Biomechanical changes after carpal tunnel release: a cadaveric model for comparing open, endoscopic, and step-cut lengthening techniques.

We used a previously described cadaveric model for evaluating changes in flexor tendon biomechanics after open carpal tunnel release to evaluate endoscopic and step-cut lengthening techniques. A 26% and 18% increase in tendon excursion consumed by wrist motion was demonstrated for flexor digitorum profundus and flexor digitorum superficialis tendons respectively after open transection of the transverse carpal ligament. A 21% and 15% increase in tendon excursion was demonstrated after endoscopic carpal tunnel release and a 21% and 16% increase after step-cut lengthening of the transverse carpal ligament. Increased excursion was noted after 20-30 degrees of wrist flexion as tendon bowstringing occurred. Although division of the transverse carpal ligament by all methods resulted in a significant increase in tendon excursion, the differences between methods of carpal tunnel release were not significant. This cadaveric study evaluates one potential cause for weakness after carpal tunnel release, palmar displacement of the flexor tendons, which results in increased flexor tendon excursion consumed by wrist motion.