I dislocated my knee cap twice. Once in the Army, my leg was jammed up and I pulled the outside of my thigh next thin I know my thigh moved but my lower leg didn't and I was wearing my knee cap on the inside of my leg for about 2 seconds before it popped back when I freaked and let go of my thigh. Second time was riding several years later. Ever since I have to ride with a knee brace that has good strapping to secure the kneecap as a precaution. I swear when it happens it just feels like you lost the lower half of your leg for a few minutes. Problem I have I have yet to find one that doesn't ride down. When it does that it pulls on the kneecap and aggravates it. So I just use cheap fox shin, knee guards, not that they really do much to help the risk of that kneed getting dislocated but does protect them from getting bashed. They don't really seem to make very good braces, knee protection for tall guys (6'7). Anyone have one that corrects this please share with me.