Ulnar dimelia.

Ulnar dimelia ("mirror hand") is a rare congenital anomaly of the upper extremity characterized by duplication of the ulna, absence of the radial ray, and polydactyly. A case report is presented in which the patient had seven triphalangeal digits arranged in a radial cluster of three and an ulnar cluster of four. Emphasis is placed on the technique of one-stage thumb reconstruction with the use of the principles described by Buck-Gramcko.