<p>Osteoarthritis is a disease that affects the joints. It can involve any joint, but usually concerns hands and weight-bearing joints such as hips, knees, feet and spine.</p>
<p>Cartilage is the tough elastic material that covers and protects the ends of bones. In healthy joints cartilage acts as a shock absorber when you put weight on the joint. The slippery surface of the cartilage allows the bones to move smoothly. When a joint develops osteoarthritis the cartilage gradually becomes rough and thin, and the bone underneath thickens.</p>
