I had some cartilage removed from my knee in 2002.
I had an arthroscopy done on it, it just leaves 3 little marks which you can barely see.
I started training last year and was leg-pressing 385 kg's for reps with a good range of motion at 90 degrees.
I've since changed to squatting instead (less hassle with the plates) and go as low down as I can and so far have no problems.
I could do any sport now, even martial arts if I wanted to. But I wouldn't recommend long-distance running....sprints or hill-sprints are fine though in my experience.
There's no pain at the moment, though it does feel a bit 'different' like there's a small amount of pressure if I really push it, but it hasn't given me any problems.
But it takes a few months to heal properly but I was able to walk fine just after a few weeks.
I also used lots of MSM and glucosamine which do make a difference.
For a while there was some scar tissue so it would swell up a bit if I pushed it, but eventually this goes away. I think the excess tissue just gets ground down. It's important just to take your time with the rehab exercises though and gradually build up.
