Doctor Thomas P. Sculco, Surgeon-in-Chief at the Hospital for Special Surgery in New York, explains just what osteoarthritis is physically as well as reviewing some symptoms that give it away.

Dr. Sculco: Osteoarthritis affects almost 40 million Americans. It is a disease where the cartilage, where the covering of the ball of the hip, is affected and gets destroyed. Now once that material becomes destroyed, then bone is exposed beneath that cartilage, and then that bone grates against the other side of the joint and destroys the other side of the joint. When that happens the motion in the hip becomes impaired and pain occurs. Osteoarthritis affects almost 40 million Americans. So we see this very commonly, and patients notice a loss in their ability to walk and to function in a day to day way. And the pain will gradually increase as time goes on.