osteoarthritis (ah-stee-oh-ar-threye-tis) is the most common type of arthritis and is seen especially among older people. sometimes it is called degenerative joint disease or osteoarthrosis. osteoarthritis mostly affects cartilage (kar-til-uj) the hard but slippery tissue that covers the ends of bones where they meet to form a joint. healthy cartilage allows bones to glide over one another. it also absorbs energy from the shock of physical movement. in osteoarthritis the surface layer of cartilage breaks down and wears away. this allows bones under the cartilage to rub together causing pain swelling and loss of motion of the joint. over time the joint may lose its normal shape. also small deposits of bone – called osteophytes or bone spurs – may grow on the edges of the joint. bits of bone or cartilage can break off and float inside the joint space. this causes more pain and damage. people with osteoarthritis usually have joint pain and some movement limitations. unlike some other forms of arthritis such as rheumatoid arthritis osteoarthritis affects only joint function and does not affect skin tissue the lungs the eyes or the blood vessels. in rheumatoid arthritis the second most common form of arthritis the immune system attacks the tissues of the joints leading to pain inflammation and eventually joint damage and malformation. it typically begins at a younger age than osteoarthritis causes swelling and redness in joints and may make people feel sick tired and uncommonly feverish.
what is osteoarthritis?