title: Anterior Cruciate Ligament and Knee Injury Prevention Programs for Soccer Players: A Systematic Review and Meta-analysis.
abstract: BACKGROUND
  Soccer has one of the highest incidences of anterior cruciate ligament (ACL) injuries for both males and females. Several injury prevention programs have been developed to address this concern. However, an analysis of the pooled effect has yet to be elicited.
  
  
  OBJECTIVE
  To conduct a systematic review and meta-analysis of ACL and knee injury prevention programs for soccer players, assess the heterogeneity among the studies, and evaluate the reported effectiveness of the prevention programs.
  
  
  METHODS
  Systematic review and meta-analysis.
  
  
  METHODS
  A systematic search of the literature was conducted on PubMed (Medline), Embase, CINAHL, and Central-Cochrane Database. Studies were limited to randomized controlled trials (RCTs) of injury prevention programs specific to the knee and/or ACL in soccer players. The Cochrane Q test and I (2) index were independently used to assess heterogeneity among the studies. The pooled risk difference, assessing knee and/or ACL injury rates between intervention and control groups, was calculated by random-effects models with use of the DerSimonian-Laird method. Publication bias was assessed with a funnel plot and Egger weighted regression technique.
  
  
  RESULTS
  Nine studies met the inclusion criteria as RCTs. A total of 11,562 athletes were included, of whom 7889 were analyzed for ACL-specific injuries. Moderate heterogeneity was found among studies of knee injury prevention (P = .041); however, there was insignificant variation found among studies of ACL injury prevention programs (P = .222). For studies of knee injury prevention programs, the risk ratio was 0.74 (95% CI, 0.55-0.89), and a significant reduction in risk of knee injury was found in the prevention group (P = .039). For studies of ACL injury prevention programs, the risk ratio was 0.66 (95% CI, 0.33-1.32), and a nonsignificant reduction in risk of ACL injury was found in the prevention group (P = .238). No evidence of publication bias was found among studies of either knee or ACL injury prevention programs.
  
  
  CONCLUSIONS
  This systematic review and meta-analysis of ACL and knee injury prevention program studies found a statistically significant reduction in injury risk for knee injuries but did not find a statistically significant reduction of ACL injuries.
authors.affiliation: Department of Orthopaedic Surgery, Duke University Medical Center, Durham, North Carolina, USA nathan.grimm@duke.edu.
authors.forename: Nathan L
authors.initials: NL
authors.lastname: Grimm
authors.affiliation: University of Utah School of Medicine, Salt Lake City, Utah, USA.
authors.forename: John C
authors.initials: JC
authors.lastname: Jacobs
authors.affiliation: Division of Public Health, Study Design, & Biostatistic Center, University of Utah School of Medicine, Salt Lake City, Utah, USA.
authors.forename: Jaewhan
authors.initials: J
authors.lastname: Kim
authors.affiliation: University of Utah School of Medicine, Salt Lake City, Utah, USA.
authors.forename: Brandon S
authors.initials: BS
authors.lastname: Denney
authors.affiliation: St Luke's Intermountain Orthopaedics, Boise, Idaho, USA.
authors.forename: Kevin G
authors.initials: KG
authors.lastname: Shea
mesh_terms: D000070598:Anterior Cruciate Ligament Injuries; D001265:Athletic Injuries / Q000517:prevention & control*; D006801:Humans; D007718:Knee Injuries / Q000517:prevention & control*; D012916:Soccer / Q000293:injuries*
keywords: anterior cruciate ligament injury prevention; injury prevention; knee injury; meta-analysis; systematic review