Thumb reconstruction by digital transposition.

In traumatic loss or congenital aplasia of the thumb, transposition of a digit on its neurovascular pedicle is the preferable method for thumb reconstruction. The index finger is the digit of choice, but any other finger or a portion of a finger can be used, especially if it is damaged. The operative techniques differ considerably, depending on the level of thumb loss. In total amputation or total aplasia all the parts of the new thumb have to be constructed with the structures of the transposed index finger. The skeletal readjustment consists of shortening in the metacarpal region, rotation on the longitudinal axis, and fixation in palmar abduction; the metacarpophalangeal joint has to be preserved. A well established muscular stabilization is essential for good function. The skin cover is obtained by a dorsally pedicled skin flap in contrast to the palmar based skin flap in cases of partial loss or partial aplasia of the thumb. Here the muscle balance is easier to obtain by suturing the distal tendons of the index finger to the present thumb muscles. The amount of shortening depends on the length of the transposed digit (an intact or a partially amputed one). Operative technique, complications, and results in 223 cases are described and illustrated.