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Background: At 2 to 3 years after anterior cruciate ligament reconstruction (ACLR), the relationship between known modifiable osteoarthritis (OA) risk factors and recurrent knee injury is unknown. This study aimed to determine the odds of new or recurrent traumatic knee injury in a cohort of young female athletes with ACLR 2 to 3 years postsurgery compared with healthy control participants. Secondary objectives were to explore the relationships of moderate and vigorous physical activity (MVPA) and body mass index (BMI) with knee injury, and to document self-reported MVPA satisfaction and beliefs about OA. Study Design: Prospective cohort. Level of Evidence: Level 2. Methods: A total of 51 female athletes with unilateral ACLR 1 to 2 years previously and 51 age and sport-matched control participants underwent assessment of MVPA (GT3X accelerometers) and BMI. One year later, participants self-reported knee injuries. Bivariable conditional logistic regression explored the association between knee injury, MVPA, and BMI in each group (injury/control). Results: At 1-year follow-up (n = 101), 19.6% of the injured cohort and 6.0% of control participants sustained a new or recurrent knee injury. The odds of knee injury for the injury group increased 7-fold over controls [odds ratio (OR) = 7.00 (95% CI = 0.86, 56.90)], although this was not statistically significant. The OR for MVPA was 0.98 (95% CI = 0.93, 1.03) and BMI was OR = 1.24 (95% CI = 0.85, 1.82). Half (56.0%) of injury participants and 66% of controls were satisfied with their MVPA; 81.6% of injury participants believed they had increased knee OA risk compared with someone who had never had a knee injury. Conclusion: In the 2 to 3 years after ACLR, 1 in 5 young female athletes had a new or recurrent knee injury. Based on the point estimate, injured participants were more likely to suffer a traumatic knee injury than matched control participants. MVPA and BMI were not associated with increased odds of knee injury. Clinical Relevance: Clinicians should be encouraged to have in-depth conversations with female athletes with previous ACLR regarding enjoyable and sustainable MVPA participation to promote long-term joint health.

Rugby Union is team-based collision sport with increasing global popularity, particularly in the women's game. Despite this, there is currently no evidence demonstrating the frequency of match events outside of the international game. Therefore, the aim of this study is to outline the frequency and distribution of match events in non-international female rugby union to both outline the demands placed on players and to assess the patterns of play for future injury prevention strategies. Forty-eight games from three seasons of varsity rugby were coded and rates of events per match were calculated. Average ball in play percentage was 51%. The tackle was the most frequent contact match event [280.0 (95% CIs: 270.2-289.7)] while passes were the most frequent non-contact match events [323.2 (95% CIs: 311.8-334.5)]. The distribution of events across match quarter was largely consistent and neither the fixture type, nor the season was consistently associated with differences in match event count per game. This study provides the first analysis of match events outside of international game and provides a useful reference for coaches in preparation of players as well as comparable data for the women's game when informing decision making on injury prevention.

Background:Return to sports (RTS) is frequently considered an indicator of successful recovery after anterior cruciate ligament reconstruction (ACLR). However, despite the well-recognized health benefits of physical activity (PA), little is known about objectively measured PA in the 1 to 2 years after ACLR. Given that young female athletes have a high prevalence of ACLR and lower RTS rates as compared with their male counterparts, an in-depth examination of PA in this subgroup is warranted.Hypothesis:We hypothesized that female youth and young adults who have had ACLR in the previous 1 to 2 years would have less moderate or vigorous PA (MVPA) compared with healthy matched controls. We also hypothesized that the ACLR group would report lower levels of sports participation, patient-reported health outcomes, and physical function.Study Design:Cohort study; Level of evidence, 3.Methods:Participants included 51 female athletes with primary unilateral ACLR for a sports-related injury in the previous 1 to 2 years and 51 age- and sports-matched controls. Outcomes included objectively measured PA (GT3X accelerometers), previous and current sports participation and RTS, body mass index, Knee injury and Osteoarthritis Outcome Score (KOOS), triple single-leg hop, and one-leg rise. Mean within-pair differences with 95% CIs were used to assess differences between groups across all outcomes. Multivariable linear regression (clustered by pair) was used to examine whether the ACLR group had less MVPA than did the age- and sports-matched control group, adjusting for total wear time, age, time since injury, and body mass index.Results:Median age was 17.8 years (range, 14.6-22.6 years). There was no significant difference between groups in MVPA. However, the injury group had fewer mean minutes per day of vigorous PA (–1.22; 95% CI, −2.40 to −0.04), poorer KOOS values on all subscales, and shorter triple single-leg hop distance. In the injury group, 28 (55%) returned to sports, including 14 (27.5%) who returned at preinjury performance level. Across both groups, over one-third changed their most important sport, shifting toward an individual-based sport.Conclusion:At 1 to 2 years after ACLR, female athletes demonstrated no differences in combined MVPA and only a very small reduction in vigorous PA, yet they had higher levels of self-reported knee pain and symptoms, reduced knee function in sports, lower quality of life, and poorer objective knee function compared with matched controls.

Background: To reduce the risk of concussion in youth ice hockey, Hockey Canada implemented a national “zero tolerance for head contact” (HC) policy in 2011. A previous cohort study revealed higher concussion rates after this implementation in players aged 11 to 14 years. However, it is unknown whether the elevated risk was due to higher HC rates or factors such as increased concussion awareness and reporting. Purpose: To compare the rates of primary and secondary HCs and HC policy enforcement in elite U15 ice hockey leagues (players Study Design: Cohort study; Level of evidence, 3. Methods: A total of 32 elite U15 games before (n2008-2009 = 16; 510 players) and after (n2013-2014 = 16; 486 players) HC policy implementation were video recorded. Videos were analyzed with validated criteria for identifying HC types (primary/direct contact by players [HC1], secondary/indirect contact via boards, glass, or ice surface [HC2]) and other player-to-player contact behavior. Referee-assessed penalties were cross-referenced with the official Hockey Canada casebook, and penalty types were displayed using proportions. Univariate Poisson regression (adjusted for cluster by team game, offset by game length [minutes]) was used to estimate HC incidence rates (IRs) and incidence rate ratios (IRRs) between cohorts. Results: A total of 506 HCs were analyzed, 261 before HC policy implementation (IR, 16.6/100 team minutes) and 245 after implementation (IR, 15.5/100 team minutes). The HC1 rate (IRR, 1.05; 95% CI, 0.86-1.28) and HC2 rate (IRR, 0.74; 95% CI, 0.50-1.11) did not significantly differ before versus after implementation. Only 12.0% and 13.6% of HC1s were penalized pre- and postimplementation, respectively. Before implementation, HC1s were commonly penalized as roughing or elbowing penalties (59%), while after implementation, HC1s were penalized with the HC penalty (76%), and only 8% as roughing or elbowing. Conclusion: Despite implementation of the “zero tolerance for HC” policy, there was no difference in the rate of HC1s and HC2s or the proportion of HC1 penalized from before to after implementation. This research is instrumental in informing Hockey Canada’s future referee training and rule enforcement modifications.

Policy that disallows body checking (BC) lowers the injury and concussion rate for youth ice hockey players. However, little is known about how disallowing BC influences in-game metrics of performance. This prospective cohort video-analysis study examined offensive performance in Under-15 (ages 13–14) and Under-18 (ages 15–17) youth ice hockey players in leagues allowing and disallowing BC. Fifty-two games were filmed (n = 13 BC, n = 13 non-BC) for Under-15 and Under-18 non-elite (lowest 60% and 45% divisions, respectively) divisions in Calgary, Canada. Footage was analyzed for offensive performance metrics on the puck-carrier using the validated ice hockey adapted team sport assessment procedure. Puck metrics included how the player acquired puck possession (e.g. conquered puck from an opponent, received pass from a teammate) and the outcome (e.g. shot on goal, lost puck to opponent). The puck metrics were used to compute a performance composite score for each player that accounted for the quantity (rate of puck possessions per shift time) and quality (a ratio of positive performance metrics to all metrics) of play. Mean difference's (MD) in performance composite scores were compared using multivariable linear regression (adjusted for player position and cluster by team-game) between leagues allowing and disallowing BC for both age groups. Analyses revealed no significant MD in the performance composite scores between players in BC and non-BC leagues for both age groups (Under-15: MD = 0.02, 95%CI: −0.08, 0.12; Under-18: MD = −0.06, 95%CI: −0.16, 0.03). These findings suggest no differences in offensive performance when BC is disallowed in Under-15 and Under-18 non-elite leagues.

Background: A better understanding of movement biomechanics after anterior cruciate ligament reconstruction (ACLR) could inform injury prevention, knee injury rehabilitation, and osteoarthritis prevention strategies. Purpose: To investigate differences in vertical drop jump (VDJ) biomechanics between patients with a 3- to 10-year history of youth sport–related ACLR and uninjured peers of a similar age, sex, and sport. Study Design: Cross-sectional study. Level of evidence III. Methods: Lower limb kinematics and bilateral ground-reaction forces (GRFs) were recorded for participants performing 10 VDJs. Joint angles and GRF data were analyzed, and statistical analysis was performed using 2 multivariate models. Dependent variables included sagittal (ankle, knee, and hip) and coronal (knee and hip) angles at initial contact and maximum knee flexion, the rate of change of coronal knee angles (35%-90% of the support phase; ie, slopes of linear regression lines), and vertical and mediolateral GRFs (normalized to body weight [BW]). Fixed effects included group, sex, and time since injury. Participant clusters, defined by sex and sport, were considered as random effects. Results: Participants included 48 patients with a history of ACLR and 48 uninjured age-, sex-, and sport-matched controls (median age, 22 years [range, 18-26 years]; 67% female). Patients with ACLR demonstrated steeper negative coronal knee angle slopes (β = –0.04 deg/% [95% CI, –0.07 to –0.00 deg/%]; P = .025). A longer time since injury was associated with reduced knee flexion (β = –0.2° [95% CI, –0.3° to –0.0°]; P = .014) and hip flexion (β = –0.1° [95% CI, –0.2° to –0.0°]; P = .018). Regardless of ACLR history, women displayed greater knee valgus at initial contact (β = 2.1° [95% CI, 0.4° to 3.8°]; P = .017), greater coronal knee angle slopes (β = 0.05 deg/% [95% CI, 0.02 to 0.09 deg/%]; P = .004), and larger vertical GRFs (landing: β = –0.34 BW [95% CI, –0.61 to –0.07 BW]; P = .014) (pushoff: β = –0.20 BW [95% CI, –0.32 to –0.08 BW]; P = .001). Conclusion: Women and patients with a 3- to 10-year history of ACLR demonstrated VDJ biomechanics that may be associated with knee motion control challenges. Clinical Relevance: It is important to consider knee motion control during activities such as VDJs when developing injury prevention and rehabilitation interventions aimed at improving joint health after youth sport–related ACLR.

Background: Ice hockey is a popular winter sport in Canada. Concussions account for the greatest proportion of all injuries in youth ice hockey. In 2011, a policy change enforcing “zero tolerance for head contact” was implemented in all leagues in Canada. Purpose: To determine if the risk of game-related concussions and more severe concussions (ie, resulting in >10 days of time loss) and the mechanisms of a concussion differed for Pee Wee class (ages 11-12 years) and Bantam class (ages 13-14 years) players after the 2011 “zero tolerance for head contact” policy change compared with players in similar divisions before the policy change. Study Design: Cohort study; Level of evidence, 3. Methods: The retrospective cohort included Pee Wee (most elite 70%, 2007-2008; n = 891) and Bantam (most elite 30%, 2008-2009; n = 378) players before the rule change and Pee Wee (2011-2012; n = 588) and Bantam (2011-2012; n = 242) players in the same levels of play after the policy change. Suspected concussions were identified by a team designate and referred to a sport medicine physician for diagnosis. Incidence rate ratios (IRRs) were estimated based on multiple Poisson regression analysis, controlling for clustering by team and other important covariates and offset by game-exposure hours. Incidence rates based on the mechanisms of a concussion were estimated based on univariate Poisson regression analysis. Results: The risk of game-related concussions increased after the head contact rule in Pee Wee (IRR, 1.85; 95% CI, 1.20-2.86) and Bantam (IRR, 2.48; 95% CI, 1.17-5.24) players. The risk of more severe concussions increased after the head contact rule in Pee Wee (IRR, 4.12; 95% CI, 2.00-8.50) and Bantam (IRR, 7.91; 95% CI, 3.13-19.94) players. The rates of concussions due to body checking and direct head contact increased after the rule change. Conclusion: The “zero tolerance for head contact” policy change did not reduce the risk of game-related concussions in Pee Wee or Bantam class ice hockey players. Increased concussion awareness and education after the policy change may have contributed to the increased risk of concussions found after the policy change.

Background:Evidence regarding longer-term psychiatric, psychological, and behavioural outcomes (for example, anxiety, mood disorders, depression, and attention disorders) following mild traumatic brain injury (mTBI) in children and adolescents has not been previously synthesized.Objective:To conduct a systematic review of the available evidence examining psychiatric, psychological, and behavioural outcomes following mTBI in children and adolescents.Materials and Methods:Nine electronic databases were systematically searched from 1980 to August 2014. Studies selected met the following criteria: original data; study design was a randomized controlled trial, quasi-experimental design, cohort or historical cohort study, case-control study, or cross-sectional study; exposure included mTBI (including concussion); population included children and adolescents (Results:Of 9472 studies identified in the initial search, 30 were included and scored. Heterogeneity in methodology and injury definition precluded meta-analyses. The median methodological quality for all 30 studies, based on the DB criteria, was 15/33 (range 6 to 19). The highest level of evidence demonstrated by all reviewed studies was level 2b based on OCEBM criteria, with the majority (28/30 studies) classified at this level. Based on the literature included in this systematic review, psychological and psychiatric problems in children with a history of mTBI were found to be more prevalent when mTBI is associated with hospitalization, when assessment occurs earlier in the recovery period (that is, resolves over time), when there are multiple previous mTBIs, in individuals with preexisting psychiatric illness, when outcomes are based on retrospective recall, and when the comparison group is noninjured healthy children (as opposed to children with injuries not involving the head).Conclusions:Overall, few rigorous prospective studies have examined psychological, behavioural, and psychiatric outcomes following mTBI. In the absence of true reports of preinjury problems and when ideally comparing mild TBI to non-TBI injured controls, there is little evidence to suggest that psychological, behavioural, and/or psychiatric problems persist beyond the acute and subacute period following an mTBI in children and adolescents.

Background: The Sport Concussion Assessment Tool 5 (SCAT5) is a standardized instrument designed to assist with the clinical and sideline assessment of concussion. Following the 5th International Conference on Concussion in Sport in 2016, the SCAT5 was released. Compared to the previous version (SCAT3), the SCAT5 includes more detailed instructions regarding the symptom checklist and a 10-word list in the immediate memory section to diminish ceiling effects. This study aims to examine the association between having a previous history of concussion and SCAT5 scores in high school rugby players. A second objective is to provide reference values for healthy rugby players for the SCAT5, including typical scores on immediate memory using the 10-word list. Methods: High school rugby players (ages 15-18) from Calgary, Alberta participating in the 2018 high school rugby season (n=388, male=212, female=176) were recruited to a cohort study and asked to complete a baseline SCAT5 assessment administered by trained research assistants at the beginning of the playing season. Outcome measures included baseline symptom evaluation (/22 symptoms)], self-reported rating of percentage of normal (100% perfectly normal) felt at time of testing, immediate memory score using a 10-word list [/30)], digits backward (/4), delayed word memory (/10), and modified Balance Error Scoring System [BESS (/30)]. Players also completed a preseason demographic questionnaire, which assessed their history of concussion. Results: A total of 237/388 (61.08%) rugby players reported no history of concussion (NC) and 151/388 (38.92%) reported at least 1 previous concussion (PC). Ninety of the 212 males (42.45%) and 61 of the 176 females (34.66%) reported a history of previous concussion. Median SCAT5 symptom score was 6 (range; 0-21) for NC and 7 (0-22) for PC groups. At the time of baseline testing, only 30.51% of NC players and 21.85% of PC players reported feeling 100% of normal. Median total scores on the immediate memory score (/30) were 21 (range; 9-28) for NC and 21 (range; 9-29) for PC. Median total score on digits backward (/4) was 3 (range; 0-4) and the delayed memory score (/10) was 7 (range; 0-20), for both NC and PC groups. Median total errors made on the BESS were 4 (range; 0-20) for NC players and 5 (range; 0-17) for PC players. Conclusions: Players with and without a previous history of concussion obtained similar scores on all components of the SCAT5 at baseline. Many high school rugby players did not report feeling 100% of normal during typical baseline testing sessions. The addition of the 10-word list option in the immediate and delayed memory section reduces the likelihood of a ceiling effect. This study informs the use and interpretation of the SCAT5 in high school rugby players.

Background Hockey is one of the top sports for participation in youth in Canada. There are limited data on the epidemiology of injury in youth hockey. Purpose Through implementation and validation of an injury surveillance system, youth ice hockey injury rates, risk factors, and mechanisms of injury will be examined. Study Design Descriptive epidemiology study. Methods During the 2004-2005 season in minor hockey in Calgary, Alberta, Canada, 71 hockey teams (N = 986) were studied, including teams from each age group (Atom, 9/10 years; Pee Wee, 11/12 years; Bantam, 13/14 years; Midget, 15/16 years) and division of play (7-10 divisions per age group). A certified athletic therapist or candidate did weekly assessments of any identified hockey injury. Injury definition included any injury occurring during the regular hockey season that required medical attention, removal from a session, or missing a subsequent session. Results Of the 986 participating players, 216 players sustained a total of 296 injuries in the 2004-2005 season. The overall injury rate was 30.02 injuries per 100 players per season (95% confidence interval, 27.17-32.99) or 4.13 injuries per 1000 player hours (95% confidence interval, 3.67-4.62). Forty-five percent of all injuries occurred during body checking. Compared with the youngest age group, Atom, the risk of injury was greater in Pee Wee (relative risk, 2.97; 95% confidence interval, 1.63-5.8), Bantam (relative risk, 3.72; 95% confidence interval, 2.08-7.14), and Midget (relative risk, 5.43; 95% confidence interval, 3.14-10.17) leagues. The risk of injury in Pee Wee was greatest in the most elite divisions (relative risk, 2.45; 95% confidence interval, 1.15-5.81). Concussion, shoulder sprain/dislocation, and knee sprain were the most common injuries. Conclusion Significant differences in injury rates were found by age and division of play. The public health significance of body checking injury in minor hockey is great. Future research will include expansion of surveillance to further examine body checking injuries and prevention strategies in minor hockey.