A Regional Mapping of Articular Cartilage Integrity and Biphasic Properties in Healthy and Osteoarthritic Trapeziometacarpal Joints.

PURPOSE: To identify the mechanical and morphological regional changes of articular cartilage on the first metacarpal and trapezium and their association with attenuation of the volar ligament complex (VLC) during trapeziometacarpal (TMC) osteoarthritis (OA) progression.

METHODS

Twenty-four fresh-frozen female cadaveric TMCs were separated into (1) younger healthy/early-stage osteoarthritic, (2) elder healthy/early-stage osteoarthritic, and (3) advanced-stage osteoarthritic groups based on age and Eaton-Littler grading. Metacarpal and trapezium surfaces were split into six regions. Microindentation testing was performed to characterize the biphasic properties of each region. Light imaging, scanning electron microscopy/energy dispersive spectroscopy, and magnetic resonance imaging were performed to assess cartilage integrity and identify wear patterns.

RESULTS

The volar ulnar region of the metacarpal, along with the volar central and volar ulnar regions of the trapezium, had a higher equilibrium modulus in the advanced-stage OA specimens. SEM/EDS revealed these regions to be fully eburnated in most cases. MRI revealed eburnation, as well as the degeneration and/or detachment of the beak ligament portion of the VLC. In the advanced-stage OA TMCs, an increased equilibrium modulus in the volar portion of the trapezium correlates to attenuated VLC stiffness from our previous study.

CONCLUSION

A regional pattern in articular cartilage degeneration, including changes in biphasic properties evidenced by an increased equilibrium modulus, during TMC OA progression is evident with the most significant changes occurring in the volar ulnar region of the metacarpal and volar central and volar ulnar regions of the trapezium. These changes in articular cartilage can be correlated to an attenuated VLC.