title: Efficacy and degree of bias in knee injury prevention studies: a systematic review of RCTs.
abstract: BACKGROUND
  Knee injury prevention programs have been developed to address the epidemic of knee injuries in young athletes. These programs include exercises that focus on balance, proprioception, and neuromuscular control. Some studies have suggested such specialized exercise programs may reduce the risk of knee injury.
  
  
  OBJECTIVE
  We conducted a systematic review of randomized controlled trials (RCTs) of knee injury prevention programs and evaluated the risks of bias in these studies.
  
  
  METHODS
  We performed a systematic search using MEDLINE (from 1966), CINAHL (from 1982), Cochrane (CENTRAL), and EMBASE (from 1974) in April 2011. The searches were limited to RCTs. Two reviewers independently assessed the internal validity of the included studies using the van Tulder critical appraisal tool for RCTs. Authors were contacted when internal validity was unclear in the methodology. Ten Level I studies (RCTs) met the inclusion criteria. The average risk of bias score for these studies was 7 of 11 (range, 5-10).
  
  
  RESULTS
  Two of the 10 studies reported a reduction in knee injuries. Of the three studies that provided ACL injuries as an outcome measure, none showed a reduction in overall ACL injury.
  
  
  CONCLUSIONS
  Current evidence suggests most (eight of 10) well-designed RCTs show no difference of treatment benefit. Perhaps refinements of interventions may lead to a reduction in knee and ACL injuries in future trials. Limitations in the number and heterogeneity of currently published RCTs of injury prevention programs place restraints on quantifying intervention efficacy with a meta-analytic approach. Future research articles should more clearly describe the different elements of their methodology, consistent with the standards set forth by the CONSORT statement.
authors.affiliation: Department of Orthopaedics, University of Utah School of Medicine, 516 Medical Plaza, Salt Lake City, UT 84112, USA. nathan.grimm@hsc.utah.edu
authors.forename: Nathan L
authors.initials: NL
authors.lastname: Grimm
authors.forename: Kevin G
authors.initials: KG
authors.lastname: Shea
authors.forename: Ryan W
authors.initials: RW
authors.lastname: Leaver
authors.forename: Stephen K
authors.initials: SK
authors.lastname: Aoki
authors.forename: James L
authors.initials: JL
authors.lastname: Carey
mesh_terms: D015982:Bias; D006801:Humans; D007718:Knee Injuries / Q000517:prevention & control*; D015397:Program Evaluation / Q000592:standards*; D016032:Randomized Controlled Trials as Topic; D012107:Research Design / Q000592:standards; D016896:Treatment Outcome