My orthopod once explained to me that there are connective tissue disorders that can cause muscles to tear away from the bone. I am not sure about the aging aspect, but would not be surprised if there is a connection. When I was in my early 30's, I tore some muscles from my shoulder that required major surgery. NOT fun. I would do some research and ask your doctor after surgery if this injury could be age related. Good luck, and do not rush your recovery.
Leigh Costello
Epilog Mini 24, 45W, Corel X4
Smile, make them wonder what ya did.