Epidemiology of Injuries in National Collegiate Athletic Association Men's Ice Hockey: 2014–2015 Through 2018–2019

Men's ice hockey exposure and injury data collected in the NCAA ISP during the 2014–2015 through 2018–2019 athletic seasons were analyzed in this study. The methods of the NCAA ISP have been reviewed and approved as an exempt study by the NCAA Research Review Board. In brief, athletic trainers (ATs) at participating institutions contributed exposure and injury data using their clinical electronic medical record systems. A reportable injury was one that occurred due to participation in an organized intercollegiate practice or competition and required medical attention by a team certified AT or physician, regardless of time lost. Scheduled team practices and competitions were considered reportable exposures for this analysis. Data from 41 (30% of membership with sponsored programs) participating programs in 2014–2015; from 23 (16% of membership with sponsored programs) in 2015–2016; from 26 (18% of membership with sponsored programs) in 2016–2017; from 23 (16% of membership with sponsored programs) in 2017–2018; and from 35 (23% of membership with sponsored programs) in 2018–2019 qualified for inclusion in analyses. Qualification criteria are detailed further in the methods article in this issue.¹³ 

Injury counts and rates per 1000 AEs were examined by event type (practice, competition), season segment (preseason, regular season, postseason), and time loss (time loss [TL], non–time loss [NTL]). An AE was defined as 1 athlete participating in 1 exposure event. Weighted and unweighted rates were estimated; however, results are presented in terms of unweighted rates (unless otherwise specified) due to low frequencies of injury observations across levels of certain covariates. Temporal trends in injury rates across the study period were evaluated using rate profile plots stratified by levels of explanatory variables. Similarly, temporal trends in rates of most commonly reported injuries were also examined across the study period. Injury counts and proportions were examined by TL, body part injured, mechanism of injury, injury diagnosis, player position, and activity at the time of injury. Injury rate ratios (IRR) were used to examine differential injury rates across event types and season segments. The IRRs with associated 95% confidence intervals (CIs) excluding 1.00 were considered statistically significant. All analyses were conducted using SAS (version 9.4; SAS Institute).

Overall, a total of 3330 men's ice hockey injuries (national estimate: 18 109) from 435 120 AEs were reported to the NCAA ISP between 2014–2015 to 2018–2019; this equated to an injury rate of 7.65 injuries per 1000 AEs (Table 1). A total of 1014 injuries from practice events and 2316 injuries from competition events were reported. The competition injury rate was significantly higher than the practice injury rate (IRR = 6.54, 95% CI = 6.08, 7.04). Competition and practice injury rates by year were relatively stable across the study period (Figure A).

During the study period, 260 preseason injuries (national estimate: 1759), 2872 regular season injuries (national estimate: 15 213), and 198 postseason injuries (national estimate: 1138) were reported to the NCAA ISP (Table 1). The preseason (IRR = 1.35; 95% CI = 1.12, 1.62) and regular season (IRR = 1.48; 95% CI = 1.28, 1.71) injury rates were higher than the postseason injury rate. Trajectories of preseason, regular, and postseason injury rates were comparable across the study period (Figure B), though preseason and postseason injury rates appeared to consistently increase between 2016–2017 and 2018–2019.

Among all reported injuries, 43.1% resulted in TL greater than or equal to 1 day (9% of all injuries were missing TL information). The prevalence of TL injuries was similar between practice- (44.1%) and competition-related (42.7%) injuries. The practice TL injury rate was stable across the study period. Conversely, the competition TL injury appeared to fluctuate across the study period (Figure C). Across the study period, the competition-related TL injury rate (rate = 8.78) was significantly higher than the practice-related TL injury rate (rate = 1.39; IRR = 6.34, 95% CI = 5.67, 7.09).

Overall, the most commonly injured body parts were the shoulder (16.1%), head or face (15.2%), and hip or groin (12.1%; Table 2). Hip and groin (19.7%), trunk (11.5%), shoulder (10.4%), and hand and wrist (10.4%) were among the most prevalently reported practice-related injuries. Shoulder (18.7%), head and face (17.4%), and hand and wrist (12.1%) were among the most prevalently reported competition-related injuries. In general, most injuries were attributed to player contact (38.6%) and apparatus contact (30.2%). Most competition-related injuries were attributed to player contact (46.8%) and apparatus contact (30.5%); whereas most practice-related injuries were attributed to apparatus (29.6%) and noncontact (24.7%) mechanisms. Most reported injuries were classified as contusions (25.9%), sprains (19.1%), or strains (16.1%).

Whereas competition-related injuries were classified more prevalently as contusions or sprains, practice-related injuries were classified more prevalently as strains than competition-related injuries (Table 2).The most commonly reported specific injuries during the study period were concussions (9.6%), partial or complete acromioclavicular (AC)-joint sprain (7.3%), and partial or complete medial collateral ligament (MCL) tear (3.7%). Concussion rates varied across the study period (Figure D). The incidence trajectories of both AC-joint sprains and MCL tears mirrored each other across the study period, steadily increasing between 2015–2016 and 2017–2018 before decreasing during the final year of the study period (Figure D).

Most reported injuries in men's ice hockey between 2014–2015 and 2018–2019 occurred during general play (28.6%), checking (22.2%), and shot blocking (11.1%; Table 3). Most reported injuries were among forwards (61.7%), followed by defensemen (29.8%) and goaltenders (6.3%).

In this study we described the epidemiology of NCAA men's ice hockey–related injuries reported to the NCAA ISP between 2014–2015 and 2018–2019. Injuries occurred at a significantly higher rate during competitions than practices, which is consistent with previous epidemiological studies of this population.^3,9  The overall competition injury rate observed between 2014–2015 to 2018–2019 (20.57 per 1000 AEs) was higher than those observed between 2004–2005 to 2013–2014 (13.5 per 1000 AEs)⁹  and from 2000–2001 to 2003–2004 (16.3 per 1000 AEs)³  within the same population (although previous analyses have only included TL injuries). Across all 3 study periods, preseason and regular season injury rates were comparable, although consistently higher than postseason injury rates.^3,9  Injury rates across all season segments in the present study were markedly greater in magnitude than those reported in previous studies.^3,9  The observed differences are likely attributable to a multitude of factors; nonetheless, improvements in surveillance methods, greater numbers of participating institutions,¹⁴  and changing culture of injury-reporting behaviors and disclosure among athletes may have contributed to the aforementioned observation.¹⁵  Whereas injury surveillance is an effective tool for identifying temporal patterns, surveillance systems are not well positioned to capture factors such as athlete reporting behaviors. Targeted studies should focus on juxtaposing observed injury rates with the dynamic nature of sport culture. Also, continued surveillance during periods of healthy participation in injury surveillance is needed to better appraise the stability of observed temporal patterns in injury incidence. Continued surveillance may also further elucidate underlying mechanisms and relationships contributing to varying injury manifestations. This, coupled with more nuanced ascertainment of unique sport-specific injury-risk exposures (during competition and practice), such as total ice time, distance skated, number of rotational and linear force impacts or collisions, and workload monitoring should be prioritized in future studies.

Most competition-related injuries were to the shoulder, head or face, and hand or wrist and were classified as contusions, sprains, and strains. This is unsurprising for a collision sport in which players move at a fast pace, particularly considering that most competition-related injuries were the result of player and apparatus (ie, sticks, boards, puck) contact. Flexible boards with qualities to absorb forceful impact have been used to reduce the incidence of injury attributed to contact with the boards.¹⁶  It has been suggested that they are more effective in decreasing the risk of concussion and shoulder injuries than traditional inelastic boards.¹⁶  It is important to note the NCAA ISP does not capture contextual information on setting such as board type, and future researchers may aim to collect such information with small-scale studies to better appraise their effectiveness in reducing injury risk. In contrast with competition injuries, most practice injuries were to the hip or groin, trunk, hand or wrist, and shoulder; and a large proportion of practice-related injuries were attributed to noncontact mechanisms, as observed in previous studies.^3,17  This may be expected given the greater amount of time athletes spend performing limited contact maneuvers (drills) on the ice during practices than during competitions. However, researchers have conducted few investigations into the etiology of practice-related noncontact injuries. Targeted analyses in this population may help researchers gain a better understanding of the etiology of noncontact practice-related injuries and may direct ATs, coaches, and players to assess notable risk factors that can be addressed to decrease the incidence of these injuries.

Between 2014–2015 and 2018–2019, concussions were among the 3 most commonly reported injuries in NCAA men's ice hockey. Aside from men's football, men's ice hockey has one of the highest concussion incidence rates across NCAA sports.¹⁸  It has been previously noted that these deleterious injuries largely occur as a result of player contact during gameplay.^18,19  Moreover, the results of the present study suggest that the incidence of concussion has increased in recent years.^3,9  We acknowledge that the determinants of concussion incidence, especially in this high-velocity sport, are multifactorial. In particular, widespread concussion education has been critical in improving attitudes towards concussion and concussion-reporting behaviors among athletes.^20,21  Moreover, recently initiated large, multisite studies of sport-related concussions may have also heightened awareness with regards to this injury and may have consequently influenced diagnostic sensitivity as well as reporting behaviors.^22,23  Nonetheless, using strategies aimed to reduce the incidence of concussions including the implementation of educational programs to alert stakeholders (coaches, players, parents) of signs and symptoms, specific rule changes to further inhibit illegal player contact, and advancements in protective equipment, as well as appropriate management after diagnosis, are likely to reduce the prevalence and burden of this injury.^24–27 

Another commonly reported injury in men's ice hockey players is an AC-joint sprain.²⁷  It has been previously reported that AC-joint sprains in men's ice hockey were largely caused by legal player contact, specifically body-checking, and contact with the boards.^12,29  Frequency of player-to-player collisions is a known risk factor among sports that predispose athletes to this injury, as observed among men's football.^29,30  Despite gameplay of football comprising a higher incidence of player-to-player collisions, AC-joint sprain injury rates were higher among men's ice hockey athletes. We postulate that this increased incidence may be partially attributed to greater flexibility of ice hockey shoulder pads, juxtaposed with football shoulder pads. There has been evidence to suggest that improvements in shoulder pad design and technology reduce the linear acceleration of player-to-player and player-to-shoulder impacts.^31,32  Due to the high velocity and physical nature of this sport, it may be difficult to eradicate the risk of AC joint sprains entirely; implementing shoulder pad standards may contribute to reducing the burden of injury, though future targeted studies will be warranted to assess their efficacy.

Injury to the medial collateral ligament (MCL) was observed as the third most common injury among NCAA men's ice hockey players in the present study and as one of the most prevalent types of knee injury across ice hockey levels.^33–35  In ice hockey, MCL tears can occur when an athlete's legs (or skate) gets tangled with another player's leg (or skate) as they fall down, causing a twisting valgus force on the knee because the foot is in a fixed position.^8,36  Although not extensively studied, it has been previously suggested that differential age (freshman vs senior), experience, skill level, and history of musculoskeletal injury between competitors is associated with MCL injury risk.³⁷  It has been noted in ice hockey players that preseason functional movement screens such as postural analysis, single-leg stance, hip mobility, pelvic alignment, and squat screen are likely to aid in identifying athletes at greater risk of sustaining a MCL tear.³⁸  In contrast to preventative techniques, the efficacy of prophylactic knee bracing has been observed to have little effect in reducing the risk of this injury in ice hockey players.³³  Identifying the distribution of MCL severity across ice hockey players may serve as a critical next step of investigation given differences in athletes' plans of care.³⁹  Given the existing body of literature, implementation of preseason screenings, expanding the understanding of lower extremity biomechanics, and further attention toward the grade of MCL tears may all serve to reduce the burden of this injury among men's ice hockey athletes. Taken together, the moderate yet clinically meaningful incidence of concussions, AC-joint sprains, and MCL tears precipitate the need for continued monitoring of these injuries after 2018–2019. It is important to note that factors such as preseason screening measures, impact biomechanics, and protective equipment (eq. helmets, shoulder pads) are not captured within the NCAA ISP. Future studies should aim to measure these factors to better understand the most commonly observed injuries in men's ice hockey.

In summary, participation in NCAA men's ice hockey continues to grow, and it is critical to capture and report emerging injury trends in an effort to better equip sports medicine and coaching staff to manage injuries. Furthermore, it has been shown that educating stakeholders on signs and symptoms of such serious injuries, such as concussions, leads to positive outcomes and should remain as a part of an ongoing dialogue aimed at improving the safety of men's ice hockey.^25,40,41  Although the NCAA ISP is capable of generally describing injury risk exposures, there remain new opportunities to augment surveillance and enhance the methods of capturing ice hockey–specific characteristics.⁴²  Being able to explain specific characteristics of injured athletes may also lead to ways of not only making the game safer by reducing injury risk, but also improving the evaluation and management of such injuries as they naturally occur.

The NCAA Injury Surveillance Program was funded by the NCAA. The Datalys Center is an independent nonprofit organization that manages the operations of the NCAA ISP. The content of this report is solely the responsibility of the authors and does not necessarily represent the official views of the funding organization. We thank the many ATs who have volunteered their time and efforts to submit data to the NCAA- ISP. Their efforts are greatly appreciated and have had a tremendously positive effect on the safety of collegiate student-athletes.