Congenital absence of the median-innervated intrinsic muscles and flexor
pollicis longus was seen in varying degrees of severity in eleven hands of
eight patients. Three members were involved in one family in which the
anomaly was probably an autosomal dominant. There were no chromosomal
abnormalities. Surgical treatment of seven hands, including release of the
adduction contracture and transfer of the ring-finger superficialis tendon
to provide opposition and to reinforce the ulnar collateral ligament of the
metacarpophalangeal joint, resulted in significant improvement in pinch and
grasp.