Pathophysiology of OA

Osteoarthritis is an imbalance in cartilage breakdown and cartilage synthesis, yet ultimately, OA affects all structures within the knee joint. There is no single cause of OA, and the exact aetiology is unknown- there are a host of biological and mechanical factors that culminate in the development of OA.

Features of OA include:

• Thinning and fibrillation of the cartilage, with loss of joint space, osteophyte formation, subchondral bony sclerosis, subchondral cysts and deformity⁴

• Not just cartilage degradation, but also changes in subchondral bone, synovium, ligaments, tendons, muscle, meniscus, nerve tissues.

Risk factors for osteoarthritis and its consequences##⁵

Systemic risk factors for knee OA include increasing age, female gender, excess body weight, physical inactivity and genetic predisposition.

Local risk factors for knee OA include previous joint injury, knee joint malalignment, abnormalities in gait biomechanics and muscle weakness.

_{(Risk factors for osteoarthritis and its consequences. Adapted from: Dieppe and Lohmander, 2005)}⁵