In HS I was undercut while in the air going to the rim hard....I had a pretty good vertical back then...about 33" and my knees hit the kid right in the chest and it made me top heavy and I came down face first and landed chin first into the floor. Busted open my chin a little wider and about as deep as a quarter....required about 10 stitches...there was blood everywhere....
In College in a pick-up game a dude took off for a dunk on a fast break and when he planted it sounded like a gunshot followed by screaming and he went to the floor like a 50' redwood tree going down....he basically put his knee on backwards when he planted to take off....It was a little scary...IIRC, he tore up just about every major ligament!
