i'm gonna go with a compound fracture of the femur. seen a video of that happening to a skateboarder and the bone ripped right through his jeans from the impact. If i remember right he went into severe shock and passed out immediately. I mean that just seemed brutal.
never severely broke a bone myself but I tore major ligiments in the leg. the right leg bent back like a flamingos. ouch, 4 months on crutches but atleast I got it on video lol.