Are Youth ACL Biomechanics Studies Growth-Aware? A Systematic Methodological Review of Maturation Assessment, Task Scaling, Biomechanical Normalization, and Statistical Analysis in Landing and Cutting

Background and Objectives: Anterior cruciate ligament (ACL) injury prevention research in pediatric and adolescent athletes frequently relies on biomechanical assessments of landing and cutting tasks. However, interpretation of developmental biomechanics is complicated by changes in body size, neuromuscular control, and biological maturation during growth. This systematic methodological review evaluated whether youth ACL biomechanics studies adequately account for growth and maturation in study design, task prescription, biomechanical normalization, modeling assumptions, and statistical analysis. Methods: A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. MEDLINE, Embase, CINAHL, SPORTDiscus, Scopus, Google Scholar, and Web of Science were searched through July 2026. Eligible studies included participants ≤19 years performing ACL-relevant landing, cutting, change-of-direction, pivoting, or deceleration tasks with quantitative biomechanical or neuromuscular outcomes. Data were extracted regarding maturity assessment, task scaling, normalization, modeling assumptions, and statistical treatment of developmental variables. Results: Fifty-four reports met eligibility criteria. Forty-three reports (79.6%) evaluated landing tasks exclusively, seven (13%) evaluated cutting and change of direction tasks exclusively, and four (7.4%) evaluated both landing and cutting tasks. Cross-sectional/observational designs were most common (28/54; 51.9%), followed by intervention/repeated-measures (16/54; 29.6%) and longitudinal/cohort studies (10/54; 18.5%). Formal biological-maturity assessment with a specified method was documented in 25 reports (46.3%). Two additional reports (3.7%) described a formal or group maturity classification but did not identify the method. Nine reports (16.7%) used age/development groupings only, and 18 (33.3%) reported no formal maturity assessment. Variability was observed in task prescription, normalization, and reporting of growth-related statistical methods. Conclusions: Youth ACL biomechanics research is not consistently growth-aware. Future studies should integrate maturity assessment, task scaling, biomechanical normalization, and developmentally appropriate statistical approaches to improve interpretation and reproducibility.