Ligament length during circumduction of the trapeziometacarpal joint

The length of the ligaments in the trapeziometacarpal joint in 12 fresh human cadaveric hands was studied with a magnetic tracking system. The location of the insertion and origin of five trapeziometacarpal ligaments was precisely identified and digitized. The distances between the digitized points were calculated throughout the range of motion. The anterior oblique ligament (AOL) and ulnar collateral ligament (UCL) had similar patterns of variation in ligament length during circumduction motion, reaching the maximum length in the extension-abduction position. The first intermetacarpal ligament (IML) and the posterior oblique ligament (POL) exhibited similar patterns of variation in ligament length, reaching their maximum lengths in the flexion-abduction position. The dorsoradial ligament (DRL) had a different pattern, with the maximum length occurring in the adduction position. The ligaments reached their minimum length when the metacarpal head position was nearly opposite the position that produced maximum length. The total variation in length of each ligament in circumduction was about 5%-9% of the maximum length.