Isolated Fifth Metatarsocuboid Coalition: A Case Report

Isolated tarsometatarsal coalitions are extremely rare, and the previous 5 documented cases involved the first and third metatarsocuneiform joints. We report the case of a 69-year-old female with symptomatic fifth metatarsocuboid coalition associated with ipsilateral varus-type ankle osteoarthritis and instability. The patient was successfully treated by arthrodesis of the fifth metatarsocuboid joint, resection of the hypertrophied tuberosity of the fifth metatarsal, advancement of the peroneus brevis tendon, opening wedge distal tibial osteotomy, and calcaneal displacement osteotomy. After 1 year, 6 months, she was able to walk well, although she complained of minor discomfort under the fifth metatarsal base, which resolved with the use of protective padding. Radiographs at this stage confirmed consolidation of both the arthrodesis and the osteotomy sites. Although isolated fifth metatarsocuboid coalition is less likely to be encountered than other tarsal coalitions, it can sometimes be painful enough to necessitate surgery.