title: The effect of playing surface on the incidence of ACL injuries in National Collegiate Athletic Association American Football.
abstract: BACKGROUND
  Artificial playing surfaces are widely used for American football practice and competition and anterior cruciate ligament (ACL) injuries are common. This study analyzed the National Collegiate Athletic Association (NCAA) Injury Surveillance System (ISS) men's football ACL injury database from 2004-2005 through 2008-2009 to determine the effect of playing surface on ACL injury in NCAA football athletes.
  
  
  METHODS
  This database was reviewed from the 2004-2005 through 2008-2009 seasons using the specific injury code, "Anterior cruciate ligament (ACL) complete tear." The injury rate was computed for competition and practice exposures. Ninety-five percent confidence intervals were calculated using assumptions of a Poisson distribution. Pair-wise, two-sample tests of equality of proportions with a continuity correction were used to estimate the associations of risk factors.
  
  
  RESULTS
  There was an incidence rate of 1.73 ACL injuries per 10,000 athlete-exposures (A-Es) (95% CI 1.47-2.0) on artificial playing surfaces compared with a rate of 1.24 per 10,000 A-Es (1.05-1.45, p<0.001) on natural grass. The rate of ACL injury on artificial surfaces is 1.39 times higher than the injury rate on grass surfaces. Non-contact injuries occurred more frequently on artificial turf surfaces (44.29%) than on natural grass (36.12%).
  
  
  CONCLUSIONS
  NCAA football players experience a greater number of ACL injuries when playing on artificial surfaces.
authors.affiliation: Department of Orthopaedic Surgery, Stanford University, Palo Alto, CA 94063-6342, USA. jdragoo@stanford.edu
authors.forename: Jason L
authors.initials: JL
authors.lastname: Dragoo
authors.forename: Hillary J
authors.initials: HJ
authors.lastname: Braun
authors.forename: Alex H S
authors.initials: AH
authors.lastname: Harris
mesh_terms: D000070598:Anterior Cruciate Ligament Injuries; D001265:Athletic Injuries / Q000453:epidemiology / Q000209:etiology*; D004777:Environment; D004867:Equipment Design; D005538:Football; D006801:Humans; D007718:Knee Injuries / Q000453:epidemiology / Q000209:etiology*; D008297:Male; D006109:Poaceae; D013499:Surface Properties; D014481:United States / Q000453:epidemiology; D014495:Universities