i was recently in lake placid, doing some bouncing, one of the kids in our group, was doing a 5 or someghing, came down and landed outside of the tramp on the matts but still spinnning and leg extended fully. He fell on the ground and started screaming grabbing his leg, we thought he was just joking, and he continued, so coaches came over. When he left to the hospital, the back of his knee, like the inside part was all black and blue and extremely sweelled. Turns our he blew out his knee, broke his patella or seomthing like that, and and artery in the back of his knee broke or soemthing and caused internal bleeding. He had to go through 4 surgerys after he was air lifted from the first hospital to a bigger one.