Ultrasonographically assisted carpal tunnel release.

An operative technique of carpal tunnel release using intraoperative ultrasonography is described. In this technique, "safe line" is defined in the transverse carpal ligament and the adjacent deep forearm fascia midway between the ulnar margin of the median nerve and the radial margin of the ulnar artery. After ultrasonographic design of a 1.0 to 1.5-cm skin incision along the safe line at the distal carpal tunnel, the distal ligament is released under direct vision. Proximal release is performed along this line under ultrasonographic monitoring using a device that consists of a basket punch and an outer metal tube. In a prospective randomized study, the outcomes were compared for carpal tunnel release using either this technique in 50 hands of 50 patients or conventional open release in 53 hands of 53 patients. Follow-up assessment at 3, 6, 13, 26, 52, and 104 weeks showed no significant difference with respect to numbness and paresthesias, static two-point discrimination, findings on Semmes-Weinstein monofilament testing, findings on manual muscle testing of the abductor pollicis brevis, and electrophysiologic findings. The ultrasonographic-release group had better outcomes regarding pain, tenderness of the scar, and key-pinch strength at 3, 6, and 13 weeks, and grip strength at 3 and 6 weeks after surgery. The scar was more aesthetic in this group. There were no complications with either technique.