Polydactyly of the hand.

Polydactyly is considered either the most or second most (after syndactyly) common congenital hand abnormality. Polydactyly is not simply a duplication; the anatomy is abnormal with hypoplastic structures, abnormally contoured joints, and anomalous tendon and ligament insertions. There are many ways to classify polydactyly, and surgical options range from simple excision to complicated bone, ligament, and tendon realignments.