I'm 6 days recovering from arthroscopic surgery to repair torn meniscus. Mine wouldn't go away and was greatly aggravated by kneeling. It's surprising how quickly arthroscopia recovers. I'm walking fine and flexing almost to previous limits. It's still a little weak though. I'd probably already be bike commuting again except we've been hammered with snow for 2 days, and I figured the rest (working VO) couldn't hurt.

(mentioned in other posts: I originally tore it by forgetting to adjust newly installed pedals. I just clipped in and started riding. When it came time to clip out, the left side was so tight I screwed up my knee yanking it loose.)