I have torn my ACL in my left knee twice (damn you college soccer!!!) and had reconstruction done the last time in 01. I just make sure I wear my knee brace (the one from the orthopaedist, not a cheapie) and haven't had a problem. The surgeon told me that with that brace on if I damaged my knee again I had ripped my leg completely off. Only problem I have is if I ride switch at all (I am regular not goofy) it kills my left knee to be in back. I guess just that extra pressure and angle on it. Biggest warning is don't go if you will be tentative. The more you play scared, the more you risk injury. Thats the whole reason I tore mine the second time.