Toe of left foot hits the ground and sticks, when the foot is being brought forward, so the bottom of the foot is facing upward. With nothing underneath to hold it up, all the weight comes down and you can hear a nasty crunch even from that distance as the ankle is shattered. With all the forward momentum it probably also did some knee or ligament damage. Tendons can be really loud when they pop, and a ham hurtling at that speed is almost certainly too much force for a poor knee ligament to bear.