Mal-union of sustentaculum tali fracture with talo-calcaneal coalition leading to tarsal tunnel syndrome: A case report

Displaced isolated fractures of sustentaculum tali are rare. Inadequate treatment of these injuries can rarely lead to non-union or mal-union and in most cases are treated non-surgically. We report a unique case of undiagnosed mal-union of sustentaculum tali in the setting of underlying tarsal coalition that resulted in symptoms of tarsal tunnel. Osteotomy and excision of the mal-united fragment and coalition along with decompression of the tarsal tunnel was performed. The patient had immediate improvement in pain and the paraesthesia recovered by the end of 6 weeks post-operatively. The Foot and Ankle disability score (FADI) score improved from 26.0 pre-operatively to 96.2 at 3 years’ follow-up. This case highlights that isolated fractures of sustentaculum tali warrant advanced imaging and surgical reduction and fixation may be appropriate to avoid long-term disability where displacement compromises the tarsal tunnel or function of the subtalar joint.