Epidemiology of Injuries in National Collegiate Athletic Association Women's Lacrosse: 2014–2015 Through 2018–2019

In this study we analyzed women's lacrosse exposure and injury data collected in the NCAA ISP during the 2014–2015 through 2018–2019 athletic seasons. The methods of the NCAA ISP have been reviewed and approved as an exempt study by the NCAA Research Review Board. 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 an AT or physician regardless of time loss. Reportable exposures included scheduled team practices and competitions for this analysis. Data from 18 (4% of membership) participating programs in 2014–2015, 12 (3% of membership) in 2015–2016, 17 (3% of membership) in 2016–2017, 23 (5% of membership) in 2017–2018, and 69 (13% of membership) in 2018–2019 qualified for inclusion in analyses. The methods manuscript in this special issue further details the surveillance program and qualification criteria for participating programs.¹⁰ 

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

A total of 1435 women's lacrosse injuries from 287 622 AEs were reported to the NCAA ISP during the 2014–2015 through 2018–2019 athletic seasons, yielding an overall injury rate of 4.99 per 1000 AEs (95% CI = 4.33, 5.25). This equated to a national estimate of 25 624 injuries overall (Table 1). Across the study period, the competition injury rate was higher than the practice injury rate (IRR = 2.18; 95% CI = 1.95, 2.43). Competition injury rates remained relatively stable throughout the study period, with the exception of an increase during the 2017–2018 season (Figure A). Practice injury rates also remained stable between 2014–2015 and 2017–2018, with a slight increase during the final year of the study (Figure A). Injury rates were highest in Division III, and statistically significant differences were observed when comparing the overall Division I (IRR = 0.62; 95% CI = 0.55, 0.70) and Division II (IRR = 0.50; 95% CI = 0.44, 0.57) injury rates to the overall Division III injury rate (Table 1).

A total of 528 preseason injuries (national estimate = 8797), 852 regular season injuries (national estimate = 15 990), and 55 postseason injuries (national estimate = 837) were reported between 2014–2015 and 2018–2019 (Table 2). The overall preseason injury rates were higher than regular season (IRR = 1.29; 95% CI = 1.16, 1.44) and postseason (IRR = 2.11; 95% CI = 1.60, 2.79) injury rates. While regular season injury rates remained stable, preseason injury rates fluctuated across the study period (Figure B). Increases in preseason injury rates were seen between 2015–2016 and 2016–2017 and again between 2017–2018 and 2018–2019 (Figure B). Temporal trends in postseason rates were not examined due to the low counts of reported postseason injuries in certain years of the study period.

Approximately 40.1% of all reported injuries were NTL, less than a third (29.7%) resulted in TL ≥1 day, and ∼30% had missing/unknown TL. The prevalence of TL injuries was higher among practice-related (31.9%) than competition-related (25.5%) injuries. The prevalence of TL injuries varied across the study period (2014–2015 = 38.5%; 2015–2016 = 47.3%; 2016–2017 = 40.2%; 2017–2018 = 21.3%; 2018–2019 = 25.6%), as did the prevalence of injuries with missing TL data (2014–2015 = 14.7%; 2015–2016 = 8.2%; 2016–2017 = 20.7%; 2017–2018 = 43.8%; 2018–2019 = 34.5%). Over one-third of all TL injuries (35.0%) resulted in TL of 10 or more days. The prevalence of TL injuries were higher among practice-related (31.9%) than competition-related (25.5%) injuries. Rates of competition-related TL injuries decreased notably between 2014–2015 and 2015–2016 and remained stable throughout the remainder of the study period (Figure C). Rates of practice-related TL injuries fluctuated throughout the study period, decreasing consistently between 2015–2016 and 2017–2018 before increasing sharply during the final year of the study (Figure C).

Knee injuries (17.4%) and ankle injuries (13.2%) accounted for the largest proportions of all women's lacrosse injuries reported during the study period. Also commonly reported were lower leg injuries (11.7%) and injuries to the head/face (11.6%). Knee injuries and ankle injuries accounted for comparable proportions of reported practice and competition injuries (Table 3). In contrast, lower leg injuries were more prevalent among reported practice injuries (14.4%) than competition injuries (6.6%), while head/face injuries accounted for a larger proportion of competition injuries (15.2%) than practice injuries (9.7%). Most reported injuries were attributed to noncontact (26.6%) and overuse (25.2%) mechanisms. Comparable proportions of practice and competition injuries were attributed to noncontact mechanisms (Table 3), while a larger proportion of practice injuries (34.0%) than competition injuries (8.0%) were attributed to overuse mechanisms. Player contact, surface contact, and apparatus (other than ball) contact injuries were more prevalent among competition injuries than practice injuries (Table 3).

Overall, most women's lacrosse injuries reported between 2014–2015 and 2018–2019 were sprains (19.9%), strains (19.2%), and inflammatory conditions (15.3%). Contusions (12.8%) were also commonly reported during the study period. While strains accounted for comparable proportions of reported practice and competition injuries (Table 3), sprains accounted for a larger proportion of competition injuries (25.9%) than practice injuries (16.8%), and inflammatory conditions accounted for a larger proportion of practice injuries (19.7%) than competition injuries (6.8%). The most commonly reported specific injuries during the study period were partial or complete lateral ligament complex tears (ankle sprains; 9.1%), concussions (7.2%; overall rate = 3.58 per 10 000 AEs; 95% CI = 2.89, 4.27), and partial or complete hamstring tears (3.8%). Rates of lateral ligament complex tears steadily increased between 2014–2015 and 2017–2018 before decreasing during the final year of the study (Figure D). Rates of hamstring tears increased between 2014–2015 and 2015–2016 before decreasing steadily until 2017-2018 (Figure D). Temporal patterns in concussion rates were not described due to low counts of concussions observed during certain years of the study period.

Most injuries in women's lacrosse between 2014–2015 and 2018–2019 occurred during general play (35.3%) and then during running (18.5%) and defending (10.9%). While comparable proportions of competition (33.5%) and practice (36.2%) injuries occurred during general play, the proportion of injuries attributed to running was larger among practice injuries (21.3%) than competition injuries (12.9%). In contrast, defending accounted for a slightly larger proportion of competition injuries (14.4%) than practice injuries (9.2%). Forwards/attackers and midfielders accounted for the largest proportions of injured women's lacrosse players reported in this study period (Table 4).

In this study we describe the epidemiology of injuries in NCAA women's lacrosse during the 2014–2015 through 2018–2019 athletic seasons. The overall injury rate was ∼5 injuries per 1,000 AEs, and the rate of injury was twice as high in competitions as in practices. The injury rate in Division III was higher than those in Divisions I and II, which is similar to findings previously reported by Pierpoint et al.⁵  Recent research indicated that ATs at Division III programs typically incurred a greater patient load than their Division I and II counterparts.¹¹  Further, schools with a greater number of clinicians per student-athletes have also been shown to have lower injury rates than schools in which ATs have higher patient loads,¹²  which has been hypothesized to be related to clinicians' involvement in injury prevention programs, attitudes toward athlete health and well-being, and documentation practices. The injury rates observed in this study were comparable to previous findings, albeit marginally higher than select previous reports within this population.^3,5  Practice injury rates were relatively stable during this 5-year study period; however, a notable increase was observed during the final year of the study. In comparison, the competition injury rate increased between 2014–2015 and 2017–2018 (most sharply between 2016–2017 and 2017–2018) and decreased notably during the final year of the study. Importantly, the current study included TL and NTL injuries, which is not the case in previous reports and therefore may influence the practice and competition injury rates.⁵  Further, given that participation in the NCAA ISP among women's lacrosse programs increased dramatically during the final year of the study, it is reasonable to suggest that the higher practice injury rates observed in 2018–2019 are a more stable representation of the injury burden in this population compared with those from previous years. It is therefore important to examine the contrasting trajectories of practice and competition injury rates observed between 2017–2018 and 2018–2019 more closely and to identify potential contributing factors. We note that increases in participation across the study period are due to new recruitment strategies (in particular, the NCAA Sport Science Institute's role in association-wide communication). With that said, limitations to the external validity of the present study should be considered as the ISP uses a convenience sampling scheme, and participation in the ISP is therefore not compulsory for ATs at NCAA-sponsored institutions. Therefore, given the findings of this study it is important to continue monitoring practice-related injury incidence in this population after 2018–2019 to determine whether the increasing trajectory is maintained. Furthermore, the marked increase in competition injury rates between 2016–2017 and 2017–2018 is noteworthy and warrants juxtaposition with competition rule changes and policy updates from the same time period. Important playing rule changes with regards to free movement, self-starting after minor fouls, and permission to kick the ball (to move away from congested spaces) were implemented in NCAA women's lacrosse during the study period.^13–15  The observed trajectories indicate that these changes may have required a familiarization period for athletes to adapt to gameplay, during which competition injury risk may have been higher than previously recorded. Future researchers may wish to measure features (eg, penalty event) and phases (eg, pace of play after the penalty) of gameplay to appraise how rule additions, amendments, or both affect gameplay and injury incidence. In examining competition-related injury incidence more closely, it is also salient to consider the dynamic nature of NCAA women's lacrosse sponsorship over time.²  Indeed, the rise in the total number of women's lacrosse teams sponsored by the NCAA may change the nature of competition within the sport, consequently yielding fluctuating competition injury rates.

We identified that the preseason injury rate was higher than the regular season and postseason injury rates. This may be attributed to a sudden increase in training workload that most athletes encounter while transitioning from the offseason to preseason as well as a rapid reintroduction to dynamic team play in an intense and competitive atmosphere.¹⁶  Interestingly, these findings contrast with those of previous reports indicating no differences between preseason and regular season injury rates in this setting.⁵  In comparing the results observed here with previously reported surveillance-based findings within this population, it is important to consider that the present study leveraged a larger volume of data given the improved participation in the NCAA ISP over time. In addition, potential differences in findings between studies may be due to the inclusion of both TL and NTL injuries in the current study; previous studies only included TL injury events.⁵  Further, it is important to note that the preseason injury rates followed an increasing trajectory for most of the study period (between 2015–2016 and 2018–2019), suggesting that the preseason injury incidence has been increasing in recent years. It is important to further examine recent changes in preseason training practices and workload accumulation during preseason to better understand preseason injury risk in this population. In its current form, the NCAA ISP is not positioned to capture information on training details or workload. Given the inherent limitations of sports injury surveillance systems, these investigations may be better carried out using small-sample, targeted examinations.¹⁷ 

In the current study, we also found that the knee, ankle, lower leg, and head/face were the most commonly injured body parts among NCAA women's lacrosse athletes, and this is generally consistent with previously reported findings in this population.³  Overuse mechanisms contributed a large proportion of reported injuries during 2014–2015 through 2018–2019 seasons. Overuse mechanisms were largely attributed to the lower extremity, were most often reported from practice-related exposures, and were predominantly NTL injuries. The observed prevalence of overuse injuries mirror previous studies of this population, and the findings of the present study may be even be more reflective of the distribution of injuries incurred by women's lacrosse athletes given the additional capture of NTL injuries in the present study in contrast to previous studies.⁵  In this regard, it is important to acknowledge that the prevalence of injuries missing TL data was relatively high across the study period, and the TL distribution of overuse injuries therefore may not be entirely reflected in these results. Missing outcome information is an inherent limitation of sports injury surveillance, and future studies should aim to more comprehensively capture outcome data to better examine overuse injuries in this population. Given that it has been previously reported that lower extremity injuries accounted for approximately 70% of overuse injuries in NCAA athletes (albeit not specifically in women's lacrosse athletes),¹⁸  the distributions of injuries by body part and injury mechanism observed in this study are unsurprising. Close monitoring of workload accumulation and acute to chronic workload ratio may be needed to facilitate detection of these injuries and better identify effective preventive strategies.^19,20  In particular, lateral ligament complex tear (ankle sprain) and hamstring tear (partial or complete) were the most common diagnoses in this sample, which may be due to demands within lacrosse, including quick or unanticipated changes of direction²⁰  and acceleration/deceleration during play.²²  Therefore, ATs should aim to include primary and secondary areas of prevention for these specific injury diagnoses. Further, with regard to injury mechanism, despite restrictions for player-to-player contact in women's lacrosse, player contact accounted for 14% of reported injuries during the study period. While this is also consistent with previously reported findings,^3,8  the inciting mechanisms are modifiable risk factors influenced by rules, officiating, and protective equipment and suggest an area for future injury prevention study. It is also important to consider that head/face injuries accounted for ∼12% of all reported injuries and that concussion was one of the most common specific injuries reported during the time period. The topic of protective headgear in women's lacrosse has gathered much academic and media attention in recent years.^9,23–25  While evidence indicates a reduction of eye and head/face injuries after institution of protective eyewear requirements in youth girls' lacrosse,⁶  the efficacy of helmets in reducing concussion risk has not been robustly demonstrated using empirical evidence. Given that helmets are used in boys' and men's lacrosse, previous researchers have compared injury incidence in boys' and girls' lacrosse to determine the protective effect of helmet use in lacrosse.^9,23–25  Subsequently, it was observed that in high school girl's lacrosse, concussions were most often attributed to ball or stick contact.^9,23–25  These mechanisms, and their resulting effect on head movements, may be abated by requiring a hard-shelled helmet in women's lacrosse. However, due to the inherent differences between the sports, targeted studies in women's lacrosse are needed to better determine the protective effect of helmets in this population.

Routine monitoring of NCAA women's lacrosse injuries will provide valuable insight into injury incidence and outcomes in this population. The results of this study indicate that injury incidence in practices and during preseason warrant further attention in this population. The prevalence of player-contact resultant injuries is also noteworthy given the playing rules and regulations of the sport. In the interest of obtaining a robust and stable representation of the injury burden in women's lacrosse, it is important for surveillance participation to align with the increasing popularity of the sport at the collegiate level. A stable representation of emerging patterns in women's lacrosse will offer the platform upon which to build targeted studies that reconcile etiologic determinants of injury risk in this group.

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.