Data from the FIS Injury Surveillance System (FIS ISS), a prospective injury recording system established at the Oslo Sport Trauma Research Center (OSTRC) since 2006, show that every third freestyle skier suffers a time-loss injury each season.
Many of these are severe (>28 days) and lead to a long-term absence from training and competition. Knee injuries, particular tears of the anterior cruciate ligament (ACL) represent a major problem.
To reduce the risk of these serious knee injuries, we have to know why and how the injuries occur. So far, the knowledge is limited.
The aim of this study is to describe in detail the mechanisms of injury among World Cup freestyle skiing, with a particular focus on severe knee injuries, ACL tears.
Videotape of ACL tears reported through the FIS ISS has been recorded from four seasons (2006-10). More than 20 injuries have been captured on video and will be visually and biomechanically analyzed. The injury cases will be visually analyzed by a group of experts, and an analysis form will be developed in order to describe in detail the mechanisms of ACL tears. This information will include an evaluation of the injury situation, skiing situation and body motion. In addition, injury cases and matched controls will be compared to distinguish between injury and no injury situations.
Joint kinematics of ACL tears will be estimated by using a model-based image-matching technique for three-dimensional reconstruction of human motion. By utilizing this technique, it is possible to estimate joint angles to the hip and knee. The method has been developed and validated at OSTRC.
The results will provide a better understanding for how it may be possible to reduce the risk of injury and improve skiing safety in the future.