Surgical treatment of congenital metacarpal synostosis of the ring and little fingers.

Fifteen hands with congenital metacarpal fusions were treated operatively by osteotomy combined either with the use of a silicone block or a distraction device. The aim of the silicone block was to separate the fused metacarpals, but it was buried in the metacarpals at follow-up, with recurrence of fusion. By the distraction technique, 13 mm of lengthening was obtained. The average length of the little metacarpal was 88% of that of the long finger metacarpal. Both methods were effective in correcting the abduction deformity of the little finger by a mean of 34 degrees, and increasing the range of motion of the metacarpophalangeal joint to 28 degrees of active flexion. Although the distraction method took longer than the silicone block method, the final appearance of the hand was better.