Incidence of Sport-Related Internal Organ Injuries Due to Direct-Contact Mechanisms Among High School and Collegiate Athletes Across 3 National Surveillance Systems

High School RIO

High School RIO is currently the largest HS sports-related injury surveillance system in the United States.³¹ The methods for HS RIO have been previously described³² and are summarized here as they pertain to this study. Data have been continuously collected for each academic year since 2005–2006, with the sport selection varying by year. Given the rare nature of internal organ injuries, we used the convenience sample of the HS RIO dataset (all 24 sports) for all available years (2005–2006 through 2014–2015). In 2014–2015, a total of 240 schools participated in the HS RIO with a volunteer group of athletic trainers (ATs) providing weekly AE reports (practice, competition, or performance) and injury reports. All information was entered online by the ATs. Injuries were included if they were incurred during an organized practice, competition, or performance; required medical attention; and resulted in participation restriction of 1 or more days.

With regard to outcome inclusion and exclusion criteria, HS RIO does not have organ-specific body part variables. Injuries to body parts other than abdomen (internal), chest/T-spine/ribs, or other were excluded. Injury diagnoses other than internal injury for the body part of chest/T-spine/ribs were excluded. For ATs selecting other body part, free text responses describing the body part injured were assessed and only those responses indicating an organ injury were included. Only injuries resulting from a contact mechanism (contact with another player, contact with a playing apparatus, contact with playing surface, or contact with an out-of-bounds object) were included.

In keeping with these inclusions and exclusions, injury types in the abdominal (internal) category that indicated the injury was not internal were excluded (eg, diagnoses of sprains, strains, nerve injuries). Finally, athletes with injuries who either (1) were not seen by a health care professional (eg, [orthopaedic] physician, physician assistant, nurse practitioner) other than an AT or (2) did not receive assessment beyond evaluation (eg, computed tomography scan, radiographs, laboratory work) were excluded as their conditions were unlikely to be internal organ injuries resulting in time loss from sport participation.

The NCAA-ISP

The NCAA began surveillance for all sponsored sports at its member institutions in 1982. The system evolved from paper-based collection to a Web-based system beginning in 2004–2005. The methods for the NCAA injury surveillance system have been previously described in detail³³ and are summarized as they pertain to this study. From 2005–2006 through 2008–2009, a volunteer group of collegiate ATs at participating NCAA member institutions reported AEs (practice, competition, or performance) and injury data in real time via the Web-based platform provided by the NCAA. This included a convenience sample of 25 sports. Injuries from men's and women's swimming were collected only from 2006–2007 through 2008–2009. From 2004–2005 through 2008–2009, the annual average number of teams providing data was 33 per sport (range, 8–84).³³ In 2009–2010, the Datalys Center for Sports Injury Research and Prevention, Inc (Indianapolis, IN), assumed management of the system—now referred to as the NCAA-ISP.³⁴ From 2009–2010 through 2014–2015, deidentified data were extracted from existing electronic medical record platforms used by the ATs. Participation in the ISP varies by year and sport. From 2009–2010 through 2014–2015, the annual average number of teams providing data was 14 per sport (range, 2–44). Although men's and women's indoor and outdoor track and field data were collected separately through the study period, indoor and outdoor were combined into men's track and field and women's track and field for reporting purposes. Injuries were included if they resulted from a sponsored practice or competition, received medical attention, and resulted in participation restriction for 1 or more days.

With regard to outcome inclusion and exclusion criteria, both data-collection systems collected 4 specific injuries listed as internal organ injuries: spleen injury, kidney injury, intestinal injury, and liver injury. Beginning in 2009–2010, lung contusion injury data were also collected and included in the analyses.

Injuries not resulting from a contact mechanism (ie, contact with another player, contact with a playing apparatus, contact with the playing surface, or contact with an out-of-bounds object) were excluded. Although the NCAA-ISP from 2009–2010 through 2014–2015 included non–time-loss injuries, only injuries that resulted in removal from play for at least 24 hours were included.

National Center for Catastrophic Sport Injury Research

The NCCSIR has been conducting catastrophic injury and illness surveillance for all sponsored HS and collegiate sports on a national level since 1982.³⁵ Catastrophic sport-related injuries and illnesses are defined as severe events that result in temporary, semipermanent, or permanent disability or death.^29,36 An athlete must be a participant in a school-sponsored, organized sport for the catastrophic event to be included. The NCCSIR monitors 42 HS and 35 collegiate sports (including cheer and rodeo).³⁶ It captures events primarily through searches of publicly available sources, including online media reports, news articles, social media, and blogs. Events are also directly reported to NCCSIR via athletes, parents, ATs, school staff, researchers, and sport organizations. Once an event is captured, research staff contact the athletes, parents, and schools to obtain details about the athlete, event, and injury through a brief form or telephone interview or both. Medical examiner or coroner and medical records are also collected when available. All available information sources about the event are reviewed to determine eligibility and classification. In 2013–2014, the NCCSIR expanded to a consortium model with 3 research divisions representing the most frequent types of catastrophic events: Traumatic Injury, Exertional/Environmental, and Cardiac.³⁶ The NCCSIR and division staff work collaboratively on event capture, reporting, and investigation. In January 2015, an online Web-based portal was launched for catastrophic injury reporting; anyone (eg, athletes, parents, ATs) can report catastrophic events at http://www.sportinjuryreport.org. For the current study, catastrophic traumatic injuries resulting directly from the activities of the sponsored sport (practice, competition, performance, conditioning session) were included.

With regard to outcome inclusion and exclusion criteria, traumatic injuries to the following body parts were included: kidney, spleen, liver, appendix, pancreas, heart, intestine, stomach, and lung (Table 1). All injury events to the identified organs were reviewed for inclusion. Injuries to these body parts that were not due to a direct-contact mechanism (such as contact with a person, apparatus, surface, or object) were excluded. Commotio cordis events, though due to direct contact, were not included because these are disruptions of the heart rhythm due to a direct blow to the chest resulting in cardiac arrest.

Statistical Analysis

Descriptive statistics included frequencies and percentages. Characteristics of the athlete (sex, level of play), event (sport, event type, mechanism or activity, playing surface), and injury (type, severity, outcome) were described and stratified by data source (HS, collegiate, or NCCSIR) and sport. Incidence rates per 1 000 000 AEs and 95% confidence intervals (CIs) were calculated. High school RIO and the NCAA-ISP collect AEs directly from participating ATs; an AE is defined as 1 athlete participating in 1 school-sanctioned practice, competition, or performance. The NCCSIR does not directly collect AEs and instead uses annual participation statistics from the NFHS³⁷ and NCAA.³⁸ For the NCCSIR, exposure was reported as an athlete-season, which was defined as 1 athlete participating in 1 sport season.

The injury report completed by ATs participating in HS RIO included an item about prevention. For catastrophic injuries, case details were summarized and reviewed to identify the causes and potential countermeasure strategies for injury prevention as defined by Haddon.³⁹

Incidence Rates

Over the 10-year period, the overall rate of noncatastrophic internal organ injury per 1 000 000 AEs was similar for the HS (IR = 3.49; 95% CI = 2.87, 4.10) and collegiate (IR = 3.55; 95% CI = 2.46, 4.63; Table 3) levels. High school contact-sport athletes experienced higher rates of both catastrophic and noncatastrophic direct-contact internal organ injuries compared with those in noncontact sports (RIO incidence rate ratio [IRR] = 10.49; 95% CI = 4.89, 22.49; NCCSIR IRR = 7.56; 95% CI = 0.91, 62.80). No catastrophic or noncatastrophic direct-contact internal organ injuries occurred in collegiate-level noncontact sports. The highest rates of injury were in male contact sports: HS football (IR = 11.7; 95% CI = 9.1, 14.2) and lacrosse (IR = 10.0; 95% CI = 3.1, 16.9) in RIO and collegiate football (IR = 8.3; 95% CI = 5.0, 11.6) and ice hockey (IR = 7.9; 95% CI = 1.0, 14.7; Table 3) in the ISP. Other sports with higher IRs were HS boys' wrestling, boys' and girls' soccer, girls' field hockey, and girls' basketball in RIO and collegiate men's and women's soccer in the ISP.

For sex-comparable sports, the rate of direct-contact internal organ injury was higher during competitions than during practices for the following sports: female basketball (IRR = 6.84; 95% CI = 0.71, 65.74) and male lacrosse (IRR = 6.75; 95% CI = 1.36, 33.47) in RIO and male soccer (IRR = 7.39; 95% CI = 0.67, 81.47), female soccer (IRR = 3.12; 95% CI = 0.19, 49.84), male basketball (IRR = 3.84; 95% CI = 0.24, 61.36), female basketball (IRR = 3.45; 95% CI = 0.22, 55.20), and male lacrosse (IRR = 5.35; 95% CI = 1.08, 26.51; Supplemental Table 2) in the ISP. All noncatastrophic direct-contact internal organ injuries occurred during competitions in RIO: HS boys' and girls' soccer, boys' basketball, and softball. Rates were not substantively different in practices versus competitions for HS baseball, softball, boys' basketball, and girls' lacrosse. Due to low injury counts, these estimates were imprecise, as illustrated by the wide CIs.

For sex-comparable sports, the rate of noncatastrophic direct-contact internal organ injury was lower among boys' HS sports during competitions compared with girls' HS sports for soccer (IRR = 0.75; 95% CI = 0.25, 2.24), basketball (IRR = 0.27; 95% CI = 0.03, 2.60), and baseball and softball (IRR = 0.73; 95% CI = 0.05, 11.66; Supplemental Table 2). During practices, the rate of direct-contact internal organ injury was higher among HS boys' lacrosse players compared with their female counterparts (IRR = 1.45; 95% CI = 0.13, 16.01). Conversely, the rate of noncatastrophic internal organ injury was higher among collegiate men's athletes during competition compared with their women counterparts for soccer (IRR = 2.68; 95% CI = 0.24, 29.60). Due to low injury counts, these estimates were imprecise, as illustrated by the wide CIs.

Incidence-rate trends over the 10-year period were examined for football (Figure, Supplemental Table 3). The RIO HS football IRs per 1 000 000 AEs ranged from a high of 21.6 in 2009–2010 (14 events) to a low of 6.2 in 2011–2012 (4 events). The ISP collegiate football IRs per 1 000 000 AEs ranged from a high of 13.77 in 2005–2006 (6 events) to a low of 4.24 in 2007–2008 (2 events). Catastrophic injury rates per 1 000 000 athlete-seasons in HS football did not substantially change over the 10-year period (range, 0 to 1.80 per 1 000 000 athlete-seasons) and only 1 catastrophic injury occurred in collegiate football in 2014–2015 (IR = 13.7 per 1 000 000 athlete-seasons).

View Figure

• Download as Powerpoint
• Download Figure

Additional Details and Prevention Measures

Details for all 9 catastrophic injuries and corresponding Haddon injury-prevention countermeasure strategies are presented in Table 4. Two HS football deaths were the result of the athlete (wide receiver and offensive tight end) being tackled by 2 players—1 from each side. A HS cheerleader flier was fatally injured after a basket toss when she underrotated during a flip and was caught on her stomach. A collegiate rodeo participant was injured during practice when the bull he was riding stepped on his chest; he died from his injuries, despite wearing a chest protector.

Table 4 Descriptions of 9 Catastrophic Internal Organ Injuries Due to Direct-Contact Mechanisms in High School and Collegiate Organized Sports and Associated Haddon Energy-Damage Countermeasures, the National Center for Catastrophic Sport Injury Research, 2005–2006 Through 2014–2015^a Continued on Next Page

View Fullscreen

The injury report completed by ATs participating in HS RIO included an item about prevention. The ATs in 25.0% of cases (n = 31) noted that they believed additional or more appropriate use of protective equipment could have prevented or reduced the severity of the injury. In 65.3% of cases (n = 81), they stated that additional or more appropriate use of protective equipment could not have prevented or reduced the severity of the injury, and in 9.7% (n = 12), they responded that it was unknown. The most commonly reported personal protective equipment that might have helped were flak jackets or rib protectors, which were mentioned by 27 of the 31 ATs (87.1%) who believed that additional or more appropriate use of protective equipment could have prevented or reduced the severity of the injury. The ATs participating in the ISP were not surveyed on this item.

Overall Numbers and Rates

Although 3 times as many internal organ injuries were reported at the HS level (n = 124) compared with the collegiate level (n = 41), the overall IRs of internal organ injuries in this study did not differ between the high school and collegiate levels (3.49 and 3.55 per 1 000 000 AEs, respectively). National cross-sectional surveys conducted from 1999 through 2008 indicated life-threatening, sport-related internal organ injuries were more frequent among 13- to 18-year-olds than those more than 18 years old²⁰; however, the older group included individuals beyond college age. A previous study¹⁸ of national trauma-registry–data showed that patients 15 to 18 and 12 to 14 years old had equal frequencies of sport-related internal organ injuries. Analyses of regional trauma-registry data provided sport-related internal organ injury IRs for children ages 5 to 18 years using census data: 6.9 kidney and 5.6 spleen injuries per 1 000 000 children.¹⁹ Though these rates were higher than the rates we observed, our ability to compare rates was hampered by methodologic differences between the studies: only kidney and spleen injuries were included in the previous study, age ranges varied, injury data sources were different (hospital records versus school AT surveillance reports), athlete status was known in the surveillance data and unknown in the trauma registry, and trauma-registry denominators were per child and represented the general population rather than the population participating in the sport.

Internal Organ Versus Other Injuries

Compared with other sport-related injuries, internal organ injuries are infrequent events. Research²⁰ suggested that 14% of life-threatening injuries seen in the emergency department from 1999–2008 were sport related, and of these, only 5.4% involved the torso or abdomen. Furthermore, 39% of life-threatening, sport-related injuries were among US children aged 13 to 18 years, which translates to 333 000 life-threatening, sport-related injuries, of which 17 982 (1798 per year) involved the torso or abdomen.²⁰ Regarding fatal football injuries at the HS and collegiate levels, 3 of 79 (3.7%) direct traumatic injury deaths from 1990–2010 were due to intra-abdominal injuries.⁴¹ We reported 9 catastrophic or life-threatening events captured over the 10-year period by the NCCSIR, the majority of which were in football players (7/9). Of these, 4 resulted in death. In-depth review of the catastrophic cases and Haddon³⁹ countermeasure strategies highlighted the importance of early recognition and prompt medical evaluation and treatment to ensure the best possible outcome. Emergency action plans, access to ATs, and on-site emergency medical services for sport competitions at higher risk for direct-contact injury constitute best-practice strategies for these injuries.^42,43

The current study included both severe and less severe internal organ injuries. The ISP and NCCSIR data support previous research^15,18,19 demonstrating that the kidney and spleen were the internal organs injured most often. Anatomically, the kidneys are retroperitoneal and protected by the ribs, which, if fractured, can lacerate the kidneys. They are also susceptible to direct blows, particularly in adolescents, who have a greater percentage of mass below the level of rib protection along with less developed musculature, rendering them more susceptible to injury.⁴⁴ During contact sports, an enlarged spleen from an unidentified, underlying illness (eg, mononucleosis) may be injured, emphasizing the importance of symptom reporting and diagnosis and removal from sport-specific contact until the athlete has recovered.

Type of Sport, Mechanism, and Activity

It is not surprising that contact sports had higher rates of direct-contact internal organ injuries than noncontact sports. In our study, football, male ice hockey, and male lacrosse in HS and college were the sports with the highest rates. Previous trauma-registry, hospital, and surveillance research supports these sport-specific findings for football,^16,18,19,21 ice hockey,^15,16,18,19 and soccer.^15,21 Though wrestling was not classified in this study as a contact sport, HS wrestlers had a rate equivalent to that of male HS soccer players. Eighty percent of wrestling injuries were a result of take-down maneuvers. Overall, most injuries were due to player-player contact, but contact with an apparatus, surface, or object was also noted. Among HS sports, 8 events were due to contact with balls. Identifying whether player-player contact was intentional or unintentional and the specific apparatus, surface, or object is also important for prevention.

Prevention

A better understanding of the activity and mechanism of injury, the source and location of contact, and protective gear worn may be helpful in determining whether the injury could have been prevented. Athletic trainers' reports to HS RIO indicated that in their opinions, additional protective equipment could have prevented injury in 25% of patients. For example, football shoulder pads were designed to protect the shoulder, chest, and upper rib cage but not the lower rib cage and abdominal area. Using protective gear (eg, padded belt or shirt) that extends beyond the bottom of the shoulder pads and covers the torso may have a role in protecting internal organs from direct contact. Further research on the use and effects of protective equipment for internal injury prevention are needed. Education and information about internal organ injuries, mechanisms of injury, and types of protective equipment available are important to ensure that athletes and parents can make informed decisions.⁴⁰

Whereas primary prevention measures will reduce the likelihood of an event occurring, secondary prevention may help to limit the potential severity associated with internal organ injuries. Early recognition and serial follow-up of patients with suspected internal organ injuries may reduce the severity of injury. This may require medical staff to be present at high-risk events and to be available at the time of the injury. Best practices for preventing sudden death and severe injury include emergency action plans and availability of ATs.⁴² Colleges and universities have staff ATs who are on-site for competitions and the majority of practices, whereas 70% of public HSs have access to an AT; of those, only 47% have ATs present at both competitions and practices.⁴⁵

Strengths and Limitations

All 3 surveillance systems have been in operation for 10 or more years—2 since 1982—and the data are disseminated annually and used by national sport bodies and medical organizations. Athlete status is known, as are the specific sport, level of participation (HS, college), and other details such as the injury mechanism, activity at time of injury, and playing position, which are critical for identifying potential prevention measures. The RIO and ISP rely on ATs for injury data collection and AE tracking, which translates to accurate, high-quality data for both descriptive and comparative analyses. The data quality of the RIO and ISP systems has been previously evaluated.^46,47 The RIO and ISP do not collect identifiers, whereas the NCCSIR does. Results were provided separately for each system for this reason.

Despite these strengths, the following limitations should be noted. First, both the HS RIO and collegiate ISP surveillance systems use convenience samples of schools with ATs who voluntarily report injury and exposure data. Internal organ injuries are rare events in sport; consequently, generalizing these study results beyond the sample to schools without ATs or non-NCAA schools or organizations (eg, National Association of Intercollegiate Athletics or junior colleges) should be done cautiously. National trauma registries¹⁸ and surveys such as the National Hospital Ambulatory Medical Care Survey²⁰ have the advantage of broader and more representative coverage; however, athlete status, sport level, and the number of athlete participants at risk (rate denominator data) are unknown in these sources. Athlete status is known in all 3 systems, and both HS RIO and the ISP directly collect AE data, whereas the NCCSIR uses sport participation estimates from the NFHS and NCAA.^37,38

Second, the injury definitions in each of the systems were slightly different. The specific internal organ affected (eg, spleen, kidney) was classified in collegiate ISP and NCCSIR data sources. However, RIO data fields did not identify injury to the specific internal organ beyond the abdomen or chest, rib, or thorax region in general. Thus, injuries may be misclassified within the RIO dataset. To decrease the likelihood of misclassification, injuries reported to RIO that did not require medical evaluation beyond the AT or specific diagnostics were excluded. However, this exclusionary provision may miss less severe internal organ injuries, which would result in an underestimate of the injury frequency and rate.

Third, the NCCSIR data source relies predominantly on media reports for event capture.³⁶ It is possible that internal organ injuries that did not result in death or permanent disability were not covered by the media and therefore were not captured by the NCCSIR. The online portal (http://www.sportinjuryreport.org) that allows anyone to report catastrophic injuries should improve future capture of these events. Increasing awareness and use of this portal is critical for obtaining accurate numbers on the burden and incidence of these and other catastrophic injuries.

Last, use of protective gear at the time of the injury was not reported. With the exception of the fatal injury in collegiate rodeo, whether protective equipment could have prevented the injury is unknown. Future researchers who collect information on protective equipment worn by all athletes may be able to determine whether the equipment reduces the frequency of internal organ injuries.