Risk analysis of trampolines

Recently, a story about a three-year old child breaking his femur at a trampoline park went viral on Facebook and popular media. But are trampolines really dangerous? Or is this story simply reflective of alarmism that is rampant in popular media?

I remember jumping on trampolines (and bounce houses, for that matter) as a child. In fact, a friend of mine had a big trampoline in her backyard, and I vividly remember practicing flips and trying to bounce as high as we could. Now, trampolines are even more readily available with the dawn of the indoor trampoline park, many of which specifically advertise "toddler time" for younger children.

I started looking into trampoline safety data when a science educator that I follow (MommyPhD) posted about her son breaking his leg at a trampoline gym. It turns out that the American Academy of Pediatrics does not recommend trampolines of any kind for children under age 6 (full policy statement here). When I passed this information along on social media, some parents responded by claiming that children can get hurt in a variety of activities and that we as parents cannot protect them from every injury; they also argued that there's no point in singling out trampolines in the recommendations because kids can get hurt from a variety of activities. To address this argument, we need to compare injury rates for other common childhood activities to injury rates for trampolines; only then can we make an appropriate judgment about the risks that trampolines involve.

The Centers for Disease Control reports that falls are the leading cause of non-fatal injuries in children ages 1-4, but does not separate out the statistics by cause. Data from the Consumer Product Safety Commission suggests that about 1.8% of children using a bicycle have an ER-related injury (4% a medically treated injury); 0.8% of children on playground equipment have an ER injury (slightly overestimated because the usage number includes only home equipment but the injury data include home and public; 1.8% medically treated); 1% ER visits for children using skateboards (3% medically treated); and 4.4% for trampolines (11% medically treated). That means the rate of ER visits for trampolines is almost 2.5 times higher than an ER visit for falling off a bike, and 10% of kids using trampolines are medically treated for an injury (roughly). For anyone who is interested, you can actually access the full data from the National Electronic Injury Surveillance system and use that to look at prevalence of different kinds of injuries. To me, this indicates that the risk of injury on a trampoline is appreciably higher than the risk of injury when engaging in other standard childhood activities.

In light of theses data, the growing number of trampoline parks is concerning. A recent study actually compared trampoline park injuries to home trampoline injuries. The authors found that ER visits for trampoline park injuries have increased from 2010 (330 visits) to 2014 (7933 visits), presumably due to increased availability and popularity. Indeed, the number of trampoline parks in the US has increased from approximately 30 in 2011 to an estimated 450 in 2015. The study found that, in general, kids who were injured at trampoline parks were older than those injured at home and were more likely to be injured severely enough to require hospital admission. The types of injuries also differed, with home trampoline injuries more likely involving head injury and trampoline park injuries more likely involving lower extremity injuries and dislocations (see below; Kasmire, Rogers, & Sturm, 2016).

However, the majority of trampoline injuries still occur in homes; only 11% of trampoline injuries in a known location occurred in trampoline parks.

The AAP Council of Sports Medicine and Fitness elaborates on the causes of trampoline-related injuries. Risks of injury are increased when multiple children use a trampoline at the same time, particularly for the smallest members of the group, who are 14 times more likely to be injured than larger children. Falls from trampolines account for between 27% and 39% of all trampoline injuries and have not been reduced by the availability of netting or trampoline enclosures. Similarly, increased padding over frames and springs has not reduced injuries caused by these mechanisms, which make up approximately 20% of injuries.

Ultimately, every parent will make their own decisions when it comes to allowing their kids on trampolines, either at home or in a trampoline park. I for one will be following the AAP's recommendations, and keeping Little Bear off trampolines until she is at least 6 years old, if not permanently.