Regional cartilage properties of three quadruped tibiofemoral joints used in musculoskeletal research studies.

Quadruped joints are commonly used in musculoskeletal studies as a surrogate for human joints despite inherent differences in tissue properties. Although concerns exist regarding model validity, relatively few studies comparing the mechanical properties of quadruped tissue exist. This study aimed to characterise the regional intrinsic mechanical properties and thickness of tibiofemoral cartilage from three quadrupeds used in modern musculoskeletal research. Osteochondral plugs were removed from the major weight-bearing regions of porcine (6 months), bovine (18-24 months) and ovine (approximately 5 years) tibiofemoral joints. The equilibrium elastic modulus and permeability of the cartilage were derived by combining the creep indention deformation results and calculated tissue thickness within an in-silica model. Results showed significant interspecies and regional variation in cartilage thickness. Cartilage was thickest on porcine femoral condyles whereas ovine cartilage was consistently thinner across all sites. Furthermore, porcine tissue had a significantly lower equilibrium elastic modulus and significantly higher permeability than ovine cartilage. The results highlight the importance of considering the interspecies and regional variation in quadruped tissue properties when selecting animal joints for musculoskeletal investigations.