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Year |
2001 |
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Question Number |
88 |
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Category |
Select |
Question
A woman with degenerative arthritis and a fixed genu valgum deformity of 17 degrees undergoes primary total knee arthroplasty under general anesthesia. In the recovery room she is unable to dorsiflex her foot. Immediate management should include:
1. fasciotomies
2. surgical nerve decompression
3. flexion of the knee
4 continuous passive motion
5. electromyography
Figures
Answer (click for answer)
The correct answer is #3. Damage to the peroneal nerve a result from musculoskeletal trauma to the hip, ankle, or foot as well as from direct pressure on the nerve at the knee from a constrictive dressing, splint, or cast. The common peroneal nerve can be damaged anywhere along its course, from its origin in the pelvis as the lateral trunk of the sciatic nerve to its bifurcation just distal to the knee. The pressure from the proximal portion of a below-the-knee cast that ends just distal to the neck of the fibula can result in peroneal nerve palsy. A hematoma in the nerve sheath may produce sufficient compression of the peroneal nerve to result in the gradual development of a palsy. The cumulative reported prevalence of peroneal nerve palsy was 0.58 per cent after total
knee arthroplasty and 10 per cent after proximal tibial osteotomy. After total knee arthroplasty in 138 knees that had a fixed valgus deformity, it was noted a 3 per cent prevalence of peroneal nerve palsy. If a peroneal nerve palsy is recognized in the immediate postoperative period, the initial treatment should involve removal of any constrictive dressing to allow for 30 to 40 degrees of flexion of the knee. If there is evidence of an expanding hematoma about the proximal aspect of the fibula, urgent exploration of the wound may be necessary. If there is no clear evidence of a compressive hematoma and dysfunction of the peroneal nerve persists despite the measures just
described, some advocate observation for years, as these palsies have been found to resolve with time. However, the results of the present study suggest that the prognosis for sensorimotor recovery deteriorates with time and that operative decompression should be considered earlier. Although the peroneal nerve palsies in our patients may have resolved with non-operative treatment after an extended period of time, operative decompression spared these patients
many months of pain and disability. (The operative treatment of peroneal nerve palsy, JBJS 1996)
Reference: J Bone Joint Surg Am., 1996; 78:863-869