Case 6

Discussion:

Congenital tarsal coalition is a diagnosis that is often overlooked in young patients who first present with foot and ankle pain. may be osseous, cartilaginous, or fibrous. Calcaneonavicular coalitions are readily detected on oblique radiographs. Radiographic confirmation of talocalcaneal coalition is more difficult. About 90% of cases involve the talocalcaneal or calcaneonavicular joints. Although many investigators believe that calcaneonavicular coalitions are the most common type which could be due to the fact that they are more readily diagnosed with conventional radiography. Calcaneonavicular coalitions are best depicted on 45° internal oblique radiographs. With osseous coalition, a bony bar that bridges the two bones is seen. With fibrous or cartilaginous coalition, the bones are in close proximity, both have irregular surfaces, and the anteromedial calcaneus is abnormally widened or flattened. On lateral radiographs, elongation of the anterior dorsal calcaneus may simulate an anteater’s nose. Hypoplasia of the talus may also be observed with calcaneonavicular coalition.

References:

• Perlman MD, Wertheimer SJ. Tarsal coalitions. J Foot Surg 1986; 25:58-67.
• Kulik SA, Clanton TO. Tarsal coalition. Foot Ankle Int 1996; 17:286-296.
• Mosier KM, Asher M. Tarsal coalition and peroneal spastic flat foot: a review. J Bone Joint Surg Am 1984; 66:976-984.
• Pachuda NM, Lasday SD, Jay RM. Tarsal coalition: etiology, diagnosis, and treatment. J Foot Surg 1990; 29:474-488