title: A systematic video analysis of National Hockey League (NHL) concussions, part I: who, when, where and what?
abstract: BACKGROUND
  Although there is a growing understanding of the consequences of concussions in hockey, very little is known about the precipitating factors associated with this type of injury.
  
  
  OBJECTIVE
  To describe player characteristics and situational factors associated with concussions in the National Hockey League (NHL).
  
  
  METHODS
  Case series of medically diagnosed concussions for regular season games over a 3.5-year period during the 2006-2010 seasons using an inclusive cohort of professional hockey players. Digital video records were coded and analysed using the Heads Up Checklist.
  
  
  RESULTS
  Of 197 medically diagnosed concussions, 88% involved contact with an opponent. Forwards accounted for more concussions than expected compared with on-ice proportional representation (95% CI 60 to 73; p=0.04). Significantly more concussions occurred in the first period (47%) compared with the second and third periods (p=0.047), with the majority of concussions occurring in the defensive zone (45%). Approximately 47% of the concussions occurred in open ice, 53% occurred in the perimeter. Finally, 37% of the concussions involved injured players' heads contacting the boards or glass.
  
  
  CONCLUSIONS
  This study describes several specific factors associated with concussions in the NHL, including period of the game, player position, body size, and specific locations on the ice and particular situations based on a player's position.
authors.affiliation: David L MacIntosh Sport Medicine Clinic, Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, Ontario, Canada Injury Prevention Research Office, Keenan Research Centre, St Michael's Hospital, Toronto, Ontario, Canada.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Hutchison
authors.affiliation: David L MacIntosh Sport Medicine Clinic, Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, Ontario, Canada Faculty of Kinesiology and Physical Education & Graduate Department of Rehabilitation Science, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Paul
authors.initials: P
authors.lastname: Comper
authors.affiliation: Faculty of Kinesiology and Hotchkiss Brain Institute, Sport Injury Prevention Research Centre, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Willem H
authors.initials: WH
authors.lastname: Meeuwisse
authors.affiliation: Psychological and Neurobehavioral Associates, Inc, State College, Pennsylvania, USA University of Missouri-Kansas City, Kansas City, Missouri, USA.
authors.forename: Ruben J
authors.initials: RJ
authors.lastname: Echemendia
mesh_terms: D000328:Adult; D001265:Athletic Injuries / Q000453:epidemiology / Q000209:etiology; D001827:Body Height / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D001924:Brain Concussion / Q000453:epidemiology* / Q000209:etiology; D002170:Canada / Q000453:epidemiology; D057189:Checklist; D006260:Head Protective Devices / Q000706:statistics & numerical data; D006688:Hockey / Q000293:injuries* / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D019876:Sports Equipment / Q000706:statistics & numerical data; D014741:Video Recording; D055815:Young Adult
keywords: Concussion; Contact sports; Ice hockey; Injury Prevention