I have known a few dancers in my life-time and many have survived past their middle years without crippling arthritis. Sure they have their aches and pains, but so is life.
Modern medicine is beginning to understand that osteoarthritis is not really based in the wear-and-tear theory that was popular years ago, and that there might be a genetic pre-disposition to OA. Many peolple develop "arthritis" (there are about 205 forms of "arthritis") without having had excessive wear-and-tear. Rheumatoid Arthritis is known to be an immunological disease.
So, while some may blame poor training, improper treatment and rehabilitation, etc., there are other factors we just don't understand.
balletboy[/i]