Author
Marie Morrissette
Faculty Mentors
Dr. Jim Mensch, Physical Education and Athletic Training
Dr. Daheia Barr-Anderson, Epidemiology and Biostatistics
ABSTRACT
There has been an increase in the media attention surrounding retired National Football League players and the lasting effects from previous injuries. With more than 20 million children under the age of 17 participating in competitive sports, the attention in the lasting effects of injuries in professional players has trickled down to the youth level. Of the approximately 20 million children participating in competitive sports, the largest portion of the participants is playing youth football. The University of South Carolina Athletic Training Department is partaking in a multisite research study conducted by the Datalys Center to track the injuries of two different types of youth football leagues in the Midlands area. One of the leagues is an age-weight league, meaning if an athlete is within a certain age and weight range then they can play in a specific league. The other is an age-only league, meaning that any athlete within an age range can play in this league, regardless of weight. Graduate athletic trainers are assigned to assist the two football leagues by offering emergency response services and injury diagnostics. The data collected are compiled into a database and are going to be synthesized to find trends amongst the leagues. Here we examine the frequency, mechanism and location of injuries sustained during practices and games. The most prominent injury for both the age-weight and the age-only league was contusions. Most players from both leagues returned to play during the same session in which they were injured (68% and 54%, respectively). In the future, this study will be expanded to other sports and leagues across the Midlands area to allow comparisons between different sports.
INTRODUCTION
In recent years, youth participation in sports has increased dramatically. It has been estimated that approximately 20-30 million kids from the ages of 5 to 17 years have participated in sports [11]. American football has followed these trends and has one of the highest participation rates, with approximately 10,793,000 kids between the ages of 5 and 17 years participating in youth football programs across the nation [10]. Because of this increase in participation, there has been an increase in the number of injuries in youth football [11]. Both the National Football League (NFL) and college football programs have been under scrutiny because of their high injury rates. In response to observations made in both leagues and high school football, new rules and regulations have been implemented to reduce injuries. However, research on sports injuries in adolescents younger than high school age, especially football, is not as prominent.
The Datalys Center, a center for sports injury research and prevention, is heading a multi-site research initiative to look more in-depth at injuries in youth football. Research initiatives, like the one through the University of South Carolina Athletic Training department, aim to look at the prevalence and incidence rates of injuries in youth football to combat some of the detrimental side effects of injuries. Specific injuries that are under close scrutiny include heat-related illnesses, musculoskeletal injuries, and concussions. In particular, concussion awareness has risen in the past couple years to do the increase in media attention from major sporting leagues. Kids participating in youth football have increased in size and power and because of this increase, there has been as increase in the number of kids that have been taken into emergency departments due to a sports-related traumatic brain injury. The importance of injury prevention studies is paramount because they help active youth in the United States stay healthy through prevention. By knowing the causes of specific injuries, especially in youth football, it will help coaches, officials, and parents to better understand the signs of injuries and subsequently help to combat those injuries.
METHODS
Injury data were collected from two different football leagues in the Midlands area of South Carolina during the 2012 and 2013 seasons. One league was an age-weight league and the other was an age-only league. The players in the age-weight league were placed on teams based on their age and weight, so that players at the same stage of physical maturity and development are grouped together. The players in the age-only league were placed on teams based on their age, regardless of their developmental status. Before each season started, athletes provided assent and the parents or legal guardians of the athletes provided consent for the athletes to receive medical attention provided by the athletic trainers in case of injury.
Graduate athletic trainers, who were assigned to work with the respective leagues, collected information about each injury. The information collected included the time and location of the injury, the mechanism of injury, side the injury occurred, and descriptive information about the injury. The athletic trainers were the emergency responders for each of the leagues and were the main point of contact for anything medical related. These trainers also diagnosed any injury and administered preventative actions as seen fit.
Once the injury data were collected, it was then entered into a database provided by the Datalys Center. All information regarding games and practices, including weather conditions and number of athletes present, were entered into the database. There was also a space to count the number of plays each player had during a game session. At the end of each season, the data from each league were compiled and analyzed by the Datalys Center to compare the information to the other sites participating in the research study.
For the current study, the database was used to compare information gathered at the two sites in the Midlands area. Information specific to the injury, such as date and location, mechanism of injury, body part, specific injury, and field surface, was collected based on the specific players over the course of two seasons. Injury information was then de-identified and analyzed in the X2 Biosystems statistical software.
RESULTS
During the 2012 season, there were 235 athletes participating in the age-only league with 12 teams that had an average of 19 players per team. The age-weight league had 152 athletes on 7 teams with an average of 22 players per team during the same season. During the 2013 season, the age-only league had 177 participants on 9 different teams with an average of 19 players per team. The age-weight league had 141 athletes on 6 different teams with an average of 24 players per team during the 2013 season. The results were analyzed to find the number of occurrences and the percentage of the total injuries that have occurred. Below are the results of the statistical analyses.
Table 1 presents the frequency of the various injuries experienced for the athletes registered in the age-only and the age-weight leagues. Of the 109 injuries reported for the age-only league, the most common were contusions, concussions, and sprains. The vast majority of the injuries occurred only once. Of the 208 injuries reported for the age-weight league, the most frequent injuries were contusions, sprains, and headaches.
Table 1 Type of Injury
|
|
AGE-ONLY LEAGUE |
AGE-WEIGHT LEAGUE |
||
|
INJURY |
NUMBER OF OCCURRENCES |
PERCENTAGE |
NUMBER OF OCCURRENCES |
PERCENTAGE |
|
Contusion |
37 |
33.94 |
91 |
43.75 |
|
Concussion |
10 |
9.17 |
3 |
1.44 |
|
Sprain |
21 |
19.27 |
38 |
18.27 |
|
Solar Plexus Injury |
5 |
4.59 |
2 |
0.96 |
|
Abrasion |
4 |
3.67 |
5 |
2.40 |
|
Spasm |
2 |
1.83 |
1 |
0.48 |
|
Gamekeeper’s Thumb |
4 |
3.67 |
4 |
1.92 |
|
Tear |
6 |
5.50 |
8 |
3.85 |
|
Dehydration |
2 |
1.83 |
0 |
0.00 |
|
Fracture |
9 |
8.26 |
4 |
1.92 |
|
Anxiety |
1 |
0.92 |
0 |
0.00 |
|
Epistaxis |
1 |
0.92 |
4 |
1.92 |
|
GI Disorder |
1 |
0.92 |
0 |
0.00 |
|
Heat Exhaustion |
1 |
0.92 |
8 |
3.85 |
|
Hip Pointer |
1 |
0.92 |
0 |
0.00 |
|
Impingement |
1 |
0.92 |
0 |
0.00 |
|
Laceration |
1 |
0.92 |
1 |
0.48 |
|
Other Injury |
1 |
0.92 |
1 |
0.48 |
|
Soleus Tendinosis |
1 |
0.92 |
0 |
0.00 |
|
Dislocation |
0 |
0.00 |
1 |
0.48 |
|
Achilles Tendonitis |
0 |
0.00 |
1 |
0.48 |
|
Calcaneal Apophysitis |
0 |
0.00 |
1 |
0.48 |
|
Headache |
0 |
0.00 |
17 |
8.17 |
|
Heat Cramps |
0 |
0.00 |
3 |
1.44 |
|
Hyperextension |
0 |
0.00 |
2 |
0.96 |
|
Jammed Finger |
0 |
0.00 |
2 |
0.96 |
|
Knee Pain |
0 |
0.00 |
2 |
0.96 |
|
Lateral Epicondylitis |
0 |
0.00 |
1 |
0.48 |
|
SI Dysfunction |
0 |
0.00 |
1 |
0.48 |
|
Strain |
0 |
0.00 |
1 |
0.48 |
|
Turf Toe |
0 |
0.00 |
1 |
0.48 |
|
Whiplash |
0 |
0.00 |
4 |
1.92 |
Frequencies of different injury types are given for the Age-Only and Age-Weight leagues. These data were collected over two seasons from 2012-2013.
Table 2 presents the frequency of the injuries reported for both of the leagues in this study. In the age-only league, the majority of the injuries occurred during games. In the age-weight league, the majority of the injuries occurred during practices.
Table 2. Practice/Game
|
|
AGE-ONLY LEAGUE |
AGE-WEIGHT LEAGUE |
||
|
LOCATION |
FREQUENCY |
PERCENT |
FREQUENCY |
PERCENT |
|
Game |
60 |
55.05 |
89 |
42.79 |
|
Practice |
49 |
44.95 |
119 |
57.21 |
Frequency of injuries observed during games and practices for the two leagues. These data were collected over two seasons from 2012-2013.
Table 3 presents the time needed before returning to play after an injury in both the age-weight league and the age-only league. For both leagues, over 50% of the injuries allowed the injured athlete to return to play within the same session in which they were injured.
Table 3. Return to Play
|
|
AGE-ONLY LEAGUE |
AGE-WEIGHT LEAGUE |
||
|
TIMEFRAME |
FREQUENCY |
PERCENT |
FREQUENCY |
PERCENT |
|
Same Session |
59 |
54.13 |
142 |
68.27 |
|
1-6 Days |
24 |
22.02 |
29 |
13.94 |
|
7-13 Days |
12 |
11.01 |
6 |
2.88 |
|
14-29 Days |
5 |
4.59 |
2 |
0.96 |
|
Removed from Team Activity |
5 |
4.59 |
26 |
12.5 |
|
Out for Remainder of Season |
3 |
2.75 |
2 |
0.96 |
|
Unknown |
1 |
0.92 |
0 |
0 |
Amount of time needed by youth athletes to return to play after an injury. These data were collected from the age-weight and age-only leagues over two seasons from 2012-2013.
Table 4 presents the mechanism of injury for those youth athletes that were injured during the two seasons that the data were collected. For both leagues, the majority of the injuries occurred because of direct contact. For the age-weight league, approximately a quarter of the injuries did not have a specific mechanism or no apparent contact.
Table 4. Mechanism of Injury
|
|
AGE-ONLY LEAGUE |
AGE-WEIGHT LEAGUE |
||
|
MECHANISM |
FREQUENCY |
PERCENTAGE |
FREQUENCY |
PERCENTAGE |
|
Direct Contact |
89 |
81.85 |
130 |
62.5 |
|
No Apparent Contact |
8 |
7.34 |
26 |
12.5 |
|
Illness |
5 |
4.59 |
1 |
0.48 |
|
Indirect Contact with Another Person |
4 |
3.67 |
17 |
8.17 |
|
No Specific Mechanism |
2 |
1.83 |
21 |
10.10 |
|
Gradual Onset |
1 |
0.92 |
2 |
0.96 |
|
None |
0 |
0 |
7 |
3.37 |
|
Other |
0 |
0 |
4 |
1.92 |
Mechanisms of injury observed in the age-weight and age-only leagues. These data were collected over two seasons from 2012-2013.
Table 4.1 shows the specificity of the mechanism of injury for those who had a direct contact injury. For both the age-only league and the age-weight league, the largest portion of the injuries happened because of contact with another person, followed by contact with the playing surface.
Table 4.1. Type of Direct Contact
|
|
AGE-ONLY LEAGUE |
AGE-WEIGHT LEAGUE |
||
|
TYPE |
FREQUENCY |
PERCENTAGE |
FREQUENCY |
PERCENTAGE |
|
Contact with Another Person |
67 |
61.47 |
100 |
48.08 |
|
Contact with Playing Surface |
16 |
14.68 |
28 |
13.46 |
|
Contact with Playing Apparatus |
6 |
5.5 |
2 |
0.96 |
Frequency of injuries resulting from different types of direct contact. These data were collected from the age-only league over the course of two seasons from 2012-2013.
Table 5 presents the distribution of injuries for each team over the course of two seasons for the age-only league. The range of injuries per team is quite large because not all teams participated in both seasons.
Table 5. Team – Age-Only League
|
TEAM |
FREQUENCY |
PERCENTAGE |
|
Bills |
19 |
17.43 |
|
Chargers |
15 |
13.76 |
|
Titans |
15 |
13.76 |
|
Steelers |
14 |
12.84 |
|
Texans |
13 |
11.93 |
|
Raiders |
8 |
7.34 |
|
Falcons |
6 |
5.5 |
|
Packers* |
6 |
5.5 |
|
Rams* |
5 |
4.59 |
|
Vikings |
4 |
3.67 |
|
Seahawks* |
3 |
2.75 |
|
Cowboys* |
1 |
0.92 |
Frequency of injuries observed for each team in the age-only league. These data were collected over the course of two seasons from 2012-2013. The asterisks denote which teams played for only one season.
Table 5.1 presents the distribution of injuries for each team over the course of two seasons for the age-weight league. The range of injuries per team is large because not all teams participated in both seasons. In the age-weight league, some of the teams combined for the second season.
Table 5.1. Team – Age-Weight League
|
TEAM |
FREQUENCY |
PERCENTAGE |
|
Junior Midget |
41 |
19.71 |
|
Junior Pee Wee |
42 |
20.19 |
|
Junior Pee Wee Blue* |
6 |
2.88 |
|
Junior Pee Wee White* |
2 |
0.96 |
|
Mighty Mite Red |
27 |
12.98 |
|
Mighty Mite White |
38 |
18.27 |
|
Pee Wee |
34 |
16.35 |
|
Tiny Mite |
18 |
8.65 |
Frequency of injuries observed for each team in the age-weight league. These data were collected over the course of two seasons from 2012-2013. The asterisks denote which teams played for only one season.
Table 6 presents the distribution of injuries based upon age for the age-only and the age-weight leagues. The age-only leagues only had two divisions for their athletes, whereas the age-weight league had five age divisions. For the age-only league, the injuries were distributed fairly evenly between the 8-10 and 11-14 age groups. The age-weight league had the most injuries in the 7-9 year old age group.
Table 6. Age
|
|
AGE-ONLY LEAGUE |
AGE-WEIGHT LEAGUE |
||
|
AGE |
FREQUENCY |
PERCENTAGE |
FREQUENCY |
PERCENTAGE |
|
5-7 |
0 |
0 |
18 |
8.65 |
|
7-9 |
0 |
0 |
65 |
31.25 |
|
8-10 |
50 |
45.87 |
50 |
24.04 |
|
9-11 |
0 |
0 |
34 |
16.35 |
|
11-14 |
59 |
54.13 |
41 |
19.71 |
Frequency of injuries dependent on age. These data were collected from the age-only league over the course of two seasons from 2012-2013.
A t-test was performed to determine if the weight of the youth athlete was related to the likelihood of getting a concussion. This t-test was performed for the age-only league because there were not enough data points to perform the same test with the age-weight league. The average weight of concussed athletes (n =10) in the age-only league was 107.5 pounds with a standard deviation of 31.13 pounds and the average weight of non-concussed athletes was 109.6 pounds with a standard deviation of 36.11 pounds (p = 0.8608). Based off of this t-test, we failed to reject null hypothesis; there is no difference in the rate of concussions based upon weight.
DISCUSSION
This study, being the first of its kind, is instrumental in determining how youth athletes are getting hurt. Because of the prevalence of long-term injury effects in the media, this research project helps to look at how the athletes are getting hurt and how these injuries may affect the athletes later in life. Through this study, it was found that there is no correlation between the weight or age of the youth athlete and the likeliness of them sustaining an injury. We found that the majority of injuries were contusions and most athletes returned to play within the same session in which they were hurt. These realizations can be used to help implement guidelines for different leagues as to how to prevent more serious injuries. As this study continues to take place, it can be used to track athletes that participate in the leagues for multiple seasons. This project also explains the importance of having an athletic trainer or other medical profession at the practices and games. Because these individuals can diagnose injuries, it can help those who get severely injured receive the care that they need as soon as possible. This project is also being conducted in different locations across the nation so the data collected can be used to see if there are regional differences and then help figure out how to combat these issues nationally. There has been a lot of injury research conducted nationally, at the college level, and in some high schools, but there has not been an opportunity to look at the youth level and this project is an in-depth look at two leagues in the Midlands area to see injury trends.
There were 109 injuries sustained over the two seasons at the age-only league. Contusions were the most common type of injury that occurred, with concussions being the next most common type of injury. There were only two instances when emergency services were needed because of the severity of the injury, a talar fracture and a tibial fracture. Both of these injuries caused the athletes to be out for the remainder of the season. For the age-weight league, there were 208 injuries that occurred. Of those injuries, contusions were the most common type. There were two injuries that required emergency transportation. The first injury was an ankle dislocation that needed immediate surgery and caused the athlete to miss the remainder of the season. The second injury was a heat-related issue that escalated quickly to a probable heat stroke. This athlete was out for a week before he returned to practicing with his team.
When comparing the injury occurrences in the practice or game setting, 55% of the injuries occurred during a game situation while 45% occurred during a practice at the age-only league. In the age-weight league, 57% of the injuries occurred during a practice situation and 43% occurred during a game situation. Because there was not a significant difference between the two numbers in both of the leagues, it cannot be determined if youth athletes are more likely to be hurt during games or practices. For the two seasons that the age-only league had the injuries tracked, 54.13% of the injuries allowed the athlete to return to play during the same session, whether it was during a practice session or game in which they were injured. The age-weight league had 68% of the injured participants return to play during the same session. Both leagues are lower than the average of 90% of the athletes returning to play during the same session [2]. There were only three injuries that caused the athletes to stop playing football for the remainder of the season in the age-only league, while in the age-weight league, only two injuries caused the athlete to be out for the rest of the season. The rest of the injuries ranged anywhere from 1-29 days to return to play.
The mechanism of injury is important in determining how to keep youth athletes safe while playing their sport. In the age-only league, it was found that direct contact was the main mechanism of injury with 89 (81.65%) of the injuries resulting from direct contact. Direct contact includes with another person (61%), with the playing surface (14.68%), and with the playing apparatus (5.5%). This is compared to the 130 injuries that occurred because of direct contact in the age-weight league. Of these 130 injuries, 100 were because of contact with a person, 28 were because of contact with the playing surface, and 2 were because of contact with a playing apparatus.
Age is an important consideration in determining how to keep youth athletes safe while playing their sport. Because this is a younger demographic and they are more resilient, there was only one gradual onset injury in the age-only league, soleus tendinosis, and there were two gradual onset injuries in the age-weight league, Achilles tendinosis and patellar pain. Based upon age, in the age-only league, the younger age group of 8-10 year olds was injured 50 times over the two seasons, whereas the older age group of 11-12 year olds was injured 59 times over the two seasons. In the age-weight league, there were more divisions of age. The age group that had the most injuries for the age-weight league was the 7-9 year old group with 65 injuries. The group that had the least amount of injuries was the 5-7 year old group with 18 injuries. For the entire age-weight league, there was not a large range of number of injuries. There was also no correlation with the injury rate and age.
There are many sources of error in this research project because of the nature of the demographic upon which this project is based. Children cannot always perceive pain the same way that someone older can because they are not as aware of their bodies yet. Many times when asking the youth athletes in this study how much pain they were in on a scale of 1-10, they would give scores of seven or above, not really understanding the differences between the numbers. This affects the data because the athletic trainers were not able to get an accurate identification of the injury that did occur. Also, because these athletes could not perceive pain well, they had issues deciding whether they could continue to play after they were injured. Many youth athletes came over with a minor bump or bruise, even though they were not hurt, because they could not perceive how much pain they were having. Another source of error when working with this population was that they have a hard time conveying what they were feeling. Plenty of times, when asked by the athletic trainers, the injured athlete could not articulate what happened to cause the injury or what exactly hurts. During a few instances, the athletic trainer would ask probing questions only to find that the athlete would answer either yes or no to every question. The trainers could not get a good diagnosis from these responses. Because the youth athletes in this study were not aware of their bodies and how injured or hurt they were, it was hard to get an accurate diagnosis of the injury. Therefore, the youth athletes were the biggest source of error during this study. Better diagnostic tools for younger ages or perhaps using Athletic Trainers with more experience working with children would help to combat the biggest source of error that was found in this study.
Because this study was conducted over the course of two seasons up to this point, there have been multiple athletic trainers who have worked with the leagues. Another source of error that may bias the results is how the athletic trainers diagnose the injuries. In the age-weight league there were only three diagnosed concussions. One concussion was diagnosed in the 2013 season, while the other two were diagnosed in the 2012 season. The age-only league had 10 concussions evenly dispersed over the two seasons. In the age-weight league, there were 17 headaches diagnosed, while in the age-only league there were none documented over the two seasons. What is most interesting about this large difference between the two leagues is that all of the documented headaches in the age-weight league were diagnosed in the same season by the same athletic trainer. Twelve of the 17 headaches were caused by direct contact of some sort, while the other five headaches had no specific mechanism or no apparent contact. Five of these headaches were removed from the team activity and one was removed from play for 1-6 days after the injury. Many times a headache is one of the first signs of a concussion. Because of the sensitivity of some people to head impacts, it is important for athletes to have a full concussion test to ensure that a headache is not in fact a concussion. In the future, it is important to implement a protocol for when to test for a concussion because of the long-term effects of having brain injuries. This can help to account for bias in the injury data as well as help to properly treat the athletes that have headaches versus an actual concussion.
In the future, the research project at the University of South Carolina hopes to expand into different sports, including soccer, baseball, and swimming. The same type of injury collection will occur. The relationships with the youth football leagues in the Midlands area of South Carolina will continue past these two seasons. It is the hope of USC Sports Medicine to have certified athletic trainers with every major youth sports league in the Midlands area. Eventually, there will be a youth sports injury research center located in Columbia, South Carolina.
About the Author
Marie Morrissette
My name is Marie Morrissette and I'm a graduate of the Arnold School of Public Health with a degree in Exercise Science. I am originally from Cary, North Carolina and I am now a physical therapist practicing in North Carolina after pursuing my Doctorate in Physical Therapy at East Carolina University. Having grown up playing sports all my life, I have always been fascinated with how the body works. Because I was very interested in pursuing undergraduate research, I took Dr. Alexander's Initiating Research Experiences class through the Honors College. In this class I learned how to refine my question and it also helped me to get in touch with my research director Dr. Jim Mensch of the athletic training department. He helped me get started on my research project working with youth football athletes and documenting injuries. With the help of Dr. Alexander, I was awarded the SCHC Exploration Grant to help fund the project. What I enjoyed most about this project is that I was able to see the entire research process from the beginning. I witnessed everything from the IRB approval process and getting leagues interested to seeing branch projects form from this main project. I really enjoyed getting to work with all of the youth athletes and getting to watch them play football. This experience has greatly prepared me for graduate school and the field of physical therapy because it has taught me about the research project as week as communicating effectively with different groups of people. I enjoyed conducting research so much during my undergraduate career, that I became a Graduate Research Assistant in graduate school. As a graduate assistant, I conducted research on movement variability during running in those with history of meniscectomy and have presented my findings at the local, state, and national levels. This research project has been one of my greatest accomplishments in my college career and has sparked a lifelong interest in asking a question and finding the answer.
References
- Bergeron, M. F., McKeag, D. B., Casa, D. J., Clarkson, P. M., Dick, R. W., Eichner, E. R., & Horswill, C. A. (2005). Youth Football: Heat Stress and Injury Risk. Medicine and Science in Sports and Exercise, 37, 1421-1430.
- Daniel, . W., Rowson, S., & Duma, S. M. (2012, April). Head Impact Exposure in Youth Football. Biomedical Engineering Society, 40(4), 976-981.
- Dompier, T. P., Powell, J. W., Barron, M. J., & Moore, M. T. (2007). Time-Loss and Non-Time-Loss Injuries in Youth Football Players. Journal of Athletic Training, 42, 395-402.
- Duhaime, A., Beckwith, J. G., Mearlender, A. C., McAllister, T. W., Crisco, J. J., Duma, S. M., & Brolinson, P. G. (2012, December). Spectrum of Acute Clinical Characteristics of Diagnosed Concussions in College Athletes Wearing Instrumented Helmets. J Neurosurg, 117, 1092-1099.
- Emery, C. A. (2005). Injury Prevention and Future Research. Med Sport Sci, 49, 170-191.
- Emery, C. A. (2012, April 12). Injury Prevention in Paediatric Sport-Related Injuries: A Scientific Approach. Br J Sports Med, 44(1), 64-69.
- Gage, B. E., McIlvain, N. M., Collins, C. L., Fields, S. K., & Comstock, R. D. (2012). Epidemiology of 6.6 Million Knee Injuries Presenting to United States Emergency Departments from 1999 Through 2008. Society for Academic Emergency Medicine, 19(4), 378-385.
- Gilbert, F., & Johnson, S. M. (2011). The Impact of American Tackle Football-Related Concussion in Youth Athletes. AJOB Neuroscience, 2(4), 48-59.
- Goldberg, B., Rosenthal, P. R., Robertson, L. S., & Nicholas, J. A. (1988, February). Injuries in Youth Football. Pediatrics, 81, 255-261.
- Nation, A. D., Nelson, N. G., Yard, E. E., Comstock, R. D., & McKenzie, L. B. (2010, December 2). Football-Related Injuries Among 6- to 17-year-olds Treated in US Emergency Departments, 1990-2007. Clinical Pediatrics, 50(3), 200-207.
- Radelet, M. A., Lephart, S. M., Rubinstein, E. N., & Myers, J. B. (2002, September). Survey of the Injury Rate for Children in Community Sports. Pediatrics, 110(3),