The role of biomechanics in the initiation and progression of OA of the knee.

The knee is one of the most common joints affected by osteoarthritis (OA), frequently with clinical presentation by middle age or even earlier. Accumulating evidence supports that knee OA progression is often driven by biomechanical forces, and the pathological response of tissues to such forces leads to structural joint deterioration, knee symptoms and reduced function. Well-known biomechanical risk factors for progression include joint malalignment and meniscal tear. The high risk of OA after knee injury demonstrates the critical role of biomechanical factors also in incident disease in susceptible individuals. However, our knowledge of the contributing biomechanical mechanisms in the development of early disease and their order of significance is limited. Part of the problem is our current lack of understanding of early-stage OA, when it starts and how to define it.