[Ball and socket ankle joint and tarsal synostosis (author's transl)].

Ball and socket ankle joints in 4 patients with "tarsal coalition" have first been described by Lamb and later by others. This report deals with a further case. The boy with a congenitally short left leg and absence of the lateral two toes was seen at the age of 4 months. He was again seen at 11 years of age after a sprain of the right ankle. Roentgen-examination showed calcaneotarsal synostosis and a ball and socket ankle joint with a fatigue fracture of the lateral metatarsal. The shape of the ankle joint appears to be part of a non-inheritable congenital defect with early embryonal disturbance of cleft formation in the tarsus.