Effects of Exercise-Based ACL Injury Prevention Interventions on Knee Motion in Athletes: A Systematic Review and Bayesian Network Meta-Analysis

OBJECTIVE: To compare the effectiveness of injury prevention programs (IPPs) for improving high-risk knee motion patterns in the context of reducing the risk of noncontact anterior cruciate ligament (ACL) injury. DESIGN: Systematic review with Bayesian network meta-analysis (NMA). DATA SOURCES: PubMed, Embase, Web of Science, Cochrane Library, and the Cumulative Index to Nursing and Allied Health Literature were searched until September 10 th , 2023. ELIGIBILITY CRITERIA: We included randomized controlled trials (RCTs) involving athletes without prior ACL injury. The trials had to provide data on peak knee flexion and valgus angles, obtained from two-leg drop vertical jump, single-leg drop vertical jump, or side-step cutting test. RESULTS: The NMA synthesized data from 22 RCTs involving 878 participants, evaluating 12 different IPPs. Results of meta-analyses indicated that, in jumping tests, the external focus instructions (mean difference (MD)=26, Credible interval (CrI)=7.5 to 44, Surface Under the Cumulative Ranking curve (SUCRA)=0.94) and internal focus of attention (MD=19, CrI=0.19 to 37, SUCRA=0.81) was effective for increasing peak knee flexion, and core stability training ranked first for reducing knee valgus (MD=−4.40, CrI=−7.7 to -1.1, SUCRA=0.96). None of the IPPs revealed statistically significant effects for the cutting test. CONCLUSION: The external focus instructions and internal focus of attention increased knee flexion, while core stability exercise reduced knee valgus in jumping tests. Intervention effects were inconsistent for cutting tests.