title: Prevalence of increased alpha angles as a measure of cam-type femoroacetabular impingement in youth ice hockey players.
abstract: BACKGROUND
  It has been reported that relative to other sports participants, ice hockey players suffer from cam-type femoroacetabular impingement (FAI) in higher numbers. α angles have been reported to increase with the likelihood of symptomatic FAI. It is unclear how prevalent increased α angles, commonly associated with cam FAI, are in asymptomatic young ice hockey players.
  
  
  OBJECTIVE
  There would be a higher prevalence of α angles associated with cam FAI in youth ice hockey players than in a non-hockey-playing (skier) youth control group.
  
  
  METHODS
  Cohort study; Level of evidence, 3.
  
  
  METHODS
  A total of 61 asymptomatic youth ice hockey players (aged 10-18 years) and 27 youth skiers (controls) (aged 10-18 years) underwent a clinical hip examination consisting of the flexion/abduction/external rotation (FABER) distance test, impingement testing, and measurement of hip internal rotation. The hip α angle was measured by magnetic resonance imaging, and labral tears and articular cartilage lesions were documented. Hockey players were grouped according to their USA Hockey classification as peewees (ages 10-12 years), bantams (ages 13-15 years), and midgets (ages 16-19 years).
  
  
  RESULTS
  Overall, ice hockey players had significantly higher α angles than did the control group, and hockey players had a significant correlation between increased age and increased α angles, while the control group did not. In the ice hockey group, 75% had an α angle of ≥55°, while in the skier group, 42% had an α angle of ≥55° (P < .006). Hockey players were 4.5 times more likely to have an α angle commonly associated with cam impingement than skiers. Midget players had the highest risk of increased α angles.
  
  
  CONCLUSIONS
  Even at young ages, ice hockey players have a greater prevalence of α angles associated with cam FAI than do skier-matched controls. Properties inherent to ice hockey likely enhance the development of a bony overgrowth on the femoral neck, leading to cam FAI.
authors.affiliation: Steadman Philippon Research Institute, Attn: Center for Outcomes-based Orthopaedic Research, 181 West Meadow Drive, Suite 1000, Vail, CO 81657, USA. drphilippon@sprivail.org
authors.forename: Marc J
authors.initials: MJ
authors.lastname: Philippon
authors.forename: Charles P
authors.initials: CP
authors.lastname: Ho
authors.forename: Karen K
authors.initials: KK
authors.lastname: Briggs
authors.forename: Justin
authors.initials: J
authors.lastname: Stull
authors.forename: Robert F
authors.initials: RF
authors.lastname: LaPrade
mesh_terms: D000293:Adolescent; D002358:Cartilage, Articular / Q000293:injuries; D002648:Child; D057925:Femoracetabular Impingement / Q000145:classification / Q000453:epidemiology / Q000503:physiopathology*; D025981:Hip Injuries / Q000503:physiopathology*; D006621:Hip Joint / Q000503:physiopathology*; D006688:Hockey / Q000293:injuries*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D015995:Prevalence; D012399:Rotation; D012865:Skiing / Q000293:injuries
keywords: cam lesion; femoroacetabular impingement; ice hockey; magnetic resonance imaging; α angle