A prospective clinical study of the A1 pulley in trigger thumbs.

A prospective study was performed in 19 patients with trigger thumbs to define the anatomy of the A1 pulley of the thumb in this condition and to evaluate biomechanical parameters of the thumb after complete division of the A1 pulley. Pre- and postoperatively, flexion of the interphalangeal and metacarpophalangeal joints, key pinch strength and tip pinch strength were measured and compared with these measurements on the contralateral thumb. We identified three types of A1 pulley. The clinical data showed that there is no deficit with respect to motion and strength of the thumb after completely sectioning any of the three types of A1 pulley.