The College of New Jersey



Effectiveness of Electric Stimulation of the Vastus Medialis Muscle in the Rehabilitation of Patients After Total Knee ArthroplastyKyriakos Avramidis, MD, RRCS, Paul W. Strike, MPhil, Paul N. Taylor, MSc, CEng, Ian D. Swain, PhD, CEngArch Phys Med Rehabil Vol 84, December 2003Control group – conventional physical therapy – protocol in article (weight bearing an CPM)Experimental Group – PT + EMS (protocol below)Starting on the second postoperative day immediately after removal of the surgical drains, EMS was applied twice daily, for 2 hours on each occasion, while the patient was sitting or lying in bed with the knee extended. The stimulator used was the MicroStim 2-channel (MS-2) neuromuscular stimulator. For the purposes of the study only 1 channel was selected. The MS-2 has a maximum output of 120mA. Stimulation was applied at a frequency of 40Hz with a pulse width fixed at 300 micro sec.What was measured:Walking speed was estimated by performing a 3-minute walking test and recording the distance covered in meters.The PCI was derived by dividing the heart rate increase (heart rate at the end of the 3-minute walk minus resting heart rate in beats per minute) by the walking speed (in meters per minute). The HSS knee scoring system assigns 30 points for lack of pain, 22 points for function, 10 points for strength, 10 points for lack of instability, 10 points for lack of a flexion deformity, and 18 points for range of motion. This scoring system is among the most commonly quoted in North American literature.Results: Experimental group had a significant increase in walking speed at 6 and 12 weeks, but no significant change in PCI or HSS.Sports Med 2008; 38 (2): 161-177 Combined Application of Neuromuscular Electrical Stimulation and Voluntary Muscular ContractionsThierry PaillardFrom abstract: “In a rehabilitation context, EMS is complementary to voluntary exercise because in the early phase of rehabilitation it elicits a strength increase, which is necessary to perform voluntary training during the later rehabilitation sessions.”Difference between voluntary muscle contraction (VC) and EMS is that in VC, motor units are recruited in an orderly manner, from small to large. Larger axons have lower input impedence and are therefore activated first in EMS. This results in a reverse activation order to that of VC. EMS doesn’t produce as much force because it only stimulates the surface units (this leads to faster fatigue as well). Because they induce different physiological effects, EMS can be seen as complimentary to VC. This leads to the use of combined therapy, which uses both of these techniques in rehabilitation (not at the same time.)These studies were for muscular training.>> As a whole, maximum intensity of stimulation was either 60% MVC or the maximum tolerated. Frequencies used (in Hz) 50, 75, 80, 85, 100, 110, 115, 120, rectangular or square biphasic, for (in microseconds) 200, 300, 400, 450. Most results pointed to an increase in various strengths of combined therapy over VC.The superimposed technique (supramaximal electrical stimulation is superimposed onto a voluntary contraction) showed the presence of a deficit of the activation level and a decrease of the quadriceps strength after a surgical operation. Major cause of diminished performance is altered MU utilization. Extensor muscles, for example, quadriceps, are generally more sensitive to atrophy than flexor muscles, e.g. hamstrings. (+ more explanation why we care about the quadriceps)EMS is complementary to voluntary exercise because in the early phases of rehab it elicits a strength increase, which is necessary to perform voluntary training in later rehabilitation.These studies were done specifically after TKA to the knee. (more knee surgeries in article)>> triangular, biphasic, biphasic sinusoidal, 40 – 75Hz, 50 Hz, 75 Hz, and 2500Hz modulated at 50Hz. Biphasic at 250 microseconds. All at isometric action angle of 60 degrees, CT had a strength increase over VC.Stimulation ParametersHigh intensity stimulation restored strength of quadriceps better than low intensity. Efficient frequencies were between 30 and 75 Hz. The authors used steady titanic stimulations of between 6 and 15 secons, which were followee by pauses between 10 and 80 seconds for 10 to 60 minutes. The sessions ranges from bi-weekly to dealy for 3-12 weeks. 2-3 electrodes used proximally or distally on the belly of the muscle or over the motor point.A new method of EMS – stimulating antagonist (hamstring) muscles to resist agonist muscles. This can be a crucial part of our design. Because combined therapy alternates between voluntary contraction and muscular stimulation, our design should use both as well, receiving sensory data during the VC portion, and automatically adjusting the NMES to the results given by the involved and uninvolved knees.Sports Med 2005; 35 (11): 951-966Electrical Stimulation Superimposed onto Voluntary Muscular ContractionThierry Paillard,1 Fr?ed?eric No?e,1 Philippe Passelergue1 and Philippe Dupui2This focuses on the superimposed technique, which involves stimulating the muscle while performing a voluntary contraction. This type of rehab did not experience much success.?Synergy 2004 ElectroMyoStimulation By Brian D. Johnston This article is more on sports training using electromyostimulation, and explains the optimal pulse frequencies and amplitudes to use for each desired effect of training. ................
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