title: Increasing Lower Extremity Injury Rates Across the 2009-2010 to 2014-2015 Seasons of National Collegiate Athletic Association Football: An Unintended Consequence of the "Targeting" Rule Used to Prevent Concussions?
abstract: Sports-related concussions (SRCs) have gained increased societal interest in the past decade. The National Collegiate Athletic Association (NCAA) has implemented legislation and rule changes to decrease the incidence and risk of head injury impacts. The "targeting" rule forbids initiating contact with the crown of a helmet and targeting defenseless players in the head and neck area; however, there are concerns that this rule change has unintentionally led to an increased incidence of lower extremity injuries.
  
  
  
  The purpose of this study was to evaluate the change in lower extremity injury rates in NCAA football during the 2009-2010 to 2014-2015 seasons. We hypothesized that the lower extremity injury rate has increased across the time period.
  
  
  
  Descriptive epidemiology study.
  
  
  
  Sixty-eight NCAA football programs provided 153 team-seasons of data to the NCAA Injury Surveillance Program. Lower extremity injuries (ie, hip/groin, upper leg/thigh, knee, lower leg/Achilles, foot/toes) and SRCs sustained during NCAA football games were examined. We calculated injury rates per 1000 athlete-exposures (AEs) for lower extremity injuries and SRCs. Rate ratios (RRs) compared injury rates between the 2009-2010 to 2011-2012 and 2012-2013 to 2014-2015 seasons.
  
  
  
  Overall, 2400 lower extremity injuries were reported during the 2009-2010 to 2014-2015 seasons; most were to the knee (33.6%) and ankle (28.5%) and caused by player contact (59.2%). The lower extremity injury rate increased in 2012-2013 to 2014-2015 compared with 2009-2010 to 2011-2012 (23.55 vs 20.45/1000 AEs, respectively; RR, 1.15; 95% CI, 1.06-1.25). This finding was retained when restricted to injuries due to player contact (RR, 1.19; 95% CI, 1.07-1.32) but not for injuries due to noncontact/overuse (RR, 0.96; 95% CI, 0.80-1.14). When examining player contact injury rates by anatomic site, only ankle injuries had an increase (RR, 1.36; 95% CI, 1.13-1.64). The SRC rate also increased in 2012-2013 to 2014-2015 compared with 2009-2010 to 2011-2012 (3.52 vs 2.63/1000 AEs, respectively; RR, 1.34; 95% CI, 1.08-1.66).
  
  
  
  The lower extremity injury rate has increased in NCAA football athletes. Similarly, SRC rates have increased, although this may be caused by concurrent policies related to better education, identification, and management. Targeting rule changes may be contributing to increased rates of player contact-related ankle injuries. Alongside continued surveillance research to examine longitudinal time trends, more in-depth individual-level examinations of how targeting rule changes influence coaching and player behaviors are warranted.
authors: University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA robert-westermann@uiowa.edu.
authors: Robert W
authors: RW
authors: Westermann
authors: Datalys Center for Sports Injury Research and Prevention, Indianapolis, Indiana, USA.
authors: Zachary Y
authors: ZY
authors: Kerr
authors: University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA.
authors: Peter
authors: P
authors: Wehr
authors: Duke University, Durham, North Carolina, USA.
authors: Annuziato
authors: A
authors: Amendola
mesh_terms: D016512:Ankle Injuries / Q000453:epidemiology; D001924:Brain Concussion / Q000453:epidemiology / Q000517:prevention & control; D005538:Football / Q000293:injuries*; D006260:Head Protective Devices; D006801:Humans; D015994:Incidence; D007718:Knee Injuries / Q000453:epidemiology; D035002:Lower Extremity / Q000293:injuries*; D008297:Male; D012621:Seasons; D014481:United States / Q000453:epidemiology; D014495:Universities
keywords: ankle injury; concussion; football; knee; rule change