[Calcaneonavicular coalition fracture. A rare differential diagnosis of post-traumatic ankle pain].

The causes of chronic posttraumatic ankle pain are manifold, ranging from ligament and tendon injuries and fractures to joint degeneration. Calcaneonavicular coalition, a bridge between the calcaneus and navicular bones, is a rare disease with an incidence below 1%. The morphology of this coalition is variable. It can occur as either a fibrous, cartilaginous or bony union of the involved bones. Symptoms usually occur in adolescence with chronic pain around the ankle, mainly lateral and anterior, following distortion trauma. Patients often claim to have a lateral ankle sprain. We report 2 cases of a fracture of the calcaneonavicular coalition as the cause of chronic posttraumatic ankle pain and demonstrate the characteristics of tarsal coalitions with a review of the literature.