Review Question - QID 1144

Peroneal tendon instability can occur during an inversion injury to a dorsiflexed ankle with rapid reflexive contraction of the peroneus longus and peroneus brevis tendons.

Patients often hear a "pop" or feel a snapping sensation, followed by pain and swelling. The peroneals have a vascular watershed region just posterior to the fibula and are prone to longitudinal tears. Radiographs often show an avulsion fracture of the distal fibula (rim fracture) at the insertion of the superior peroneal retinaculum. Chronic instability of the peroneal tendons can be best demonstrated by positioning the ankle in dorsiflexion and resisting eversion. With ankle plantarflexion and inversion the line of pull is more direct and thus there is much less tendency for subluxation.

Treatment for acute injuries involves cast immobilization to allow the superior peroneal retinaculum to heal. Injuries recalcitrant to conservative management or high level athletes may benefit from superficial peroneal retinaculum repair and fibular groove-deepening procedures.

Illustration A shows a "rim fracture" which is characterized by avulsion of the superior peroneal retinaculum.