Osteoarthritis (OA) is the most common type of arthritis and is caused by the breakdown of cartilage in the joints. When the cartilage in a joint begins to break down it results in the swelling and pain in the joint. As the cartilage continues to wear away the bones begin to rub against each other; this bone on bone contact causes stiffness, swelling, and pain in the joint.
OA is a degenerative form of arthritis and is a chronic (long-term) disease. As it is caused by wearing away of the cartilage, more people develop OA as they age. It usually occurs when people are aged 50 years or older. OA is more common in women than in men.
OA can sometimes run in families, especially when it affects the small joints in the hands. Other risk factors for OA include age, being overweight, excessive use of a joint, and suffering a serious injury to a joint. People who are overweight are at higher risk of getting OA in their weight-bearing joints such as the knees, hips, and the joints in their feet.