Crash safety analysis of currently available vehicular restraint systems for hip spica casted children utilizing specially designed spica-casted pediatric crash test dummies
Grant Recipient: Jeffrey Peck, MD
- Institution:
- McLaren-Fling/Kettering University Michigan
- Additional Information:
- Safe Transport of Spica Casted Children in Passenger Vehicles is Possible: A Frontal Crash Test Analysis of Child Restraint Systems Using Spica Casted Crash Test Dummies
Purpose: There is a paucity of data defining safe transport protocols for children treated with hip spica casting. While restraint devices for casted children are available, all federally mandated testing has been done using non-casted anthropomorphic test devices (ATDs), also known as crash test dummies. No current commercially available or specially designed restraint device has been tested using casted ATDs. In light of this significant lack of data, the purpose of this study was to evaluate current restraint options in simulated frontal crash testing using a casted pediatric ATD to determine injury to the head, cervical spine, chest, and pelvis.
Methods: Using an ATD simulating a 3 year old child, dynamic crash sled tests simulating a frontal crash were performed in accordance with Federal Motor Vehicle Safety Standards 213 (FMVSS 213). Sensors within the ATD recorded the following injury metrics: HIC36 (Head Injury Criterion score; predictive of skull fracture), neck injury assessment (Nij), chest compression (measured via mm and g-force), and pelvic injury assessment (g-force). The FMVSS 213 takes into account the HIC36 and chest compression values and is a “pass/fail” metric. Additionally, visual assessment of the video of the test crashes was also performed by the authors. The ATD was casted in a double-leg spica. Five restraint devices were formally tested: a seat designed for spica casted children (Merrit Wallenberg), a modified restraint harness (Modified EZ-On-Vest), a commercially available booster seat (Britax Parkway SGL Booster), and two commercially available forward facing car seats able to accommodate the casted ATD (Diono Radian R100, Graco Nautilus 65 LX). One test was performed for each restraint system. All tests were performed at 30 MPH on a deceleration sled.
Results: Although the presence of the cast increased many of the injury metrics measured, all 5 seats that were tested passed current FMVSS 213 federal guidelines for the head and chest. However, there were marked differences between the 5 different restraint options (Figures 1-4). Also, while not required as a part of current standard testing protocols, cervical spine injury metrics were elevated beyond generally accepted levels in all seats tested, both with and without a cast (Figure 5). No single seat performed best in all metrics tested. Additionally, visual analysis of the video from the test crash of the EZ-On-Vest demonstrated that the face of the ATD is impacted during the crash, suggesting the possibility of facial fractures and potential upper airway injury. The video also demonstrates that the upper extremities are subjected to impact forces that could result in injury. The ATD does not have a way to record injury to the extremities, thus this is not captured in the quantitative data.
Conclusions: Per the FMVSS 213 standard, these results suggest safe transport in the five evaluated restraint systems is possible with the child properly restrained in a correctly fitting system. However, the Nautilus and Diono were found to have both the lowest HIC36 and chest acceleration values. They performed better than the specially designed Merritt seat or the currently recommended EZ-On Vest suggesting that casted children may not need those specially designed seats if they can fit in to a commercially available car seat. Additionally, while the recorded injury metrics alone would suggest the EZ-On Vest is a safe method of restraint in this population, review of the video appears to demonstrate that the vest may expose the casted child to additional facial and extremity injuries compared to a traditional car seat that allows the child to sit upright. That being said, parents should not assume a restraint system is automatically appropriate for use with their child. Each child and the position of the child’s cast are unique and a caseworker trained in child safety should be consulted to ensure the child is properly restrained. While this work has the potential to reduce the number of spica casted children requiring ambulance transport, it is important to recognize that some children may still require emergency vehicle transport. Collaboration between caregivers, the orthopaedic surgeon, and a trained child seat technician is vital to determine the best transport option for each individual child.
Our primary outcome measures (FMVSS 213, HIC36, Chest acceleration, Nij, and Chest compression forces) were instrumental in the determination of our findings.
The total budget for the project was $30,000. Use of POSNA micro grant funds: $900 for child restraint systems and $100 for casting supplies.
Plans for presentation/publication:
This project was presented at the 2018 Flint Area Medical Education Community Research Forum and the 2018 Michigan Orthopaedic Society Annual Scientific Meeting as well as a Michigan CPS workshop for child passenger safety and hospital social workers. An abstract will be submitted to the POSNA 2019 Annual Meeting. Submission to the Journal of Pediatric Orthopedics is anticipated in the near future.
Side impact crashes account for about one quarter of passenger vehicle occupant deaths in the United States. Therefore, we hope to pursue analysis of side impact crash testing of these seats to further delineate safe transportation options in spica casted children.
Figure 1: HIC36 Scores Figure 2: Pelvic Acceleration
Figure 3: Chest Acceleration Figure 4: Chest Deflection
Figure 5: Nij values (a ratio and therefore does not have a unit)
