Risk Factors Associated with Anterior Cruciate Ligament Injuries in Athletes During Physical Activity According to Sex: A Scoping Review

Background: Anterior cruciate ligament (ACL) injury is one of the most common injuries among athletes and demonstrates significant sex-based differences in incidence, with a higher documented risk in females. Various anatomical, biomechanical, neuromuscular, and hormonal factors have been proposed to explain this disparity; however, the available evidence remains inconclusive due to methodological heterogeneity across studies, variability in outcome measures, and inconsistencies in the assessment of hormonal and biomechanical variables. Objective: To map and synthesize the scientific evidence regarding risk factors associated with ACL injury during sports activity, incorporating a sex-specific analytical perspective. Methods: A scoping review was conducted following the methodological framework proposed by Arksey and O’Malley, the Joanna Briggs Institute guidelines, and the PRISMA Extension for Scoping Reviews (PRISMA-ScR). A systematic search was performed in PubMed and Scopus through September 2025. Observational and experimental studies assessing ACL injury risk factors and analyzing sex-based differences were included. Findings were synthesized using a descriptive and narrative approach. Results: Nineteen studies were included. Biomechanical and neuromuscular factors were the most frequently investigated domains among the included studies (68.4%), followed by hormonal (42%) and anatomical factors (36.8%). These percentages reflect the distribution of research focus across the literature rather than the relative strength or importance of each risk factor. In females, injury risk was primarily associated with high-risk biomechanical patterns, cyclical hormonal variations, and specific anatomical characteristics. In males, risk factors were mainly related to muscular weakness, joint laxity, and structural ligament characteristics. Conclusions: ACL injury risk in athletes appears to be influenced by multiple interacting intrinsic and extrinsic factors. The available evidence suggests that sex-related differences may exist in the contribution of biomechanical, anatomical, hormonal, and neuromuscular factors; however, these relationships are multifactorial and should be interpreted cautiously given the heterogeneity of the included studies.