Extensor carpi radialis brevis tendon transfer for thumb adduction--a study of power pinch

Eighteen patients with disability due to weak pinch were treated with extensor carpi radialis brevis (ECRB) adductor-plasty. Weakness was due to loss of function of the adductor pollicis because of ulnar nerve injury, peripheral neuropathy, local muscle avulsion, partial amputation, or aplasia. At operation, a tendon graft was passed distally through the interspace between the second and third metacarpals, deep to the adductor pollicis, and then sutured to the tendon of the adductor pollicis. Proximally, the graft was tunneled subcutaneously at the dorsum of the wrist and sutured to the detached ECRB. Tendon length was adjusted so that the radial side of the thumb was in the plane of the palm with the wrist straight. For patients with weak thumb abduction due to combined median and ulnar nerve palsy, the graft was made slightly longer. Of the 18 patients operated upon, eight had tendon transfers for abduction of the index finger performed simultaneously with thumb adductor-aplasty. In those patients treated for weakness due to adductor paralysis or avulsion, the mean tip-to-side pinch in the injured hand was 25% that of the normal hand. Postoperatively, mean pinch force was doubled. No patient had difficulty in phase conversion. Two patients had limited thumb abduction postoperatively. Both had thenar paralysis. No patient lost wrist function as a result of the operation.