Biomechanical predictors of primary ACL injury: A scoping review of prospective studies

• Published in: Gait & posture 2025-02, Vol.116, p.22-29
• Main Authors: Straub, Rachel K., Powers, Christopher M.
• Format: Article
• Language: English
• Subjects: Anterior cruciate ligament; Anterior Cruciate Ligament Injuries - physiopathology; Athletic Injuries - physiopathology; Biomechanical Phenomena; Humans; Kinematics; Kinetics; Prospective Studies; Rehabilitation; Risk Factors
• ISSN: 0966-6362; 1879-2219; 1879-2219
• DOI: 10.1016/j.gaitpost.2024.11.013

ACL injuries commonly occur in non-contact situations, particularly in sports involving jumping, landing, and cutting. Numerous biomechanical predictors for non-contact ACL injury have been proposed, yet existing reviews on biomechanical predictors vary in scope and findings. This review aims to identify biomechanical predictors of primary ACL injury using a scoping review. PubMed and EBSCO host (CINAHL Complete, MEDLINE Complete, SPORTDiscus) were searched from inception to March 1, 2023. Prospective studies that (1) examined discrete kinematic/kinetic variables during whole body movements (e.g., landing from a jump, cutting, and single-leg squatting) using 3D lab-based motion analysis, 2D video, or observational (non-instrumented) methods; and (2) produced a prediction model for the association between biomechanical variables (independent variable) and primary ACL injury (dependent variable) were included. 11 studies were included. Jump-landing tasks were the most studied (9 studies), followed by change in direction (2 studies) and single-leg squatting (2 studies). Significant biomechanical predictors for non-contact ACL injury were reported in 7 studies during jump-landing/change in directions tasks. Kinematic predictors included decreased flexion (hip and knee) and increased knee valgus/internal rotation. Kinetic predictors included increased vertical ground reaction forces (landing/takeoff) and increased knee moments (valgus and knee extensor). Limited/conflicting evidence was found for all predictors. None of studies that employed 2D or observational methods (n=3) were able to identify predictors of ACL injury. Biomechanical predictors of primary ACL injury were identified in 7 of 11 prospective studies included within this scoping review. The majority of the reported risk factors were identified using the drop jump, which was the most studied task (8 of 11 studies). The lack of standardization in biomechanical testing across studies limits the determination of specific predictive variables for primary ACL injury. •Biomechanics predicts ACL injury in most prospective studies (7 of 11).•Jump-landing and change in direction tasks have identified predictors.•Squatting tasks and 2D/observational methods have not identified predictors.•All kinematic and kinetic predictors have limited/conflicting evidence.•To compare results across studies, standardized biomechanical metrics are needed.