Tarsal coalitions: an instructional review.

Tarsal coalitions, the majority of which are congenital, are abnormal unions between two or more tarsal bones. Acquired tarsal coalitions may result from trauma or from rheumatic conditions. Tarsal coalition may cause peroneal spastic flatfoot or rigid valgus foot without peroneal spasm. Surgery is not always essential in the treatment of tarsal coalitions; some patients will respond to conservative treatment.