Osteochondritis dissecans of the subtalar articular facet: an unusual diagnosis.

Osteochondritis dissecans of the talus is classically characterized by an abnormality of the articular cartilage of the talar dome. We report a rare case of a lesion of the subtalar facet in a 10-year-old boy. The lesion was responsible for a painful ankle with secondary instability. The diagnosis was made using plain radiographs and CT, which showed a well-circumscribed osteochondral fragment demarcated from the adjacent bone by a radiolucent line. The clinical outcome was favourable after a 6-week period with a non-weight-bearing short-leg cast.