The 2014 Winter Olympics are upon us, and Vermonters are eager to watch their favorite winter sports, especially downhill skiing. We will watch some of the world’s best ski racers triumph, but we also will inevitably see others sustain injuries from falls, catching an edge, and collisions with gates.
Among Olympic-level competitors, common career-impacting injuries include concussions, fractures to the bones of the arms and legs, shoulder dislocations, and anterior cruciate ligament (ACL) injuries.
ACL injuries can be devastating to amateur and professional athletes. While ACL rupture is the most common serious knee injury in recreational and professional skiers, the mechanism of injury varies between the two groups. The most common mechanism for an ACL injury in a recreational skier is the “phantom foot,” in which the skier transitions into a seated position with the hips below the knees. The uphill arm points behind the skier and the torso turns towards the downhill ski. The downhill ski catches the internal edge and the knee forcibly rotates, tearing the ACL.
Olympic skiers’ skill-level typically precludes them from assuming the “phantom foot” position; however, this population is not immune to ACL rupture. Ski-racers achieve greater speeds, maneuver through difficult courses, and ski challenging terrain in unpredictable weather conditions.
A 2011 study reviewed twenty cases of ACL injuries over three World Cup seasons and identified three main categories of mechanism: the “slip catch,” “landing back-weighted,” and the “dynamic snowplow.” In the “slip-catch” mechanism, the skier’s balance is thrown backward while turning. The skier removes pressure from the downhill ski to compensate, thus extending the outer leg. ACL rupture occurs when the outer ski catches and edge, forcing the knee into flexion and internal rotation. The “landing back-weighted” mechanism occurs when the racer loses balance towards the back while airborne, resulting in a ski tail-first landing with straight knees. Finally, the “dynamic snowplow” describes another situation in which the skier simultaneously slips backwards with more weight on one ski. The unweighted ski migrates away from the body. Compensating for the abrupt change in center of gravity, the skier shifts the load on the weighted ski from the external to internal edge. This forces abrupt internal rotation, which tears the ACL.
We have limited insight into the factors that predispose an elite ski-racer to injury. Injuries have been reported through the International Ski Federation Injury Surveillance System for three World Cup Seasons and identified nearly 70 injuries. Video analyses identified that head and upper body injuries resulted as part of a crash; however, most of the knee injuries occurred while the athlete was still in a skiing position. Gate contact contributed to injury almost 30 percent of the time, and half of the observed injuries occurred in the last 25 percent of the course. In another video analysis of World Cup alpine skiing, injuries were categorized into three groups: poor skier technique, inappropriate tactical strategy, and poor visibility. Additionally, skiing on bumpy terrain, in aggressive snow and in reduced visibility were also assumed to contribute to injuries.
Let’s we hope for a safe and exciting Winter Olympic Games with a low number of injuries and high number of historic events. Unpredictable skiing conditions and incredible pressures of the athletes’ to perform at their best often place them at high risk for injury in this exciting sport.
Go USA! And best of luck to all the competing athletes – and to the athletes we serve throughout Vermont and Northern New York State. Stay safe!
The UVM Medical Center has a dedicated phone line for injured skiers and ski patrol to call in the event of a ski-related musculoskeletal injury. Please call us at 802-847-7479.
James Slauterbeck, MD, is an orthopedic surgeon at the University of Vermont Medical Center and associate professor at the Larner College of Medicine at UVM. Bianca Yoo, a student at the Larner College of Medicine at UVM, also contributed to this article.