Figure 1

Pathogenesis of osteoarthritis. Osteoarthritis is a progressively degenerative disease of multiple etiology in which injury and aging lead to gradual breakdown of articular cartilage. The pathogenesis is categorized by severe inflammation, recruitment of inflammatory cells, proinflammatory cytokine production, and activation of proteinases that results in extracellular matrix (ECM) degradation and ultimately apoptotic cell death of differentiated chondrocytes. IL, interleukin; MMP, matrix metalloproteinase; TNF-α, tumor necrosis factor-alpha.