The rigid flatfoot. Tarsal coalitions.

Tarsal coalitions are the major cause of painful rigid flatfoot deformity in children and adolescents. Talocalcaneal and calcaneonavicular coalitions are the most common sites. They are often bilateral and may be asymptomatic. They represent a failure of fetal mesenchymal differentiation, and onset of symptoms in children often corresponds to the time of ossification of the fibrous or cartilaginous coalition. The most common presenting symptom is pain, and diagnosis is aided by plain radiographs and computerized tomography. Some patients respond to conservative measures, but surgical treatment is often required. Resection and interposition of fat or tendon (talocalcaneal) or muscle (calcaneonavicular) are the most common operative treatments, with arthrodesis reserved for symptomatic recurrences, patients with degenerative changes, and those with multiple coalitions.