Distal posterolateral corner injury in the setting of multiligament knee injury increases risk of common peroneal palsy.

PURPOSE: The purpose of this study was to identify if the location of posterolateral corner (PLC) injury was predictive of clinical common peroneal nerve (CPN) palsy.

METHODS

A retrospective chart review was conducted of patients presenting to our institution with operative PLC injuries. Assessment of concomitant injuries and presence of neurologic injury was completed via chart review and magnetic resonance imaging (MRI) review. A fellowship-trained musculoskeletal radiologist reviewed the PLC injury and categorized it into distal, middle and proximal injuries with or without a biceps femoral avulsion. The CPN was evaluated for signs of displacement or neuritis.

RESULTS

Forty-seven operatively managed patients between 2014 and 2019 (mean age-at-injury 29.5 ± 10.7 years) were included in this study. Eleven (23.4%) total patients presented with a clinical CPN palsy. Distal PLC injuries were significantly associated with CPN palsy [9 (81.8%) patients, (P = 0.041)]. Nine of 11 (81.8%) patients with CPN palsy had biceps femoral avulsion (P = 0.041). Of the patients presenting with CPN palsy, only four (36.4%) patients experienced complete neurologic recovery. Three of 7 patients (43%) with an intact CPN had full resolution of their clinically complete CPN palsy at the time of follow-up (482 ± 357 days). All patients presenting with a CPN palsy also had a complete anterior cruciate ligament (ACL) rupture in addition to a PLC injury (P = 0.009), with or without a posterior cruciate ligament (PCL) injury. No patient presenting with an isolated pattern of PCL-PLC injury (those without ACL tears) had a clinical CPN palsy.

CONCLUSION

Distal PLC injuries have a strong association with clinical CPN palsy, with suboptimal resolution in the initial post-operative period. Specifically, the presence of a biceps femoris avulsion injury was highly associated with a clinical CPN palsy. Additionally, CPN palsy in the context of PLC injury has a strong association with concomitant ACL injury. Furthermore, the relative rates of involvement of the ACL vs. PCL suggest that specific injury mechanism may have an important role in CPN palsy.

LEVEL OF EVIDENCE: IV.