Successful reconstruction of distal peroneus longus tendon dislocation associated with a split lesion - a case report

Peroneal tendon injuries are one of the differential diagnoses in lateral ankle and rearfoot pain. While partial tears are not uncommon, peroneal tendon dislocation at the peroneal tubercle is very rare. Until now, only three papers have been published, presenting five cases of peroneus longus tendon dislocation over the peroneal tubercle. This report adds a previously undescribed case of a peroneus longus tendon split tear that was partially dislocated and entrapped over the peroneal tubercle. The respective operative approach and the outcome are described.

A 25-year-old international top-level speed skater developed a painful mass over the lateral calcaneal wall. There was no specific inducing injury in his medical history. In contrast to previous reports, according to the patient's history, a snapping phenomenon was not present. Conservative treatment was not effective. By inspection and palpation an enlarged peroneal tubercle was assumed. During operative exploration, we found an incomplete longitudinal split tear of the peroneus longus tendon, which was partially dislocated and entrapped over the peroneal tubercle. This mimicked an enlarged peroneal tubercle. A portion of the split tendon was resected. A deepening procedure of the flat groove of the peroneus longus tendon below the peroneal tubercle and a transosseous reconstruction of the avulsed inferior peroneal retinaculum were performed. After six months, the patient had completely reintegrated into his elite sport and has been free of symptoms since then.

From the presented case it can be speculated that the inferior peroneal retinaculum was overused, worn out, detached, or ruptured due to overpronation and friction the lateral edge of the low-cut speed skating shoe. Then the peroneus longus tendon experienced substantial friction with the peroneal tubercle with possible dislocation during ankle motion. This frictional contact may have finally led to further degeneration and a longitudinal tear of the tendon. Obviously, dislocations can develop insidiously resulting in lesions of the peroneus longus tendon at the peroneal tubercle, ultimately leading to a tendon entrapment. This mimics an enlarged tubercle. The pathology is very rare and can be successfully addressed surgically.