Congenital hypoplasia of the thumb with absence of the extrinsic extensors, abductor pollicis longus, and thenar muscles.

An unusual congenital anomaly of the thumb has been seen in 10 hands of eight patients. It consists of skeletal hypoplasia, instability of the metacarpophalangeal joint, absence of the extrinsic extensors and abductor, and adduction contracture of the first web space. Surgical reconstruction consisted of transfer of the extensor indicis proprius, the palmaris longus, and the abductor digiti minimi, as well as ankylosis of the metacarpophalangeal joint and release of the web space contracture. Useful grasp and pinch were provided for all patients. The patients were followed from 2 to 5 years.