The injuries shown on this x-ray are: - iiNet



The injuries shown on this x-ray are:

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• A central dislocation of the hip

• An isolated pelvic ring fracture

• A dislocation of symphysis pubis

• A dislocation of the sacro-iliac joint

• A complete pelvic ring disruption Correct, The x-ray shows a complete pelvic ring disruption with a fracture through the base of the acetabulum as well as fracture dislocation through the sacro-iliac joint. Therefore, a large segment is relatively free and weight bearing would displace it. This is therefore a complete pelvic ring disruption.

The character of the pain that this patient would have experienced as a result of the pathology shown in this resected femoral head would be:

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• Malign

• Rheumatic

• Neurogenic

• Mechanical Correct, This is the femoral head of a patient with degenerative disease. You can see the complete loss of cartilage in the greyish areas and the destruction of cartilage in the remainder. The pain would be mechanical in type. It would be worse on mechanical stress and relieved by rest.

• Dystrophic

The test demonstrated here is:

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• A positive Thomas' test

• A positive McMurray test

• A positive Trendelenburg test

• A negative Thomas' test

• A negative Trendelenburg test Correct, The test shown is a negative Trendelenburg test. In a normal individual when you stand on one leg, the abductors on that side pull the pelvis upwards around the axis of the femoral head so that there is a tilt of the line of th epelvis upwards on the non weightbearing side. This is what happens in this patient and it is normal. A positive Trendelenburg test occurs when, in the same circumstances, the pelvis on the non weightbearing side drops down. It is caused by relative weakness of the abductor muscles on the weightbearing side. The relative weakness in muscles can be caused by either a direct weakness of the muscle or a problem with its innervation, or because the hip is dislocated and therefore the length of the muscle is reduced. Thomas' test is for a flexion contracture of the hip and is performed with the patient lying on the back. McMurray's test is a test to see whether or not there is a torn meniscus. It is an attempt to trap a torn fragment of meniscus between the femoral condyles and the tibia.

Which one of the following factors in this patient's history is unlikely to be related to the hip pathology?

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• Excessive alcohol intake

• Steroid therapy

• Epilepsy Correct, This x-ray shows a segmental collapse of the upper part of the femoral head which is compatible with ischaemic necrosis. There are three groups of conditions which cause ischaemic necrosis. Trauma to the femoral head, either in the form of a subcapital fracture or a hip dislocation which disrupts the blood supply and subsequently gives rise to segmental collapse when the bone starts to revascularise. The second group are composed of patients with blood dyscrasias such as sickle cell disease and thalasaemia. It is though that these people get an intraosseous block of the small vessels through sludging of red cells. The third group is a mixed group in which the common element seems to be a secondary lipid disorder. Thus, patients with familiar hyperlipidaemias, alcholic liver failure, on steroid treatment and suffering from acute pancreatitis can all develop iscaemic necrosis. Divers also suffer from dysbaric osteonecrosis which is histologically and clinically indistinguishable from ischaemic necrosis of bone. The exact mechanism is uncertain. There is the suspicion that it may be caused by nitrogen bubbles coming out and causing an intraosseous vascular obstruction. However, there is an alternative explanation. Decompression causes a denaturation of lipoproteins and it may well be that this disturbance of fat transport may cause the disorder.

• Previous trauma to the hip

• SCUBA diving

This radiograph is:

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• A subcapital fracture

• An inter-trochanteric fracture Correct, The left hip shows a comminuted inter-trochanteric fracture with the lesser trochanter detached and lying medially. The shaft of the femur has been pulled upward and laterally and the proximal femoral fragment is rotated and horizontal. A subcapital fracture shows an intact segment of femoral neck on the femoral shaft. The femoral head is enlocated normally and the shaft is normal below the inter-trochanteric line.

• A subtrochanteric fracture

• A fracture dislocation of the hip

• Diastasis of the symphysis pubis

In relation to the hip disorder shown which of the following statements is NOT true:

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• It predisposes to degenerative disease in adult life

• It is more common in boys than girls

• It never occurs after epiphyseal fusion

• It is a septic arthritis Correct, The left hip of this child shows the fragmentation of the epiphysis which is typical of Perthe's disease. Although the disorder does not necessarily cause problems in later life it certainly may do so and degenerative disease is the pattern of presentation. It is a disease of the opiphysis and does not occur after the epiphysis has fused. Perthe's disease is more common in boys and like any other hip pathology in children it may present with knee pain. The appearances of septic arthritis are quite different with osteoporosis, initially an incrase in joint space and subsequently progressive destruction of both articular surfaces.

• It may present with knee pain

When considering the radiographs of this hip which of the following statements is NOT true:

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• There has been a total replacement arthroplasty of the hip

• The femoral component has dislocated

• Dislocations of hip arthroplasties occur in less than 5% of all patients with hip replacements

• The patient is suffering from shortening of the affected leg

• There is a risk of an associated femoral nerve palsy Correct, This shows a total hip replacement which is dislocated. The femoral component is now riding above the acetabulum and therefore there must be leg length shortening as a result. The dislocation must be posterior as anteriorly the reflected head of rectus femoris prevents upward displacement of the prosthesis. Because the dislocation is posterior the nerve that is damaged is the asiatic and not the femoral nerve. The incidence of dislocation after total hip replacement is about 5%. The hip is potentially unstable for a number of months after replacement and therefore patients are taught to avoid the movements which tend to dislocate the hip. The real danger is of flexion, adduction and internal rotation of the hip.

The injury shown:

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• Is an isolated pelvic ring fracture

• Is a complete pelvic ring disruption Correct, There are fractures across the superior and inferior pubic rami on the right with a fracture dislocation of the right sacro-iliac joint. The complete ring must be disrupted to permit upward displacement of the right half of the pelvis. This is therefore a highly unstable situation which would not permit any weightbearing. An isolated pelvic ring fracture means that only one part of the ring is disrupted. Though pain on weightbearing results the ring is not grossly unstable. It is a common injury as pathological fracture of the symphysis are common in the elderly, and are part of the differential diagnosis of fractures of the proximal femur.

• Is a central dislocation of the hip

• Is a fracture dislocation of the symphysis pubis

• A displaced Looser zone

This patient is demonstrating:

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• Thomas' Test Correct, The patient is demonstrating Hugh Owen Thomas' test for a flexion contracture of the hip. The good hip is bent up until it rotates the pelvis backwards and abolishes the lumbar lordosis. Any fixed flexion deformity is 45%. A Sciatic Stretch test is done with the leg held straight. MacMurray's test is a flexion rotation strain on the knee. There is no such thing as an ileo-psoas spasm test.

• A Sciatic Stretch Test

• MacMurray's Test

• The ileo-psoas spasm test

Which of the following would you be least likely to see on x-ray of this patient's hip prior to resection?

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• Loss of joint space

• Sub-chondral sclerosis

• Marginal osteophytes

• Osteoporosis Correct, This is the gross pathological appearance of a patient with osteoarthritis of the hip. The shiny area is eburnated bone or bone without a cartilage cover. The remainder shows remnants of hyaline cartilage on the femoral head. Radiographically, you would expect to see a loss of joint space, sub-chondral sclerosis around the area where the eburnated bone is, marginal osteophytes, sub-chondral cysts, all of which are associated with osteoarthritis. Osteoporosis would be unlikely to be a feature of this hip radiograph.

• Sub-chondral cysts

This hip has had what type of surgery?

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• Partial replacement arthroplasty

• Total replacement arthroplasty Correct, This is a total replacement arthroplasty of the hip. The femoral component has been replaced by a metal prosthesis which is anchored with methyl acrylic cement. The acetabulum has been replaced with a high density polyethylene acetabulum. This is virtually radiolucent and the main indicators of its presence are the wire which looks like a halo and the surrounding layer of methyl acrylic cement. Partial replacement arthroplasties imply that only one of the two articulating components has been replaced. Interposition arthroplasty does not attempt to reconstruct the joint in any way, but simply puts in a spacer between two articulating bone ends. The most commonly used form is silastic and is used in the hands and feet. Previously, fascia and muscle was used to interpose between articulating bones. In the hip a cup arthroplasty is the straight forward removal of articulating surfaces without any attempt to interpose anything. The gaps fill up with fibrous tissue and a short fibrous ankylosis develops.

• Interposition arthroplasty

• Excision arthroplasty

This patient was 30 years old and sustained a minor fall while pregnant. This x-ray was taken six months afterwards. Which statement describes the current position?

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• A subcapital fractures has failed to unite because of associated degenerative disease and inadequate fixation.

• An intertrochanteric fracture has gone on to malunion because of the hormonal disturbance associated with the pregnancy

• There is fracture of the femoral head which had been missed at the time of the initial injury because adequate x-rays were not taken during the pregnancy?

• There is fracture of the femoral head which had been missed at the time of the initial injury because adequate x-rays were not taken during the pregnancy

• A pathological subcapital fracture has been complicated by ischaemic necrosis and segmental collapse of the femoral head Correct, The x-ray shows one of the classical complications of subcapital fractures of the femur. There is a segmental collapse produced by avascular necrosis. The fracture was not missed because it was fixed with three screws. An intertrochanteric fracture is never treated with screws and does not give rise to avascular necrosis. However, they are complications of posterior dislocations of the hip. Such a fracture would not be treated by screw fixation. The fracture is pathological by definition. A minor fall in a thirty year old should not cause the femoral neck to fail. In this case the patient had osteomalacia.

The complication of total hip arthroplasty that is shown occurs in approximately:

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• 50% of patients over 70 years of age

• 40% of patients with rheumatoid arthritis

• 30% of obese women

• 20% of patients on subcutaneous heparin

• 10% of patients treated with aspirin Correct, This is the venographic appearance of a femoral vein thrombosis. The incidence is very variable because it depends on so many different factors, including age, previous mobility, the nature of the hip disease and the degree of intra-operative disturbance that the patient has suffered. Overall it is about 40%. Of all thrombi about one in four develop in the femoral vein, rather than propagating proximally from a calf vein thrombus. Thus the incidence of femoral vein thrombosis is about 10%. In orthopaedic surgery, none of the conventionally used prophylactic techniques have a demonstrable effect.

The problem shown here is:

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• An anterior dislocation of the hip

• A congenital dislocation of the hip

• A posterior dislocation of the hip Correct, This is a posterior dislocation of the hip. A femur which dislocates anteriorly cannot ride up and therefore shorten to a significant degree because the reflected head of rectus femoris lies immediately above the anterior lip of the acetabulum. The dislocation is not pathological because, if it was, there would be evidence of destruction or malformation of both femoral head and acetabulum.

• A slipped upper femoral epiphysis

• A pathological dislocation of the hip

In considering this computerised axial tomogram which of the following statements is true:

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• The appearances are within normal limits

• The left hip is dislocated

• There is congenital sacral agenesis Correct

• The right hip shows unequivocal evidence of degenerative arthropathy

• The left rectus femoris muscle is absent

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