk ratio (incidence rate ratio (IRR) 0.61; 95% CI 0.48 to 0.77, p< 0.001) was present in favour of the FIFA 11+ prevention programme. No reduction was present when pooling the 2 studies including the FIFA 11 prevention programme (IRR 0.99; 95% CI 0.80 to 1.23, p=0.940). CONCLUSIONS: An injury-preventing effect of the FIFA injury prevention programmes compared with controls was shown in football. This effect was induced by the FIFA 11+ prevention programme which has a substantial injury-preventing effect by reducing football injuries by 39%, whereas a preventive effect of the FIFA 11 prevention programme could not be documented. TRIAL REGISTRATION NUMBER: PROSPERO CRD42015024120. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to .","author":[{"family":"Thorborg","given":"Kristian"},{"family":"Krommes","given":"Kasper Kühn"},{"family":"Esteve","given":"Ernest"},{"family":"Clausen","given":"Mikkel Bek"},{"family":"Bartels","given":"Else Marie"},{"family":"Rathleff","given":"Michael Skovdal"}],"citation-label":"5824173","container-title":"British Journal of Sports Medicine","container-title-short":"Br. J. Sports Med.","id":"5824173","invisible":false,"issue":"7","issued":{"date-parts":[["2017","4"]]},"journalAbbreviation":"Br. J. Sports Med.","page":"562-571","suppress-author":false,"title":"Effect of specific exercise-based football injury prevention programmes on the overall injury rate in football: a systematic review and meta-analysis of the FIFA 11 and 11+ programmes.","type":"article-journal","volume":"51"}]23 The program focuses on proper lower extremity alignment during activities and good landing mechanics. See Appendix 7 for a sample of the FIFA 11+ protocol. A meta-analysis by Thorborg et al. found that participation in the FIFA 11+ injury prevention program reduced soccer-related injury rates by 39% (IRR 0.61; 95% CI 0.48 – 0.77, p<0.001) in comparison to a control.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bjsports-2016-097066","First":false,"Last":false,"PMID":"28087568","abstract":"OBJECTIVE: To investigate the effect of FIFA injury prevention programmes in football (FIFA 11 and FIFA 11+). DESIGN: Systematic review and meta-analysis. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Randomised controlled trials comparing the FIFA injury prevention programmes with a control (no or sham intervention) among football players. DATA SOURCES: MEDLINE via PubMed, EMBASE via OVID, CINAHL via Ebsco, Web of Science, SportDiscus and Cochrane Central Register of Controlled Trials, from 2004 to 14 March 2016. RESULTS: 6 cluster-randomised controlled trials had assessed the effect of FIFA injury prevention programmes compared with controls on the overall football injury incidence in recreational/subelite football. These studies included 2 specific exercise-based injury prevention programmes: FIFA 11 (2 studies) and FIFA 11+ (4 studies). The primary analysis showed a reduction in the overall injury risk ratio of 0.75 (95% CI 0.57 to 0.98), p=0.04, in favour of the FIFA injury prevention programmes. Secondary analyses revealed that when pooling the 4 studies applying the FIFA 11+ prevention programme, a reduction in the overall injury risk ratio (incidence rate ratio (IRR) 0.61; 95% CI 0.48 to 0.77, p< 0.001) was present in favour of the FIFA 11+ prevention programme. No reduction was present when pooling the 2 studies including the FIFA 11 prevention programme (IRR 0.99; 95% CI 0.80 to 1.23, p=0.940). CONCLUSIONS: An injury-preventing effect of the FIFA injury prevention programmes compared with controls was shown in football. This effect was induced by the FIFA 11+ prevention programme which has a substantial injury-preventing effect by reducing football injuries by 39%, whereas a preventive effect of the FIFA 11 prevention programme could not be documented. TRIAL REGISTRATION NUMBER: PROSPERO CRD42015024120. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to .","author":[{"family":"Thorborg","given":"Kristian"},{"family":"Krommes","given":"Kasper Kühn"},{"family":"Esteve","given":"Ernest"},{"family":"Clausen","given":"Mikkel Bek"},{"family":"Bartels","given":"Else Marie"},{"family":"Rathleff","given":"Michael Skovdal"}],"citation-label":"5824173","container-title":"British Journal of Sports Medicine","container-title-short":"Br. J. Sports Med.","id":"5824173","invisible":false,"issue":"7","issued":{"date-parts":[["2017","4"]]},"journalAbbreviation":"Br. J. Sports Med.","page":"562-571","suppress-author":false,"title":"Effect of specific exercise-based football injury prevention programmes on the overall injury rate in football: a systematic review and meta-analysis of the FIFA 11 and 11+ programmes.","type":"article-journal","volume":"51"}]23 They found that the FIFA 11+ program reduced knee injury rates by 48% (IRR 0.52; 95% CI 0.38-0.72) in comparison to a control.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bjsports-2016-097066","First":false,"Last":false,"PMID":"28087568","abstract":"OBJECTIVE: To investigate the effect of FIFA injury prevention programmes in football (FIFA 11 and FIFA 11+). DESIGN: Systematic review and meta-analysis. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Randomised controlled trials comparing the FIFA injury prevention programmes with a control (no or sham intervention) among football players. DATA SOURCES: MEDLINE via PubMed, EMBASE via OVID, CINAHL via Ebsco, Web of Science, SportDiscus and Cochrane Central Register of Controlled Trials, from 2004 to 14 March 2016. RESULTS: 6 cluster-randomised controlled trials had assessed the effect of FIFA injury prevention programmes compared with controls on the overall football injury incidence in recreational/subelite football. These studies included 2 specific exercise-based injury prevention programmes: FIFA 11 (2 studies) and FIFA 11+ (4 studies). The primary analysis showed a reduction in the overall injury risk ratio of 0.75 (95% CI 0.57 to 0.98), p=0.04, in favour of the FIFA injury prevention programmes. Secondary analyses revealed that when pooling the 4 studies applying the FIFA 11+ prevention programme, a reduction in the overall injury risk ratio (incidence rate ratio (IRR) 0.61; 95% CI 0.48 to 0.77, p< 0.001) was present in favour of the FIFA 11+ prevention programme. No reduction was present when pooling the 2 studies including the FIFA 11 prevention programme (IRR 0.99; 95% CI 0.80 to 1.23, p=0.940). CONCLUSIONS: An injury-preventing effect of the FIFA injury prevention programmes compared with controls was shown in football. This effect was induced by the FIFA 11+ prevention programme which has a substantial injury-preventing effect by reducing football injuries by 39%, whereas a preventive effect of the FIFA 11 prevention programme could not be documented. TRIAL REGISTRATION NUMBER: PROSPERO CRD42015024120. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to .","author":[{"family":"Thorborg","given":"Kristian"},{"family":"Krommes","given":"Kasper Kühn"},{"family":"Esteve","given":"Ernest"},{"family":"Clausen","given":"Mikkel Bek"},{"family":"Bartels","given":"Else Marie"},{"family":"Rathleff","given":"Michael Skovdal"}],"citation-label":"5824173","container-title":"British Journal of Sports Medicine","container-title-short":"Br. J. Sports Med.","id":"5824173","invisible":false,"issue":"7","issued":{"date-parts":[["2017","4"]]},"journalAbbreviation":"Br. J. Sports Med.","page":"562-571","suppress-author":false,"title":"Effect of specific exercise-based football injury prevention programmes on the overall injury rate in football: a systematic review and meta-analysis of the FIFA 11 and 11+ programmes.","type":"article-journal","volume":"51"}]23 These results were similar to those of Silvers-Granelli 2015 who found that the FIFA 11+ program reduced the overall incidence of injuries by 46% (RR: 0.54; 95% CI: 0.49-0.59) and the rate of knee injuries by 58% (RR: 0.54; 95% CI: 0.29-0.61) in a randomized cluster controlled trial of college male soccer players.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/0363546515602009","First":false,"Last":false,"PMCID":"PMC4839291","PMID":"26378030","abstract":"BACKGROUND: The Fédération Internationale de Football Association (FIFA) 11+ program has been shown to be an effective injury prevention program in the female soccer cohort, but there is a paucity of research to demonstrate its efficacy in the male population. HYPOTHESIS: To examine the efficacy of the FIFA 11+ program in men's collegiate United States National Collegiate Athletic Association (NCAA) Division I and Division II soccer. STUDY DESIGN: Randomized controlled trial; Level of evidence, 1. METHODS: Before the commencement of the fall 2012 season, every NCAA Division I and Division II men's collegiate soccer team (N = 396) was solicited to participate in this research study. Human ethics review board approval was obtained through Quorum Review IRB. Sixty-five teams were randomized: 34 to the control group (CG; 850 players) and 31 to the intervention group (IG; 675 players). Four teams in the IG did not complete the study, reducing the number for analysis to 61. The FIFA 11+ injury prevention program served as the intervention and was utilized weekly. Athlete-exposures (AEs), compliance, and injury data were recorded using a secure Internet-based system. RESULTS: In the CG, 665 injuries (mean ± SD, 19.56 ± 11.01) were reported for 34 teams, which corresponded to an incidence rate (IR) of 15.04 injuries per 1000 AEs. In the IG, 285 injuries (mean ± SD, 10.56 ± 3.64) were reported for 27 teams, which corresponded to an IR of 8.09 injuries per 1000 AEs. Total days missed because of injury were significantly higher for the CG (mean ± SD, 13.20 ± 26.6 days) than for the IG (mean ± SD, 10.08 ± 14.68 days) (P = .007). There was no difference for time loss due to injury based on field type (P = .341). CONCLUSION: The FIFA 11+ significantly reduced injury rates by 46.1% and decreased time loss to injury by 28.6% in the competitive male collegiate soccer player (rate ratio, 0.54 [95% CI, 0.49-0.59]; P < .0001) (number needed to treat = 2.64). ? 2015 The Author(s).","author":[{"family":"Silvers-Granelli","given":"Holly"},{"family":"Mandelbaum","given":"Bert"},{"family":"Adeniji","given":"Ola"},{"family":"Insler","given":"Stephanie"},{"family":"Bizzini","given":"Mario"},{"family":"Pohlig","given":"Ryan"},{"family":"Junge","given":"Astrid"},{"family":"Snyder-Mackler","given":"Lynn"},{"family":"Dvorak","given":"Jiri"}],"citation-label":"5824178","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"5824178","invisible":false,"issue":"11","issued":{"date-parts":[["2015","11"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"2628-2637","suppress-author":false,"title":"Efficacy of the FIFA 11+ injury prevention program in the collegiate male soccer player.","type":"article-journal","volume":"43"}]24 Silvers-Granelli 2017 re-evaluated the data set from their earlier study of male college soccer players to determine the impact of the FIFA 11+ injury prevention program on the incidence of ACL injuries.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1007/s11999-017-5342-5","First":false,"Last":false,"PMCID":"PMC5599387","PMID":"28389864","author":[{"family":"Silvers-Granelli","given":"Holly J"},{"family":"Bizzini","given":"Mario"},{"family":"Arundale","given":"Amelia"},{"family":"Mandelbaum","given":"Bert R"},{"family":"Snyder-Mackler","given":"Lynn"}],"citation-label":"5824127","container-title":"Clinical Orthopaedics and Related Research","container-title-short":"Clin. Orthop. Relat. Res.","id":"5824127","invisible":false,"issue":"10","issued":{"date-parts":[["2017","10"]]},"journalAbbreviation":"Clin. Orthop. Relat. Res.","page":"2447-2455","suppress-author":false,"title":"Does the FIFA 11+?injury prevention program reduce the incidence of ACL injury in male soccer players?","type":"article-journal","volume":"475"}]25 Silvers-Granelli 2017 observed that the FIFA 11+ program led to a reduction in the incidence rate of ACL injuries in male college soccer players by 76.4% (RR: 0.236; 95% CI: 0.07-0.81) versus a control.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1007/s11999-017-5342-5","First":false,"Last":false,"PMCID":"PMC5599387","PMID":"28389864","author":[{"family":"Silvers-Granelli","given":"Holly J"},{"family":"Bizzini","given":"Mario"},{"family":"Arundale","given":"Amelia"},{"family":"Mandelbaum","given":"Bert R"},{"family":"Snyder-Mackler","given":"Lynn"}],"citation-label":"5824127","container-title":"Clinical Orthopaedics and Related Research","container-title-short":"Clin. Orthop. Relat. Res.","id":"5824127","invisible":false,"issue":"10","issued":{"date-parts":[["2017","10"]]},"journalAbbreviation":"Clin. Orthop. Relat. Res.","page":"2447-2455","suppress-author":false,"title":"Does the FIFA 11+?injury prevention program reduce the incidence of ACL injury in male soccer players?","type":"article-journal","volume":"475"}]25 This provides promising preliminary results regarding the utility of the FIFA 11+ program for reduction of ACL injuries. The study had a relatively wide confidence interval, given the comparatively rare nature of ACL injuries among male soccer players, especially when evaluating only a single season.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1007/s11999-017-5342-5","First":false,"Last":false,"PMCID":"PMC5599387","PMID":"28389864","author":[{"family":"Silvers-Granelli","given":"Holly J"},{"family":"Bizzini","given":"Mario"},{"family":"Arundale","given":"Amelia"},{"family":"Mandelbaum","given":"Bert R"},{"family":"Snyder-Mackler","given":"Lynn"}],"citation-label":"5824127","container-title":"Clinical Orthopaedics and Related Research","container-title-short":"Clin. Orthop. Relat. Res.","id":"5824127","invisible":false,"issue":"10","issued":{"date-parts":[["2017","10"]]},"journalAbbreviation":"Clin. Orthop. Relat. Res.","page":"2447-2455","suppress-author":false,"title":"Does the FIFA 11+?injury prevention program reduce the incidence of ACL injury in male soccer players?","type":"article-journal","volume":"475"}]25 Despite a large sample size, 1525 subjects, the study was underpowered to perform secondary analysis of ACL injuries in subgroups such as by player position or field type to further differential other external factors that may be contributing to the risk of an ACL injury.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1007/s11999-017-5342-5","First":false,"Last":false,"PMCID":"PMC5599387","PMID":"28389864","author":[{"family":"Silvers-Granelli","given":"Holly J"},{"family":"Bizzini","given":"Mario"},{"family":"Arundale","given":"Amelia"},{"family":"Mandelbaum","given":"Bert R"},{"family":"Snyder-Mackler","given":"Lynn"}],"citation-label":"5824127","container-title":"Clinical Orthopaedics and Related Research","container-title-short":"Clin. Orthop. Relat. Res.","id":"5824127","invisible":false,"issue":"10","issued":{"date-parts":[["2017","10"]]},"journalAbbreviation":"Clin. Orthop. Relat. Res.","page":"2447-2455","suppress-author":false,"title":"Does the FIFA 11+?injury prevention program reduce the incidence of ACL injury in male soccer players?","type":"article-journal","volume":"475"}]25 Research regarding the impact of injury prevention programs on the incidence of ACL injuries is limited secondary to the relatively rare nature of the injury.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1007/s11999-017-5342-5","First":false,"Last":false,"PMCID":"PMC5599387","PMID":"28389864","author":[{"family":"Silvers-Granelli","given":"Holly J"},{"family":"Bizzini","given":"Mario"},{"family":"Arundale","given":"Amelia"},{"family":"Mandelbaum","given":"Bert R"},{"family":"Snyder-Mackler","given":"Lynn"}],"citation-label":"5824127","container-title":"Clinical Orthopaedics and Related Research","container-title-short":"Clin. Orthop. Relat. Res.","id":"5824127","invisible":false,"issue":"10","issued":{"date-parts":[["2017","10"]]},"journalAbbreviation":"Clin. Orthop. Relat. Res.","page":"2447-2455","suppress-author":false,"title":"Does the FIFA 11+?injury prevention program reduce the incidence of ACL injury in male soccer players?","type":"article-journal","volume":"475"}]25 Studies with large sample sizes would need to be conducted to determine the true impact the programs mentioned above on the prevention of ACL injuries. Further research should address the lasting impact of the injury prevention programs regarding injury risk reduction and the utility of the program performed by an individual, apart from a team setting. Additional research should also attempt to improve the quality of the evidence by blinding the participants and assessors, possibly through the use of a sham intervention. Research should also evaluate appropriate dosage for the intervention, including both durations of the programs and number of sessions per week.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/0363546515602009","First":false,"Last":false,"PMCID":"PMC4839291","PMID":"26378030","abstract":"BACKGROUND: The Fédération Internationale de Football Association (FIFA) 11+ program has been shown to be an effective injury prevention program in the female soccer cohort, but there is a paucity of research to demonstrate its efficacy in the male population. HYPOTHESIS: To examine the efficacy of the FIFA 11+ program in men's collegiate United States National Collegiate Athletic Association (NCAA) Division I and Division II soccer. STUDY DESIGN: Randomized controlled trial; Level of evidence, 1. METHODS: Before the commencement of the fall 2012 season, every NCAA Division I and Division II men's collegiate soccer team (N = 396) was solicited to participate in this research study. Human ethics review board approval was obtained through Quorum Review IRB. Sixty-five teams were randomized: 34 to the control group (CG; 850 players) and 31 to the intervention group (IG; 675 players). Four teams in the IG did not complete the study, reducing the number for analysis to 61. The FIFA 11+ injury prevention program served as the intervention and was utilized weekly. Athlete-exposures (AEs), compliance, and injury data were recorded using a secure Internet-based system. RESULTS: In the CG, 665 injuries (mean ± SD, 19.56 ± 11.01) were reported for 34 teams, which corresponded to an incidence rate (IR) of 15.04 injuries per 1000 AEs. In the IG, 285 injuries (mean ± SD, 10.56 ± 3.64) were reported for 27 teams, which corresponded to an IR of 8.09 injuries per 1000 AEs. Total days missed because of injury were significantly higher for the CG (mean ± SD, 13.20 ± 26.6 days) than for the IG (mean ± SD, 10.08 ± 14.68 days) (P = .007). There was no difference for time loss due to injury based on field type (P = .341). CONCLUSION: The FIFA 11+ significantly reduced injury rates by 46.1% and decreased time loss to injury by 28.6% in the competitive male collegiate soccer player (rate ratio, 0.54 [95% CI, 0.49-0.59]; P < .0001) (number needed to treat = 2.64). ? 2015 The Author(s).","author":[{"family":"Silvers-Granelli","given":"Holly"},{"family":"Mandelbaum","given":"Bert"},{"family":"Adeniji","given":"Ola"},{"family":"Insler","given":"Stephanie"},{"family":"Bizzini","given":"Mario"},{"family":"Pohlig","given":"Ryan"},{"family":"Junge","given":"Astrid"},{"family":"Snyder-Mackler","given":"Lynn"},{"family":"Dvorak","given":"Jiri"}],"citation-label":"5824178","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"5824178","invisible":false,"issue":"11","issued":{"date-parts":[["2015","11"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"2628-2637","suppress-author":false,"title":"Efficacy of the FIFA 11+ injury prevention program in the collegiate male soccer player.","type":"article-journal","volume":"43"}]24,ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1007/s11999-017-5342-5","First":false,"Last":false,"PMCID":"PMC5599387","PMID":"28389864","author":[{"family":"Silvers-Granelli","given":"Holly J"},{"family":"Bizzini","given":"Mario"},{"family":"Arundale","given":"Amelia"},{"family":"Mandelbaum","given":"Bert R"},{"family":"Snyder-Mackler","given":"Lynn"}],"citation-label":"5824127","container-title":"Clinical Orthopaedics and Related Research","container-title-short":"Clin. Orthop. Relat. Res.","id":"5824127","invisible":false,"issue":"10","issued":{"date-parts":[["2017","10"]]},"journalAbbreviation":"Clin. Orthop. Relat. Res.","page":"2447-2455","suppress-author":false,"title":"Does the FIFA 11+?injury prevention program reduce the incidence of ACL injury in male soccer players?","type":"article-journal","volume":"475"}]25 Evidence is mixed regarding when the programs are most effective, as part of warmup for competition or throughout the day.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1007/s11999-017-5342-5","First":false,"Last":false,"PMCID":"PMC5599387","PMID":"28389864","author":[{"family":"Silvers-Granelli","given":"Holly J"},{"family":"Bizzini","given":"Mario"},{"family":"Arundale","given":"Amelia"},{"family":"Mandelbaum","given":"Bert R"},{"family":"Snyder-Mackler","given":"Lynn"}],"citation-label":"5824127","container-title":"Clinical Orthopaedics and Related Research","container-title-short":"Clin. Orthop. Relat. Res.","id":"5824127","invisible":false,"issue":"10","issued":{"date-parts":[["2017","10"]]},"journalAbbreviation":"Clin. Orthop. Relat. Res.","page":"2447-2455","suppress-author":false,"title":"Does the FIFA 11+?injury prevention program reduce the incidence of ACL injury in male soccer players?","type":"article-journal","volume":"475"},{"DOI":"10.1136/bmj.e3042","First":false,"Last":false,"PMCID":"PMC3342926","PMID":"22556050","abstract":"OBJECTIVE: To evaluate the effectiveness of neuromuscular training in reducing the rate of acute knee injury in adolescent female football players.\n \n \nDESIGN: Stratified cluster randomised controlled trial with clubs as the unit of randomisation.\n \n \nSETTING: 230 Swedish football clubs (121 in the intervention group, 109 in the control group) were followed for one season (2009, seven months).\n \n \nPARTICIPANTS: 4564 players aged 12-17 years (2479 in the intervention group, 2085 in the control group) completed the study.\n \n \nINTERVENTION: 15 minute neuromuscular warm-up programme (targeting core stability, balance, and proper knee alignment) to be carried out twice a week throughout the season.\n \n \nMAIN OUTCOME MEASURES: The primary outcome was rate of anterior cruciate ligament injury; secondary outcomes were rates of severe knee injury (>4 weeks' absence) and any acute knee injury.\n \n \nRESULTS: Seven players (0.28%) in the intervention group, and 14 (0.67%) in the control group had an anterior cruciate ligament injury. By Cox regression analysis according to intention to treat, a 64% reduction in the rate of anterior cruciate ligament injury was seen in the intervention group (rate ratio 0.36, 95% confidence interval 0.15 to 0.85). The absolute rate difference was -0.07 (95% confidence interval -0.13 to 0.001) per 1000 playing hours in favour of the intervention group. No significant rate reductions were seen for secondary outcomes.\n \n \nCONCLUSIONS: A neuromuscular warm-up programme significantly reduced the rate of anterior cruciate ligament injury in adolescent female football players. However, the absolute rate difference did not reach statistical significance, possibly owing to the small number of events.\n \n \nTRIAL REGISTRATION: Clinical trials NCT00894595.","author":[{"family":"Waldén","given":"Markus"},{"family":"Atroshi","given":"Isam"},{"family":"Magnusson","given":"Henrik"},{"family":"Wagner","given":"Philippe"},{"family":"H?gglund","given":"Martin"}],"citation-label":"1129629","container-title":"BMJ (Clinical Research Ed.)","container-title-short":"BMJ","id":"1129629","invisible":false,"issued":{"date-parts":[["2012","5","3"]]},"journalAbbreviation":"BMJ","page":"e3042","suppress-author":false,"title":"Prevention of acute knee injuries in adolescent female football players: cluster randomised controlled trial.","type":"article-journal","volume":"344"},{"First":false,"Last":false,"PMID":"8963746","abstract":"Proprioceptive training has been shown to reduce the incidence of ankle sprains in different sports. It can also improve rehabilitation after anterior cruciate ligament (ACL) injuries whether treated operatively or nonoperatively. Since ACL injuries lead to long absence from sports and are one of the main causes of permanent sports disability, it is essential to try to prevent them. In a prospective controlled study of 600 soccer players in 40 semiprofessional or amateur teams, we studied the possible preventive effect of a gradually increasing proprioceptive training on four different types of wobble-boards during three soccer seasons. Three hundred players were instructed to train 20 min per day with 5 different phases of increasing difficulty. The first phase consisted of balance training without any balance board; phase 2 of training on a rectangular balance board; phase 3 of training on a round board; phase 4 of training on a combined round and rectangular board; phase 5 of training on a so-called BABS board. A control group of 300 players from other, comparable teams trained \"normally\" and received no special balance training. Both groups were observed for three whole soccer seasons, and possible ACL lesions were diagnosed by clinical examination, KT-1000 measurements, magnetic resonance imaging or computed tomography, and arthroscopy. We found an incidence of 1.15 ACL injuries per team per year in the proprioceptively trained group (P < 0.001). Proprioceptive training can thus significantly reduce the incidence of ACL injuries in soccer players.","author":[{"family":"Caraffa","given":"A"},{"family":"Cerulli","given":"G"},{"family":"Projetti","given":"M"},{"family":"Aisa","given":"G"},{"family":"Rizzo","given":"A"}],"citation-label":"6072844","container-title":"Knee Surgery, Sports Traumatology, Arthroscopy","container-title-short":"Knee Surg. Sports Traumatol. Arthrosc.","id":"6072844","invisible":false,"issue":"1","issued":{"date-parts":[["1996"]]},"journalAbbreviation":"Knee Surg. Sports Traumatol. Arthrosc.","page":"19-21","suppress-author":false,"title":"Prevention of anterior cruciate ligament injuries in soccer. A prospective controlled study of proprioceptive training.","type":"article-journal","volume":"4"},{"DOI":"10.1177/03635465990270060301","First":false,"Last":false,"PMID":"10569353","abstract":"To prospectively evaluate the effect of neuromuscular training on the incidence of knee injury in female athletes, we monitored two groups of female athletes, one trained before sports participation and the other not trained, and a group of untrained male athletes throughout the high school soccer, volleyball, and basketball seasons. Weekly reports included the number of practice and competition exposures and mechanism of injury. There were 14 serious knee injuries in the 1263 athletes tracked through the study. Ten of 463 untrained female athletes sustained serious knee injuries (8 noncontact), 2 of 366 trained female athletes sustained serious knee injuries (0 noncontact), and 2 of 434 male athletes sustained serious knee injuries (1 noncontact). The knee injury incidence per 1000 athlete-exposures was 0.43 in untrained female athletes, 0.12 in trained female athletes, and 0.09 in male athletes (P = 0.02, chi-square analysis). Untrained female athletes had a 3.6 times higher incidence of knee injury than trained female athletes (P = 0.05) and 4.8 times higher than male athletes (P = 0.03). The incidence of knee injury in trained female athletes was not significantly different from that in untrained male athletes (P = 0.86). The difference in the incidence of noncontact injuries between the female groups was also significant (P = 0.01). This prospective study demonstrated a decreased incidence of knee injury in female athletes after a specific plyometric training program.","author":[{"family":"Hewett","given":"T E"},{"family":"Lindenfeld","given":"T N"},{"family":"Riccobene","given":"J V"},{"family":"Noyes","given":"F R"}],"citation-label":"3625077","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"3625077","invisible":false,"issue":"6","issued":{"date-parts":[["1999","12"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"699-706","suppress-author":false,"title":"The effect of neuromuscular training on the incidence of knee injury in female athletes. A prospective study.","type":"article-journal","volume":"27"}]16,21,22,25 Finally, the cost-effectiveness of the intervention should be explored to determine its utility in the real world setting. Larger sample sizes are required to determine the real impact of these programs, and determine if they are reducing the risk of ACL injuries by addressing modifiable risk factors that relate to common mechanisms of injury. Conclusions:Available research support for the utility of a comprehensive strength, balance, flexibility and proprioceptive program for the reduction of severe knee injuries. Except for the protocol outlined in Caraffa et al., the other prevention programs aim to decrease the rate of ACL injuries by strengthening muscles around the knee joint and improving landing/jumping mechanics.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1007/s11999-017-5342-5","First":false,"Last":false,"PMCID":"PMC5599387","PMID":"28389864","author":[{"family":"Silvers-Granelli","given":"Holly J"},{"family":"Bizzini","given":"Mario"},{"family":"Arundale","given":"Amelia"},{"family":"Mandelbaum","given":"Bert R"},{"family":"Snyder-Mackler","given":"Lynn"}],"citation-label":"5824127","container-title":"Clinical Orthopaedics and Related Research","container-title-short":"Clin. Orthop. Relat. Res.","id":"5824127","invisible":false,"issue":"10","issued":{"date-parts":[["2017","10"]]},"journalAbbreviation":"Clin. Orthop. Relat. Res.","page":"2447-2455","suppress-author":false,"title":"Does the FIFA 11+?injury prevention program reduce the incidence of ACL injury in male soccer players?","type":"article-journal","volume":"475"},{"DOI":"10.1136/bmj.e3042","First":false,"Last":false,"PMCID":"PMC3342926","PMID":"22556050","abstract":"OBJECTIVE: To evaluate the effectiveness of neuromuscular training in reducing the rate of acute knee injury in adolescent female football players.\n \n \nDESIGN: Stratified cluster randomised controlled trial with clubs as the unit of randomisation.\n \n \nSETTING: 230 Swedish football clubs (121 in the intervention group, 109 in the control group) were followed for one season (2009, seven months).\n \n \nPARTICIPANTS: 4564 players aged 12-17 years (2479 in the intervention group, 2085 in the control group) completed the study.\n \n \nINTERVENTION: 15 minute neuromuscular warm-up programme (targeting core stability, balance, and proper knee alignment) to be carried out twice a week throughout the season.\n \n \nMAIN OUTCOME MEASURES: The primary outcome was rate of anterior cruciate ligament injury; secondary outcomes were rates of severe knee injury (>4 weeks' absence) and any acute knee injury.\n \n \nRESULTS: Seven players (0.28%) in the intervention group, and 14 (0.67%) in the control group had an anterior cruciate ligament injury. By Cox regression analysis according to intention to treat, a 64% reduction in the rate of anterior cruciate ligament injury was seen in the intervention group (rate ratio 0.36, 95% confidence interval 0.15 to 0.85). The absolute rate difference was -0.07 (95% confidence interval -0.13 to 0.001) per 1000 playing hours in favour of the intervention group. No significant rate reductions were seen for secondary outcomes.\n \n \nCONCLUSIONS: A neuromuscular warm-up programme significantly reduced the rate of anterior cruciate ligament injury in adolescent female football players. However, the absolute rate difference did not reach statistical significance, possibly owing to the small number of events.\n \n \nTRIAL REGISTRATION: Clinical trials NCT00894595.","author":[{"family":"Waldén","given":"Markus"},{"family":"Atroshi","given":"Isam"},{"family":"Magnusson","given":"Henrik"},{"family":"Wagner","given":"Philippe"},{"family":"H?gglund","given":"Martin"}],"citation-label":"1129629","container-title":"BMJ (Clinical Research Ed.)","container-title-short":"BMJ","id":"1129629","invisible":false,"issued":{"date-parts":[["2012","5","3"]]},"journalAbbreviation":"BMJ","page":"e3042","suppress-author":false,"title":"Prevention of acute knee injuries in adolescent female football players: cluster randomised controlled trial.","type":"article-journal","volume":"344"},{"First":false,"Last":false,"PMID":"8963746","abstract":"Proprioceptive training has been shown to reduce the incidence of ankle sprains in different sports. It can also improve rehabilitation after anterior cruciate ligament (ACL) injuries whether treated operatively or nonoperatively. Since ACL injuries lead to long absence from sports and are one of the main causes of permanent sports disability, it is essential to try to prevent them. In a prospective controlled study of 600 soccer players in 40 semiprofessional or amateur teams, we studied the possible preventive effect of a gradually increasing proprioceptive training on four different types of wobble-boards during three soccer seasons. Three hundred players were instructed to train 20 min per day with 5 different phases of increasing difficulty. The first phase consisted of balance training without any balance board; phase 2 of training on a rectangular balance board; phase 3 of training on a round board; phase 4 of training on a combined round and rectangular board; phase 5 of training on a so-called BABS board. A control group of 300 players from other, comparable teams trained \"normally\" and received no special balance training. Both groups were observed for three whole soccer seasons, and possible ACL lesions were diagnosed by clinical examination, KT-1000 measurements, magnetic resonance imaging or computed tomography, and arthroscopy. We found an incidence of 1.15 ACL injuries per team per year in the proprioceptively trained group (P < 0.001). Proprioceptive training can thus significantly reduce the incidence of ACL injuries in soccer players.","author":[{"family":"Caraffa","given":"A"},{"family":"Cerulli","given":"G"},{"family":"Projetti","given":"M"},{"family":"Aisa","given":"G"},{"family":"Rizzo","given":"A"}],"citation-label":"6072844","container-title":"Knee Surgery, Sports Traumatology, Arthroscopy","container-title-short":"Knee Surg. Sports Traumatol. Arthrosc.","id":"6072844","invisible":false,"issue":"1","issued":{"date-parts":[["1996"]]},"journalAbbreviation":"Knee Surg. Sports Traumatol. Arthrosc.","page":"19-21","suppress-author":false,"title":"Prevention of anterior cruciate ligament injuries in soccer. A prospective controlled study of proprioceptive training.","type":"article-journal","volume":"4"},{"DOI":"10.1177/03635465990270060301","First":false,"Last":false,"PMID":"10569353","abstract":"To prospectively evaluate the effect of neuromuscular training on the incidence of knee injury in female athletes, we monitored two groups of female athletes, one trained before sports participation and the other not trained, and a group of untrained male athletes throughout the high school soccer, volleyball, and basketball seasons. Weekly reports included the number of practice and competition exposures and mechanism of injury. There were 14 serious knee injuries in the 1263 athletes tracked through the study. Ten of 463 untrained female athletes sustained serious knee injuries (8 noncontact), 2 of 366 trained female athletes sustained serious knee injuries (0 noncontact), and 2 of 434 male athletes sustained serious knee injuries (1 noncontact). The knee injury incidence per 1000 athlete-exposures was 0.43 in untrained female athletes, 0.12 in trained female athletes, and 0.09 in male athletes (P = 0.02, chi-square analysis). Untrained female athletes had a 3.6 times higher incidence of knee injury than trained female athletes (P = 0.05) and 4.8 times higher than male athletes (P = 0.03). The incidence of knee injury in trained female athletes was not significantly different from that in untrained male athletes (P = 0.86). The difference in the incidence of noncontact injuries between the female groups was also significant (P = 0.01). This prospective study demonstrated a decreased incidence of knee injury in female athletes after a specific plyometric training program.","author":[{"family":"Hewett","given":"T E"},{"family":"Lindenfeld","given":"T N"},{"family":"Riccobene","given":"J V"},{"family":"Noyes","given":"F R"}],"citation-label":"3625077","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"3625077","invisible":false,"issue":"6","issued":{"date-parts":[["1999","12"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"699-706","suppress-author":false,"title":"The effect of neuromuscular training on the incidence of knee injury in female athletes. A prospective study.","type":"article-journal","volume":"27"}]16,21,22,25 Arundale et al. recommend the implantation of a multifaceted injury prevention program for 20 minutes or more multiple times each week.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.2519/jospt.2018.0303","First":false,"Last":false,"PMID":"30170521","abstract":"The Academy of Orthopaedic Physical Therapy and the American Academy of Sports Physical Therapy have an ongoing effort to create evidence-based clinical practice guidelines (CPGs) for orthopaedic and sports physical therapy management and prevention of musculoskeletal impairments described in the World Health Organization's International Classification of Functioning, Disability and Health (ICF). This particular guideline focuses on the exercise-based prevention of knee injuries. J Orthop Sports Phys Ther. 2018;48(9):A1-A42. doi:10.2519/jospt.2018.0303.","author":[{"family":"Arundale","given":"Amelia J H"},{"family":"Bizzini","given":"Mario"},{"family":"Giordano","given":"Airelle"},{"family":"Hewett","given":"Timothy E"},{"family":"Logerstedt","given":"David S"},{"family":"Mandelbaum","given":"Bert"},{"family":"Scalzitti","given":"David A"},{"family":"Silvers-Granelli","given":"Holly"},{"family":"Snyder-Mackler","given":"Lynn"}],"citation-label":"6006049","container-title":"The Journal of Orthopaedic and Sports Physical Therapy","container-title-short":"J. Orthop. Sports Phys. Ther.","id":"6006049","invisible":false,"issue":"9","issued":{"date-parts":[["2018","9"]]},"journalAbbreviation":"J. Orthop. Sports Phys. Ther.","page":"A1-A42","suppress-author":false,"title":"Exercise-Based Knee and Anterior Cruciate Ligament Injury Prevention.","type":"article-journal","volume":"48"}]20 They recommend the performance of these programs during the preseason and throughout the season for all youth athletes (ages 12-25).ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.2519/jospt.2018.0303","First":false,"Last":false,"PMID":"30170521","abstract":"The Academy of Orthopaedic Physical Therapy and the American Academy of Sports Physical Therapy have an ongoing effort to create evidence-based clinical practice guidelines (CPGs) for orthopaedic and sports physical therapy management and prevention of musculoskeletal impairments described in the World Health Organization's International Classification of Functioning, Disability and Health (ICF). This particular guideline focuses on the exercise-based prevention of knee injuries. J Orthop Sports Phys Ther. 2018;48(9):A1-A42. doi:10.2519/jospt.2018.0303.","author":[{"family":"Arundale","given":"Amelia J H"},{"family":"Bizzini","given":"Mario"},{"family":"Giordano","given":"Airelle"},{"family":"Hewett","given":"Timothy E"},{"family":"Logerstedt","given":"David S"},{"family":"Mandelbaum","given":"Bert"},{"family":"Scalzitti","given":"David A"},{"family":"Silvers-Granelli","given":"Holly"},{"family":"Snyder-Mackler","given":"Lynn"}],"citation-label":"6006049","container-title":"The Journal of Orthopaedic and Sports Physical Therapy","container-title-short":"J. Orthop. Sports Phys. Ther.","id":"6006049","invisible":false,"issue":"9","issued":{"date-parts":[["2018","9"]]},"journalAbbreviation":"J. Orthop. Sports Phys. Ther.","page":"A1-A42","suppress-author":false,"title":"Exercise-Based Knee and Anterior Cruciate Ligament Injury Prevention.","type":"article-journal","volume":"48"}]20 These programs are consistent with the known mechanisms of ACL stress and injury that are common in soccer players. Given the high incidence of ACL injuries among soccer players, and the devastating short and long-term impact an ACL injury can have on an athlete, these programs, or similar ones aimed at improving landing mechanics, balance and strengthening quadriceps muscles, should be implemented as routine components of soccer training, especially female athletes.ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1007/s11999-017-5342-5","First":false,"Last":false,"PMCID":"PMC5599387","PMID":"28389864","author":[{"family":"Silvers-Granelli","given":"Holly J"},{"family":"Bizzini","given":"Mario"},{"family":"Arundale","given":"Amelia"},{"family":"Mandelbaum","given":"Bert R"},{"family":"Snyder-Mackler","given":"Lynn"}],"citation-label":"5824127","container-title":"Clinical Orthopaedics and Related Research","container-title-short":"Clin. Orthop. Relat. Res.","id":"5824127","invisible":false,"issue":"10","issued":{"date-parts":[["2017","10"]]},"journalAbbreviation":"Clin. Orthop. Relat. Res.","page":"2447-2455","suppress-author":false,"title":"Does the FIFA 11+?injury prevention program reduce the incidence of ACL injury in male soccer players?","type":"article-journal","volume":"475"},{"DOI":"10.1136/bmj.e3042","First":false,"Last":false,"PMCID":"PMC3342926","PMID":"22556050","abstract":"OBJECTIVE: To evaluate the effectiveness of neuromuscular training in reducing the rate of acute knee injury in adolescent female football players.\n \n \nDESIGN: Stratified cluster randomised controlled trial with clubs as the unit of randomisation.\n \n \nSETTING: 230 Swedish football clubs (121 in the intervention group, 109 in the control group) were followed for one season (2009, seven months).\n \n \nPARTICIPANTS: 4564 players aged 12-17 years (2479 in the intervention group, 2085 in the control group) completed the study.\n \n \nINTERVENTION: 15 minute neuromuscular warm-up programme (targeting core stability, balance, and proper knee alignment) to be carried out twice a week throughout the season.\n \n \nMAIN OUTCOME MEASURES: The primary outcome was rate of anterior cruciate ligament injury; secondary outcomes were rates of severe knee injury (>4 weeks' absence) and any acute knee injury.\n \n \nRESULTS: Seven players (0.28%) in the intervention group, and 14 (0.67%) in the control group had an anterior cruciate ligament injury. By Cox regression analysis according to intention to treat, a 64% reduction in the rate of anterior cruciate ligament injury was seen in the intervention group (rate ratio 0.36, 95% confidence interval 0.15 to 0.85). The absolute rate difference was -0.07 (95% confidence interval -0.13 to 0.001) per 1000 playing hours in favour of the intervention group. No significant rate reductions were seen for secondary outcomes.\n \n \nCONCLUSIONS: A neuromuscular warm-up programme significantly reduced the rate of anterior cruciate ligament injury in adolescent female football players. However, the absolute rate difference did not reach statistical significance, possibly owing to the small number of events.\n \n \nTRIAL REGISTRATION: Clinical trials NCT00894595.","author":[{"family":"Waldén","given":"Markus"},{"family":"Atroshi","given":"Isam"},{"family":"Magnusson","given":"Henrik"},{"family":"Wagner","given":"Philippe"},{"family":"H?gglund","given":"Martin"}],"citation-label":"1129629","container-title":"BMJ (Clinical Research Ed.)","container-title-short":"BMJ","id":"1129629","invisible":false,"issued":{"date-parts":[["2012","5","3"]]},"journalAbbreviation":"BMJ","page":"e3042","suppress-author":false,"title":"Prevention of acute knee injuries in adolescent female football players: cluster randomised controlled trial.","type":"article-journal","volume":"344"},{"First":false,"Last":false,"PMID":"8963746","abstract":"Proprioceptive training has been shown to reduce the incidence of ankle sprains in different sports. It can also improve rehabilitation after anterior cruciate ligament (ACL) injuries whether treated operatively or nonoperatively. Since ACL injuries lead to long absence from sports and are one of the main causes of permanent sports disability, it is essential to try to prevent them. In a prospective controlled study of 600 soccer players in 40 semiprofessional or amateur teams, we studied the possible preventive effect of a gradually increasing proprioceptive training on four different types of wobble-boards during three soccer seasons. Three hundred players were instructed to train 20 min per day with 5 different phases of increasing difficulty. The first phase consisted of balance training without any balance board; phase 2 of training on a rectangular balance board; phase 3 of training on a round board; phase 4 of training on a combined round and rectangular board; phase 5 of training on a so-called BABS board. A control group of 300 players from other, comparable teams trained \"normally\" and received no special balance training. Both groups were observed for three whole soccer seasons, and possible ACL lesions were diagnosed by clinical examination, KT-1000 measurements, magnetic resonance imaging or computed tomography, and arthroscopy. We found an incidence of 1.15 ACL injuries per team per year in the proprioceptively trained group (P < 0.001). Proprioceptive training can thus significantly reduce the incidence of ACL injuries in soccer players.","author":[{"family":"Caraffa","given":"A"},{"family":"Cerulli","given":"G"},{"family":"Projetti","given":"M"},{"family":"Aisa","given":"G"},{"family":"Rizzo","given":"A"}],"citation-label":"6072844","container-title":"Knee Surgery, Sports Traumatology, Arthroscopy","container-title-short":"Knee Surg. Sports Traumatol. Arthrosc.","id":"6072844","invisible":false,"issue":"1","issued":{"date-parts":[["1996"]]},"journalAbbreviation":"Knee Surg. Sports Traumatol. Arthrosc.","page":"19-21","suppress-author":false,"title":"Prevention of anterior cruciate ligament injuries in soccer. A prospective controlled study of proprioceptive training.","type":"article-journal","volume":"4"},{"DOI":"10.1177/03635465990270060301","First":false,"Last":false,"PMID":"10569353","abstract":"To prospectively evaluate the effect of neuromuscular training on the incidence of knee injury in female athletes, we monitored two groups of female athletes, one trained before sports participation and the other not trained, and a group of untrained male athletes throughout the high school soccer, volleyball, and basketball seasons. Weekly reports included the number of practice and competition exposures and mechanism of injury. There were 14 serious knee injuries in the 1263 athletes tracked through the study. Ten of 463 untrained female athletes sustained serious knee injuries (8 noncontact), 2 of 366 trained female athletes sustained serious knee injuries (0 noncontact), and 2 of 434 male athletes sustained serious knee injuries (1 noncontact). The knee injury incidence per 1000 athlete-exposures was 0.43 in untrained female athletes, 0.12 in trained female athletes, and 0.09 in male athletes (P = 0.02, chi-square analysis). Untrained female athletes had a 3.6 times higher incidence of knee injury than trained female athletes (P = 0.05) and 4.8 times higher than male athletes (P = 0.03). The incidence of knee injury in trained female athletes was not significantly different from that in untrained male athletes (P = 0.86). The difference in the incidence of noncontact injuries between the female groups was also significant (P = 0.01). This prospective study demonstrated a decreased incidence of knee injury in female athletes after a specific plyometric training program.","author":[{"family":"Hewett","given":"T E"},{"family":"Lindenfeld","given":"T N"},{"family":"Riccobene","given":"J V"},{"family":"Noyes","given":"F R"}],"citation-label":"3625077","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"3625077","invisible":false,"issue":"6","issued":{"date-parts":[["1999","12"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"699-706","suppress-author":false,"title":"The effect of neuromuscular training on the incidence of knee injury in female athletes. A prospective study.","type":"article-journal","volume":"27"}]16,ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.2519/jospt.2018.0303","First":false,"Last":false,"PMID":"30170521","abstract":"The Academy of Orthopaedic Physical Therapy and the American Academy of Sports Physical Therapy have an ongoing effort to create evidence-based clinical practice guidelines (CPGs) for orthopaedic and sports physical therapy management and prevention of musculoskeletal impairments described in the World Health Organization's International Classification of Functioning, Disability and Health (ICF). This particular guideline focuses on the exercise-based prevention of knee injuries. J Orthop Sports Phys Ther. 2018;48(9):A1-A42. doi:10.2519/jospt.2018.0303.","author":[{"family":"Arundale","given":"Amelia J H"},{"family":"Bizzini","given":"Mario"},{"family":"Giordano","given":"Airelle"},{"family":"Hewett","given":"Timothy E"},{"family":"Logerstedt","given":"David S"},{"family":"Mandelbaum","given":"Bert"},{"family":"Scalzitti","given":"David A"},{"family":"Silvers-Granelli","given":"Holly"},{"family":"Snyder-Mackler","given":"Lynn"}],"citation-label":"6006049","container-title":"The Journal of Orthopaedic and Sports Physical Therapy","container-title-short":"J. Orthop. Sports Phys. Ther.","id":"6006049","invisible":false,"issue":"9","issued":{"date-parts":[["2018","9"]]},"journalAbbreviation":"J. Orthop. Sports Phys. Ther.","page":"A1-A42","suppress-author":false,"title":"Exercise-Based Knee and Anterior Cruciate Ligament Injury Prevention.","type":"article-journal","volume":"48"}]20,21,22,25BibliographyADDIN F1000_CSL_BIBLIOGRAPHY1. Alentorn-Geli E, Myer GD, Silvers HJ, et al. Prevention of non-contact anterior cruciate ligament injuries in soccer players. Part 1: Mechanisms of injury and underlying risk factors. Knee Surg Sports Traumatol Arthrosc 2009;17(7):705-729. doi:10.1007/s00167-009-0813-1.2. Lohmander LS, Ostenberg A, Englund M, Roos H. High prevalence of knee osteoarthritis, pain, and functional limitations in female soccer players twelve years after anterior cruciate ligament injury. Arthritis Rheum 2004;50(10):3145-3152. doi:10.1002/art.20589.3. Bahr R, Krosshaug T. Understanding injury mechanisms: a key component of preventing injuries in sport. Br J Sports Med 2005;39(6):324-329. doi:10.1136/bjsm.2005.018341.4. Allen MM, Pareek A, Krych AJ, et al. Are female soccer players at an increased risk of second anterior cruciate ligament injury compared with their athletic peers? Am J Sports Med 2016;44(10):2492-2498. doi:10.1177/0363546516648439.5. Dai B, Mao D, Garrett WE, Yu B. Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and prevention programs. J. Sport Health Sci. 2014;3(4):299-306. doi:10.1016/j.jshs.2014.06.002.6. van Meer BL, Meuffels DE, van Eijsden WA, Verhaar JAN, Bierma-Zeinstra SMA, Reijman M. Which determinants predict tibiofemoral and patellofemoral osteoarthritis after anterior cruciate ligament injury? A systematic review. Br J Sports Med 2015;49(15):975-983. doi:10.1136/bjsports-2013-093258.7. Boden BP, Dean GS, Feagin JA, Garrett WE. Mechanisms of anterior cruciate ligament injury. Orthopedics 2000;23(6):573-578.8. Fu FH, Bennett CH, Lattermann C, Ma CB. Current trends in anterior cruciate ligament reconstruction. Part 1: Biology and biomechanics of reconstruction. Am J Sports Med 1999;27(6):821-830. doi:10.1177/03635465990270062501.9. Markolf KL, Burchfield DM, Shapiro MM, Shepard MF, Finerman GA, Slauterbeck JL. Combined knee loading states that generate high anterior cruciate ligament forces. J Orthop Res 1995;13(6):930-935. doi:10.1002/jor.1100130618.10. Levine JW, Kiapour AM, Quatman CE, et al. Clinically relevant injury patterns after an anterior cruciate ligament injury provide insight into injury mechanisms. Am J Sports Med 2013;41(2):385-395. doi:10.1177/0363546512465167.11. Cochrane JL, Lloyd DG, Buttfield A, Seward H, McGivern J. Characteristics of anterior cruciate ligament injuries in Australian football. J Sci Med Sport 2007;10(2):96-104. doi:10.1016/j.jsams.2006.05.015.12. Waldén M, Krosshaug T, Bj?rneboe J, Andersen TE, Faul O, H?gglund M. Three distinct mechanisms predominate in non-contact anterior cruciate ligament injuries in male professional football players: a systematic video analysis of 39 cases. Br J Sports Med 2015;49(22):1452-1460. doi:10.1136/bjsports-2014-094573.13. Grassi A, Smiley SP, Roberti di Sarsina T, et al. Mechanisms and situations of anterior cruciate ligament injuries in professional male soccer players: a YouTube-based video analysis. Eur J Orthop Surg Traumatol 2017;27(7):967-981. doi:10.1007/s00590-017-1905-0.14. Anderson MJ, Browning WM, Urband CE, Kluczynski MA, Bisson LJ. A systematic summary of systematic reviews on the topic of the anterior cruciate ligament. Orthop. J. Sports Med. 2016;4(3):2325967116634074. doi:10.1177/2325967116634074.15. Waldén M, H?gglund M, Werner J, Ekstrand J. The epidemiology of anterior cruciate ligament injury in football (soccer): a review of the literature from a gender-related perspective. Knee Surg Sports Traumatol Arthrosc 2011;19(1):3-10. doi:10.1007/s00167-010-1172-7.16. Hewett TE, Lindenfeld TN, Riccobene JV, Noyes FR. The effect of neuromuscular training on the incidence of knee injury in female athletes. A prospective study. Am J Sports Med 1999;27(6):699-706. doi:10.1177/03635465990270060301.17. Carson DW, Ford KR. Sex differences in knee abduction during landing: a systematic review. Sports Health 2011;3(4):373-382. doi:10.1177/1941738111410180.18. Kiapour AM, Murray MM. Basic science of anterior cruciate ligament injury and repair. Bone Joint Res. 2014;3(2):20-31. doi:10.1302/2046-3758.32.2000241.19. Zebis MK, Andersen LL, Ellingsgaard H, Aagaard P. Rapid hamstring/quadriceps force capacity in male vs. female elite soccer players. J Strength Cond Res 2011;25(7):1989-1993. doi:10.1519/JSC.0b013e3181e501a6.20. Arundale AJH, Bizzini M, Giordano A, et al. Exercise-Based Knee and Anterior Cruciate Ligament Injury Prevention. J Orthop Sports Phys Ther 2018;48(9):A1-A42. doi:10.2519/jospt.2018.0303.21. Caraffa A, Cerulli G, Projetti M, Aisa G, Rizzo A. Prevention of anterior cruciate ligament injuries in soccer. A prospective controlled study of proprioceptive training. Knee Surg Sports Traumatol Arthrosc 1996;4(1):19-21.22. Waldén M, Atroshi I, Magnusson H, Wagner P, H?gglund M. Prevention of acute knee injuries in adolescent female football players: cluster randomised controlled trial. BMJ 2012;344:e3042. doi:10.1136/bmj.e3042.23. Thorborg K, Krommes KK, Esteve E, Clausen MB, Bartels EM, Rathleff MS. Effect of specific exercise-based football injury prevention programmes on the overall injury rate in football: a systematic review and meta-analysis of the FIFA 11 and 11+ programmes. Br J Sports Med 2017;51(7):562-571. doi:10.1136/bjsports-2016-097066.24. Silvers-Granelli H, Mandelbaum B, Adeniji O, et al. Efficacy of the FIFA 11+ injury prevention program in the collegiate male soccer player. Am J Sports Med 2015;43(11):2628-2637. doi:10.1177/0363546515602009.25. Silvers-Granelli HJ, Bizzini M, Arundale A, Mandelbaum BR, Snyder-Mackler L. Does the FIFA 11+?injury prevention program reduce the incidence of ACL injury in male soccer players? Clin Orthop Relat Res 2017;475(10):2447-2455. doi:10.1007/s11999-017-5342-5.26. Kernozek T, Torry M, Shelburne K, Durall CJ, Willson J. From the gait laboratory to the rehabilitation clinic: translation of motion analysis and modeling data to interventions that impact anterior cruciate ligament loads in gait and drop landing. Crit Rev Biomed Eng 2013;41(3):243-258.Appendix 1: Injury Causation Model proposed by Bahr & Krosshaug (2005) Appendix 2: Anterior and posterior shear forces produced by patella tendon and hamstrings (modified from Kernozek et al 2013)ADDIN F1000_CSL_CITATION<~#@#~>[{"First":false,"Last":false,"PMID":"24579646","abstract":"In female athletes the risk of anterior cruciate ligament (ACL) injury during impact-related activities such as landing is higher compared to males. Both how and why this occurs has been at the forefront of orthopedic sports medicine research over the past 20 years. Many individuals with an ACL-deficient knee compensate for joint instability in an effort to remain physically active. Yet others do not compensate and are faced with a reduction in their activities and/or meniscus tears and eventually osteoarthritis. In this article we attempt to link 2 distinct but related scientific disciplines (in vivo motion analysis assessment and computational modeling) to show how these techniques have emerged as powerful tools in our understanding of knee function. Normal knee function and the biomechanics of the ACL-deficient (ACLd) and ACL-reconstructed (ACLr) knee are summarized. Basic experiments concerning the mechanism of noncontact ACL injury as well as performance adaptations in ACLd and ACLr knees are reviewed, and the biomechanics of the normal, ACLd, and ACLr knees under more strenuous activities, such as landing from a jump, are provided. ","author":[{"family":"Kernozek","given":"Thomas"},{"family":"Torry","given":"Michael"},{"family":"Shelburne","given":"Kevin"},{"family":"Durall","given":"Christopher J"},{"family":"Willson","given":"John"}],"citation-label":"6055158","container-title":"Critical reviews in biomedical engineering","container-title-short":"Crit. Rev. Biomed. Eng.","id":"6055158","invisible":false,"issue":"3","issued":{"date-parts":[["2013"]]},"journalAbbreviation":"Crit. Rev. Biomed. Eng.","page":"243-258","suppress-author":false,"title":"From the gait laboratory to the rehabilitation clinic: translation of motion analysis and modeling data to interventions that impact anterior cruciate ligament loads in gait and drop landing.","type":"article-journal","volume":"41"}]26Appendix 3: Anterior Tibial Translation at Various Knee Flexion Angles from FH et al. 1999ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/03635465990270062501","First":false,"Last":false,"PMID":"10569374","abstract":"With today's increasing emphasis on sporting activities, the incidence of anterior cruciate ligament injuries has also increased. Epidemiologic studies estimate that the prevalence of anterior cruciate ligament injuries is about 1 per 3000 Americans. Management of these injuries has evolved from nonoperative treatment to extracapsular augmentation and primary ligament repair to anterior cruciate ligament reconstruction. Treatment of these injuries has significantly improved over the last few decades with the application of knowledge gained from both basic science and clinical research. This article is composed of two parts. The first part reviews the biology and biomechanics of the injured anterior cruciate ligament and the basic science of reconstruction. In the second part, to be published later, current operative concepts of reconstruction, as well as clinical correlations, are reviewed. Summarizing the latest information on basic scientific as well as clinical studies regarding the anterior cruciate ligament, this article intends to demonstrate the correlation between the application of basic science knowledge and improvement of clinical outcomes.","author":[{"family":"Fu","given":"F H"},{"family":"Bennett","given":"C H"},{"family":"Lattermann","given":"C"},{"family":"Ma","given":"C B"}],"citation-label":"6055142","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"6055142","invisible":false,"issue":"6","issued":{"date-parts":[["1999","12"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"821-830","suppress-author":false,"title":"Current trends in anterior cruciate ligament reconstruction. Part 1: Biology and biomechanics of reconstruction.","type":"article-journal","volume":"27"}]8Appendix 4: Mechanism of non-contact ACL – pressing (graphic obtained from Walden et al. 2015)ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bjsports-2014-094573","First":false,"Last":false,"PMCID":"PMC4680158","PMID":"25907183","abstract":"BACKGROUND: Current knowledge on anterior cruciate ligament (ACL) injury mechanisms in male football players is limited. AIM: To describe ACL injury mechanisms in male professional football players using systematic video analysis. METHODS: We assessed videos from 39 complete ACL tears recorded via prospective professional football injury surveillance between 2001 and 2011. Five analysts independently reviewed all videos to estimate the time of initial foot contact with the ground and the time of ACL tear. We then analysed all videos according to a structured format describing the injury circumstances and lower limb joint biomechanics. RESULTS: Twenty-five injuries were non-contact, eight indirect contact and six direct contact injuries. We identified three main categories of non-contact and indirect contact injury situations: (1) pressing (n=11), (2) re-gaining balance after kicking (n=5) and (3) landing after heading (n=5). The fourth main injury situation was direct contact with the injured leg or knee (n=6). Knee valgus was frequently seen in the main categories of non-contact and indirect contact playing situations (n=11), but a dynamic valgus collapse was infrequent (n=3). This was in contrast to the tackling-induced direct contact situations where a knee valgus collapse occurred in all cases (n=3). CONCLUSIONS: Eighty-five per cent of the ACL injuries in male professional football players resulted from non-contact or indirect contact mechanisms. The most common playing situation leading to injury was pressing followed by kicking and heading. Knee valgus was frequently seen regardless of the playing situation, but a dynamic valgus collapse was rare. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to ","author":[{"family":"Waldén","given":"Markus"},{"family":"Krosshaug","given":"Tron"},{"family":"Bj?rneboe","given":"John"},{"family":"Andersen","given":"Thor Einar"},{"family":"Faul","given":"Oliver"},{"family":"H?gglund","given":"Martin"}],"citation-label":"1129936","container-title":"British Journal of Sports Medicine","container-title-short":"Br. J. Sports Med.","id":"1129936","invisible":false,"issue":"22","issued":{"date-parts":[["2015","11"]]},"journalAbbreviation":"Br. J. Sports Med.","page":"1452-1460","suppress-author":false,"title":"Three distinct mechanisms predominate in non-contact anterior cruciate ligament injuries in male professional football players: a systematic video analysis of 39 cases.","type":"article-journal","volume":"49"}]12 Appendix 5: Caraffa et al. protocol for proprioceptive training in the reduction of ACL injuries“Phase 1 consisted of balance training without a board. The athletes were instructed to stand alternately on one leg for 2.5 min four times a day. Phase 2 consisted of training each leg alternately on a rectangular balance board, for the same time period each day (Fig. 2). In phase 3 the rectangular board was exchanged for a round board. In phase 4 they trained on a combined round and rectangular board, and in phase 5 the training was performed on a so-called BAPS board (Camp, Jackson, Mich.) or a similar multi- planar board (Fig. 3).”Appendix 6: Sportsmetrics Protocol – per Hewett et alADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1177/03635465990270060301","First":false,"Last":false,"PMID":"10569353","abstract":"To prospectively evaluate the effect of neuromuscular training on the incidence of knee injury in female athletes, we monitored two groups of female athletes, one trained before sports participation and the other not trained, and a group of untrained male athletes throughout the high school soccer, volleyball, and basketball seasons. Weekly reports included the number of practice and competition exposures and mechanism of injury. There were 14 serious knee injuries in the 1263 athletes tracked through the study. Ten of 463 untrained female athletes sustained serious knee injuries (8 noncontact), 2 of 366 trained female athletes sustained serious knee injuries (0 noncontact), and 2 of 434 male athletes sustained serious knee injuries (1 noncontact). The knee injury incidence per 1000 athlete-exposures was 0.43 in untrained female athletes, 0.12 in trained female athletes, and 0.09 in male athletes (P = 0.02, chi-square analysis). Untrained female athletes had a 3.6 times higher incidence of knee injury than trained female athletes (P = 0.05) and 4.8 times higher than male athletes (P = 0.03). The incidence of knee injury in trained female athletes was not significantly different from that in untrained male athletes (P = 0.86). The difference in the incidence of noncontact injuries between the female groups was also significant (P = 0.01). This prospective study demonstrated a decreased incidence of knee injury in female athletes after a specific plyometric training program.","author":[{"family":"Hewett","given":"T E"},{"family":"Lindenfeld","given":"T N"},{"family":"Riccobene","given":"J V"},{"family":"Noyes","given":"F R"}],"citation-label":"3625077","container-title":"The American Journal of Sports Medicine","container-title-short":"Am. J. Sports Med.","id":"3625077","invisible":false,"issue":"6","issued":{"date-parts":[["1999","12"]]},"journalAbbreviation":"Am. J. Sports Med.","page":"699-706","suppress-author":false,"title":"The effect of neuromuscular training on the incidence of knee injury in female athletes. A prospective study.","type":"article-journal","volume":"27"}]16 Appendix 7: Kn?kontroll neuromuscular warm-up program protocol per Walden et al (2012)ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bmj.e3042","First":false,"Last":false,"PMCID":"PMC3342926","PMID":"22556050","abstract":"OBJECTIVE: To evaluate the effectiveness of neuromuscular training in reducing the rate of acute knee injury in adolescent female football players.\n \n \nDESIGN: Stratified cluster randomised controlled trial with clubs as the unit of randomisation.\n \n \nSETTING: 230 Swedish football clubs (121 in the intervention group, 109 in the control group) were followed for one season (2009, seven months).\n \n \nPARTICIPANTS: 4564 players aged 12-17 years (2479 in the intervention group, 2085 in the control group) completed the study.\n \n \nINTERVENTION: 15 minute neuromuscular warm-up programme (targeting core stability, balance, and proper knee alignment) to be carried out twice a week throughout the season.\n \n \nMAIN OUTCOME MEASURES: The primary outcome was rate of anterior cruciate ligament injury; secondary outcomes were rates of severe knee injury (>4 weeks' absence) and any acute knee injury.\n \n \nRESULTS: Seven players (0.28%) in the intervention group, and 14 (0.67%) in the control group had an anterior cruciate ligament injury. By Cox regression analysis according to intention to treat, a 64% reduction in the rate of anterior cruciate ligament injury was seen in the intervention group (rate ratio 0.36, 95% confidence interval 0.15 to 0.85). The absolute rate difference was -0.07 (95% confidence interval -0.13 to 0.001) per 1000 playing hours in favour of the intervention group. No significant rate reductions were seen for secondary outcomes.\n \n \nCONCLUSIONS: A neuromuscular warm-up programme significantly reduced the rate of anterior cruciate ligament injury in adolescent female football players. However, the absolute rate difference did not reach statistical significance, possibly owing to the small number of events.\n \n \nTRIAL REGISTRATION: Clinical trials NCT00894595.","author":[{"family":"Waldén","given":"Markus"},{"family":"Atroshi","given":"Isam"},{"family":"Magnusson","given":"Henrik"},{"family":"Wagner","given":"Philippe"},{"family":"H?gglund","given":"Martin"}],"citation-label":"1129629","container-title":"BMJ (Clinical Research Ed.)","container-title-short":"BMJ","id":"1129629","invisible":false,"issued":{"date-parts":[["2012","5","3"]]},"journalAbbreviation":"BMJ","page":"e3042","suppress-author":false,"title":"Prevention of acute knee injuries in adolescent female football players: cluster randomised controlled trial.","type":"article-journal","volume":"344"}]22ExerciseInstructionsRepetitions/durationOne legged knee squat:Slow movement with smooth turn, horizontal pelvis and non-supporting foot in front of body with slightly flexed hip and knee?Level AHands on hips3×8-15 reps?Level BHold ball over head with straight arms3×8-15 reps?Level CHands on hips; mark with non-supporting foot just above ground at 12-02-04-06 o’clock positions3×5 reps?Level DBend down while holding ball and let ball touch ground outside supporting foot; make diagonal movement upwards and raise ball over head with straight arms on contralateral side3×8-15 reps?Pair exercise?Teammate stands slightly oblique in front of you and ball is pressed between lateral sides of feet of non-supporting legs3×5-10 repsPelvic lift:Supine position; lift pelvis from ground while keeping back straight?Level ABoth feet on ground and hands across chest3×8-15 reps?Level BOne foot on ground and contralateral leg flexed in hip and knee 90° with both hands on knee3×8-15 reps?Level COne foot on football and contralateral leg flexed in hip and knee 90° with arms on ground alongside body3×8-15 reps?Level DOne foot on ground and other in air; keep upper arms on ground with elbows flexed 90°; push away supporting foot and land on contralateral foot3×8-15 reps?Pair exerciseTeammate stands with flexed knees and supports heel of one of your feet in her hands; hands across chest and lift pelvis3×8-15 repsTwo legged knee squat:Slow movement with smooth turn, back in straight position and feet shoulder-wide apart with soles in contact with ground?Level AHold ball in front of body with straight arms3×8-15 reps?Level BHands on hips3×8-15 reps?Level CHold ball over head with straight arms3×8-15 reps?Level DSame as level C but continue movement and rise up on toes after returning to starting position and stay briefly in that position3×8-15 reps?Pair exercise?Teammate stands next to you approximately 1 m away, facing opposite directions; hold ball between you with one hand and other hand on hip; apply slight pressure on ball while performing knee squat3×8-15 repsThe bench:Lift body and keep it in straight line?Level AProne position; support on knees and on lower arms with elbows kept under shoulders15-30 sec?Level BSame as level A but with support on tip of feet15-30 sec?Level CSame as level B, but move foot to side and back to starting position; alternate sides15-30 sec?Level DLie sideways with support on foot and lower arm with elbow kept under shoulder and other hand on hip; lift hip off ground and stay briefly in that position with good control before slowly returning to starting position5-10 reps?Pair exercise?Teammate stands behind you and holds your feet or lower legs; lift the body and walk forward by using hands on ground15-30 secThe lunge:Take deep step with marked knee lift and soft landing; rear knee should not touch ground?Level AHands on hips; move forward with each step3×8-15 reps?Level BHold ball in front of body with straight arms; rotate upper body while stepping forward and position ball laterally of front leg; move forward with each step and alternate sides3×8-15 reps?Level CHold ball over head with straight arms; perform forward lunge and push back with front leg and return to starting position3×8-15 reps?Level DHold ball in front of body with straight arms; perform sideways lunge and return to starting position3×8-15 reps?Pair-exercise?Teammate stands in front of you 5-10 m away; perform forward lunge while making throw-in with ball3×8-15 repsJump/landing:Make jump with soft landing; stay briefly in landing position?Level AStand on one leg with knee slightly bent and hands on hips; make short forward jump and land on same foot; jump backwards to starting position3×8-15 reps?Level BStand on two legs shoulder-wide apart with hands on back; make sideways jump and land on one foot; alternate sides3×8-15 reps?Level CTake a few quick steps on same spot and make short jump straight forward landing on one foot3×5 reps?Level DSame as level C, but change direction and jump to one side (90° turn); alternate sides3×5 reps?Pair exercise?Teammate stands in front of you approximately 5 m away; make two legged jump while heading football and land on two legs3×8-15 repsAppendix 8: FIFA 11+ injury prevention protocol per Thorborg et al. 2017ADDIN F1000_CSL_CITATION<~#@#~>[{"DOI":"10.1136/bjsports-2016-097066","First":false,"Last":false,"PMID":"28087568","abstract":"OBJECTIVE: To investigate the effect of FIFA injury prevention programmes in football (FIFA 11 and FIFA 11+). DESIGN: Systematic review and meta-analysis. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Randomised controlled trials comparing the FIFA injury prevention programmes with a control (no or sham intervention) among football players. DATA SOURCES: MEDLINE via PubMed, EMBASE via OVID, CINAHL via Ebsco, Web of Science, SportDiscus and Cochrane Central Register of Controlled Trials, from 2004 to 14 March 2016. RESULTS: 6 cluster-randomised controlled trials had assessed the effect of FIFA injury prevention programmes compared with controls on the overall football injury incidence in recreational/subelite football. These studies included 2 specific exercise-based injury prevention programmes: FIFA 11 (2 studies) and FIFA 11+ (4 studies). The primary analysis showed a reduction in the overall injury risk ratio of 0.75 (95% CI 0.57 to 0.98), p=0.04, in favour of the FIFA injury prevention programmes. Secondary analyses revealed that when pooling the 4 studies applying the FIFA 11+ prevention programme, a reduction in the overall injury risk ratio (incidence rate ratio (IRR) 0.61; 95% CI 0.48 to 0.77, p< 0.001) was present in favour of the FIFA 11+ prevention programme. No reduction was present when pooling the 2 studies including the FIFA 11 prevention programme (IRR 0.99; 95% CI 0.80 to 1.23, p=0.940). CONCLUSIONS: An injury-preventing effect of the FIFA injury prevention programmes compared with controls was shown in football. This effect was induced by the FIFA 11+ prevention programme which has a substantial injury-preventing effect by reducing football injuries by 39%, whereas a preventive effect of the FIFA 11 prevention programme could not be documented. TRIAL REGISTRATION NUMBER: PROSPERO CRD42015024120. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to .","author":[{"family":"Thorborg","given":"Kristian"},{"family":"Krommes","given":"Kasper Kühn"},{"family":"Esteve","given":"Ernest"},{"family":"Clausen","given":"Mikkel Bek"},{"family":"Bartels","given":"Else Marie"},{"family":"Rathleff","given":"Michael Skovdal"}],"citation-label":"5824173","container-title":"British Journal of Sports Medicine","container-title-short":"Br. J. Sports Med.","id":"5824173","invisible":false,"issue":"7","issued":{"date-parts":[["2017","4"]]},"journalAbbreviation":"Br. J. Sports Med.","page":"562-571","suppress-author":false,"title":"Effect of specific exercise-based football injury prevention programmes on the overall injury rate in football: a systematic review and meta-analysis of the FIFA 11 and 11+ programmes.","type":"article-journal","volume":"51"}]23Link to the full FIFA 11+ manual: ................
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