I know a fella who's 54. Has been a powerlifter for the last 30years, non stop. The weights he's still squatting are beyond me. Guess what - his knees are perfectly fine, as is his back. Go figure.
and buddy of mine has killed his spine (chronic back pain now), blown out both kneecaps and destroyed something in his foot within 3 years of "powerlifting" while not even getting a 1000lbs total and hes natural.
genetics make or break you