Anatomy of trapeziometacarpal ligaments.

The stabilizing ligaments of the thumb trapeziometacarpal joint were identified and studied during anatomic dissections of 30 hand specimens. Five main ligamentous structures were identified: (1) the anterior oblique ligament, (2) the ulnar collateral ligament, (3) the first intermetacarpal ligament, (4) the posterior oblique ligament, and (5) the dorsoradial ligament. It was observed that the anterior oblique ligament is the primary stabilizer of the trapeziometacarpal joint and is taut in abduction, extension, and pronation. The first intermetacarpal, ulnar collateral, and posterior oblique ligaments appear to be secondary stabilizers. In every specimen, the first intermetacarpal, ulnar collateral, and posterior oblique ligaments merged to form a force nucleus at the base of the first metacarpal. The dorsoradial ligament did not play a primary or secondary role in thumb stability. The clinical correlation of this anatomic study suggests that, at the minimum, the reconstruction of a primary thumb trapeziometacarpal ligament (anterior oblique ligament) is essential in the treatment of degenerative arthritis to maintain thumb stability.