Osteoarthritis is a disease in which the spongy tissue that coats the ends of bones and joints (also known as cartilage) breaks down. Normally, damaged cartilage repairs itself as older cartilage is degraded. When the balance between degradation and repair is thrown off, cartilage breakdown occurs and damage to bone results. The outcome can be painful and cause tender, creaky joints and limitations in joint movement. Osteoarthritis is the most common form of arthritis and affects more than 20 million Americans, mostly adults over the age of 65.
The most common symptom of osteoarthritis is pain and stiffness in the joint. Sometimes there is swelling in the joint as well as downward radiating pain; sometimes the pain is so severe that it awakens a sufferer from sleep. Learn more about the Osteoarthritis Initiative at HSS.