Association of ligament mechanical properties and articular surface topography with trapeziometacarpal kinematics across osteoarthritis stages.

OBJECTIVE

The trapeziometacarpal (TMC) joint, a common site of osteoarthritis (OA) in postmenopausal women, relies on ligamentous structures for stability due to minimal bony constraint. However, the role of ligamentous constraint in OA pathomechanics, specifically its relationship with joint kinematics and surface morphology across disease stages, remains poorly understood.

METHOD: Forty-six cadaveric female TMC joints across OA stages were analyzed. Articular surface topography was assessed via space distance, curvedness, congruence, and global curvature. Kinematics were recorded via 3D motion tracking of cadaveric hand tasks, examining first metacarpal motion. Ligament mechanical properties were quantified through stress-relaxation and pull-to-failure testing. Specimens were grouped using principal component analysis (PCA) and K-means clustering.

RESULTS

Three clusters emerged: Cluster 1 (healthy bone, kinematics, ligament), Cluster 2 (mild surface remodeling, excess range-of-motion (ROM)/unstable kinematics, attenuated ligament), and Cluster 3 (remodeled surface, reduced ROM, degenerated ligament). Cluster analysis showed topographical changes, with reduced metacarpal ulnar-radial global curvature in Cluster 3. ROM increased from Cluster 1-2 and decreased significantly from Cluster 2-3. Ligament data revealed volar ligament complex (VLC) attenuation and minor dorsal radial ligament (DRL) attenuation from Cluster 1-2, and from Cluster 2-3.

CONCLUSIONS

This study suggests a relationship between ligament mechanics, articular surface topography, and joint kinematics. Clustering revealed links between VLC attenuation and kinematics in early OA. Age and Eaton-Littler classification captured late-stage topographic changes but was less sensitive to ligament mechanics and kinematics. Incorporating ligament mechanics and kinematics may reveal dysfunction missed by current grading systems.