Osteoarthritis is a common disease of the joints that primarily occurs in older adults. This condition is characterized by the breakdown of cartilage, the tough but flexible tissue that covers the ends of the bones at the joints and allows smooth joint movements. One or more parts of the body can be affected, most often the hands, shoulders, spine, knees, or hips.Osteoarthritis usually develops slowly, causing pain, stiffness, and restricted movement as the condition gets worse. Areas of bone no longer cushioned by cartilage rub against each other and start to break down. Further damage is caused as the body attempts to repair and rebuild these tissues. The immune system, which plays a role in healing injuries, targets these areas, and its response leads to inflammation of the joint tissues. Abnormal growths of bone (osteophytes) and other tissue can also occur, and may be visible as enlarged joints. Enlargement of the joints of the fingers is especially noticeable.People with osteoarthritis typically experience stiffness following periods of inactivity such as upon awakening or rising from a chair; the stiffness usually improves as they move around. In some affected individuals, the condition never causes major problems. In others, severe osteoarthritis can impair mobility and the ability to perform daily tasks, affecting quality of life and increasing the risk of other health conditions such as cardiovascular disease.Osteoarthritis is most common in middle age or late adulthood, because the cartilage at the joints naturally begins to thin as people age. However, it can occur earlier in life, especially after injuries affecting the joints such as a type of knee injury called an anterior cruciate ligament (ACL) tear. People who are overweight or whose activities are particularly stressful to the joints are also at increased risk of developing osteoarthritis.
