A preliminary report on intra-sheath peroneal tendon subluxation: a prospective review of 7 patients with ultrasound verification.

UNLABELLED: Peroneal tendon dislocation with recurrent subluxation over the lateral malleolus, both acute and chronic, is well documented in the literature. However, there remains a subset of patients who report symptoms similar to peroneal subluxation that do not actually display active or passive displacement of the tendon over the lateral malleolus. In this article, we describe 7 patients who were followed prospectively for the treatment of ultrasound-confirmed, retrofibular, intrasheath subluxation without the typical lateral subluxation or dislocation of the tendon over the malleolus. Six of the 7 patients had either a low-lying peroneal muscle belly or a peroneus quartus muscle and tendon, 6 experienced a tear of either 1 or both of the peroneal tendons, and 1 of the 7 had only a peroneus brevis tendon tear without any other muscle anomaly. Repair of concomitant tendon pathology and resection of the low-lying muscle belly to a point proximal to the fibro-osseous tunnel of the retromalleolar space resulted in elimination of the subluxation symptoms and improvement in American College of Foot and Ankle Surgery ankle scores in 3 patients who were treated operatively. LEVEL OF CLINICAL EVIDENCE: 4.