Reconstruction of a balanced thumb through tendon transfers.

The ability to use the thumb determines its functional relation to the fingers and the resulting dexterity of the hand. Median palsy results in a failure of abduction and pronation. Ulnar palsy results in loss of adduction and flexion at the metacarpophalangeal joint. Following median, ulnar, and even radial palsy, the thumb can develop adduction deformity. Thumb contracture must be released prior to tendon transfers. Abduction and pronation are best substituted by transfer of the extensor indicis proprius. Adduction is best substituted by transfer of the extensor carpi radialis brevis and arthrodesis of the metacarpophalangeal joint. Median cutaneous sensibility should be reconstructed after appropriate tendon transfers are functional.