Epidemiology of severe injuries among United States high school athletes: 2005-2007.

Abstract

Over 7 million students participate in high school athletics annually. Despite numerous health benefits, high school athletes are at risk for injury.
Severe injury rates and patterns differ by gender and type of exposure. Study Design Descriptive epidemiology study.
Sports-related injury data were collected during the 2005-2007 academic years from 100 nationally representative United States high schools via RIO (Reporting Information Online). Severe injury was defined as any injury that resulted in the loss of more than 21 days of sports participation.
Participating certified athletic trainers (ATCs) reported 1378 severe injuries during 3 550 141 athlete-exposures (0.39 severe injuries per 1000 athletic exposures). Football had the highest severe injury rate (0.69), followed by wrestling (0.52), girls' basketball (0.34), and girls' soccer (0.33). The rate in all boys' sports (0.45) was higher than all girls' sports (0.26) (rate ratio [RR], 1.74; 95% confidence interval [CI], 1.54-1.98; P < .001). However, among directly comparable sports (soccer, basketball, and baseball/softball), girls sustained a higher severe injury rate (0.29) than boys (0.23) (RR, 1.28; 95% CI, 1.08-1.52; P = .006). More specifically, girls' basketball had a higher rate (0.34) than boys' basketball (0.24) (RR, 1.43; 95% CI, 1.10-1.86; P = .009). Differences between boys' and girls' soccer and baseball/softball were not statistically significant. The severe injury rate was greater in competition (0.79) than practice (0.24) (RR, 3.30; 95% CI, 2.97-3.67; P < .001). Nationally, high school athletes sustained an estimated 446 715 severe injuries from 2005-2007. The most commonly injured body sites were the knee (29.0%), ankle (12.3%), and shoulder (10.9%). The most common diagnoses were fractures (36.0%), complete ligament sprains (15.3%), and incomplete ligament sprains (14.3%). Of severe sports injuries, 0.3% resulted in medical disqualification for the athletes' career, and an additional 56.8% resulted in medical disqualification for the entire season. One in 4 (28.3%) severe injuries required surgery, with over half (53.9%) being knee surgeries.
Severe injury rates and patterns varied by sport, gender, and type of exposure. Because severe injuries negatively affect athletes' health and often place an increased burden on the health care system, future research should focus on developing interventions to decrease the incidence and severity of sports-related injuries.

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The American Journal of Sports
http://ajs.sagepub.com/content/37/9/1798
The online version of this article can be found at:

DOI: 10.1177/0363546509333015
2009 37: 1798 originally published online June 16, 2009Am J Sports Med
Cory J. Darrow, Christy L. Collins, Ellen E. Yard and R. Dawn Comstock
2007
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Epidemiology of Severe Injuries Among United States High School Athletes : 2005


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1798
at University of Liverpool on September 18, 2010
‡Address correspondence to Christy L. Collins, MA, The Research
Institute at Nationwide Children’s Hospital, Center for Injury Research
and Policy, 700 Children’s Drive, Columbus, OH 43205 (e-mail: christy.
collins@nationwidechildrens.org).
No potential conflict of interest declared.
The American Journal of Sports Medicine, Vol. 37, No. 9
DOI: 10.1177/0363546509333015
© 2009 The Author(s)
Epidemiology of Severe Injuries Among
United States High School Athletes
2005-2007
Cory J. Darrow,* BS, Christy L. Collins,†‡ MA, Ellen E. Yard,† PhD, and R. Dawn Comstock,*† PhD
From the *College of Medicine, The Ohio State University, Columbus, Ohio, and †The Research
Institute at Nationwide Children’s Hospital, Center for Injury Research and Policy, Columbus, Ohio
Background: Over 7 million students participate in high school athletics annually. Despite numerous health benefits, high school
athletes are at risk for injury.
Hypothesis: Severe injury rates and patterns differ by gender and type of exposure.
Study Design: Descriptive epidemiology study.
Methods: Sports-related injury data were collected during the 2005-2007 academic years from 100 nationally representative
United States high schools via RIO (Reporting Information Online). Severe injury was defined as any injury that resulted in the
loss of more than 21 days of sports participation.
Results: Participating certified athletic trainers (ATCs) reported 1378 severe injuries during 3 550 141 athlete-exposures (0.39
severe injuries per 1000 athletic exposures). Football had the highest severe injury rate (0.69), followed by wrestling (0.52), girls’
basketball (0.34), and girls’ soccer (0.33). The rate in all boys’ sports (0.45) was higher than all girls’ sports (0.26) (rate ratio [RR],
1.74; 95% confidence interval [CI], 1.54-1.98; P < .001). However, among directly comparable sports (soccer, basketball, and
baseball/softball), girls sustained a higher severe injury rate (0.29) than boys (0.23) (RR, 1.28; 95% CI, 1.08-1.52; P = .006). More
specifically, girls’ basketball had a higher rate (0.34) than boys’ basketball (0.24) (RR, 1.43; 95% CI, 1.10-1.86; P = .009).
Differences between boys’ and girls’ soccer and baseball/softball were not statistically significant. The severe injury rate was
greater in competition (0.79) than practice (0.24) (RR, 3.30; 95% CI, 2.97-3.67; P < .001). Nationally, high school athletes sus-
tained an estimated 446 715 severe injuries from 2005-2007. The most commonly injured body sites were the knee (29.0%),
ankle (12.3%), and shoulder (10.9%). The most common diagnoses were fractures (36.0%), complete ligament sprains (15.3%),
and incomplete ligament sprains (14.3%). Of severe sports injuries, 0.3% resulted in medical disqualification for the athletes’
career, and an additional 56.8% resulted in medical disqualification for the entire season. One in 4 (28.3%) severe injuries
required surgery, with over half (53.9%) being knee surgeries.
Conclusion: Severe injury rates and patterns varied by sport, gender, and type of exposure. Because severe injuries negatively
affect athletes’ health and often place an increased burden on the health care system, future research should focus on developing
interventions to decrease the incidence and severity of sports-related injuries.
Keywords: severe; injury; high school; sports
the risk of sports-related injuries,2,8 which constitute
nearly 40% of all nonfatal, unintentional injuries among
high school youth treated in emergency departments.5
High school athletes sustain an estimated 2 million inju-
ries annually, resulting in 500 000 doctor visits and 30 000
hospitalizations.16 Sports medicine professionals and clini-
cians must work together to minimize sports-related inju-
ries to maximize the potential health benefits of a physically
active lifestyle.
Although previous studies found that high school sports
injury rates vary by sport,7,13,16 little is known whether
injury severity varies by sport. As injury severity increases,
so does the likelihood that medical resources such as
Over 7 million students participate in high school athletics
annually.15 Sports can increase strength, endurance, and
flexibility while improving weight management and self-
esteem.4,23 Unfortunately, these benefits are balanced by
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Vol. 37, No. 9, 2009 Severe Injuries Among US High School Athletes 1799
hospitalization and/or corrective procedures will be used.
In addition, severe injuries can result in psychological
stress, missed school days, and potentially permanent
physical disabilities.10,21,24 These injuries can also pose a
financial burden to both the athlete’s family and the health
care system.9,24
Most previous high school sports injury studies focused on
injury incidence and diagnoses rather than severity.1,11,13,16
Studies that examined severe injuries often concentrated on
specific injuries, such as head and/or brain injuries, rather
than looking at all severe sports injuries.6,12,18 Additionally,
previous studies examining time loss after high school
sports injury were often limited by non representative
samples, a lack of exposure information necessary to
calculate injury rates, or an inability to directly compare
results by sport and gender.1,11,13,14
Our objective was to examine severe sports injuries in a
nationally representative sample of high school athletes.
Specifically, our aims were to (1) calculate severe injury
rates; (2) describe severe injury patterns and risk factors;
and (3) compare differences by sport, gender, and type of
exposure (ie, competition vs practice). Understanding
severe injury patterns among high school athletes is the
first step in developing effective preventive interventions.
MATERIALS AND METHODS
Data Collection
High School RIO (Reporting Information Online), an
internet-based sports-related injury surveillance system,
which captured injuries during the 2005-2007 academic
years from 100 nationally representative US high schools,
has been described previously.7,19,20 Briefly, eligible schools
(ie, US high schools with a National Athletic Trainers’
Association [NATA]–affiliated certified athletic trainer
[ATC] willing to serve as reporter) were categorized by
geographic location (northeast, midwest, south, and west)22
and school size (enrollment ≤1000 or >1000). From the 8
sampling strata, 100 study schools were randomly selected.
To maintain a representative sample, if a school dropped
out of the study, a replacement school from the same stra-
tum was randomly selected.
Definition of Injury and Exposure
The ATCs at participating high schools reported athlete-
exposure (AE) and injury information for 9 sports (boys’
football, boys’ and girls’ soccer, girls’ volleyball, boys’ and
girls’ basketball, boys’ wrestling, boys’ baseball, and girls’
softball) weekly throughout the 2005-2007 academic years.
An AE was defined as a high school athlete participating in
one practice or competition. Reportable injuries (1) occurred
as a result of participation in an organized high school
athletics practice or competition, (2) required medical
attention by an ATC or physician, and (3) resulted in
restriction of the student-athlete’s participation for ≥1 days
beyond the injury. Severe injury was defined as any injury
that resulted in a loss of >21 days of sports participation.
Injury reports submitted by participating ATCs included
information about the athlete, injury, and injury event. The
ATCs were able to view and update injury reports through-
out the study period.
Data were analyzed using SPSS software, version 16.0
(SPSS, Chicago, Illinois) and Epi Info, version 6.0 (CDC,
Atlanta, Georgia). All rate calculations and rate compari-
sons used actual/unweighted case counts. Unless other-
wise noted, additional analyses used national estimates,
with the standard errors for comparisons adjusted for the
High School RIO sampling plan using the SPSS Complex
Samples module.
Injury rates were calculated as the ratio of injuries per
1000 AEs. Rate ratios (RRs) and injury proportion ratios
(IPRs) were calculated with 95% confidence intervals (CIs)
and P values (CI not including 1.00 and P values <.05 were
considered statistically significant). An example of the RR
calculation comparing the rates of severe injuries in
competition and practice follows:
(# unweighted competition severe injuries /
# competition AEs) * 1000
RR = .
(# unweighted practice severe injuries /
# practice AEs) * 1000
An example of the IPR calculation comparing the
proportion of severe knee injuries between girls and boys
follows:
(national estimated # girls’ severe knee injuries /
national estimated # girls’ severe injuries)
IPR = .
(national estimated # boys’ severe knee injuries /
national estimated # boys’ severe injuries)
This study was approved by the Institutional Review
Board at Nationwide Children’s Hospital.
RESULTS
Severe Injury Incidence
In the 9 sports studied during 2005-2007, 1378 severe inju-
ries were reported, representing an estimated 446 715
severe injuries sustained nationally. Severe injuries
accounted for 14.9% of all high school sports-related inju-
ries. These injuries occurred during 3 550 141 AEs, for an
injury rate of 0.39 per 1000 AEs (Table 1). The severe
injury rate was higher in competition (0.79) than practice
(0.24), both overall (RR, 3.30; 95% CI, 2.97-3.67; P < .001)
and in each sport. In particular, competition severe injury
rates were much higher than practice in football (RR, 5.93)
and girls’ soccer (RR, 5.16) (Table 1).
Football had the highest severe injury rate per 1000 AEs
(0.69), followed by wrestling (0.52), girls’ basketball (0.34),
and girls’ soccer (0.33) (Table 1). The rate in all boys’ sports
(0.45) was higher than all girls’ sports (0.26) (RR, 1.74; 95%
CI, 1.54-1.98; P < .001). However, among directly compar-
able sports (soccer, basketball, and baseball/softball), girls
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1800 Darrow et al The American Journal of Sports Medicine
sustained a higher severe injury rate (0.29) than boys
(0.23) (RR, 1.28; 95% CI, 1.08-1.52; P = .006). More
specifically, girls’ basketball had a higher rate (0.34) than
boys’ basketball (0.24) (RR, 1.43; 95% CI, 1.10-1.86; P =
.009). Differences between boys’ and girls’ soccer and
baseball/softball were not statistically significant.
General Severe Injury Patterns
The most common severely injured body sites were the
knee (29.0%), ankle (12.3%), and shoulder (10.9%) (Table
2). The most common severe injury diagnoses were frac-
tures (36.0%), complete ligament sprains (15.3%), and
incomplete ligament sprains (14.3%) (Table 3). Body sites
commonly fractured were the hand/finger (17.6%), ankle
(14.1%), and wrist (10.9%). The knee made up 81.8% of
complete ligament sprains. A greater proportion of severe
knee injuries were sustained during competition (34.6%)
than during practice (21.3%) (IPR, 1.62; 95% CI, 1.29-2.04;
P < .001). Similarly, a greater proportion of severe complete
ligament sprains were sustained in competition (19.4%)
than in practice (9.6%) (IPR, 2.03; 95% CI, 1.35-3.05; P <
.001). Additionally, 5.3% of severe injuries were directly
related to an action that was ruled illegal activity by a
referee, official, or disciplinary committee.
Overall, 43.0% of severe injuries resulted in a time loss
of >21 days, 56.8% in medical disqualification for the
remain der of the season, and 0.3% in medical disqualifica-
tion for the injured athletes’ career (Figure 1). Injuries
that resulted in medical disqualification for the athletes’
career (n = 6 unweighted) included 3 football injuries, a
complete ligament sprain of the knee, a shoulder fracture,
TABLE 1
Severe Injury Rates per 1000 Athlete Exposures (AEs) by Sport and Type of Exposure, National High
School Sports-Related Injury Surveillance Study, United States, 2005-2007 School Years

Sport
Type of
Exposure
No. of Severe
Injuries
National
Estimate
Rates per
1000 AEs
Rate
Ratioa
95% Confidence
Interval

AE
P Value
Boys’ football


Boys’ soccer


Girls’ soccer


Girls’ volleyball


Boys’ basketball


Girls’ basketball


Boys’ wrestling


Boys’ baseball


Girls’ softball


Boys’ total


Girls’ total


All sports


Competition
Practice
Overall
Competition
Practice
Overall
Competition
Practice
Overall
Competition
Practice
Overall
Competition
Practice
Overall
Competition
Practice
Overall
Competition
Practice
Overall
Competition
Practice
Overall
Competition
Practice
Overall
Competition
Practice
Overall
Competition
Practice
Overall
Competition
Practice
Overall
362
286
648
53
31
84
68
31
99
24
18
42
49
53
102
69
54
123
74
93
167
38
28
66
27
20
47
576
491
1067
188
123
311
764
614
1378
99 198
71 054
170 252
29 355
17 400
46 755
50 081
17 097
67 178
10 111
7247
17 358
12 323
14 294
26 617
20 310
18 313
38 623
17 433
24 308
41 741
12 133
7855
19 988
10 874
7329
18 203
170 442
134 911
305 353
91 376
49 986
141 362
261 818
184 897
446 715
164 102
769 238
933 340
100 858
232 061
332 919
90 879
213 648
304 527
96 707
183 173
279 880
122 224
301 015
423 239
104 683
252 729
357 412
81 061
241 312
322 373
121 718
220 165
341 883
89 041
165 527
254 568
589 963
1 763 791
2 353 754
381 310
815 077
1 196 387
971 273
2 578 868
3 550 141
2.21
0.37
0.69
0.53
0.13
0.25
0.75
0.15
0.33
0.25
0.10
0.15
0.40
0.18
0.24
0.66
0.21
0.34
0.91
0.39
0.52
0.31
0.13
0.19
0.30
0.12
0.18
0.98
0.28
0.45
0.49
0.15
0.26
0.79
0.24
0.39
5.93


3.93


5.16


2.53


2.28


3.09


2.37


2.46


2.51


3.51


3.27


3.30


5.08-6.93


2.53-6.13


3.37-7.89


1.27-4.65


1.54-3.36


2.16-4.40


1.75-3.21


1.51-4.00


1.41-4.47


3.11-3.96


2.60-4.10


2.97-3.67


<.001
<.001
<.001
.0035
<.001
<.001
<.001
<.001
.0021
<.001
<.001
<.001
aRate ratios compare the competition severe injury rate to the practice severe injury rate.
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Vol. 37, No. 9, 2009 Severe Injuries Among US High School Athletes 1801
and a neck/cervical spine nerve injury, and 3 wrestling
injuries, a neck/cervical spine fracture, a muscle strain
(complete tear) of the knee, and a shoulder fracture. Of all
severe sports injuries, 28.3% required surgery (Figure 2).
Surgery was required most commonly for severe injuries in
girls’ basketball (38.2%), girls’ soccer (36.6%), and baseball
(32.3%). Knee injuries made up the greatest proportion
of all severe injuries requiring surgery (53.9%), followed
by hand/finger (10.7%) and shoulder (7.3%) injuries.
Common diagnoses of severe injuries requiring surgery
were complete ligament sprains (41.9%), fractures (27.3%),
and torn cartilage (11.0%). Severe injuries not requiring
surgery were frequently knee (19.3%), ankle (15.4%),
and shoulder (12.3%) injuries, and the most common
diagnoses were fractures (39.3%), incomplete ligament
sprains (18.6%), and concussions (8.5%).
Severe Injury Patterns by Sport
Football. With a rate of 0.69 severe injuries per 1000 AEs
(Table 1), football accounted for 38.1% of all severe inju-
ries, the highest of any sport. Among severe football-related
injuries, the most commonly injured body parts were the
knee (25.8%), shoulder (14.2%), and hand/finger (10.3%)
(Table 2). The most common diagnoses were fracture
(38.2%), incomplete ligament sprain (14.3%), and complete
ligament sprain (10.7%) (Table 3). The general mechanism
associated with the highest proportion of severe injuries
was contact with another player (69.3%). The activities
most commonly resulting in severe injury were being tack-
led (29.8%) and tackling (20.8%) (see Appendix, available
in the online version of this article at http://ajs.sagepub.
com/supplemental/). Among severe injuries related to both
being tackled and tackling, the most commonly injured
body parts were the shoulder and knee, and the most com-
mon diagnoses were fractures and ligament sprains (incom-
plete tears).
Soccer. Boys’ and girls’ soccer players incurred 0.25 and
0.33 severe injuries, respectively, per 1000 AEs (Table 1).
Boys’ and girls’ soccer accounted for 10.5% and 15.0%,
respectively, of all severe injuries. Among all severe soc-
cer injuries, the most commonly injured body parts were
the knee (38.9%), ankle (16.0%), and head/face (11.2%). A
greater proportion of severe soccer injuries sustained by
girls were to the knee (49.7%) compared with boys (23.3%)
(IPR, 2.14; 95% CI, 1.30-3.53; P = .001) (Table 2). The most
common diagnoses were fracture (30.3%), complete ligament
sprain (20.3%), and incomplete ligament sprain (13.6%). The
most commonly fractured body sites were the ankle (24.8%),
foot/toe (15.9%), and the lower leg (15.0%). Boys sustained
a greater proportion of fractures (42.0%) than girls (22.1%)
(IPR, 1.90; 95% CI, 1.11-3.26; P = .016). Girls sustained
a greater proportion of ligament sprains (complete tear)
(31.4%) than boys (10.9%) (IPR, 2.88; 95% CI, 1.26-6.57;
P = .005) (Table 3). Of all girls’ soccer severe injuries, 65.0%
resulted in medical disqualification for the season.
TABLE 2
Body Sites of Severe Injuries by Sport, National High School Sports-Related
Injury Surveillance Study, United States, 2005-2007 School Yearsa
Sport Knee Ankle Shoulder Hand/Finger Head/Face Lower Leg Foot/Toe Wrist Other Total
Boys’ football
(n = 170 252)
Boys’ soccer
(n = 46 755)
Girls’ soccer
(n = 67 178)
Girls’ volleyball
(n = 17 358)
Boys’ basketball
(n = 26 617)
Girls’ basketball
(n = 38 623)
Boys’ wrestling
(n = 41 741)
Boys’ baseball
(n = 19 988)
Girls’ softball
(n = 18 203)
Boys’ total
(n = 305 353)
Girls’ total
(n = 141 362)
All sports
(n = 446 715)
25.8 7.6 14.2 10.3 5.4 5.6 3.3 4.7 23.1 100
23.3 15.7 8.2 2.7 15.8 12.4 6.7 4.4 10.8 100
49.7 16.3 4.3 0.3 8.0 7.8 8.8 0.0 4.8 100
31.9 28.0 0.0 12.3 8.9 3.5 1.9 9.3 4.2 100
20.7 18.3 5.7 9.5 3.7 6.7 11.3 9.7 14.4 100
44.9 20.1 1.0 7.3 6.6 3.5 2.1 3.0 11.5 100
16.7 2.1 24.0 9.9 4.8 2.2 2.4 2.7 35.2 100
3.0 10.6 21.5 13.9 4.7
6.9 3.6
11.4 24.4 100
30.7 19.2 8.7 9.5 2.8 8.4 7.0 2.5 11.2 100
22.2 9.2 14.4 9.2 6.7 6.4 4.4 5.2 22.3 100
43.8 19.1 3.4 4.9 7.0 6.2 5.9 2.3 7.4 100
29.0 12.3 10.9 7.9 6.8 6.3 4.9 4.3 17.6 100
aData, weighted to be nationally representative, are in percentages.
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