Calcaneonavicular coalition is well recognised as a malformation that restricts movement of the midfoot, and it can be responsible for sinus tarsi pain and ankle instability. Local calcaneal morphology anomalies, such as a protrusive anterior process of the calcaneus or calcaneus secundarius, can also alter the hindfoot’s biomechanics and exhibit clinical effects similar to a calcaneonavicular coalition.

This case report examines a previously undescribed hypertrophic medial process of the cuboid, which can limit the range of motion of the subtalar joint, mimicking calcaneonavicular coalition. We also explain the clinical approach used to reach our diagnosis.