Prophylactic Common Peroneal Nerve Decompression Avoids Nerve Palsy in Total Knee Arthroplasty for Severe Fixed Valgus Deformity: A Report of Four Cases and Review of Literature

Common peroneal nerve (CPN) injury is a serious complication following total knee arthroplasty (TKA). We aim to report four patients (five knees) who underwent prophylactic peroneal nerve decompression for severe rigid valgus deformity with or without associated fixed flexion deformity that was not correctable under anaesthesia. The preoperative deformity of 31.1° valgus by femorotibial angle (range 22.6–37.9°) improved to 7.1° valgus (range 4.3–9.1°) postoperatively ( p < 0.05). For two knees, varus–valgus constrained was used due to medial laxity and the other three had posterior-stabilised prosthesis. All four patients had normal motor or sensory nerve function of the CPN nerve postoperatively. There was a significant improvement in the functional outcome by knee society score and knee society functional score from 17.8 ± 6.8, 25 ± 16.2 to 84 ± 8.7, 83 ± 10.3, respectively ( p < 0.05). No complications were noted in the mean follow-up of 1.2 years. Prophylactic peroneal nerve decompression allows safe, adequate and optimal lateral soft-tissue release. It is effective in preventing common peroneal nerve palsy in high-risk patients like severe valgus and flexion deformity during total knee arthroplasty.