The most common cause of chronic knee pain is arthritis
- Osteoarthritis: is an age related wear and tear of the joint, where the cartilage or cushions covering the bones of the joint soften and wear away. The friction caused by the bones rubbing against each other causes pain and stiffness, which in turn leads to deformity. With age water content of the cartilage increases and protein in the cartilage begins to degenerate.
- Rheumatoid arthritis : is a disease in which the synovial membrane lining the joint surfaces become inflamed and thickened, leading to degeneration of the cartilage resulting in pain and deformity. The cause of this is attributed to the body treating its own cells as foreign and produces antibodies against it.
- Post-traumatic arthritis: occurs as a result of injury, which may be a single injury to the joint and bones or chronic injury such as sports injuries. Tears in the ligament or damage to bones and cartilage is the cause.