My daughter had a torn meniscus in one knee, had surgery, the doc told me she'd have problems later in life. The next year she tore her ACL and damaged the meniscus in the other knee (soccer both times). I was told the surgery would be about an hour. After two hours, I was getting pretty frantic. He finally came out and told me she was doing fine, at that point I didn't much case about the knee. This all was 20 years ago and she's OK so far.
She boxes to stay in shape, of all things. Not competitively. She's my ten thousand dollar baby.