Hey Jackie
I tore my MC, dislocated my kneecap, and tore my meniscus in Spring of 07. I had surgery to take out scar tissue (only a partial tear), smooth out the back of my kneecap, remove synovium and remove my meniscus. Honestly - right after the surgery I felt way better. Only issue I had was a bloodclot in my calf from the surgery and Birth Control - so my words of advise are to GO OFF any birth control at least two weeks prior to any joint surgery. It really reduces the risk of a blood clot.
As for my knee - I waited almost eight months to do the surgery. I was riding all summer but my knee was grinding (mainly did the surgery to fix the kneecap area). They heal! Only hard thing for me is to ride a HUS horse. I can't really crank up my knee like that. Any western event - you'll be fine!