The most common form is osteoarthritis. It is characterized by the breakdown of the articular cartilage within the joint.
Articular cartilage is a firm rubbery protein material covering the end of a bone.
It acts as a cushion or shock absorber between the bones. When articular cartilage breaks down, this cushion is lost, and the bones will grind together. This causes the development of symptoms such as pain, swelling, bone spur formation and decreased motion. Osteoarthritis commonly affects weight bearing joints such as the knee, but it may affect any joint. Initially, arthritis of the knee is usually treated non-operatively.