Osteoarthritis is a degenerative joint disease that is the most common type of arthritis. Usually, it occurs among people of advanced age. But it can begin in middle age or even sooner, especially if there’s been an injury to the joint. While there are treatments available — exercise, braces or canes, loss of excess weight, various pain relievers and anti-inflammatory medicines — these are no cures, and none of the treatments are predictably effective. In fact, often they don’t work at all, or help only a little. Injected steroids or synthetic lubricants can be tried as well. When all else fails, joint replacement surgery can be highly effective. In fact, about a million joint replacements (mostly knees and hips) are performed each year in the US.