A rare variant of mirror hand: a case report.

Mirror hand is one of the rarest congenital differences of the upper extremity. Typically, there is absence of the radius, duplication of the ulna, and 7 digits in mirrored symmetry about the middle finger. We report a case of a rarer subset of hand duplication in which there is a normal radius and ulna and a hand with 8 digits. The patient underwent surgery to excise the radial 3 digits and to reconstruct the remaining radial digit to function as an opposable, 2 phalanx thumb. Wrist extension was augmented by transferring the digital extensors from the excised fingers to the radial wrist extensors.