title: Predisposing risk factors for non-contact ACL injuries in military subjects.
abstract: OBJECTIVE
  The goal of this study was to document the incidence of anterior cruciate ligament (ACL) tears and possible risk factors for these injuries in a large population of young, athletic subjects.
  
  
  METHODS
  The authors retrospectively reviewed the US Naval Academy's database of midshipmen admitted in 1999 and 2000 (n = 2,345) and prospectively followed until graduation 4 years later or disenrollment. Excluded were 658 who had a history of preadmission ACL injury or surgery, those without initial radiographs or documented baseline height and weight, or those who had documented contact ACL injuries. Therefore, 1,687 subjects comprised the study group. Standard radiographic measurements, including condylar width, notch width, and femoral notch width index (notch width divided by condyle width), were obtained for all subjects. Statistical analyses were used to determine differences between injured and uninjured subjects.
  
  
  RESULTS
  The overall incidence of non-contact ACL injury was 2.9% (37 men, 12 women). The average BMI was 25.6 and 24.4 kg/m(2) for the injured and uninjured groups, respectively (P < 0.05). Although femoral notch width alone was not associated with non-contact ACL injuries, subjects with higher than average BMI in combination with narrow notch width were at significant risk for ACL injury (P = 0.021).
  
  
  CONCLUSIONS
  Elevated BMI combined with narrow notch width may predispose young athletes to non-contact ACL injury.
  
  
  METHODS
  Retrospective comparative study, Level III.
authors.affiliation: Walter Reed National Military Medical Center, Bethesda, MD, USA. ehenze1@jhmi.edu
authors.forename: Korboi N
authors.initials: KN
authors.lastname: Evans
authors.forename: Kelly G
authors.initials: KG
authors.lastname: Kilcoyne
authors.forename: Jonathan F
authors.initials: JF
authors.lastname: Dickens
authors.forename: John-Paul
authors.initials: JP
authors.lastname: Rue
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Giuliani
authors.forename: David
authors.initials: D
authors.lastname: Gwinn
authors.forename: John H
authors.initials: JH
authors.lastname: Wilckens
mesh_terms: D000293:Adolescent; D016118:Anterior Cruciate Ligament / Q000000981:diagnostic imaging; D000070598:Anterior Cruciate Ligament Injuries; D015992:Body Mass Index; D004198:Disease Susceptibility; D005260:Female; D006801:Humans; D015994:Incidence; D007718:Knee Injuries / Q000453:epidemiology / Q000209:etiology*; D007719:Knee Joint / Q000000981:diagnostic imaging; D008297:Male; D008889:Military Personnel; D011859:Radiography; D012189:Retrospective Studies; D012307:Risk Factors; D055815:Young Adult
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