New Zealand white rabbits are a prevalent model species used to study preclinical articular cartilage repair therapies. The composition and structure of rabbit articular cartilage have been extensively characterized, yet the local shear properties of the tissue are unknown. Characterizing the local shear properties is essential for understanding the structure–function relationship in the tissue and relating the rabbit preclinical model to human disease. Therefore, the objectives of this study were to (1) characterize the local shear properties of articular cartilage from the femoral condyles of New Zealand white rabbits, (2) determine if local protein content or matrix structure correlated with local shear properties, and (3) compare microscale shear moduli values of rabbit cartilage to those previously reported for human, equine, and bovine tissues. Local shear strains and moduli varied with rabbit cartilage tissue depth; shear modulus was highest ∼ 50 µm below the tissue surface and decreased to plateau values around 150 µm, mirroring the trend with shear strains. Local shear strains showed significant correlations with local protein content but not matrix organization. Rabbit cartilage shear properties followed similar spatial trends as bovine, equine, and human tissue in the first ∼ 100 um of the tissue depth. However, rabbit tissue then differentiated from the larger animals as shear modulus values plateaued and did not increase by an order of magnitude like that seen in the larger species. Local shear properties of rabbit articular cartilage capture the surface properties of human, equine, and bovine cartilage but mechanically lack the deep zone region.
Keywords:
Arthritis; Osteoarthritis; Preclinical model; Strain; Microscale; Zone; Mechanics