An appropriate treatment for postoperative Z-formed deformity of the duplicated thumb.

The Z-shaped deformity of the remaining thumb, often one of the sequelae to treatment of congenital duplicated thumb, may be due to a scar contracture, poorly functioning thenar muscles, and an abnormal insertion of the long flexor and extensor tendons. The deformity occurred in 14 of 49 patients treated for duplication of the thumb. A rotation flap instead of a Z-plasty was used to release the scar contracture, the flexor tendon was detached and reinserted on the ulnar side, and the radial half of the extensor tendon was removed.