EFFECT OF PENALTY MINUTE RULE CHANGE ON INJURIES AND GAME DISQUALIFICATION PENALTIES IN HIGH SCHOOL ICE HOCKEY
Authors: Kriz Peter , Lockhart Gregory , Staffa Steven , Zurakowski David , MacAskill Matthew , Kirchberg Tyler , Robert Kyle , Baird Janette 
Published: March 2019

EFFECT OF PENALTY MINUTE RULE CHANGE ON INJURIES AND GAME DISQUALIFICATION PENALTIES IN HIGH SCHOOL ICE HOCKEY Background: Ice hockey has experienced a 44% increase in participation among 6 to 17-year-old players from 2009-2014 in the United States. Body checking remains legal among male youths at bantam through junior levels and in high school (HS) hockey. In the U.S., nearly 45,000 players (35,210 boys and 9,599 girls) participate in HS ice hockey, with ˜12,000 players 19 years and younger seeking care in emergency departments (ED) for ice hockey-related injuries annually. Recent efforts have focused on reducing dangerous hits and fighting at all levels of ice hockey. Rule changes such as Fair Play have proven successful in reducing injury risk, but have not been widely implemented at state, regional, or national levels. The purpose of our study was to determine the effect of a penalty minute (PIM) rule change in HS boys’ ice hockey on injuries and game disqualification penalties. Methods: Retrospective cohort study. Injury data were collected from 2 hospital systems in Rhode Island (RI), and game/penalty data were collected through the RI Hockey Coaches Association website. Participants included HS boys’ hockey varsity players ages 13-19 years presenting to 5 RI hospital emergency departments (ED) for hockey-related injuries during 6 seasons (December 2012 to April 2018). Rule change for 2015-16 season implemented varying suspensions for players accumulating = 50 PIM and = 70 PIM during regular season and playoffs. Injuries were classified as body checking-related or non-body checking related, and injury rates pre- vs. post-rule change were compared using the Cochran-Mantel-Haenszel Chi-square test. Multivariable logistic regression was used to derive odds ratios. A sample of 18,000 emergency department visits prior to the rule change and 18,000 emergency department visits after the rule change provides over 90% power to detect a 15% reduction in the odds of sustaining body checking injury requiring ED visit, assuming a body checking ED injury rate of 5% prior to the rule change, a correlation between study period ED visit rates of 0.5, and a two-sided alpha level of 0.05. Power analyses were performed in nQuery Advisor version 8.2.0 (Statistical Solutions Ltd., Cork, Ireland). Results: During the study period, a total of 1,762 boys’ HS varsity hockey games were played. Of 134 HS varsity game-related injuries presenting to the ED, 82 (61.2%) were attributable to body checking. Most (67.2%) injured players presented to Level I trauma centers, while 17.2% received transport by Emergency Medical Services. Regarding injury severity, 97.8% of injuries were non-catastrophic, while 2.2% were categorized as catastrophic serious (1 type 3 C2 dens fracture, non-displaced; 2 splenic lacerations, 1 requiring splenectomy). Three catastrophic serious injuries occurred, two of which occurred post-rule change (both splenic lacerations). The penalty minute rule change was associated with a significant reduction in all injuries (OR 0.55; 95% CI, 0.35-0.86; P = 0.008), concussion/closed head injury (OR 0.44; 95% CI, 0.23-0.85; P = 0.012), and concussion/closed head injury and upper body injury combined (OR 0.50; 95% CI, 0.31-0.80: P = 0.003). Game disqualification penalties per season were not significantly reduced following the rule change, occurring in 5.2% of games before and 4.4% of games after the rule change (OR 0.84; 95% CI, 0.54 – 1.31; P = 0.440). Conclusion/Significance: Implementation of a statewide PIM restriction rule change effectively reduced the mean number of game-related injuries per season in HS boys’ hockey varsity players. To our knowledge, this is the first study to demonstrate a statistically significant reduction in concussion/closed head injury following implementation of a Fair Play rule change at any level of ice hockey. Despite implementation of strategies to reduce intent-to-harm hits in recent years, the potential for serious head, neck, and spinal injury remains in high school boys’ ice hockey as body checking remains legal. Current opinion among sports medicine experts remains that rule changes designed to reduce injury risk are among the most effective ways to decrease traumatic injuries such as concussion. Rule changes in collision sports can effectively mitigate injury risk without fundamentally changing the sport. Implementation of PIM rule change in HS boys’ ice hockey in other states/provinces would allow assessment of significance of rule mandate as it relates to injury reduction. Future research utilizing prospective, longitudinal study designs and data collection by certified athletic trainers can provide state high school associations and other governing bodies of sport essential data to develop policy changes targeting injury reduction. Our study design could be extrapolated to other high school collision sports such as football, lacrosse, and rugby to determine the effects of rule change on collision sport injury rates. [Table: see text][Table: see text][Table: see text][Table: see text][Figure: see text]