Osteoarthritis is one of the most common forms of arthritis. About 27 million people in America have osteoarthritis. It is a disease affecting the cartilage that cushions the joints, causing break down. This results in bones rubbing against each other, causing stiffness, pain, and loss of movement. The cause is not fully understood. There is no cure for osteoarthritis, but there are medications to help relieve the pain. If the pain is unbearable, your doctor may recommend surgery.