On-top plasty using a free metacarpal head graft for lengthening of proximal phalanx in symbrachydactyly--a case report.

A three-year old patient with symbrachydactyly (didactyly type) presented with a little finger that was too short to allow pinching and consisting of a floppy soft-tissue envelope with hypoplastic phalanges, although the thumb was functional. As the proximal phalanx was too small to permit distraction lengthening or conventional bone grafting, on-top plasty using a 4th metacarpal graft with a cartilage head was undertaken for lengthening the proximal phalanx of the little finger for pinch reconstruction. At ten weeks after surgery, the patient achieved satisfactory pinch function due to the lengthened and bone-stabilised postoperative digit and reconstruction of functional proximal interphalangeal joint. In addition, the grafted metacarpal demonstrated satisfactory bone growth throughout the six-year follow-up period.