The body can sometimes heal itself in painful conditions. A study of patients with painful osteoarthritis of the knee showed that by mechanically separating the bones in the knee that were touching and causing pain, cartilage regrew and pain and function improved. No other treatment is available that can produce structural change in an existing osteoarthritic joint. This is a potentially revolutionary discovery, and if shown to be effective in larger studies, may help patients with knee pain avoid or forestall knee replacement surgery. And give at least some temporary pain relief.