Blew up the meniscus in both knees doing leg lifts at the gym (too much weight). Tried a brace - no joy. Doc said let it heal by itself for three months. One knee apparently did but I had surgery on the other. Surgery was a one day affair and I was back riding in two days. No pain since. Surgery is the way to go; if my other knee so much as squeaks, it's off to the docs for surgery.