Anatomic risk of peroneal nerve injury with the "pie crust" technique for valgus release in total knee arthroplasty.

Peroneal nerve damage can occur during total knee arthroplasty because of indirect or direct injury. The potential for direct laceration injury exists when performing the "pie crust" lateral soft-tissue release in a valgus knee. To assess this risk, the axial, magnetic resonance images of 60 adult knees were evaluated. The distance from the peroneal nerve to the tibia was measured at the level of the standard tibial resection. At this level, the lateral gastrocnemius muscle is interposed between the capsule and the nerve. The mean nerve to bone distance was 1.49 cm (0.91-2.18 cm). These results suggest that the peroneal nerve is adequately protected at the posterolateral corner of the knee but that the "pie crust" release should be performed carefully.