title: Risk factors for syndesmotic and medial ankle sprain: role of sex, sport, and level of competition.
abstract: BACKGROUND
  Syndesmotic and medial ankle sprains constitute up to 15% of all ankle sprains in athletic populations and can result in significant time lost to injury and long-term disability.
  
  
  OBJECTIVE
  The objective of this study was to estimate the rate of syndesmotic and medial ankle sprain injuries and identify risk factors associated with these injuries within the physically active cadet population at the United States Military Academy (USMA).
  
  
  METHODS
  Cohort study; Level of evidence, 2.
  
  
  METHODS
  The Cadet Illness and Injury Tracking System (CIITS) database at USMA was queried for all ankle injuries between 2005 and 2009. Sex, level of competition, and exposure to sport were among risk factors analyzed.
  
  
  RESULTS
  Among 20 336 person-years, 1206 cadets sustained ankle sprain. Syndesmotic (6.7%) and medial (5.1%) ankle sprains had an incidence rate (IR) of 4.8 and 3.5 per 1000 person-years, respectively. Compared with women, men were 3 times more likely to experience medial ankle sprain (IR ratio [IRR] 3.37; 95% confidence interval [CI]: 1.05, 10.74], but there was no difference in rate of syndesmotic sprains by sex (IRR 1.06; 95% CI: 0.58, 1.95). Athletics accounted for 81% of syndesmotic sprains and 64% of medial sprains. Sprint football (52.3), team handball (men's, 34.7), soccer (men's, 30.5; women's, 6.5), and basketball (men's, 24.8; women's, 6.7) had the highest syndesmotic IR per 100 000 athlete-exposures. Medial sprain IR was highest in men's rugby (16.6) and gymnastics (14.0). When analyzed by athlete-exposure, male intercollegiate athletes had a greater risk of syndesmotic sprain than their female counterparts (3.53; 95% CI: 1.26, 9.83). Furthermore, intercollegiate level of competition had an increased risk of syndesmotic sprain when compared with intramural level (IRR 2.41; 95% CI: 1.03, 5.65).
  
  
  CONCLUSIONS
  Male athletes have an over threefold greater risk of medial ankle sprain. Male sex and higher level of competition are risk factors for syndesmotic ankle sprain during athletics.
authors.affiliation: William Beaumont Army Medical Center, El Paso, Texas, USA.
authors.forename: Brian R
authors.initials: BR
authors.lastname: Waterman
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Belmont
authors.forename: Kenneth L
authors.initials: KL
authors.lastname: Cameron
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Svoboda
authors.forename: Curtis J
authors.initials: CJ
authors.lastname: Alitz
authors.forename: Brett D
authors.initials: BD
authors.lastname: Owens
mesh_terms: D016512:Ankle Injuries / Q000453:epidemiology*; D001265:Athletic Injuries / Q000453:epidemiology*; D015992:Body Mass Index; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008889:Military Personnel / Q000706:statistics & numerical data; D011446:Prospective Studies; D012307:Risk Factors; D012737:Sex Factors; D013180:Sprains and Strains / Q000453:epidemiology*; D014481:United States / Q000453:epidemiology; D055815:Young Adult