I am now 25 but when I was younger, maybe 12-15 I remember when a guy, who my family knew quite well from dirt late model racing here in MN had an accident just like this. Him and his brother, both avid snowmobilers, racecar drivers and four wheeler racers were going out sledding and just like this guy who lost his leg, picked up the back of the sled to clear it and the track split and came flying out the back and went right into his shins. Split them both in half if I remember correctly. He did recover and walks fine. Doesn't race anymore though. It was quite a miracle he can walk again. Since then this doesn't seem to happen around me much.