A Majority of Anterior Cruciate Ligament Injuries Can Be Prevented by Injury Prevention Programs: A Systematic Review of Randomized Controlled Trials and Cluster–Randomized Controlled Trials With Meta-analysis

Yu-Lun Huang, PhD*, Jaehun Jung, PhD, Colin M.S. Mulligan,

First Published August 30, 2019 

Abstract

Background:

Anterior cruciate ligament (ACL) injury prevention programs (IPPs) are generally accepted as being valuable for reducing injury risk. However, significant methodological limitations of previous meta-analyses raise questions about the efficacy of these programs and the extent to which meeting current best-practice ACL IPP recommendations influences the protective effect of these programs.

Purpose:

To (1) estimate the protective effect of ACL IPPs while controlling for common methodological limitations of previous meta-analyses and (2) systematically categorize IPP components and factors related to IPP delivery to assess the validity of current best-practice IPP recommendations.

Study Design:

Systematic review with meta-analysis.

Methods:

A systematic search of 5 electronic scientific databases was conducted to identify studies testing the efficacy of ACL IPPs. Studies were included if (1) the intervention aimed to prevent ACL injury, (2) the incidence rate (IR) or other outcome data that made it possible to calculate the IR for both the intervention and control groups were reported, and (3) the study design was a prospective randomized controlled trial (RCT) or cluster-RCT.

Results:

Of the 2219 studies screened, 8 studies were included in the quantitative synthesis, and their analysis revealed a significant reduction in ACL IR when athletes received IPPs (IR ratio = 0.47; 95% CI, 0.30-0.73; P < .001). The majority of included IPPs tended to meet minimum best-practice recommendations and incorporated plyometric, strengthening, and agility exercises along with feedback on proper landing technique. However, the specific exercises included in each IPP and key factors related to IPP delivery were highly variable.

Conclusion:

Despite limiting the analysis to only high-quality studies and controlling for time at risk and potential clustering effects, the study showed that ACL IPPs had a significant protective effect and reduced injury rates by 53%. However, significant variability in the specific exercises and the manner of program delivery suggests that ACL IPPs may be able to be designed within an overarching best-practice framework. This may allow practitioners the flexibility to develop IPPs that meet the specific characteristics of the target population and potentially increase the likelihood that these programs will be widely adopted and implemented.