The incidence and clinical outcomes of peroneal nerve injuries associated with posterolateral corner injuries of the knee

PURPOSE: The purpose of the study was to investigate the incidence of complete and partial peroneal nerve injuries in patients with posterolateral corner (PLC) knee injuries; additionally, to compare patient-reported outcomes among patients with and without peroneal nerve injury and to examine the factors that predict the recovery of nerve function. METHODS: A retrospective chart review was performed to identify patients who underwent PLC reconstruction or repair from 2000 to 2012 with a minimum 6-month clinical follow-up. Peroneal nerve injuries were identified, and treatments and outcomes were analyzed. IKDC and KOOS outcome scores at the final follow-up were reported. RESULTS: There were 61 PLC injuries in 60 patients. Sixteen of the 61 knees (26.2%) had a peroneal nerve injury at initial presentation; there were 13 complete and 3 partial nerve injuries. The median age was 31 years (15 men and 1 woman) and 31 years (33 men and 12 women) in the nerve and non-nerve injury cohorts, respectively. The median follow-up in the nerve injury group was 26 months (interquartile range (IQR): 12-48), and in the non-nerve injury cohort (n.s.) 61 months (IQR 22-85). All 13 complete injuries were treated with neurolysis: 3 were complete transections and 10 were stretch injuries. Of the ten stretch injuries, five (50%) spontaneously recovered full nerve function at the final follow-up. The remaining six patients chose definitive treatment with ankle-foot orthoses. Two of the three transected nerve patients underwent successful posterior tibialis transfer, and one chose ankle-foot orthoses. All three partial nerve injuries underwent neurolysis and had complete nerve recovery at the final follow-up. The median IKDC scores in the nerve injury group and the non-nerve injury group were 64.4 (IQR 47.8-73.3) and 72.8 (IQR 59.3-87.9) (n.s.), respectively, and the median Lysholm scores were 85 (IQR 83-92) and 86.5 (IQR 79-90) (n.s.), respectively. There were no significant differences in the rates of complications, secondary surgeries, mechanism of injury, KDIII injuries, or other injuries. CONCLUSION: This study demonstrated comparable rates of peroneal nerve injuries in PLC injuries (26.2%) to that in the literature. The rates of nerve recovery for complete disrupted injury, complete stretched injury, and partial injury were 0, 50, and 100% with an overall rate of recovery of 50%. The outcome scores were similar between patients with and without nerve injuries; however, a small cohort size led to limitations in statistical analysis. Thus, a prolonged trial of non-operative treatment is recommended for peroneal nerve injuries to allow for assessment of nerve recovery and patient outcome before entertaining surgical treatments. LEVEL OF EVIDENCE: Level IV.