How Do Sex, Age, and Osteoarthritis Affect Cartilage Thickness at the Thumb Carpometacarpal Joint? Insights from Subject-Specific Cartilage Modeling

Studying the morphology of the thumb carpometacarpal (CMC) joint cartilage in both health and disease is warranted by the high incidence of CMC osteoarthritis (OA), especially in older women; however, quantifying CMC cartilage variation in vivo remains challenging with current modalities. We used a subjectspecific cartilage model that is based on joint space volume computations from sequential CT scans to find that cartilage thickness does not differ with sex and age, but that it does with early signs of OA. These findings advance the general understanding of CMC joint mechanics and OA pathogenesis by suggesting that either higher shear stress, due to higher cartilage thickness to bone size ratio, or metabolic and genetic differences, under the influence of mechanical loading, rather than mechanical factors alone, are implicated in the pathoetiology of CMC OA. The cartilage model used here may be further utilized to study cartilage degradation in vivo, may be incorporated into subject-specific mechanical simulations, and may have clinical applications for OA staging if combined with dynamic volume CT.