Events leading to anterior cruciate ligament injury in World Cup Alpine Skiing: a systematic video analysis of 20 cases

Background The authors have recently identified three main mechanisms for anterior cruciate ligament (ACL) injuries among World Cup (WC) alpine skiers, termed as "the slip-catch", "the landing back-weighted" and "the dynamic snowplow". However, for a more complete understanding of how these injuries occur, a description of the events leading to the injury situations is also needed. Objective To describe the skiing situation leading to ACL injuries in WC alpine skiing. Methods Twenty cases of ACL injuries reported through the International Ski Federation Injury Surveillance System (FIS ISS)for three consecutive WC seasons (2006-2009) were obtained on video. Ten experts (9 WC coaches, 1 former WC athlete) performed visual analyses of each case to describe in their own words, factors they thought may have contributed to the injury situation related to different predefined categories: (1) skier technique, (2) skier strategy, (3) equipment, (4) speed and course setting, (5) visibility, snow and piste conditions and (6) any other factors. Results Factors related to the three categories, namely skier technique, skier strategy, and visibility, snow and piste conditions, were assumed to be the main contributors to the injury situations. Skier errors, technical mistakes and inappropriate tactical choices, were the dominant factors. In addition, bumpy conditions, aggressive snow, reduced visibility and course difficulties were assumed to contribute. Conclusion Based on this systematic video analysis of 20 injury situations, factors related to skier technique, skier strategy and specific race conditions were identified as the main contributors leading to injury situations.