title: Anterior Cruciate Ligament Injuries in National Football League Athletes From 2010 to 2013: A Descriptive Epidemiology Study.
abstract: BACKGROUND
  There is a high incidence of anterior cruciate ligament (ACL) injuries among National Football League (NFL) athletes; however, the incidence of reinjury in this population is unknown.
  
  
  OBJECTIVE
  This retrospective epidemiological study analyzed all publicly disclosed ACL tears occurring in NFL players between 2010 and 2013 to characterize injury trends and determine the incidence of reinjury.
  
  
  METHODS
  Descriptive epidemiological study.
  
  
  METHODS
  A comprehensive online search identified any NFL player who had suffered an ACL injury from 2010 to 2013. Position, playing surface, activity, and date were recorded. Each player was researched for any history of previous ACL injury. The NFL games database from USA Today was used to determine the incidence of ACL injuries on artificial turf and grass fields. Databases from Pro Football Focus and Pro Football Reference were used to determine the injury rate for each position.
  
  
  RESULTS
  NFL players suffered 219 ACL injuries between 2010 and 2013. Forty players (18.3%) had a history of previous ACL injury, with 27 (12.3%) retears and 16 (7.3%) tears contralateral to a previous ACL injury. Five players (2.28%) suffered their third ACL tear. Receivers (wide receivers and tight ends) and backs (linebackers, fullbacks, and halfbacks) had significantly greater injury risk than the rest of the NFL players, while perimeter linemen (defensive ends and offensive tackles) had significantly lower injury risk than the rest of the players. Interior linemen (offensive guards, centers, and defensive tackles) had significantly greater injury risk compared with perimeter linemen. ACL injury rates per team games played were 0.050 for grass and 0.053 for turf fields (P > .05).
  
  
  CONCLUSIONS
  In this retrospective epidemiological study of ACL tears in NFL players, retears and ACL tears contralateral to a previously torn ACL constituted a substantial portion (18.3%) of total ACL injuries. The significant majority of ACL injuries in players with a history of previous ACL injury were retears. Skilled offensive players and linebackers had the greatest injury risk, and significantly more ACL tears occurred among interior linemen than perimeter linemen. The month of August had the highest incidence of ACL injuries, probably because of expanded roster sizes at that point in the NFL season.
authors.affiliation: Rothman Institute at Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Dodson
authors.affiliation: Sidney Kimmel Medical College of Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
authors.forename: Eric S
authors.initials: ES
authors.lastname: Secrist
authors.affiliation: Rothman Institute at Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
authors.forename: Suneel B
authors.initials: SB
authors.lastname: Bhat
authors.affiliation: Orlin & Cohen Orthopedic Group, Lynbrook, New York, USA.
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Woods
authors.affiliation: Rothman Institute at Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
authors.forename: Peter F
authors.initials: PF
authors.lastname: Deluca
keywords: anterior cruciate ligament; epidemiology; football (American); professional sports