Complete congenital duplication with incomplete separation of a lower extremity.

A case of a boy with complete duplication of the lower extremity and separation below the lower leg was described. Although x-ray examination revealed no femur, operation revealed a cartilage expected to become the femur in the future. A classification of duplication and separation of the lower extremity is proposed. The method and course of treatment in the present case were described in detail, including the application of tissue expanders on the deformity of the knee joint accompanied by a shortening of the sciatic nerve.