In osteoarthritis, the cartilage that protects and cushions the joints breaks down over time. As the cartilage wears down, the bone surfaces rub against each other. This damages the tissue and bone, which then causes pain. Osteoarthritis is common in the knee joints.
ByHealthwise Staff Primary Medical ReviewerAnne C. Poinier, MD - Internal Medicine Specialist Medical ReviewerStanford M. Shoor, MD - Rheumatology