Telling someone to "break a leg" is for good luck in the theater world. This is not such a good expression for snow boarders. They actually do break bones in their legs far too often. In fact, a rare type of ankle fracture is becoming more common among snowboarders.
This break occurs in the outside edge of the talus. The talus is the bone between the heel of the foot and the lower leg bone. Doctors need to know about this injury because it often looks just like an ankle sprain. Yet without proper treatment, a talus fracture can have a bad result. The fracture may fail to heal, eventually causing arthritis. Arthritis can cause pain and disability.
The authors of this study used cadavers (human bodies saved for study) to force a talus fracture. They applied the motion snowboarders go through when falling forward. The leading leg turns toward the front of the board, putting the weight of the body over the inside of the ankle. In the lab using human cadavers, the scientists could create this injury. The amount of motion and force was measured for each test. After each test the ankle was examined for injury.
Understanding the forces that cause this injury will help doctors recognize it more quickly. In the past it was thought that falling forward on the ankle while twisting it inward (inversion) caused a talus fracture. But the results of this study show that falling forward and twisting the ankle outward (eversion) is the real cause of injury.James R. Funk, PhD, et al. Snowboarder's Talus Fractures Experimentally Produced by Eversion and Dorsiflexion. In The American Journal of Sports Medicine. November/December 2003. Vol. 31. No. 6. Pp. 921-928.