Trends in Trampoline Fractures: 2008–2017

Discussion

Trampoline injuries remain a common source of orthopedic injuries and a significant public health issue. In the decade of 2008 to 2017, the incidence of fractures related to trampolines per person-year increased by an average of 3.85% per year. In 2017, trampolines were the cause of nearly 1 in 16 pediatric fractures presenting to US EDs. Despite this increase in the number of fractures, the hospitalization admission rate for these injuries remained relatively constant at ∼12%. Our study identified an important shift in the locale of trampoline injuries. Pediatric trampoline-related fractures were increasingly more likely to occur at a recreational or sports facility over the course of the study (Fig 4). It is expected that in any longitudinal data set fluctuations will occur from year to year. However, reporting overarching trends gives a more general picture of the impact trampolines may have on society, and for this reason, trends are the focus of the current study.

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FIGURE 4

Percentage of fractures that occurred at a sports-related location: trampoline-related fractures versus all other fractures. Highlighted is the differential shift in the proportion of pediatric fractures coded as occurring at a sports-related location among trampoline fractures compared with all other fractures. Represented by the interaction analysis, the yearly increase in the proportion of fractures coded as occurring at a sports-related location was significantly higher among trampoline fractures compared with all other fractures.

The modern trampoline design was developed in 1936 by George Nissen. The recreational and sporting use of trampolines can be traced to the 1950s with the first report of injury in 1956.¹¹ As reports of both major and minor injuries increased over the next decade,^12,13 particularly in relation to gymnastic sports, the National Collegiate Athletic Association eliminated trampolines from national competition in 1971. The AAP followed in 1977 with a recommendation to ban trampolines from schools and competitive sport in an effort to reduce the number of injuries in the pediatric population.¹⁴ Serious injuries remained a significant issue in the 1990s with a reported 14% yearly rise in trampoline-related fractures between 1991 and 1999,⁵ leading the AAOS in 1996 and the AAP in 1999 to issue policy statements recommending the abolishment of trampolines from homes, playgrounds, and education programs. Fracture incidence plateaued until 2003, when another increase was noted from 2004 to 2005.⁵ Again, policy statements from both the AAOS and AAP were published in 2005 and 2006, respectively, reaffirming each society’s previous statements. Loder et al³ and others report a subsequent overall decrease in the amount of trampoline injuries between 2006 and 2010, followed by a relative plateau in nationwide numbers from 2010 to 2013, which is potentially reflective of a public responsiveness to these policy statements. Our current findings indicate that this plateau has not continued. Pediatric trampoline fracture incidence has increased remarkably from 38.7 per 100 000 person-years in 2014 to 53.0 per 100 000 person-years in 2017.

Historically, trampoline fractures were predominantly related to injuries that occurred in the home environment. Our findings suggest that the recent increase in trampoline fractures may be partly due to the increased popularity of recreational and sport trampoline parks, which have grown from 35 in existence in North America in 2011 to nearly 400 by March 2018.¹⁵ Kasmire et al¹ reported in 2016 that trampoline park injuries increased by nearly 12-fold between 2010 and 2014. Regarding our study, it should be considered that, as previously stated, the NEISS definition of a place of recreation or sport includes locales other than trampoline parks, so it is possible that our findings reflect this limitation and that not all visits in this category are from trampoline parks. Additionally, NEISS provides granular data only, and thus, it is possible that the increase in designation of trampoline fractures as having occurred outside of the home may be due to shifts in coding practices, a factor that would impact all fractures. To test this hypothesis, we tested whether the incidence of fractures outside of the home also increased in fractures unrelated to trampoline injuries. We found that the odds of a fracture occurring in a place of recreation or sport was constant among nontrampoline fractures, <1% change in incidence per year, providing additional evidence that the shift in the locale of injuries was unique to trampoline injuries.

Although the data indicate a greater fracture burden due to injuries that occurred at a place of recreation or sport, the current data do not allow us to draw any inferences regarding changes in the risk of a trampoline fracture at these locations. The increase in trampoline fractures at a place of sport or recreation may reflect a constant level of risk, with the increase in the number of cases being attributable to an increase in exposure rather than an increase in actual risk. Additional research is needed to define the risk level at trampoline parks and sport-related trampoline events relative to other, well-studied recreational and sport-related activities that are also a common source of pediatric fractures.

Childhood injury prevention is an important aspect of our health care system because of the potential for both intermittent and lifelong implications of injury. The orthopedic surgeon, pediatrician, and emergency medical personnel have key roles and responsibilities in their ability to advocate for safety in this arena. Karkenny et al⁵ highlights both medical personnel and their respective societies as effective advocates in a review of advocacy campaigns in relation to pediatric injury rates. Although the correlation between an injury prevention campaign and injury rates can only result in the “perceived effectiveness” of a campaign because of the vast number of possible confounding factors, it is our best mechanism to proactively discern potential changes in public behavior or awareness as a consequence of the campaign. To date, AAOS and AAP position statements have traditionally focused on dangers in trampoline injuries in the home environment. However, the current study demonstrates that trampoline-related fractures are increasingly occurring outside of the home (Table 3). In turn, advocacy and injury prevention campaigns need to adapt their message to accommodate shifts in the location of trampoline-related fractures to address the risk of injury outside of the home.

The strength of the current study is the use of a nationwide database to provide nationally representative estimates of trampoline fracture injury rates. National estimates are only possible if there are at least 20 reported cases, the weighted estimate is at least 1200, and the coefficient of variation is <33%. Therefore, some of the national estimates were not calculated (Tables 1 and 2). Another limitation of our study is that we do not have a denominator for the number of youth who are using trampolines to determine the true risk of trampolines. Furthermore, the mechanism of injury and circumstances surrounding the injury, such as the number of children on the trampoline, severity of injury, treatment, and final outcome, were not available. The NEISS database also relies on providers thoroughly noting the details of each case and the staff importing and coding the information from the visit reports accurately. For example, our data are limited by a large number of trampoline fractures occurring in “unknown” locales, with 40% of trampoline-related fractures in our study period being coded as “not recorded” regarding the locale of injury. In an effort to describe potential implications of these unknown locales, we have included a table (Table 4) that summarizes the distribution of injuries by body region among trampoline fractures coded as having occurred in the home, at a sports or recreational facility, and at an unknown location. For further description of the numbers of known and unknown locales of trampoline and all other fractures, please refer to Supplemental Table 5. Finally, estimates were only obtained from emergency visits and may underrepresent the true burden of pediatric trampoline injuries that present to other facilities, such as urgent care centers.