Tendoscopic Treatment of Peroneal Intrasheath Subluxation: A New Subgroup With Superior Peroneal Retinaculum Injury.

BACKGROUND: Snapping peroneal tendons is a rare cause of lateral ankle pain. Two subgroups have been described: chronic subluxation with superior peroneal retinaculum (SPR) injury and intrasheath subluxation with SPR intact. The aim of the study was to report the tendoscopic findings and results in patients affected by snapping peroneal tendons without evident dislocation. METHODS: Between 2010 and 2015, a total of 18 patients with a retromalleolar "click" sensation and no clinical signs of peroneal tendon dislocation underwent tendoscopy. Mean age was 29 years (range, 18-47). Mean follow-up was 45 months (range, 18-72). RESULTS: Tendoscopic examination revealed an intact SPR in 12 patients. Of these 12, a space-occupying lesion was present in 7, a superficial tear of peroneus brevis in 4, and a shallow fibular groove in 7. An SPR injury without peroneal tendon dislocation was observed in the remaining 6 patients. All these 6 patients presented a shallow fibular groove. Although the SPR was injured, they had been diagnosed as intrasheath subluxation. Patients with intrasheath subluxation and intact SPR underwent debridement of a space-occupying lesion in 11 cases and fibular groove deepening in 5 cases. Patients with intrasheath subluxation and SPR injury underwent fibular groove deepening without addressing the SPR. At follow-up, the mean American Orthopaedic Foot & Ankle Society score increased from 76 (range, 69-85) preoperatively to 97 (range, 84-100). No recurrence or major complications were reported. Conclusion Intrasheath subluxation of peroneal tendons was successfully treated tendoscopically. A new subgroup of intrasheath subluxation with SPR injury but no clinically evident peroneal tendon dislocation is reported. LEVEL OF EVIDENCE: Level IV, case series.