Intrasheath subluxation of the peroneal tendons.

BACKGROUND Dislocation or subluxation of the peroneal tendons out of the peroneal groove under a torn or avulsed superior peroneal retinaculum has been well described. We identified a new subgroup of patients with intrasheath subluxation of these tendons within the peroneal groove and with an otherwise intact retinaculum. METHODS The cases of fifty-seven patients with painful snapping of the peroneal tendons posterior to the fibula were reviewed. Of these, forty-three had tendons that could be reproducibly subluxated out of the groove with a dorsiflexion-eversion maneuver of the ankle. Fourteen patients who could not subluxate the tendons out of the groove underwent a dynamic ultrasound examination of the tendons. While the same dorsiflexion and eversion maneuver was being performed, the tendons were seen to switch their relative positions (the peroneus longus came to lie deep to the peroneus brevis tendon) with a reproducible painful click. All fourteen patients underwent a peroneal groove-deepening procedure with retinacular reefing. Intraoperatively, thirteen patients were found to have a convex peroneal groove and all fourteen had an intact peroneal retinaculum. All patients subsequently underwent a follow-up dynamic ultrasound examination and an American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score evaluation at a minimum of twenty-four months after surgery. RESULTS All fourteen patients were female, with an average age of thirty-five years. Two subtypes of intrasheath subluxation were found. Type A (ten patients) involved intact tendons with relative switching of their anatomic alignment. Type B (four patients) involved a longitudinal split within the peroneus brevis tendon through which the longus tendon subluxated. Intraoperative confirmation of the ultrasound findings was 100%. At an average follow-up interval of thirty-three months, the average AOFAS score had improved from 61 points preoperatively to 93 points, and the average score on the 10-cm visual analog pain scale had improved from 6.8 to 1.2. Follow-up ultrasound evaluation revealed healed tendons without persistent subluxation in thirteen patients. Nine patients rated the result as excellent, four rated it as good, and one rated it as fair. CONCLUSIONS Patients with retrofibular pain and clicking of the peroneal tendons may not have demonstrable subluxation on physical examination and may have an intact superior peroneal retinaculum. They may have an intrasheath subluxation of the peroneal tendons, which can be confirmed with use of a dynamic ultrasound. Surgical repair of tendon tears combined with a peroneal groove-deepening procedure with retinacular reefing is a reproducibly effective procedure for this condition.