Comparison of site-specific tensile, compressive, and friction properties of human tibiofemoral joint cartilage and their relationship to degeneration.

Abstract

Site-specific differences in the compressive properties of tibiofemoral joint articular cartilage are well-documented, while exploration of tensile and frictional properties in humans remains limited. Thus, this study aimed to characterize and compare the tensile, compressive and frictional properties of articular cartilage across different sites of the tibiofemoral joint, and to establish relationships between these properties and cartilage degeneration. We cut human tibiofemoral joint (N = 5) cartilage surfaces into tensile testing samples (n = 155) and osteochondral plugs (n = 40) to determine the tensile, friction and compressive properties, as well as OARSI grades. We performed comparisons between sites using a linear mixed model and analyzed relationships with OARSI grade using Spearman's rank correlation. Cartilage samples were mostly healthy: 56 % were grade 0 or 1, 26 % grade 2, and 18 % grade 3 or higher. In tension, the medial femur was more compliant and viscous compared to the lateral femur (p < 0.05). In compression, the lateral tibia exhibited a lower equilibrium modulus than both femoral condyles (p < 0.05), while the initial friction coefficient was higher in the medial tibia compared to both femoral condyles (p < 0.05). We found no significant correlation between tensile or friction properties and OARSI grade, while compressive properties deteriorated with increasing OARSI grade. The observed site-specific differences in cartilage properties in tension, compression, and friction, demonstrate adaptations to different loading experienced by the surfaces. The comprehensive set of properties presented in this study are valuable for improving future computational knee joint models and serving as a reference for tissue engineering and prosthetic implants.