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Homemade zipline and playground track ride injuries in children
Journal of Pediatric Surgery 52 (2017) 1511–1515
Contents lists available at ScienceDirect
Journal of Pediatric Surgery journal homepage: www.elsevier.com/locate/jpedsurg
Trauma/Critical Care
Homemade zipline and playground track ride injuries in children☆ Christine M. Leeper a,b,⁎, Christine McKenna b, Barbara A. Gaines b a b
Division of General Surgery and Trauma, Department of Surgery, University of Pittsburgh Medical Center, 200 Lothrop Street, Pittsburgh, PA, 15213, USA Children's Hospital of Pittsburgh of UPMC, 7th Floor, Faculty Pavilion, One Children's Hospital Drive, 4401 Penn Avenue, Pittsburgh, PA, 15224, USA
a r t i c l e
i n f o
Article history: Received 11 October 2016 Received in revised form 8 November 2016 Accepted 6 December 2016 Key words: Zipline Injury Playground
a b s t r a c t Background/Purpose: Playground track ride and homemade zipline-related injuries are increasingly common in the emergency department, with serious injuries and even deaths reported. Methods: Retrospective review of the National Electronic Injury Surveillance System (NEISS) database (2009–2015), followed by review of our academic pediatric trauma center's prospectively-maintained database (2005–2013). We included children ages 0–17 years of age with zipline-related injuries. We recorded annual incidence of zipline-related injury, zipline type (homemade or playground), injuries and mechanism. Results: In the NEISS database, 9397 (95%CI 6728–12,065) total zipline-related injuries were reported (45.9% homemade, 54.1% playground). Homemade but not playground injuries increased over time. Common injuries were fracture (49.8%), contusion/laceration (21.2%) and head injury (12.7%). Fall was predominant mechanism (83%). Age 5–9 was most frequently affected (59%). Our center database (n = 35, 40% homemade, 1 fatality) revealed characteristics concordant with NEISS data. Head injury was related to fall height N 5 ft and impact with another structure. Conclusions: Homemade zipline injuries are increasing. Children ages 5–9 are at particular risk and should be carefully supervised. Despite protective surfaces, playground ziplines cause significant head injury, extremity fracture and high rates of hospital admission. Playground surface standards should be reviewed and revised as needed. Level of evidence: Prognosis Study, Level III. © 2017 Elsevier Inc. All rights reserved.
Outdoor play is a means to foster the physical and social development of our youth; however, injuries are common with 218,000 accidental playground incidents sending children to the emergency department each year [1]. Approximately 50,000 of these occur on home equipment [2] and more than 80% occur when children fall to the ground [3]. Track rides, where the child grabs a handle above her head and propels herself from one platform to another parallel platform, are most commonly seen in playground areas (Fig. 1). Homemade ziplines may be of this same variety, however many products have a seat/bar/stand where riders can support themselves as they glide down a gradient on a pulley between two fixed objects. Ziplines are increasingly popular in both public and private recreational areas; however, with new forms of recreation may come unintended consequences, or increased rates of injury. One recent study of emergency department visits from 1997 to 2012 indicates that injuries because of ziplining are on the rise [4] in both
children and adults, though this study omits playground injuries that represent a significant morbidity in children. While zipline devices clearly pose a safety risk to children, there are limited descriptions of zipline-related injuries in a pediatric population [5]; specific risk factors and potential mitigating factors for zipline injuries are not well characterized. We hypothesize that public and privately owned zipline-associated injuries are increasing in prevalence and are a source of morbidity in a pediatric population. Our objective is to evaluate trends using a national sample followed by a more granular evaluation of our single-center cohort of zipline injury patients to better characterize the injury patterns and associated risk factors. We also aim to identify potential areas for intervention and recommend measures to promote safer play. 1. Materials and methods 1.1. National Electronic Injury Surveillance System (NEISS) database
☆ Conflicts of Interest: None. ⁎ Corresponding author at: 7th Floor, Faculty Pavilion, One Children's Hospital Drive, 4401 Penn Avenue, Pittsburgh, PA, 15224. Tel.: +1 412 692 7280; fax: +1 412 692 7426. E-mail addresses: [email protected] (C.M. Leeper), [email protected] (C. McKenna), [email protected] (B.A. Gaines). http://dx.doi.org/10.1016/j.jpedsurg.2016.12.007 0022-3468/© 2017 Elsevier Inc. All rights reserved.
We performed a 7-year retrospective review of the most current data available in the NEISS database (2009–2015) [6]. This publicallyavailable data maintained by the United States Consumer Product Safety Commission (CPSC) is a stratified probability sample of approximately 100 hospitals in the United States. Data points include age, sex, race,
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Fig. 1. Playground zipline or “track ride”.
diagnosis, body part injured, location of injury, post-ED disposition, and a brief narrative [7]. The narrative often contains additional information about the specific location, mechanism and circumstances around the injury event. Variables generated from these data included zipline type (playground or homemade), injuries (closed head injury, fracture, contusion/laceration, sprain/dislocation and miscellaneous), injury mechanism (fall, impact with another structure, equipment failure, second user), disposition (admission or discharge), and age category (0–4 years, 5–9 years, 10–14 years, 15–17 years). All NEISS entries were complete cases. 1.1.1. Subject selection Subjects were included if age 0–17 years, NEISS injury code 3219 “Other playground equipment” and narrative text that specified a zipline injury. The code has been consistent in the database for the duration of the study period and is the recommended code for a zipline injury [8]. Patients were excluded if cause of injury not attributable to zipline or if cause of injury could not be established from the narrative. Subjects were also excluded if injury occurred on commercial zipline, as there were very few subjects and estimates too unstable to perform statistical analysis. 1.1.2. Statistical analysis Hospital weights are provided by the CPSC and are determined by the inverse of the probability of selection with adjustments for nonresponse, merged hospitals and changes in the sampling frame [9]. Confidence intervals (CI) were calculated using the coefficient of variation (CV), which is obtained based on the NEISS sample design and calculated from the square root of the variance divided by the estimate. CPSC considers estimates to be unstable and potentially unreliable if the estimate is less than 1200, the number of records used is less than 20, or the CV exceeds 33% [10]. These estimates were included with notation as indicated in tables and figures. All statistical analyses were performed with Stata 13.0 statistical software (StataCorp, College Station, TX). Survey commands were utilized to calculate incidence, proportions, and associations between variables. Tests of association included the Pearson chi-square with second-order Rao and Scott correction as well as logistic regression. 1.2. Benedum pediatric trauma center database We then performed an 8-year retrospective review of patients presenting to our single academic pediatric trauma center between 1/1/2006 and 12/31/2013. Children's Hospital of Pittsburgh of UPMC is a 300 bed pediatric-only facility that provides care to more than
1700 trauma admissions annually. As the region's only level 1 pediatric trauma center, it is the definitive care provider for injured children in Western Pennsylvania as well as parts of West Virginia and Ohio. Our institutional trauma registry, the Benedum Pediatric Trauma Center Database, is prospectively maintained by designated pediatric trauma registrars and trained data abstractors. This database was queried for all trauma patients age 0–17 with zipline-related injury based on ecodes and free text documentation of injury mechanism. There were no changes in local zipline regulations or documentation across the two time periods. Variables of interest included standard patient demographics, type of zipline (homemade or playground), injury mechanism, injuries, cause of injury (e.g. why did the subject fall), fall height, presence/absence of supervision, injury severity score (ISS), surgical procedures, hospital length of stay (LOS) and disposition. Data not available in our trauma database were obtained directly from the electronic health record. All research procedures and analyses conducted for this study were approved by the local institutional review board. 1.2.1. Statistical analysis Data were summarized as mean (SD), median (interquartile range), or percentage. Univariate analysis was conducted to determine association between selected variables and the primary outcome of interest, mortality. Student's t-test was used for normally distributed continuous data, Wilcoxon rank-sum testing for skewed continuous data, and chi-square or Fisher exact test were used for categorical data. Youden index (J), which maximizes sensitivity and specificity (vertical distance on the ROC curve) across various cutoff points, was utilized to determine the optimum cutoff point for fall height in predicting head injury [11]. The Youden index was calculated using the formula [J = sensitivity + specificity – 1]. Sample size was insufficient to support adequately-powered multivariate analyses. Differences were considered significant for p b 0.05. 2. Results 2.1. National Electronic Injury Surveillance System (NEISS) database The total estimated zipline injuries resulting in ED visits was 9397 (95% CI 6728–12,065) for the 2009–2015 time interval (Table 1). Overall, 45.9% of injuries occurred on homemade ziplines and 54.1% occurred on playground ziplines. Injury type was 49.8% fracture, 21.2% contusion/laceration, 12.7% head injury, 10.4% sprain/dislocation and 5.1% other. Fall as a mechanism of injury was by far the most frequent (83%), with impact against another structure (11%), equipment failure (3.8%) and second user on the line (2.3%) representing less common causes. Regarding disposition, 11% required admission and 89% were discharged or left from the emergency department. Sex was evenly distributed with 49.7% female and 50.3% male. Median (IQR) age was 8 (6–11), with age categories as follows: 0–4 years =4.3%, 5–9 years =59.0%, 10–14 years =25.5%, 15–17 years =11.2%. Both height of fall and parental supervision were inconsistently documented, and the amount of missing data precluded analysis of these variables. In a comparison of playground versus homemade injuries (Table 1), there was no difference in sex between groups (p = NS). As expected, younger children (age ≤ 9) were more likely to be injured on playground equipment and older children and adolescents (age N 9) were more likely to be injured on homemade devices, likely because of the difference in usage rates of each type. There were significantly more fractures in the playground group and more contusions/lacerations in the homemade group (p b 0.001). Surprisingly, the amount of head injury was the same between groups as was the rate of hospital admission (p = NS). The trend over time revealed an increase in the overall prevalence of zipline injuries. Interestingly, increases in homemade ziplines accounted for this phenomenon, with the number of playground injuries remaining relatively consistent across the time period (Fig. 2).
C.M. Leeper et al. / Journal of Pediatric Surgery 52 (2017) 1511–1515
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Table 1 NEISS pediatric zipline injury estimates, 2009–2015. Overall estimate (95% CI) Age 0–4 5–9 10–14 15–17 Sex Female Male Disposition Admitted Discharged Injuries Fracture Contusion/Laceration Head injury Dislocation/Sprain Misc Mechanism Fall Impact another structure Equipment failure Second user
Proportion %
Homemade Est. (95% CI)
Proportion %
Playground Est. (95% CI)
Proportion %
P value
533 (161–900) 7356 (5326–9386) 3787 (2532–5043) 1401 (697–2105)
4.3% 59.0% 25.5% 11.2%
94⁎ (15–172) 2311 (1301–3321) 2754 (1619–3888) 1140 (550–1730)
1.6% 40.4% 48.2% 19.9%
439⁎ (91–787) 5045 (3596–6494) 1034 (552–1516) 261⁎ (0–609)
6.5% 74.8% 15.3% 3.9%
0.004 b0.001 b0.001 0.004
6199 (4254–8143) 6265 (4624–7907)
49.7% 50.3%
2775 (1723–3827) 2940 (1840–4040)
48.6% 51.4%
3423 (2241–4606) 3326 (2211–4440)
50.7% 49.3%
NS
11% 89%
501⁎ (239–764) 5214 (3565–6862)
8.8% 91.2%
812⁎ (306–1319) 5937 (4104–7769)
12% 88%
NS
6198 (4530–7866) 2733 (1771–3696) 1576 (570–2582) 1299 (695–1904) 636⁎ (253–1019)
49.8% 22.0% 12.7% 10.4% 5.1%
1982 (1125–2840) 1961 (1105–2817) 870⁎ (451–1289) 696⁎ (252–1139) 191⁎ (5–378)
34.8% 34.4% 15.3% 12.2% 3.3%
4215 (2957–5473) 772⁎ (350–1195) 706⁎ (0–1494) 604⁎ (240–968) 445⁎ (107–784)
62.5% 11.5% 10.5% 9.0% 6.6%
b0.001 b0.001 NS NS NS
10,308 (7630,12986) 1393 (708–2079) 472⁎ (91–853) 284⁎ (37–532)
83% 11% 3.8% 2.3%
4363 (3016–5710) 911⁎ (406–1416) 169⁎ (0–346) 153⁎ (5–302)
76.4% 16.0% 5.3% 2.3%
5945 (4145–7744) 482⁎ (98,867) 303⁎ (39–568) 131⁎ (0–331)
88.1% 7.1% 2.5% 2.3%
0.016 0.033 NS NS
1314 (727–1900) 11,150 (8258–14,042)
Key: ⁎ Potentially unstable.
2.2. Benedum pediatric trauma center database 2.2.1. Demographics and patient characteristics A search of our single center yielded a total of 30 children who sustained a zipline injury in our defined time period; 12 (40%) of these were homemade, 18 (60%) were playground. There were no reported injuries on commercial ziplines. The median age was 7.5 (6–11) with age categories 0–4 (10.0%), 5–9 (56.7%), 10–14 (20.0%) 15–17 (13.3%). Females accounted for 53.3%. The median (IQR) ISS was 5 (4–9), ranging from 0 to 26. A total of 18 children (60%) underwent operative intervention (17 for fracture fixation, 1 to repair perineal laceration). There was one fatality from severe trauma. 33/34 were admitted to the floor and 1/34 was admitted to the ICU. Median (IQR) length of stay was 1 (1–2) days with a range of 0–3 days, and all surviving patients were discharged to home.
2.2.2. Injuries/Mechanism Overall, 63% (n = 19) of patients sustained an extremity fracture, all but one of which involved the upper extremity; seventeen of these required operative intervention. A total of 33% (n = 10 subjects) sustained a head injury that included skull fracture (n = 2), intracranial hemorrhage (n = 3) and concussion (n = 9). There was a single mortality in our study, a 13 year-old male who was injured when a securing bolt on a homemade zipline broke and struck him in the head, causing him to fall 3.5 ft from the line. His injuries included multiple skull fractures, severe cerebral edema and ultimately brain death. The most common mechanism of injury was fall (86%) followed by impact with another surface (including tree, wall, second user, zipline equipment) (14%). The cause of the incidents included lost grip (19), dismount failure (6), second user on the line (3), and equipment failure (2). When supervision was documented, a parent/caretaker was reported to be
Fig. 2. Estimated zipline-related injuries by zipline type.
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present for 78% (18/23) of the incidents, but seldom directly involved with the children at play (1/18). 2.2.3. Injury patterns Regarding the trend, there was an increase in the overall incidence of zipline injuries over time, with significantly more seen in the later portion of the study period (n = 21, 2011–2013) as compared to the earlier period (n = 9, 2007–2010) (p = 0.001) (Fig. 3). The small sample size precluded breakdown by zipline type. Older children tended to use homemade ziplines while younger children tended to use playground ziplines (p = 0.01), which is concordant with the NEISS data. There was no significant difference in the incidence of head injury based on zipline type (p = 0.084) or age category (p = 0.294). Not surprisingly, head injury was associated with greater fall height (p = 0.007) and with impact against a surface other than the ground (e.g. tree, rocks) (p = 0.004). For subjects of any age, every one foot increase in zipline height was associated with a 40% increased probability of head injury (OR 1.40, p = 0.044) after a fall. Youden index revealed that fall height N 5 ft had the highest sensitivity (90.0%) and specificity (90.0%) to predict head injury. 3. Discussion Zipline injuries result in significant morbidity and costs to patients and families. The incidence of homemade zipline-associated injuries is increasing, while the incidence of playground injuries appears to be stable. The popularity and accessibility of ziplines has increased in recent years; retail zipline kits are readily available and do-it-yourself instructions widely circulated on the Internet. While these devices offer the benefits of outdoor play and gross motor development, the consequence of zipline injuries is significant: injuries from both homemade and playground zipline use can be severe. According to both national data and our local data, children age 5–9 seem to be particularly vulnerable to playground-related injury [1]. The most common causes behind zipline-related incidents in this age group were losing grip, which indicates inadequate strength, and dismount failure, which indicates inadequate judgment. Track rides require a skill set that includes balance, coordination and upper body strength. Importantly, zip lines also require the judgment to know when it is safe to let go. The United States CPSC cites these factors in recommending that children be at least five years of age before utilizing
zip line equipment [3]. However, our data suggest that not all children within this age group has mastered these skills to a sufficient degree, and individual development should be taken into account prior to allowing independent use of playground equipment. Grip strength is another contributing factor; Ehrlich and colleagues determined that breakaway strength was decreased for children of all ages using larger diameter hand holds [12]. While zipline design and handhold diameter were not available in our analysis, this represents another potential area for intervention to decrease falls and related injuries. Both in our study and in the national data, the most common mechanism of injury for all playground equipment is a fall [1]. There is a significant body of literature to suggest that for playground injuries in general, the risk and severity of fall injuries is directly related to the fall height and the adequacy of the protective surfacing beneath the equipment [13–17]. In our local cohort, increasing fall height was significantly associated with head injury, and fall height N 5 ft had the highest sensitivity and specificity to predict head injury. A larger cohort is needed to confirm this finding and evaluate the protective effects of safety equipment (helmets). Playground surfaces beneath track rides must meet standards set forth by the American Society for Testing & Materials (ASTM) [3]. The odds of being injured from a playground fall on an impact absorbing surface (bark chips, sand, rubber matting/tiles) are less than half than on a non-impact absorbing surface (grass, asphalt, concrete) [18,19]. Since the implementation of guidelines for playground surfaces, the incidence of head injury is reported to be low in various studies of playground-related injury [15]. However, some studies found that even impact-reducing surfaces that are compliant with existing safety standards do not protect children from arm fracture [20]; our data support this claim given the prevalence of extremity fracture on playground zip lines in both national and local cohorts. In light of this information, a review of the current surface standards would be appropriate. The surfaces below homemade zip lines obviously are not constrained by the ASTM impact-reducing guidelines; based on the injury narratives, surfaces included dirt, bodies of water, concrete and rocks. The non-protective surfaces likely explain the increased incidence in contusions and lacerations for subjects using homemade ziplines. While we also expected to see a greater incidence of head injury on homemade ziplines for this reason, surprisingly, the amount of head injury as well as the need for hospital admission was comparable for playground versus homemade ziplines. We surmise that this is
Fig. 3. Percentage of zipline injuries over total trauma admissions.
C.M. Leeper et al. / Journal of Pediatric Surgery 52 (2017) 1511–1515 Table 2 Consumer Product Safety Commission recommendations regarding zipline use. 1) For use by children age 5 or greater 2) Takeoff areas, landing areas and the length of the track should remain clear of any obstacles 3) The handle should be between 64 in. and 78 in. from the surfacing and follow the gripping recommendations 4) Nothing should ever be tied or attached to any moving part of a track ride 5) Rolling parts should be enclosed to prevent crush hazards.
because of the younger age in relation to the height of the fall for the subjects on playgrounds, or the inability of younger children to maneuver and protect their head during a fall. The equal incidence of head injury represents another impetus for the current playground surface standards to be reviewed. In our local cohort, there was a single mortality, a 13-year-old boy who sustained massive head injury after the zip line securing system failed and struck him in the head. Other fatalities have been reported by news outlets, with cause of death being severe traumatic brain injury because of fall, impact with other structures, and equipment malfunction [21–26]. While uncommon, death is a tragic and avoidable outcome with implementation of proper safety regulations and rigorous industry standards. 3.1.1. Limitations The single center design is limited because of small sample size and relative low frequency of this injury type. Further, our patient database captures only hospital admissions; while the admission rate is relatively high following zipline-related injuries, this excludes the majority of patients seen after zipline incidents who are treated in the emergency department and discharged home. For this reason, we sought a national sample to facilitate a more robust investigation of zipline-related injuries. However, NEISS estimates are based on a weighted sample of hospital emergency rooms, and these estimates may differ from the true population incidence. Our study was further limited by access to only a brief narrative from the NEISS database, which did not always contain specifics of the injury event such as parental supervision, fall height, or injury mechanics. Finally, while anecdotal evidence confirms that these incidents can be fatal, the low incidence of mortality after ziplinerelated incidents and the limits of NEISS in capturing mortality data prevent reliable conclusions about zipline-associated deaths. Further study should include a larger sample to increase the precision of estimates. 3.1.2. Conclusions and recommendations There is inherent danger in ziplining, as with all other recreational adventure activities, however there are risk mitigation strategies to minimize dangers and allow children to participate in fun and developmentally appropriate activities. The CPSC has issued guidelines regarding zipline use (Table 2) [3]. In order to decrease the incidence and impact of zipline-related injuries, we make the following additional recommendations (Table 3): 1) A review of current playground safety standards should be undertaken to determine if they are sufficient to protect from injury; 2) Homemade and playground zipline activity should be closely supervised in children ages 5–9 and avoided entirely in children age b 5; 3) Homemade and playground zip lines should follow current guidelines or instructions to ensure appropriate installation, positioning and use; 4) Zip lines greater than 5 ft in height should be used with caution, because of the increased risk of head injury with increasing zipline height
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Table 3 Additional recommendations for zipline safety based on study results. 1) A review of current playground safety standards should be undertaken to determine if they are sufficient to protect from injury 2) Homemade and playground zipline activity should be closely supervised in children ages 5–9 and avoided entirely in children age b 5 3) Homemade and playground zip lines should follow current guidelines or instructions to ensure appropriate installation, positioning and use 4) Zip lines greater than 5 ft in height should be used with caution, because of the increased risk of head injury with increasing zipline height
References [1] O'Brien C. Injuries and investigated deaths associated with playground equipment, 2001–2008. Washington, DC: U.S. Consumer Product Safety Commission; 2009. [2] U.S. Consumer Product Safety Commission. Outdoor home product safety handbook; 2005[Bethesda MD]. [3] U.S. Consumer Product Safety Commission. Public playground safety handbook; 2010[Bethesda MD]. [4] Billock RM, Anderegg JJ, Mehan TJ, et al. Zipline-related injuries treated in US EDs, 1997-2012. Am J Emerg Med 2015;33(12):1745–9. [5] Nixon JW, Acton CH, Wallis BA, et al. Preventing injuries on horizontal ladders and track rides. Inj Control Saf Promot 2004;11(4):219–24. [6] National Electronic Injury Surveillance System. U.S. Consumer Product Safety Commission; archived full NEISS data: 2009–2015. http://www.cpsc.gov/en/Research– Statistics/NEISS-Injury-Data/. [7] U.S. Consumer Product Safety Commission. NEISS coding manual January 2016; 2016. [8] U.S. Consumer Product Safety Commission. NEISS product code comparability table January 2016; 2016. [9] Schroeder T, Ault K. The NEISS sample (design and implementation) 1997-present; 2001. [10] U.S. Consumer Product Safety Commission. Explanation of NEISS estimates obtained through the CPSC website. http://www.cpsc.gov/cgibin/neiss/webestimates. html#hist;2016. [accessed August 1, 2016]. [11] Youden WJ. Index for rating diagnostic tests. Cancer 1950;3(1):32–5. [12] Ehrlich PF, Young JG, Ulin S, et al. Maximum hand-rung coupling forces in children: the effects of handhold diameter. Hum Factors 2013;55(3):545–56. [13] Forero Rueda MA, Gilchrist MD. Comparative multibody dynamics analysis of falls from playground climbing frames. Forensic Sci Int 2009;191(1–3):52–7. [14] Laforest S, Robitaille Y, Lesage D, et al. Surface characteristics, equipment height, and the occurrence and severity of playground injuries. Inj Prev 2001;7(1): 35–40. [15] Mott A, Rolfe K, James R, et al. Safety of surfaces and equipment for children in playgrounds. Lancet 1997;349(9069):1874–6. [16] Sherker S, Ozanne-Smith J, Rechnitzer G, et al. Out on a limb: risk factors for arm fracture in playground equipment falls. Inj Prev 2005;11(2):120–4. [17] Vollman D, Witsaman R, Comstock RD, et al. Epidemiology of playground equipmentrelated injuries to children in the United States, 1996-2005. Clin Pediatr (Phila) 2009;48(1):66–71. [18] Chalmers DJ, Marshall SW, Langley JD, et al. Height and surfacing as risk factors for injury in falls from playground equipment: a case–control study. Inj Prev 1996; 2(2):98–104. [19] Bertocci GE, Pierce MC, Deemer E, et al. Influence of fall height and impact surface on biomechanics of feet-first free falls in children. Injury 2004;35(4): 417–24. [20] Choi WJ, Kaur H, Robinovitch SN. Measurement of the effect of playground surface materials on hand impact forces during upper limb fall arrests. J Appl Biomech 2014;30(2):276–81. [21] NBC 10 News. Boy, 10, injured in zip line accident dies, January 24th 2014; 2014[accessed August 24, 2016]. [22] Stambaugh JJ. Boy dies after accident. Knoxville news sentinel; 2008, TN: Patrick Birmingham CRO, Regional Publisher. [23] WNCN Staff. Girl killed in zipline accident at camp cheerio identified, June 12, 2015; 2015[accessed August 24, 2016]. [24] Investigators: Helmet strap strangled boy on zip line. Associated Press KPIC Roseberg Oregon, CBS Thursday, September 27th 2012. [25] Benson P. East Valley boy scout dies in zip line accident, January 26, 2015; 2015[accessed August 24, 2016]. [26] Shea K. McCandless family mourns ‘greatest kid’ killed by homemade zip line, June 11, 2014; 2014[accessed August 24, 2016].
Contents lists available at ScienceDirect
Journal of Pediatric Surgery journal homepage: www.elsevier.com/locate/jpedsurg
Trauma/Critical Care
Homemade zipline and playground track ride injuries in children☆ Christine M. Leeper a,b,⁎, Christine McKenna b, Barbara A. Gaines b a b
Division of General Surgery and Trauma, Department of Surgery, University of Pittsburgh Medical Center, 200 Lothrop Street, Pittsburgh, PA, 15213, USA Children's Hospital of Pittsburgh of UPMC, 7th Floor, Faculty Pavilion, One Children's Hospital Drive, 4401 Penn Avenue, Pittsburgh, PA, 15224, USA
a r t i c l e
i n f o
Article history: Received 11 October 2016 Received in revised form 8 November 2016 Accepted 6 December 2016 Key words: Zipline Injury Playground
a b s t r a c t Background/Purpose: Playground track ride and homemade zipline-related injuries are increasingly common in the emergency department, with serious injuries and even deaths reported. Methods: Retrospective review of the National Electronic Injury Surveillance System (NEISS) database (2009–2015), followed by review of our academic pediatric trauma center's prospectively-maintained database (2005–2013). We included children ages 0–17 years of age with zipline-related injuries. We recorded annual incidence of zipline-related injury, zipline type (homemade or playground), injuries and mechanism. Results: In the NEISS database, 9397 (95%CI 6728–12,065) total zipline-related injuries were reported (45.9% homemade, 54.1% playground). Homemade but not playground injuries increased over time. Common injuries were fracture (49.8%), contusion/laceration (21.2%) and head injury (12.7%). Fall was predominant mechanism (83%). Age 5–9 was most frequently affected (59%). Our center database (n = 35, 40% homemade, 1 fatality) revealed characteristics concordant with NEISS data. Head injury was related to fall height N 5 ft and impact with another structure. Conclusions: Homemade zipline injuries are increasing. Children ages 5–9 are at particular risk and should be carefully supervised. Despite protective surfaces, playground ziplines cause significant head injury, extremity fracture and high rates of hospital admission. Playground surface standards should be reviewed and revised as needed. Level of evidence: Prognosis Study, Level III. © 2017 Elsevier Inc. All rights reserved.
Outdoor play is a means to foster the physical and social development of our youth; however, injuries are common with 218,000 accidental playground incidents sending children to the emergency department each year [1]. Approximately 50,000 of these occur on home equipment [2] and more than 80% occur when children fall to the ground [3]. Track rides, where the child grabs a handle above her head and propels herself from one platform to another parallel platform, are most commonly seen in playground areas (Fig. 1). Homemade ziplines may be of this same variety, however many products have a seat/bar/stand where riders can support themselves as they glide down a gradient on a pulley between two fixed objects. Ziplines are increasingly popular in both public and private recreational areas; however, with new forms of recreation may come unintended consequences, or increased rates of injury. One recent study of emergency department visits from 1997 to 2012 indicates that injuries because of ziplining are on the rise [4] in both
children and adults, though this study omits playground injuries that represent a significant morbidity in children. While zipline devices clearly pose a safety risk to children, there are limited descriptions of zipline-related injuries in a pediatric population [5]; specific risk factors and potential mitigating factors for zipline injuries are not well characterized. We hypothesize that public and privately owned zipline-associated injuries are increasing in prevalence and are a source of morbidity in a pediatric population. Our objective is to evaluate trends using a national sample followed by a more granular evaluation of our single-center cohort of zipline injury patients to better characterize the injury patterns and associated risk factors. We also aim to identify potential areas for intervention and recommend measures to promote safer play. 1. Materials and methods 1.1. National Electronic Injury Surveillance System (NEISS) database
☆ Conflicts of Interest: None. ⁎ Corresponding author at: 7th Floor, Faculty Pavilion, One Children's Hospital Drive, 4401 Penn Avenue, Pittsburgh, PA, 15224. Tel.: +1 412 692 7280; fax: +1 412 692 7426. E-mail addresses: [email protected] (C.M. Leeper), [email protected] (C. McKenna), [email protected] (B.A. Gaines). http://dx.doi.org/10.1016/j.jpedsurg.2016.12.007 0022-3468/© 2017 Elsevier Inc. All rights reserved.
We performed a 7-year retrospective review of the most current data available in the NEISS database (2009–2015) [6]. This publicallyavailable data maintained by the United States Consumer Product Safety Commission (CPSC) is a stratified probability sample of approximately 100 hospitals in the United States. Data points include age, sex, race,
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Fig. 1. Playground zipline or “track ride”.
diagnosis, body part injured, location of injury, post-ED disposition, and a brief narrative [7]. The narrative often contains additional information about the specific location, mechanism and circumstances around the injury event. Variables generated from these data included zipline type (playground or homemade), injuries (closed head injury, fracture, contusion/laceration, sprain/dislocation and miscellaneous), injury mechanism (fall, impact with another structure, equipment failure, second user), disposition (admission or discharge), and age category (0–4 years, 5–9 years, 10–14 years, 15–17 years). All NEISS entries were complete cases. 1.1.1. Subject selection Subjects were included if age 0–17 years, NEISS injury code 3219 “Other playground equipment” and narrative text that specified a zipline injury. The code has been consistent in the database for the duration of the study period and is the recommended code for a zipline injury [8]. Patients were excluded if cause of injury not attributable to zipline or if cause of injury could not be established from the narrative. Subjects were also excluded if injury occurred on commercial zipline, as there were very few subjects and estimates too unstable to perform statistical analysis. 1.1.2. Statistical analysis Hospital weights are provided by the CPSC and are determined by the inverse of the probability of selection with adjustments for nonresponse, merged hospitals and changes in the sampling frame [9]. Confidence intervals (CI) were calculated using the coefficient of variation (CV), which is obtained based on the NEISS sample design and calculated from the square root of the variance divided by the estimate. CPSC considers estimates to be unstable and potentially unreliable if the estimate is less than 1200, the number of records used is less than 20, or the CV exceeds 33% [10]. These estimates were included with notation as indicated in tables and figures. All statistical analyses were performed with Stata 13.0 statistical software (StataCorp, College Station, TX). Survey commands were utilized to calculate incidence, proportions, and associations between variables. Tests of association included the Pearson chi-square with second-order Rao and Scott correction as well as logistic regression. 1.2. Benedum pediatric trauma center database We then performed an 8-year retrospective review of patients presenting to our single academic pediatric trauma center between 1/1/2006 and 12/31/2013. Children's Hospital of Pittsburgh of UPMC is a 300 bed pediatric-only facility that provides care to more than
1700 trauma admissions annually. As the region's only level 1 pediatric trauma center, it is the definitive care provider for injured children in Western Pennsylvania as well as parts of West Virginia and Ohio. Our institutional trauma registry, the Benedum Pediatric Trauma Center Database, is prospectively maintained by designated pediatric trauma registrars and trained data abstractors. This database was queried for all trauma patients age 0–17 with zipline-related injury based on ecodes and free text documentation of injury mechanism. There were no changes in local zipline regulations or documentation across the two time periods. Variables of interest included standard patient demographics, type of zipline (homemade or playground), injury mechanism, injuries, cause of injury (e.g. why did the subject fall), fall height, presence/absence of supervision, injury severity score (ISS), surgical procedures, hospital length of stay (LOS) and disposition. Data not available in our trauma database were obtained directly from the electronic health record. All research procedures and analyses conducted for this study were approved by the local institutional review board. 1.2.1. Statistical analysis Data were summarized as mean (SD), median (interquartile range), or percentage. Univariate analysis was conducted to determine association between selected variables and the primary outcome of interest, mortality. Student's t-test was used for normally distributed continuous data, Wilcoxon rank-sum testing for skewed continuous data, and chi-square or Fisher exact test were used for categorical data. Youden index (J), which maximizes sensitivity and specificity (vertical distance on the ROC curve) across various cutoff points, was utilized to determine the optimum cutoff point for fall height in predicting head injury [11]. The Youden index was calculated using the formula [J = sensitivity + specificity – 1]. Sample size was insufficient to support adequately-powered multivariate analyses. Differences were considered significant for p b 0.05. 2. Results 2.1. National Electronic Injury Surveillance System (NEISS) database The total estimated zipline injuries resulting in ED visits was 9397 (95% CI 6728–12,065) for the 2009–2015 time interval (Table 1). Overall, 45.9% of injuries occurred on homemade ziplines and 54.1% occurred on playground ziplines. Injury type was 49.8% fracture, 21.2% contusion/laceration, 12.7% head injury, 10.4% sprain/dislocation and 5.1% other. Fall as a mechanism of injury was by far the most frequent (83%), with impact against another structure (11%), equipment failure (3.8%) and second user on the line (2.3%) representing less common causes. Regarding disposition, 11% required admission and 89% were discharged or left from the emergency department. Sex was evenly distributed with 49.7% female and 50.3% male. Median (IQR) age was 8 (6–11), with age categories as follows: 0–4 years =4.3%, 5–9 years =59.0%, 10–14 years =25.5%, 15–17 years =11.2%. Both height of fall and parental supervision were inconsistently documented, and the amount of missing data precluded analysis of these variables. In a comparison of playground versus homemade injuries (Table 1), there was no difference in sex between groups (p = NS). As expected, younger children (age ≤ 9) were more likely to be injured on playground equipment and older children and adolescents (age N 9) were more likely to be injured on homemade devices, likely because of the difference in usage rates of each type. There were significantly more fractures in the playground group and more contusions/lacerations in the homemade group (p b 0.001). Surprisingly, the amount of head injury was the same between groups as was the rate of hospital admission (p = NS). The trend over time revealed an increase in the overall prevalence of zipline injuries. Interestingly, increases in homemade ziplines accounted for this phenomenon, with the number of playground injuries remaining relatively consistent across the time period (Fig. 2).
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Table 1 NEISS pediatric zipline injury estimates, 2009–2015. Overall estimate (95% CI) Age 0–4 5–9 10–14 15–17 Sex Female Male Disposition Admitted Discharged Injuries Fracture Contusion/Laceration Head injury Dislocation/Sprain Misc Mechanism Fall Impact another structure Equipment failure Second user
Proportion %
Homemade Est. (95% CI)
Proportion %
Playground Est. (95% CI)
Proportion %
P value
533 (161–900) 7356 (5326–9386) 3787 (2532–5043) 1401 (697–2105)
4.3% 59.0% 25.5% 11.2%
94⁎ (15–172) 2311 (1301–3321) 2754 (1619–3888) 1140 (550–1730)
1.6% 40.4% 48.2% 19.9%
439⁎ (91–787) 5045 (3596–6494) 1034 (552–1516) 261⁎ (0–609)
6.5% 74.8% 15.3% 3.9%
0.004 b0.001 b0.001 0.004
6199 (4254–8143) 6265 (4624–7907)
49.7% 50.3%
2775 (1723–3827) 2940 (1840–4040)
48.6% 51.4%
3423 (2241–4606) 3326 (2211–4440)
50.7% 49.3%
NS
11% 89%
501⁎ (239–764) 5214 (3565–6862)
8.8% 91.2%
812⁎ (306–1319) 5937 (4104–7769)
12% 88%
NS
6198 (4530–7866) 2733 (1771–3696) 1576 (570–2582) 1299 (695–1904) 636⁎ (253–1019)
49.8% 22.0% 12.7% 10.4% 5.1%
1982 (1125–2840) 1961 (1105–2817) 870⁎ (451–1289) 696⁎ (252–1139) 191⁎ (5–378)
34.8% 34.4% 15.3% 12.2% 3.3%
4215 (2957–5473) 772⁎ (350–1195) 706⁎ (0–1494) 604⁎ (240–968) 445⁎ (107–784)
62.5% 11.5% 10.5% 9.0% 6.6%
b0.001 b0.001 NS NS NS
10,308 (7630,12986) 1393 (708–2079) 472⁎ (91–853) 284⁎ (37–532)
83% 11% 3.8% 2.3%
4363 (3016–5710) 911⁎ (406–1416) 169⁎ (0–346) 153⁎ (5–302)
76.4% 16.0% 5.3% 2.3%
5945 (4145–7744) 482⁎ (98,867) 303⁎ (39–568) 131⁎ (0–331)
88.1% 7.1% 2.5% 2.3%
0.016 0.033 NS NS
1314 (727–1900) 11,150 (8258–14,042)
Key: ⁎ Potentially unstable.
2.2. Benedum pediatric trauma center database 2.2.1. Demographics and patient characteristics A search of our single center yielded a total of 30 children who sustained a zipline injury in our defined time period; 12 (40%) of these were homemade, 18 (60%) were playground. There were no reported injuries on commercial ziplines. The median age was 7.5 (6–11) with age categories 0–4 (10.0%), 5–9 (56.7%), 10–14 (20.0%) 15–17 (13.3%). Females accounted for 53.3%. The median (IQR) ISS was 5 (4–9), ranging from 0 to 26. A total of 18 children (60%) underwent operative intervention (17 for fracture fixation, 1 to repair perineal laceration). There was one fatality from severe trauma. 33/34 were admitted to the floor and 1/34 was admitted to the ICU. Median (IQR) length of stay was 1 (1–2) days with a range of 0–3 days, and all surviving patients were discharged to home.
2.2.2. Injuries/Mechanism Overall, 63% (n = 19) of patients sustained an extremity fracture, all but one of which involved the upper extremity; seventeen of these required operative intervention. A total of 33% (n = 10 subjects) sustained a head injury that included skull fracture (n = 2), intracranial hemorrhage (n = 3) and concussion (n = 9). There was a single mortality in our study, a 13 year-old male who was injured when a securing bolt on a homemade zipline broke and struck him in the head, causing him to fall 3.5 ft from the line. His injuries included multiple skull fractures, severe cerebral edema and ultimately brain death. The most common mechanism of injury was fall (86%) followed by impact with another surface (including tree, wall, second user, zipline equipment) (14%). The cause of the incidents included lost grip (19), dismount failure (6), second user on the line (3), and equipment failure (2). When supervision was documented, a parent/caretaker was reported to be
Fig. 2. Estimated zipline-related injuries by zipline type.
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present for 78% (18/23) of the incidents, but seldom directly involved with the children at play (1/18). 2.2.3. Injury patterns Regarding the trend, there was an increase in the overall incidence of zipline injuries over time, with significantly more seen in the later portion of the study period (n = 21, 2011–2013) as compared to the earlier period (n = 9, 2007–2010) (p = 0.001) (Fig. 3). The small sample size precluded breakdown by zipline type. Older children tended to use homemade ziplines while younger children tended to use playground ziplines (p = 0.01), which is concordant with the NEISS data. There was no significant difference in the incidence of head injury based on zipline type (p = 0.084) or age category (p = 0.294). Not surprisingly, head injury was associated with greater fall height (p = 0.007) and with impact against a surface other than the ground (e.g. tree, rocks) (p = 0.004). For subjects of any age, every one foot increase in zipline height was associated with a 40% increased probability of head injury (OR 1.40, p = 0.044) after a fall. Youden index revealed that fall height N 5 ft had the highest sensitivity (90.0%) and specificity (90.0%) to predict head injury. 3. Discussion Zipline injuries result in significant morbidity and costs to patients and families. The incidence of homemade zipline-associated injuries is increasing, while the incidence of playground injuries appears to be stable. The popularity and accessibility of ziplines has increased in recent years; retail zipline kits are readily available and do-it-yourself instructions widely circulated on the Internet. While these devices offer the benefits of outdoor play and gross motor development, the consequence of zipline injuries is significant: injuries from both homemade and playground zipline use can be severe. According to both national data and our local data, children age 5–9 seem to be particularly vulnerable to playground-related injury [1]. The most common causes behind zipline-related incidents in this age group were losing grip, which indicates inadequate strength, and dismount failure, which indicates inadequate judgment. Track rides require a skill set that includes balance, coordination and upper body strength. Importantly, zip lines also require the judgment to know when it is safe to let go. The United States CPSC cites these factors in recommending that children be at least five years of age before utilizing
zip line equipment [3]. However, our data suggest that not all children within this age group has mastered these skills to a sufficient degree, and individual development should be taken into account prior to allowing independent use of playground equipment. Grip strength is another contributing factor; Ehrlich and colleagues determined that breakaway strength was decreased for children of all ages using larger diameter hand holds [12]. While zipline design and handhold diameter were not available in our analysis, this represents another potential area for intervention to decrease falls and related injuries. Both in our study and in the national data, the most common mechanism of injury for all playground equipment is a fall [1]. There is a significant body of literature to suggest that for playground injuries in general, the risk and severity of fall injuries is directly related to the fall height and the adequacy of the protective surfacing beneath the equipment [13–17]. In our local cohort, increasing fall height was significantly associated with head injury, and fall height N 5 ft had the highest sensitivity and specificity to predict head injury. A larger cohort is needed to confirm this finding and evaluate the protective effects of safety equipment (helmets). Playground surfaces beneath track rides must meet standards set forth by the American Society for Testing & Materials (ASTM) [3]. The odds of being injured from a playground fall on an impact absorbing surface (bark chips, sand, rubber matting/tiles) are less than half than on a non-impact absorbing surface (grass, asphalt, concrete) [18,19]. Since the implementation of guidelines for playground surfaces, the incidence of head injury is reported to be low in various studies of playground-related injury [15]. However, some studies found that even impact-reducing surfaces that are compliant with existing safety standards do not protect children from arm fracture [20]; our data support this claim given the prevalence of extremity fracture on playground zip lines in both national and local cohorts. In light of this information, a review of the current surface standards would be appropriate. The surfaces below homemade zip lines obviously are not constrained by the ASTM impact-reducing guidelines; based on the injury narratives, surfaces included dirt, bodies of water, concrete and rocks. The non-protective surfaces likely explain the increased incidence in contusions and lacerations for subjects using homemade ziplines. While we also expected to see a greater incidence of head injury on homemade ziplines for this reason, surprisingly, the amount of head injury as well as the need for hospital admission was comparable for playground versus homemade ziplines. We surmise that this is
Fig. 3. Percentage of zipline injuries over total trauma admissions.
C.M. Leeper et al. / Journal of Pediatric Surgery 52 (2017) 1511–1515 Table 2 Consumer Product Safety Commission recommendations regarding zipline use. 1) For use by children age 5 or greater 2) Takeoff areas, landing areas and the length of the track should remain clear of any obstacles 3) The handle should be between 64 in. and 78 in. from the surfacing and follow the gripping recommendations 4) Nothing should ever be tied or attached to any moving part of a track ride 5) Rolling parts should be enclosed to prevent crush hazards.
because of the younger age in relation to the height of the fall for the subjects on playgrounds, or the inability of younger children to maneuver and protect their head during a fall. The equal incidence of head injury represents another impetus for the current playground surface standards to be reviewed. In our local cohort, there was a single mortality, a 13-year-old boy who sustained massive head injury after the zip line securing system failed and struck him in the head. Other fatalities have been reported by news outlets, with cause of death being severe traumatic brain injury because of fall, impact with other structures, and equipment malfunction [21–26]. While uncommon, death is a tragic and avoidable outcome with implementation of proper safety regulations and rigorous industry standards. 3.1.1. Limitations The single center design is limited because of small sample size and relative low frequency of this injury type. Further, our patient database captures only hospital admissions; while the admission rate is relatively high following zipline-related injuries, this excludes the majority of patients seen after zipline incidents who are treated in the emergency department and discharged home. For this reason, we sought a national sample to facilitate a more robust investigation of zipline-related injuries. However, NEISS estimates are based on a weighted sample of hospital emergency rooms, and these estimates may differ from the true population incidence. Our study was further limited by access to only a brief narrative from the NEISS database, which did not always contain specifics of the injury event such as parental supervision, fall height, or injury mechanics. Finally, while anecdotal evidence confirms that these incidents can be fatal, the low incidence of mortality after ziplinerelated incidents and the limits of NEISS in capturing mortality data prevent reliable conclusions about zipline-associated deaths. Further study should include a larger sample to increase the precision of estimates. 3.1.2. Conclusions and recommendations There is inherent danger in ziplining, as with all other recreational adventure activities, however there are risk mitigation strategies to minimize dangers and allow children to participate in fun and developmentally appropriate activities. The CPSC has issued guidelines regarding zipline use (Table 2) [3]. In order to decrease the incidence and impact of zipline-related injuries, we make the following additional recommendations (Table 3): 1) A review of current playground safety standards should be undertaken to determine if they are sufficient to protect from injury; 2) Homemade and playground zipline activity should be closely supervised in children ages 5–9 and avoided entirely in children age b 5; 3) Homemade and playground zip lines should follow current guidelines or instructions to ensure appropriate installation, positioning and use; 4) Zip lines greater than 5 ft in height should be used with caution, because of the increased risk of head injury with increasing zipline height
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Table 3 Additional recommendations for zipline safety based on study results. 1) A review of current playground safety standards should be undertaken to determine if they are sufficient to protect from injury 2) Homemade and playground zipline activity should be closely supervised in children ages 5–9 and avoided entirely in children age b 5 3) Homemade and playground zip lines should follow current guidelines or instructions to ensure appropriate installation, positioning and use 4) Zip lines greater than 5 ft in height should be used with caution, because of the increased risk of head injury with increasing zipline height
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