Three-dimensional analysis of the ligamentous attachments of the first carpometacarpal joint.

PURPOSE: To show the ligamentous locations and attachments of the first carpometacarpal (CMC) joint on a 3-dimensional (3-D) surface model.

METHODS: Ten fresh-frozen cadaver wrists were used to dissect and identify the first CMC ligaments. Their ligamentous attachments and whole bone surfaces were digitized 3-dimensionally and their areas were calculated. The attachments of each ligament were represented in a model combining 3-D computed tomography surfaces overlaid by a digitized 3-D surface and also were shown visually by a specific color on 3-D bone images. The superimposed outlines of the ligamentous attachments on both the radial and ulnar base of the first metacarpal (MC) also are described.

RESULTS: Seven ligaments of the first CMC joint were identified: the dorsoradial ligament, the posterior oblique ligament, the superficial anterior oblique ligament, the deep anterior oblique ligament, the ulnar collateral ligament, the dorsal first MC ulnar base-second MC radial base intermetacarpal ligament, and the volar first MC ulnar base-second MC radial base intermetacarpal ligament. The detailed locations and areas of the ligamentous attachments of the first CMC joint were determined. The average locations of the centroid of the ligamentous attachments of the ulnar collateral and the dorsoradial ligaments were located ulnovolar and dorsoradial on the first MC base, respectively.

CONCLUSIONS: The anatomic 3-D attachment sites of the first CMC ligaments were shown qualitatively and their areas were quantified. The results of this study improve the knowledge and understanding of the normal anatomy and its impact on the mechanics of the first CMC joint. This should help in making an accurate assessment of radiographic images and treating injuries and degenerative changes in the first CMC joint by ligament reconstruction, repair, and arthroscopy.