Date of Award

5-2025

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Bioengineering

Committee Chair/Advisor

Yongren Wu

Committee Member

Michael Kern

Committee Member

Martine LaBerge

Committee Member

Hai Yao

Abstract

The trapeziometacarpal (TMC) joint is the most common site for osteoarthritis (OA) in the upper limb. This joint is characterized by its wide range of motion and limited bony stability, making it susceptible to OA. The TMC joint relies mostly on ligaments and muscles for its static and dynamic stability, respectively. While importance of both volar and dorsal capsular TMC stabilizers has been demonstrated, the role of TMC ligamentous tissues in the development of thumb basal joint OA remains unclear.

The goal of this work was to identify morphometric and mechanical changes in key TMC ligament stabilizers, including the volar ligament complex (VLC), dorsoradial ligament (DRL), and posterior oblique ligament (POL), throughout osteoarthritis progression and determine if there is an association between these changes and TMC pathomechanics. A regional mapping of biphasic properties of the metacarpal and trapezium articular cartilage was correlated to ligament stiffness from the same TMC specimens to identify any associations. Our data found advanced-stage osteoarthritic TMCs to have a mechanically attenuated VLC, likely due to partial detachment on the intraarticular portion of the VLC and loss of a smooth mineral gradient at the metacarpal enthesis, while DRL and POL showed no changes in morphometric or mechanical properties. Additionally, the volar ulnar region of the metacarpal and volar central and volar ulnar regions on the trapezium showed an increase in equilibrium modulus in the advanced-stage osteoarthritic TMC joints as the regions transitioned from healthy cartilage to eburnated bone. The biphasic properties from the volar portion of the trapezium had a significant correlation to VLC stiffness within the advanced-stage osteoarthritic group, suggesting a potential etiological relationship between VLC ligament laxity and TMC pathomechanics.

This work fills the current knowledge gap regarding TMC pathomechanics by identifying the VLC as a ligament that undergoes significant morphometric and mechanical changes during OA progression and recognizing its impact on overall TMC pathomechanics.

Author ORCID Identifier

0009-0001-9980-6260

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