19th January 2018, Volume 131 Number 1468

Lloyd Roffe, Scott Pearson, Johnathan Sharr, Michael Ardagh

For the young and those young at heart, trampolining is an enjoyable pastime. It has benefits for children; improving fitness, balance and motor performance.1 Trampoline parks have become a worldwide sensation since the first one was opened in Las Vegas in 2004. As of 2014 the International Association of Trampoline Parks (IATP) estimated there were 280 existing parks in North America alone.2 These parks vary but typically consist of single trampolines, foam pits and multiple ‘courts’—one or more trampolines adjoined to form one large surface which is surrounded by either walls or angled trampolines. Despite padding, initially ad hoc park rules and now defined (but voluntary) safety standards,3 injuries to patrons continue to occur—much like the history of trampolines in the home setting.

The last review of trampoline use in New Zealand was completed 22 years ago by Chalmers et al,4 well before the popularity of trampoline parks. The authors audited a 10-year period and found trampoline-related injuries were increasing from 3.1 per 100,000 in 1979 to 9.3 per 100,000 in 1988.4 A recent Australian study showed that rates of trampoline-related injuries are continuing to increase.5 The authors found a 70.82% increase in trampoline injuries nationally across all age groups in the period 1 July 2002 to 30 June 2011.5 Kasmire et al showed that American emergency department presentations for injuries sustained at trampoline parks have been increasing between 2010 and 2014 with no change in home trampoline injury rates.6

Factors identified to increase the risk of suffering an injury while using a trampoline include age, multiple simultaneous users and falling from the trampoline.7 Those aged five to nine years have the highest frequency of injury following trampoline use.5 Previous analysis of trampoline-related injuries in those under 16 years have found that approximately 80% occurred on the trampoline, and between 60–80% of those were with two or more children on it at one time.8–11 The risk of injury with multiple users is greater for the lighter playmate.12 Falling from a trampoline can cause severe injury and accounts for approximately a quarter of trampoline-related injuries.7,13,14

Trampoline parks are a new and exciting trend for children (and adults), encouraging them to be active and engage with each other. There is currently little evidence assessing their injury profile and impact on communities. This study aims to assess the effect the opening of two new trampoline parks had on Christchurch Hospital Emergency Department attendance. A further aim is to analyse the types of injuries suffered, subsequent treatment and review relevant literature to provide recommendations for standards that should be followed in such large trampoline centres.

Methods

This retrospective descriptive study was conducted at Christchurch Hospital, which is the major tertiary provider of healthcare to the Canterbury region in New Zealand. It services a population of 510,000 with 7.2% Māori and 2.0% Pacific Islander. In 2016, there were 300 trauma admissions to Christchurch Hospital. In New Zealand, major trauma is defined as a patient with an Injury Severity Score (ISS) of greater than 12.15 Christchurch Emergency Department attendance is approximately 95,000 presentations annually.

Three 90-day time periods were identified relative to the opening of both trampoline parks: Period A (control period; 20 August 2015–18 November 2015), the 90 days one year earlier; Period B (control period; 21 May 2016–19 August 2016) the 90 days prior to opening and; Period C (study period; 20 August 2016–18 November 2016), the 90 days after both parks had opened (Figure 1). Patients were eligible for inclusion in the study if they presented to hospital within any of the three periods after suffering a trampoline-related injury. A trampoline-related injury was classified as an injury the treating clinician directly attributed and coded to being secondary to the use of a trampoline. Patients were excluded if they were injured outside of the study periods, not injured because of trampoline use or injured outside of the Christchurch region.

Figure 1: Timeline of Period A (20 August 2015–18 November 2015), B (21 May 2016–19 August 2015) and C (20 August 2016–18 November 2016). ‘X’ represents the opening of both trampoline parks. 

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To best capture all individuals who had suffered trampoline-related injuries, each period was analysed in a variety of ways. Firstly, the Canterbury District Health Board (CDHB) Decision Support Unit searched the diagnostic codes of all admitted patients, and the trauma type codes of all presentations to the emergency department, for ‘tramp’ or ‘trampoline’. All findings were then manually sorted to ensure those captured had presented after using a trampoline. From this information demographic (age and sex) data, injury diagnosis, injury treatment and length of hospital stay were collected. Secondly, the CDHB operating theatre booking system was used to manually review all orthopaedic operations conducted during each period and record those which involved patients who were injured during trampoline use. The only procedures undertaken on trampoline-related injuries during each period were orthopaedic other than one tooth extraction. This ensured to our best efforts that no major trauma requiring operative intervention would be missed from our data collection.

The Accident Compensation Corporation (ACC) of New Zealand is a publicly funded organisation that provides treatment for accidental injuries. The ACC is also involved in injury prevention strategies and recording statistics of accidental injuries in New Zealand. The ACC provided Christchurch-wide data for each period about all trampoline claims, all lower leg fracture claims in Christchurch and all trampoline and lower leg fracture claims in Christchurch.

Following local human ethics approval (New Zealand Northern A Regional Ethics Committee 17/NTA/1) information sheets were distributed to all those identified in Period C. One week after participants had received the information sheets they were then contacted via telephone. The primary contact as listed by each patient was used to identify either the patient or caregiver needed to complete the questionnaire. For those under the age of 16, parents were contacted if not listed as primary contact. Verbal consent was then acquired and a standardised dialogue was used to fill a questionnaire. The questionnaire collected additional data regarding location of injury, mechanism of injury, number of trampoline users at time of injury and the degree of adult supervision (Appendix 1).

Data collected was analysed using SAS 9.3 computer software. The data was skewed and therefore analysed using a non-parametric Kruskal-Wallis test to see if there was any overall difference among the three time periods. A p-value of 0.01 suggests such difference exists and hence multiple pairwise testing was done to further determine which pair dominates the detected differences. Bonferroni correction has been accounted for, so pairwise comparison is considered significant only if the p-value is less than 0.0167 (ie, 0.05/3).

Results

There were 602 trampoline-related ACC injury claims in Christchurch and 106 hospital presentations during Period C (both parks open). This was a significant increase (p<0.01) in comparison to both Period A (333 injury claims, 37 hospital presentations) and Period B (201 claims, 15 hospital presentations) (Table 1). All injuries sustained in Periods A and B occurred on domestic/home trampolines. There was a significant difference (p<0.01) in length of stay (LOS) between Period C and both Periods A and B (Table 1). Those injured in Period C who were admitted to hospital stayed for one additional day compared to the other two periods (Table 1). The following analysis applies to the 106 hospital presentations in Period C.

Table 1: Hospital presentations by sex, age, admission, length of stay and anatomical location of injury during all three examined periods.

 

Period A

Period B

Period C

 

n

%

n

%

n

%

p-value

Total number of cases

37

 

15

 

106

 

 

Sex

Male

18

48.65

6

 40

58

54.72

0.51

Female

19

51.35

9

 60

48

45.28

 

Age (years)

Median (IQR)

5 (4–12)

 

11 (4–13)

 

13.5 (8–21)

 

<0.01

Range

1–24

 

1–41

 

1–44

 

 

Age group (years)

0–4

17

45.95%

4

26.66%

15

14.15%

<0.01

5–9

7

18.92%

2

13.33%

16

15.09%

 

10–14

8

21.62%

7

46.66%

28

26.42%

 

15–19

4

10.81%

0

0.00%

17

16.03%

 

20–24

1

2.70%

1

6.66%

13

12.26%

 

25+

0

0.00%

1

6.66%

17

16.03%

 

Hospital admission

Yes

21

57%

2

13%

70

66%

<0.01

No

16

43%

13

87%

36

34%

 

Length of stay (days)

Median (IQR)

1 (1–2)

 

1 (1–1)

 

2 (1–3)

 

<0.01

Range

1–3

 

1–1

 

1–8

 

 

Anatomical location of injury

Head

2

5.41%

2

13.33%

5

4.72%

<0.01

Neck/trunk

2

5.41%

0

0.00%

15

14.15%

 

Upper limb

23

62.16%

9

60.00%

31

29.25%

 

Lower limb

10

27.03%

4

26.67%

55

51.89%

  

As reported in Table 1, of hospital presentations during Period C the median age was 13.5 years (IQR=8–21). This represented a significantly older population (p<0.01) than those in Period A (med=5) and Period B (med=11). Figure 1 shows the distribution of injuries involved an older population than those in Period A and B (p<0.01). In period C, most injuries occurred to those in the 10–14 years age group (26%, n=28). There was no significant difference (p=0.51) in sex among all periods with the overall proportion of males composing 52% (n=82/158) and females 48% (n=76/158) respectively.

The Abbreviated Injury Scale (AIS)16 was applied and is an anatomy-based injury severity scoring system, with a scale from 1 (minor) to 6 (unsurvivable). The median AIS in Period A was 2 (IQR=1–2), Period B was 2 (IQR=1–2) and Period C was 1 (IQR=1–2). There was no significant difference (p=0.59) in AIS between each period (Table 1).

The types of the main injuries for hospital presentations are summarised in Figure 2 and were predominantly fractures in all periods—Period A 59% (n=22/37), Period B 73% (n=11/15) and Period C 49% (n=52/106). In Figure 2 ‘Other’ injuries include open wounds, dislocations and head injuries.

Figure 2: Composition of injuries sustained in those presenting to the Christchurch Hospital Emergency Department.

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The response rate to the questionnaire conducted was 60% (n=64/106). No patients declined to be interviewed. Parents/caregivers completed 44 (69%) of the verbal questionnaires. Of those presenting to hospital in Period C; 42% (n=44/106) were injured on a home trampoline, 47% (n=50/106) at a trampoline park with 11% (n=12/106) injured at an unknown location. Thirty-six (34%) were admitted to hospital and 29 (27%) required operative intervention. Operations performed in Period C are reported in Table 2. There was a greater number of surgeries performed on those injured on a home trampoline, and these mostly affected the upper limbs (13/17) (Table 2). All but one of the lower limb and spinal operative procedures were performed on patients injured at a trampoline park (Table 2).Table 2: Operations performed on those injured during Period C grouped by site where injury occurred. Other includes a Tendo-achilles repair, clavicle open reduction internal fixation (ORIF), hip spica, tooth extraction and anterior cruciate ligament repair.

Table 2: Operations performed on those injured during Period C grouped by site where injury occurred. Other includes a Tendo-achilles repair, clavicle open reduction internal fixation (ORIF), hip spica, tooth extraction and anterior cruciate ligament repair.

 

Site of injury

 

Operation

Home

Trampoline park

Unknown

Total number of cases

Supracondylar open/closed Reduction internal fixation

8

0

0

8

Forearm manipulation

5

1

1

7

Spinal stabilisation

0

3

0

3

Lower limb open/closed reduction Internal fixation

0

4

0

4

Patella tendon exploration/repair

1

1

0

2

Other

3

1

1

5

Total

17

10

2

29 

There was a significant difference (p<0.01) in the anatomical location of injury in Period C compared to Periods A and B, with most injuries occurring to the lower limbs (Table 1). Of those injured while both trampoline parks were open (Period C), 29% (n=31/106) suffered upper-limb injuries and 52% (n=55/106) suffered lower-limb injuries. The remaining injuries affected the head (5%, n=5/106) and neck/trunk (14%, n=15/106). Head injuries were composed of two broken noses, two dental injuries and one concussion. Lower-limb injuries occurred in 76% (n=38/50) of patients injured at a trampoline park (Figure 3). Sixty-two percent (n=27/44) of hospital presentations injured on a home trampoline had upper-limb injuries (Figure 3). Two or more people were on the trampoline in 30% (n=32/106) of cases, a single user in 29% (n=31/106) and an unknown number in 41% (n=43/106) of cases. Unknown data includes questionnaire respondents who were uncertain of the number of users or where it is not stipulated in medical documentation for those who did not complete the questionnaire.

Figure 3: Percentage of injuries sustained to each body region during Period C in trampoline parks vs on a home trampoline. 

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There were seven cervical spine, four thoracic spine and three lumbar spine injuries. Of these two were cervical spine fracture/dislocations and two were thoracic spine fractures. The remainder were soft tissue injuries. One thoracic and two cervical spine injuries required admission and surgical intervention with stabilisation—all occurred at a trampoline park. One of those children sustained a life-changing unstable cervical fracture/dislocation.

Trampoline Park One had 35 hospital presentations, which was over twice as many as Trampoline Park Two (n=15). Eight of those 35 injured at Trampoline Park One were admitted for surgical treatment while two of those injured at Trampoline Park Two needed surgery.

Discussion

After the opening of two new trampoline parks the Christchurch Hospital Emergency Department saw a three-fold increase in the number of trampoline-related hospital presentations (Table 1). These presentations were unique in that they affected an older paediatric population with predominantly lower-limb injuries. A significant increase in operative procedures was required to treat trampoline-related injuries with two involving stabilisation of severe cervical spine injuries.

In contrast to past literature about home trampolines, this study found that a significantly older paediatric population was being injured after the two trampoline parks opened. The average age of injury was 13.5 years (IQR=8–21) after both parks opened and five years (IQR=4–12) the year prior when only home trampolines were in use. Kasmire et al compared the demographics of trampoline park versus domestic trampoline injuries and found similarly, that older children were being injured at parks.6 It has been extensively reported that most injuries sustained on home trampolines affect those aged under 10 years.4,5,7,9,10,17 Twenty-eight percent of those injured after the opening of both trampoline parks were over the age of 25 years. This indicates that future research pertaining to trampoline parks should not be restricted to paediatric populations as it risks missing a proportion of those being injured.

Upper-limb injuries often occur after falling from a trampoline.5,7,10,14,17,18 Lower-limb injuries were more common in those injured at trampoline parks compared to home (Figure 3). It is unclear if this reflects a smaller number of upper-limb injuries or that trampoline parks have an intrinsically greater risk of lower-limb injuries. Reasons for a greater risk of lower-limb injuries could include that park trampolines are based at ground level with much padding, reducing the height and force of any falls off the side of a trampoline. This lessens the effect of the injury mechanism of falling from a trampoline on to an outstretched arm, which is the most common cause of upper-limb injury.13,14 However, these parks also have ledges which can be leapt from, opportunities for multiple simultaneous trampoline use and are often used for organised sports such as volleyball/dodgeball. Due to the altered utilisation of trampolines in these settings the forces transmitted through the lower limbs could be much greater. This causes the most common mechanism of injury at a trampoline park to be due to landing—putting the lower limbs at risk.6,19 Appropriate consideration and placement of hard framework and surrounding padding is important to reduce the risk of patrons landing on them with force, thereby reducing the incidence of lower-limb injuries.6

The trampoline park that allowed more than one user on a trampoline at a time had a greater proportion of hospital presentations and surgeries than its comparator. Multiple users on a single trampoline is a known risk factor for injury at trampoline parks and on home trampolines.8,10,11,19,20 Outside of the simple mechanisms of users colliding with each other or becoming entangled and falling awkwardly is the transference of force. Menelaws et al showed using a biomechanical model that two users bouncing out of synchronisation produces a transfer of energy from the larger to the smaller mass.20 This amplifies the relative height of the fall and produces a recoiling hard surface for which the smaller individual is not appropriately flexed and prepared.20 This mechanism in conjunction with a park full of differently sized individuals using multiple trampolines together could be an additional contributor to the over-representation of lower-limb injuries. The allowance of more than one user on a trampoline at a time could account for the disproportionate rate of injury in one park compared to the other and should be avoided.

Having adult supervision and restricting the performance of flips performed on trampolines would likely reduce the risk of serious neck injuries. Cervical spine injuries are often the most potentially catastrophic of all injuries suffered on trampolines and can occur with the performance of flips/somersaults.7,13,21–23 These injuries often occur after a fall onto the trampoline mat.13,22,23 Trampoline parks typically have an area devoted to the performance of flips by untrained patrons into foam pits. No data is present to discern the injury rate of flipping into a foam pit but this activity is likely to propagate the performance of such activities on a home trampoline (if not elsewhere at the park). The prevalence of cervical spine injuries has led both the American and Canadian Paediatric Associations to advise against the use of home trampolines.7,24 Intuitively, adult supervision should produce a safer environment but multiple studies have reported 30–50% of trampoline injuries occur in spite of adult supervision.10,14 The restriction of flips in addition to limiting multiple simultaneous trampoline use would likely be the most effective way to reduce the overall incidence of injuries and specifically cervical spine injuries.

Limitations of this study include the underestimation of injuries, rate of injury reporting and unknown rate of exposure. This study is reliant upon patient presentation and accurate documentation of whether a trampoline was involved in the mechanism of injury. This was mitigated by searching multiple hospital databases with the use of broad search terms such as ‘tramp’ and ‘trampoline’. Despite this the study is likely to have captured a lower number of injuries than occurred. Relative risks are unable to be compared as the underlying rate of exposure to trampolines is unknown. The demographics of the individuals presenting to the trampoline parks were unavailable to the authors as was the exposure rate occurring in private homes.

This study reports the incidence rate of injuries in the new wave of trampoline use, which has not been previously analysed. Future research regarding the injury profile of trampoline parks should be conducted to give greater understanding of their impact on emergency department presentations. There is currently very little in terms of recommendations from regulatory bodies on the safe operation of trampoline parks and further evidence would provide them a greater base to make decisions based on participant safety. Based on these findings, recommendations for the safe operation of trampoline parks should include:

  1. Notification to caregivers that trampolining carries a risk of significant injury
  2. Use of trampolines should be restricted to a single person at a time
  3. Consideration of the placement of structures, netting and padding should be taken and frequently inspected
  4. Somersaults and flips should not be condoned even in the presence of foam pits and adult supervision
  5. Supervising adults should be actively observing patrons, adequately trained and recognise the risk factors for injury as listed above

Conclusion

There has been a significant increase in trampoline-related injuries since the opening of two new parks in Christchurch. These injuries are unusual in that they involve an older paediatric population, affect predominantly the lower limbs and are more severe than those reported from the use of domestic trampolines. Consistent with past research, the trampoline park allowing multiple users had a higher proportion of presentations and more injuries requiring operative intervention. These observations support the need for increased research regarding trampoline park injury profiles—including collection of data in non-paediatric populations—and appropriate regulation to avoid significant injury to patrons.

Appendix 1: Trampoline questionnaire. 

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Summary

Christchurch saw a significant increase in trampoline-related injuries after the opening of two new parks. These injuries involved an older group of children, affected predominantly the lower limbs and were more severe than those reported from the use of domestic trampolines. Consistent with past research, the trampoline park allowing multiple users had a higher proportion of presentations and more injuries requiring operative intervention.

Abstract

Aim

To analyse trampoline-related injuries suffered after the opening of two new trampoline parks in Christchurch.

Method

Data was collected from three 90-day periods. All trampoline-related injuries were collected from electronic documentation and coding. Those injured after both arenas opened were contacted and a semi-structured interview performed.

Results

In the 90 days after both parks opened there were 602 claims for trampoline-related injuries with 106 hospital presentations (55% male). This was a significant increase (p<0.01) from one year earlier (333 claims, 37 hospital presentations) and the 90 days prior to their opening (201 claims, 15 hospital presentations). Most injuries affected an older group of children, aged between 10–14 years (26%, n=28), compared to the other two periods (p<0.01). There was also a greater proportion of lower-limb injuries (52%, n=55) compared to the other two periods (p<0.01). Thirty-six required hospital admission, with 29 operations and an average length of stay of 2.11 days. One trampoline park allowed two or more people to use the same trampoline at the same time, and had over twice as many presentations (33%, n=35) than the other trampoline park (14%, n=15).

Conclusion

Christchurch saw a significant increase in trampoline-related injuries after the opening of two new parks. These injuries involved an older group of children, affected predominantly the lower limbs and were more severe than those reported from the use of domestic trampolines. Consistent with past research, the trampoline park allowing multiple users had a higher proportion of presentations and more injuries requiring operative intervention.

Author Information

Lloyd Roffe, Department of Orthopaedic Surgery and Musculoskeletal Medicine, Canterbury District Health Board, Christchurch; Scott Pearson, Emergency Medicine, Christchurch Hospital, Christchurch; Johnathan Sharr, Department of Orthopaedic Surgery and Musculoskeletal Medicine Canterbury District Health Board, Christchurch; Michael Ardagh, Emergency Department, Christchurch Hospital, Christchurch.

Correspondence

Dr Scott Pearson, Department of Emergency Medicine, Canterbury District Health Board, 2 Riccarton Avenue, Christchurch 8011.

Correspondence Email

scott.pearson@cdhb.health.nz

Competing Interests

Nil.

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