Upregulation of type X collagen expression in osteoarthritic cartilage.

Joint destruction of articular cartilage in osteoarthritis and rheumatoid arthritis is heralded by surface fibrillation, loss of proteoglycans from the articular surface and increasing hydration and softening of the cartilage matrix (Sokoloff 1982). These initial changes are followed by chondrocyte proliferation and formation of cell clusters and extensive remodeling of the cartilage matrix, i.e. massive degradation and synthesis of new, but partially altered cartilage components.