Complete encasement of the peroneal tendons by the peroneal tubercle

The peroneal tubercle is an osseous structure on the lateral side of the calcaneus present in 90% of individuals. Hypertrophy of the peroneal tubercle resulting in stenosing peroneal tenosynovitis has been well described in the literature. Repair of this condition involves operative treatment to remove the hypertrophied peroneal tubercle and repair any resulting tendon pathology. The authors report a unique case of a hypertrophied peroneal tubercle with an associated tarsal coalition, resulting in complete bony encasement of the peroneal tendons. In this case, a 50-year-old white man presented with worsening bilateral foot and ankle pain for several years. On examination, he had fixed hindfoot varus and bilateral equinocavovarus feet. Magnetic resonance imaging and weight-bearing radiographs showed a calcaneonavicular coalition. Intraoperatively, the authors discovered complete bony encasement of the peroneal longus and brevis tendons. On examination, the peroneal longus and brevis were severely stenotic, with the peroneal brevis to the point of near laceration. This painful condition was repaired by takedown of the calcaneonavicular coalition, the peroneal tubercle was resected, and the peroneal tendons were freed from their bony encasement. Tenodesis of the peroneus brevis to longus was performed and the hindfoot varus was corrected with wedge osteotomy of the calcaneus. The patient reported excellent postoperative results. At 3 months postoperatively, he was pain-free and his calcaneal osteotomy was well healed. This case appears to be the first of its type to be reported in the literature. The details of the case are presented along with a review of the relevant literature.