title: A systematic video analysis of National Hockey League (NHL) concussions, part II: how concussions occur in the NHL.
abstract: BACKGROUND
  Concussions in sports are a growing cause of concern, as these injuries can have debilitating short-term effects and little is known about the potential long-term consequences. This work aims to describe how concussions occur in the National Hockey League.
  
  
  METHODS
  Case series of medically diagnosed concussions for regular season games over a 3.5-year period during the 2006-2010 seasons. Digital video records were coded and analysed using a standardised protocol.
  
  
  RESULTS
  88% (n=174/197) of concussions involved player-to-opponent contact. 16 diagnosed concussions were a result of fighting. Of the 158 concussions that involved player-to-opponent body contact, the most common mechanisms were direct contact to the head initiated by the shoulder 42% of the time (n=66/158), by the elbow 15% (n=24/158) and by gloves in 5% of cases (n=8/158). When the results of anatomical location are combined with initial contact, almost half of these events (n=74/158) were classified as direct contact to the lateral aspect of the head.
  
  
  CONCLUSIONS
  The predominant mechanism of concussion was consistently characterised by player-to-opponent contact, typically directed to the head by the shoulder, elbow or gloves. Also, several important characteristics were apparent: (1) contact was often to the lateral aspect of the head; (2) the player who suffered a concussion was often not in possession of the puck and (3) no penalty was called on the play.
authors: David L. MacIntosh Sport Medicine Clinic, Faculty of Kinesiology & Physical Education, University of Toronto, Toronto, Ontario, Canada Injury Prevention Research Office, Keenan Research Centre, St. Michael's Hospital, Toronto, Ontario, Canada.
authors: Michael G
authors: MG
authors: Hutchison
authors: David L. MacIntosh Sport Medicine Clinic, Faculty of Kinesiology & Physical Education, University of Toronto, Toronto, Ontario, Canada Graduate Department of Rehabilitation Science, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
authors: Paul
authors: P
authors: Comper
authors: Faculty of Kinesiology, Hotchkiss Brain Institute, Sport Injury Prevention Research Centre, University of Calgary, Calgary, Alberta, Canada.
authors: Willem H
authors: WH
authors: Meeuwisse
authors: Psychological and Neurobehavioral Associates, Inc., State College, Pennsylvania, USA University of Missouri-Kansas City, Kansas City, Missouri, USA.
authors: Ruben J
authors: RJ
authors: Echemendia
mesh_terms: D000054:Acceleration; D000328:Adult; D001265:Athletic Injuries / Q000453:epidemiology / Q000209:etiology; D001924:Brain Concussion / Q000453:epidemiology / Q000209:etiology*; D002170:Canada / Q000453:epidemiology; D006688:Hockey / Q000293:injuries*; D006801:Humans; D008297:Male; D019876:Sports Equipment / Q000706:statistics & numerical data; D014741:Video Recording; D055815:Young Adult
keywords: Concussion; Contact sports; Head injuries; Ice hockey; Injury Prevention