Clinical features and treatment of congenital fusion of the small and ring finger metacarpals.

Nine cases of congenital fusion of the small and ring finger metacarpals are reported. The underlying etiology of congenital fusion of the small and ring finger metacarpals was ulnar ray deficiency in four hands, cleft hand in two hands, and symbrachydactyly in one hand; two hands were unclassifiable. X-ray films revealed that the small finger was hypoplastic and accompanied by brachymesophalangy in all cases. It was supposed that the main cause of congenital metacarpal fusion was the deficit of mesenchymal cells. Treatment for metacarpal fusion included splitting the metacarpal fusion and autogenous iliac bone graft in two hands, deepening of the interdigital space in two hands, and amputation of the small finger in one hand. Satisfactory improvement in appearance was achieved in three hands.