Multiple Intrinsic and Extrinsic Factors Increase the Risk of Anterior Cruciate Ligament Injury in Skiers: A Systematic Review.

To identify and synthesize risk factors associated with first-time, isolated anterior cruciate ligament (ACL) injuries in alpine skiers. A comprehensive literature search was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, and the study was registered in PROSPERO. Studies were included if they were original human research, discussed ACL injuries in skiers, and included first-time ACL injury data. Data extraction focused on study characteristics and risk factors for ACL injury in alpine skiers. Twenty-seven studies met the inclusion criteria. Female sex was associated with increased ACL injury risk, with odds ratios (ORs) ranging from 1.21 to 6.0. Risk-taking behavior was consistently linked to higher injury rates (OR range, 2.08-5.42), especially in less-skilled male skiers. Lower skill level itself was a strong predictor (OR, 3.2-6.74), along with older age (OR per year, 1.05-1.30). Equipment-related factors such as ski boot sole abrasion (OR, 1.4-1.8) and improper binding settings-with failure to release occurring in up to 96% of ACL injury cases-significantly increased injury risk. Environmental conditions were also important: fresh snow (OR, 10.49), grippy snow (OR, 7.79), and icy slopes (OR, 12.41) all posed elevated risks compared to slushy conditions. Family history and genetic predisposition were also frequently identified as important contributors. ACL injury risk in alpine skiers is influenced by a combination of intrinsic and extrinsic factors. Female sex, preovulatory hormonal phase, specific COL1A1 polymorphisms, family history, older age, lower skill level, poor physical fitness, and risk-taking behavior were all associated with increased risk. Extrinsic contributors included boot sole abrasion, improper binding settings, ski geometry, use of rented skis, and adverse environmental conditions such as fresh or icy snow and snowfall. These findings highlight the multifactorial nature of ACL injuries in skiing and underscore the importance of considering both individual and external factors when assessing risk. Level IV, systematic review of Level I to IV studies.