Snapping ankles: peroneal tendon subluxation and dislocation.

Peroneal tendon dislocation or subluxation is an orthopaedic condition that usually occurs as a result of injury to the superior peroneal retinaculum. The peroneal muscles are located in the lateral compartment of the leg, and their tendons run in the retromalleolar groove anchored by the superior peroneal retinaculum. Peroneal instability is usually classified using the Eckert and Davies classification, which was modified by Oden into a four-point grading system. The mechanism of injury is typically sudden forced dorsiflexion, resulting in aggressive tautness of the peroneal tendons, combined with a forced eversion of the hindfoot. Plain X-ray, ultrasound and magnetic resonance imaging are useful for imaging of the injury and in planning for surgery. Operative management has high success rates and there are multiple surgical techniques available, including superior peroneal retinaculum repair, tenoplasty, bone block procedures, groove deepening and endoscopic approaches, with little variation in outcome found between the approaches.