Osteoarthritis affects an estimated 15.8 million Americans, according to the Arthritis Foundation.

In the disease, cartilage that cushions the surface of joints wears away as people age. As a result, bones rub together, causing pain and loss of movement.Recently, a gene defect was discovered that leads to this condition in some people. Researchers also think a variety of other factors, including joint damage from certain types of on-the-job repeated movements, sports injuries and obesity, may lead to osteoarthritis.