Lateralizing Calcaneal Osteotomy and First Metatarsal Dorsiflexion Osteotomy for Cavovarus Foot and Peroneal Sheath Release with Peroneus Brevis Repair for Peroneal Tendinopathy in Chronic Ankle Instability and Sprain

A 47-year-old male presented with an eight-year history of pain in the posterior inferior part of the lateral malleolus, ankle instability, and repeated right-sided ankle sprains. He had pes cavus and hind-foot varus in his right foot, which is an unknown congenital entity or acquired with tenderness in the inferior peroneal retinaculum. There is no deformity in his left foot. The pain was elicited by the movement of the subtalar joint. Imaging revealed a high medial longitudinal arch, an enlarged peroneal tubercle, thinning of the peroneus brevis tendon, and hypertrophy of the peroneus longus tendon. We diagnosed peroneal tendinopathy with cavovarus foot in a chronic ankle sprain. The supination generated by pes cavus was thought to be aggravating the peroneal tendinopathy and causing the ankle sprains. Incision of the peroneal tendon sheath, repair of the peroneus brevis tendon, lateralizing calcaneal osteotomy, and first metatarsal dorsiflexion osteotomy were performed. At the one-year follow-up, Meary's angle was corrected to 0°, the calcaneal pitch was corrected to 20°, and the hindfoot varus was improved. He was pain-free and reported no further instability when walking. His Japanese Society of Surgery of the Foot ankle-hindfoot scale score improved from 59 preoperatively to a maximum of 100 and the Self-Administered Foot Evaluation Questionnaire gave an almost perfect score for non-sports-related items and a score of 83.3 for sports-related items. We believe that the addition of treatment of the pes cavus, which was the center of the pathology, as well as treatment of the peroneal tendon, resulted in a good outcome.