Contrast-enhanced CT facilitates rapid, non-destructive assessment of cartilage and bone properties of the human metacarpal

Objective: The aim of this work is to establish the human metacarpal as a new whole joint surface early-stage osteoarthritis (OA) model that enables comparisons of articular cartilage and subchondral bone through high resolution contrast-enhanced CT (CECT) imaging, mechanical testing, and biochemical analysis. Design: The fourth metacarpal was obtained from 12 human cadaveric donors and baseline μCT imaging was followed by indentation testing. The samples were then immersed in anionic (Ioxaglate) and cationic (CA4+) iodinated contrast agent solutions followed by CECT. Cartilage GAG content and distribution was measured using the 1,9 dimethylmethylene blue (DMMB) assay and Safranin-O histology staining. Linear regression was performed to compare cartilage and subchondral bone properties. Results: Strong and significant positive correlations were observed between CA4+ CECT attenuation and both GAG content (R² = 0.86) and equilibrium modulus (R² = 0.84), while correlations using Ioxaglate were insignificant (R² ≤ 0.24, P > 0.05). Subchondral bone plate (SBP) thickness negatively and significantly correlated with SBP mineral density (R² = 0.49). Cartilage GAG content significantly correlated with several trabecular bone properties, including positive correlations with bone volume fraction (%BV/TV, R² = 0.67), trabecular number (Tb.N, R² = 0.60), and trabecular thickness (R² = 0.42), and negative relationships with structural model index (SMI, R² = 0.78) and trabecular spacing (Tb.Sp, R² = 0.56). Similarly, equilibrium modulus correlated positively with %BV/TV (R² = 0.50), Tb.N (R² = 0.59) and negatively with Tb.Sp (R² = 0.55) and SMI (R² = 0.60). Conclusion: This study establishes the human metacarpal as a new early-stage OA model suitable for rapid, high resolution CECT imaging, mechanical testing, and biochemical analysis of the cartilage and subchondral bone, and for examining their inter-relationships.