Source of Support: None, Conflict of Interest: None
The roles of mechanical stresses in the genesis of osteoarthritis in animal model have been studied. Morphological, biochemical and biomechanical study were done on a freshly amputated bovine knee joint immediately after cyclic mechanical load testing on a specially designed knee joint articulating machine. Results showed that cyclic mechanical loading of joints at 150 Kg (moderate loading) produced no qualitative difference between the histologic properties of the cartilage obtained from the moderately loaded and the unloaded control specimens: in both the groups, the articular surface appeared smooth, regular and intact in the matrix. Proteoglycan content and water ratio in the moderately loaded cartilage showed significant increases along with improvement in the shear properties of the tissue. However, the articular cartilage form the joint tested at high loading (300 kg) showed early osteoarthrotic changes in the cartilage structure such as fibrillation and beginning of early osteoarthortic exposure of collagen bundles: decrease in proteoglycan content and water ratio and also in shear moduli of the cartilage tissues. These findings appear to support the hypothesis that physical stresses on the weight bearing joints are responsible for the early onset of osteoarthritis. This study may have clinical relevance in designing appropriate physiotherapeutic protocol of osteoarthritic patients management.