Objectives To understand, through video analysis, how playing characteristics and mechanism of injury contribute to concussions in the National Hockey League (NHL).

Setting National Hockey League.

Design Prospective case series of concussions over a 5 year period of regular season NHL games (2006–2011).

Subjects Digital video images of 341 diagnosed concussions of NHL players.

Outcome Measures Concussions were analysed and coded using the Heads Up Checklist (HUC). The HUC consists of 17 groups of factors, categorised within three main domains: (1) Physical Event, (2) Equipment, and (3) Game Situation. In addition, player characteristics (ie, height, weight, and position) were also captured.

Results During the first 4 years of study period, a common injury mechanism characterised by player-to-player contact and resulting in contact to the head by the shoulder, elbow, or gloves, was identified. Several important characteristics were also discerned: (i) Contact often to the lateral aspect of the head; (ii) Player was often not in possession of the puck; and (iii) No penalty was called on the play. For the 2010–11 season, despite the absolute number of concussions remaining similar to previous years of study, the mechanism of direct contact to the head accounted for fewer concussions observed.

Conclusions Based on the results from this longitudinal study, it appears that majority of concussions are a result of direct contact to the head. Initiatives to reduce eliminate specific behaviours appears to have had an impact as fewer direct contacts to the head were identified.

Competing interests One of the authors (PC) is a paid consultant for the National Hockey League Players' Association (NHLPA).