Sarah K. Fields

Epidemiology of Concussions Among United States High School Athletes in 20 Sports

Background: In the United States (US), an estimated 300,000 sports-related concussions occur annually. Among individuals 15 to 24 years of age, sports are second only to motor vehicle crashes as the leading cause of concussions. Purpose: To investigate the epidemiology of concussions in high school athletes by comparing rates and patterns of concussion among 20 sports. Study Design: Descriptive epidemiology study. Methods: Using an Internet-based data collection tool, RIO, certified athletic trainers from a large, nationally disperse sample of US high schools reported athlete exposure and injury data for 20 sports during the 2008-2010 academic years. Results: During the study period, 1936 concussions were reported during 7,780,064 athlete-exposures (AEs) for an overall injury rate of 2.5 per 10,000 AEs. The injury rate was higher in competition (6.4) than practice (1.1) (rate ratio [RR], 5.7; 95% confidence interval [CI], 5.2-6.3). The majority of concussions resulted from participation in football (47.1%, n = 912), followed by girls’ soccer (8.2%, n = 159), boys’ wrestling (5.8%, n = 112), and girls’ basketball (5.5%, n = 107). Football had the highest concussion rate (6.4), followed by boys’ ice hockey (5.4) and boys’ lacrosse (4.0). Concussions represented a greater proportion of total injuries among boys’ ice hockey (22.2%) than all other sports studied (13.0%) (injury proportion ratio [IPR], 1.7; 95% CI, 1.4-2.1; P < .01). In gender-comparable sports, girls had a higher concussion rate (1.7) than boys (1.0) (RR, 1.7; 95% CI, 1.4-2.0). The most common mechanisms of injury were player-player contact (70.3%) and player–playing surface contact (17.2%). In more than 40% of athletes in sports other than girls’ swimming and girls’ track, concussion symptoms resolved in 3 days or less. Athletes most commonly returned to play in 1 to 3 weeks (55.3%), with 22.8% returning in less than 1 week and 2.0% returning in less than 1 day. Conclusion: Although interest in sports-related concussions is usually focused on full-contact sports like football and ice hockey, concussions occur across a wide variety of high school sports. Concussion rates vary by sport, gender, and type of exposure. An understanding of concussion rates, patterns of injury, and risk factors can drive targeted preventive measures and help reduce the risk for concussion among high school athletes in all sports.

Epidemiology of High School and Collegiate Football Injuries in the United States, 2005–2006

Background Football, one of the most popular sports among male high school students in the United States, is a leading cause of sports-related injuries, with an injury rate almost twice that of basketball, the second most popular sport. Hypothesis Injury patterns will vary between competition and practice exposures and between levels of play (ie, high school vs. National Collegiate Athletic Association [NCAA]). Study Design Descriptive epidemiology study. Methods Football-related injury data were collected over the 2005-2006 school year from 100 nationally representative high schools via High School RIO™ (Reporting Information Online) and from 55 Division I, II, and III colleges via the NCAA Injury Surveillance System. Results Nationally, an estimated 517 726 high school football-related injuries (1881 unweighted injuries) occurred during the 2005-2006 season. The rate of injury per 1000 athlete-exposures was greater during high school competitions (12.04) than during practices (2.56). The rate of injury per 1000 athlete-exposures was also greater during collegiate competitions (40.23) than during practices (5.77). While the overall rate of injury per 1000 athlete-exposures was greater in the NCAA (8.61) than in high school (4.36), high school football players sustained a greater proportion of fractures and concussions. Running plays were the leading cause of injury, with running backs and linebackers being the positions most commonly injured. Conclusion Patterns of football injuries vary, especially by type of exposure and level of play. Future studies should continue to compare differences in injury patterns in high school and collegiate football, with particular emphasis placed on high-risk plays (running plays) and positions (running backs and linebackers).

The Epidemiology of US High School Basketball Injuries, 2005–2007

Background With more than a million high school athletes playing during the 2006–2007 academic year, basketball is one of the most popular sports in the United States. Hypothesis Basketball injury rates and patterns differ by gender and type of exposure. Study Design Descriptive epidemiology study. Methods Basketball-related injury data were collected during the 2005–2006 and 2006–2007 academic years from 100 nationally representative US high schools via Reporting Information Online. Results High school basketball players sustained 1518 injuries during 780 651 athlete exposures for an injury rate of 1.94 per 1000 athlete exposures. The injury rate per 1000 athlete exposures was greater during competition (3.27) than during practice (1.40; rate ratio, 2.33; 95% confidence interval, 2.10–2.57) and was greater among girls (2.08) than among boys (1.83; rate ratio, 1.14; 95% confidence interval, 1.03–1.26). The ankle/foot (39.7%), knee (14.7%), head/face/neck (13.6%), arm/hand (9.6%), and hip/thigh/upper leg (8.4%) were most commonly injured. The most frequent injury diagnoses were ligament sprains (44.0%), muscle/tendon strains (17.7%), contusions (8.6%), fractures (8.5%), and concussions (7.0%). Female basketball players sustained a greater proportion of concussions (injury proportion ratio, 2.41; 95% confidence interval, 1.49–3.91) and knee injuries (injury proportion ratio, 1.71; 95% confidence interval, 1.27–2.30), whereas boys more frequently sustained fractures (injury proportion ratio, 1.87; 95% confidence interval, 1.27–2.77) and contusions (injury proportion ratio, 1.52; 95% confidence interval, 1.00–2.31). The most common girls’ injury requiring surgery was knee ligament sprains (47.9%). Conclusion High school basketball injury patterns vary by gender and type of exposure. This study suggests several areas of emphasis for targeted injury prevention interventions.

The Epidemiology of United States High School Soccer Injuries, 2005–2007

Background United States high school soccer participation increased 5 fold over the last 30 years. With increased participation comes increased injury incidence. Hypothesis High school soccer injury patterns will vary by gender and type of exposure. Study Design Descriptive epidemiologic study. Methods Soccer-related injury data were collected over the 2005–2006 and 2006–2007 school years from 100 nationally representative United States high schools via Reporting Information Online (RIO, an Internet-based sports-related injury surveillance system). Results Participating certified athletic trainers reported 1524 soccer injuries during 637 446 athlete exposures (AEs), for an injury rate of 2.39 per 1000 AEs, corresponding to a nationally estimated 807 492 soccer-related injuries during the 2005–2006 and 2006–2007 seasons. The injury rate per 1000 AEs was greater during competition (4.77) than practice (1.37) (rate ratio [RR] = 3.49; 95% confidence interval [CI], 3.15–3.87). Overall, the most frequent diagnoses were incomplete ligament sprains (26.8%), incomplete muscle strains (17.9%), contusions (13.8%), and concussions (10.8%). The most commonly injured body sites were the ankle (23.4%), knee (18.7%), head/face (13.7%), and thigh/upper leg (13.1%). Similar proportions of boys (57.9%) and girls (53.9%) returned to activity in <1 week. During competition, girls sustained complete knee ligament sprains requiring surgery at a rate of 26.4 per 100 000 AEs, higher than the rate among boys during competition (1.98 per 100 000 AEs) (RR = 13.3; 95% CI, 3.15–56.35) and among girls during practice (2.34 per 100 000 AEs) (RR = 11.3; 95% CI, 4.31–29.58). Player-to-player contact was more common among competition injuries (injury proportion ratio [IPR] = 2.42; 95% CI, 2.01–2.92), while noncontact mechanisms were more common among practice injuries (IPR = 2.39; 95% CI, 1.90–3.01). Conclusions High school soccer injury patterns vary by gender and type of exposure. Identifying such differences in injury patterns is the important first step in the development of evidence-based, targeted injury prevention efforts.

Epidemiology of Knee Injuries Among Boys and Girls in US High School Athletics

Background The knee joint is the second most commonly injured body site and the leading cause of high school sports-related surgeries. Knee injuries are among the most economically costly sports injuries and may require subsequent surgery or extensive and expensive rehabilitation. Purpose To report the incidence, risk, and severity of high school knee injuries across sports, genders, and type of exposure. Study Design Descriptive epidemiology study. Methods During the 2005–2006 and 2006–2007 school years, 100 US high schools were randomly selected for a nationally representative sample. Certified athletic trainers tracked injuries using an online injury surveillance system, High School RIO™, in 9 high school sports. Results There were 1383 knee injuries reported during 3 551 131 athlete exposures for a rate of 3.89 knee injuries per 10 000 athlete exposures. Although boys had a higher overall rate of knee injury (rate ratio, 1.38; confidence interval, 1.22–1.55), girls were twice as likely to sustain knee injuries requiring surgery (major knee injuries) than were boys (injury proportion ratio, 1.98; confidence interval, 1.45–2.70) and twice as likely to incur noncontact major knee injuries (injury proportion ratio, 1.98; confidence interval, 1.23–3.19) as were boys. Although illegal play was identified as a contributing factor in only 5.7% of all knee injuries, 20% of knee injuries resulting from illegal play required surgery. Conclusion Knee injury rates and patterns varied by sport, gender, and type of exposure. Identified gender differences included differences in injury rates, injury severity, and basic injury mechanism. Further surveillance is crucial for the development of targeted, evidence-based injury prevention strategies to reduce the morbidity and economic impact of knee surgeries.

Patterns of Recurrent Injuries Among US High School Athletes, 2005-2008

Background High school sports participants sustain millions of injuries annually; many are recurrent injuries that can be more severe than new injuries. Hypothesis Recurrent injury patterns differ from new injury patterns by sport and gender. Study Design Descriptive epidemiology study. Methods High school sports injury data for the 2005 through 2008 academic years were collected via High School Reporting Information Online (RIO) from a nationally representative sample of 100 US high schools. Results From 2005 through 2008, certified athletic trainers reported 13 755 injuries during 5 627 921 athlete exposures (24.4 injuries per 10 000 athlete exposures). Recurrent injuries accounted for 10.5% of all injuries. Football players had the highest rate of recurrent injury (4.36 per 10 000 athlete exposures). Girls had higher rates of recurrent injuries than boys in soccer (injury rate ratio = 1.39; 95% confidence interval, 1.07-1.82). Recurrent injuries most often involved the ankle (28.3%), knee (16.8%), head/ face (12.1%), and shoulder (12.0%), and were most often ligament sprains (incomplete tears) (34.9%), muscle strains (incomplete tears) (13.3%), and concussions (11.6%). A greater proportion of recurrent injuries than new injuries resulted in the student choosing to end participation (recurrent = 2.4%, new = 0.7%). Recurrent shoulder injuries were more likely to require surgery than new shoulder injuries (injury proportion ratio = 4.51; 95% confidence interval, 2.82-7.20). Conclusion Recurrent injury rates and patterns differed by sport. Because recurrent injuries can have severe consequences on an athletes health and future sports participation, injury prevention must be a priority. Knowledge of injury patterns can drive targeted preventive efforts.

Epidemiology of 6.6 Million Knee Injuries Presenting to United States Emergency Departments From 1999 Through 2008

BACKGROUND While knee injuries are treated by a wide range of clinicians, patients with knee injuries frequently present to emergency departments (EDs). The knee is the most commonly injured joint by adolescent athletes with an estimated 2.5 million sports-related injuries presenting to EDs annually. OBJECTIVES The objective was to examine the epidemiology of knee injuries presenting to EDs in the United States from 1999 through 2008. METHODS The Consumer Product Safety Commission National Electronic Injury Surveillance System database (NEISS) was used to examine causes of knee injuries treated in U.S. EDs from 1999 through 2008. RESULTS An estimated 6,664,324 knee injuries presented to U.S. EDs from 1999 through 2008, for a rate of 2.29 knee injuries per 1,000 population. Those 15 to 24 years of age had the highest injury rate (3.83), while children younger than 5 years had the lowest rate (0.55). The most common diagnoses were strains and sprains (42.1%), contusions and abrasions (27.1%), and lacerations and punctures (10.5%). The most common general product categories causing injury were sports and recreation (49.3%), home structures (30.2%), and home furnishings (13.6%). Several sex and age group differences were identified. For example, males sustained a higher proportion of basketball-related injuries (11.1%) than females (3.6%; injury proportion ratio [IPR] = 3.11, 95% confidence interval [CI] = 2.79 to 3.46, p < 0.001). Additionally, individuals 65 years and older sustained a higher proportion of injury due to stairs, ramps, landings, and floors (42.0%), compared to all other ages (20.1%; IPR = 2.09, 95% CI = 1.95 to 2.23, p < 0.001). CONCLUSIONS Rates and patterns of knee injuries vary by sex and age. Although knee injuries will likely continue to occur most frequently among youth and young adult athletes, anticipating and responding to trends such as an increase in the incidence of knee injuries among adult and senior patients will enable clinicians to better anticipate caseloads, allocate resources, and determine best practices for diagnosis and treatment of knee injuries in different age groups.

Shoulder injuries among United States high school athletes during the 2005-2006 and 2006-2007 school years

CONTEXT The shoulder is one of the most commonly injured body sites among athletes. Little previous research describes shoulder injury patterns in high school athletes. OBJECTIVE To describe and compare shoulder injury rates and patterns among high school athletes in 9 sports (football, soccer, basketball, baseball, and wrestling for boys and soccer, volleyball, basketball, and softball for girls). DESIGN Prospective injury surveillance study. SETTING Injury data were collected from 100 nationally representative US high schools via High School Reporting Information Online. PATIENTS OR OTHER PARTICIPANTS Athletes from participating high schools injured while involved in a school-sanctioned practice or competition in 1 of the above sports during the 2005-2006 and 2006-2007 school years. MAIN OUTCOME MEASURE(S) Shoulder injury rates, diagnoses, severity, and mechanisms. RESULTS During the 2005-2006 and 2006-2007 school years, athletes in this study sustained 805 shoulder injuries during 3 550 141 athlete-exposures (AEs), for an injury rate of 2.27 shoulder injuries per 10 000 AEs. This corresponds to an estimated 232 258 shoulder injuries occurring nationwide during this time. Shoulder injuries were more likely to occur during competition than practice (rate ratio = 3.01, 95% confidence interval = 2.62, 3.46). Shoulder injury rates per 10 000 AEs were highest in football (5.09), wrestling (4.34), and baseball (1.90). Common shoulder injury diagnoses included sprains/strains (39.6%), dislocations/separations (23.7%), contusions (11.5%), and fractures (6.6%). Although 44.8% of athletes sustaining a shoulder injury returned to play in less than 1 week, 22.9% were out of play for more than 3 weeks, and 6.2% of shoulder injuries required surgery. Common mechanisms of shoulder injury included player-to-player contact (57.6%) and contact with the playing surface (22.8%). CONCLUSIONS High school shoulder injury rates and patterns varied by sport. Continued surveillance is warranted to understand trends and patterns over time and to develop and evaluate evidence-based preventive interventions.

Epidemiology of United States High School Sports-Related Fractures, 2008-09 to 2010-11

Background: High school athletes sustain millions of injuries annually, many of which are fractures. Fractures can severely affect athletes physically, emotionally, and financially and should be targeted with focused prevention methods. Hypothesis: Patterns and primary mechanisms of fractures differ by sport and gender. Study Design: Descriptive epidemiology study. Methods: High school sports-related injury data were collected from academic years 2008-09 to 2010-11 for 18 sports and from 2009-10 to 2010-11 for 2 additional sports. We used linear regression to describe annual fracture rate trends and calculated fractures rates, rate ratios (RRs), and injury proportion ratios (IPRs). Results: From 2008-09 to 2010-11, certified athletic trainers reported a total of 21,251 injuries during 11,544,455 athlete exposures (AEs), of which 2103 (9.9%) were fractures, with an overall rate of 1.82 fractures per 10,000 AEs. Fracture rates were highest in football (4.37 per 10,000 AE), boys’ ice hockey (3.08), and boys’ lacrosse (2.59). Boys sustained 79.1% of all fractures, and the overall rates of fractures were greater in boys’ sports than in girls’ sports for competition (RR, 2.82; 95% CI, 2.45-3.24) and practice (RR, 2.43; 95% CI, 2.07-2.86). The most commonly fractured body sites were the hand/finger (32.1%), lower leg (10.1%), and wrist (9.5%). Overall, 17.2% of fractures required surgery, which was higher than for all other injuries combined (IPR, 3.14; 95% CI, 2.81-3.52). The most common mechanism of fracture involved contact with another player (45.5%). Using linear regression, we found the proportion of all injuries that were fractures was inversely correlated with the athlete’s age (P = .02) but was not correlated with the athletes’ age- and gender-adjusted body mass index. Conclusion: Fractures are a significant problem for high school athletes. Targeted preventive interventions should be implemented to reduce the burdens these injuries cause the athletes.

EPIDEMIOLOGY OF US HIGH SCHOOL SPORTS-RELATED LIGAMENTOUS ANKLE INJURIES, 2005/06-2010/11

Objective:Describe ankle injury epidemiology among US high school athletes in 20 sports. Design:Descriptive prospective epidemiology study. Setting:Sports injury data for the 2005/06 to 2010/11 academic years were collected using an Internet-based injury surveillance system, Reporting Information Online. Participants:A nationwide convenience sample of US high schools. Assessment of Risk Factors:Injuries sustained as a function of sport and gender. Main Outcome Measures:Ankle sprain rates and patterns, outcomes, and mechanisms. Results:From 2005/06 to 2010/11, certified athletic trainers reported 5373 ankle sprains in 17 172 376 athlete exposures (AEs), for a rate of 3.13 ankle sprains per 10 000 AEs. Rates were higher for girls than for boys (rate ratio [RR], 1.25; 95% confidence interval [CI], 1.17-1.34) in gender-comparable sports and higher in competition than practice for boys (RR, 3.42; 95% CI, 3.20-3.66) and girls (RR, 2.71; 95% CI, 2.48-2.95). The anterior talofibular ligament was most commonly injured (involved in 85.3% of sprains). Overall, 49.7% of sprains resulted in loss of participation from 1 to 6 days. Although 0.5% of all ankle sprains required surgery, 6.6% of those involving the deltoid ligament also required surgery. The athletes were wearing ankle braces in 10.6% of all the sprains. The most common injury mechanism was contact with another person (42.4% of all ankle sprains). Conclusions:Ankle sprains are a serious problem in high school sports, with high rates of recurrent injury and loss of participation from sport.