The effects of postural support padding modifications to child restraints for children with disability on crash protection

Abstract

Objective Many children with physical disabilities need additional postural support when sitting and supplementary padding is used on standards approved child restraints to achieve this when traveling in a motor vehicle. However, the effect of this padding on crash protection for a child is unknown. This study aimed to investigate the effect of additional padding for postural support on crash protection for child occupants in forward facing child restraints. Methods Forty frontal sled tests at 49 km/h were conducted to compare Q1 anthropometric test device (ATD) responses in a forward-facing restraint, with and without additional padding in locations to increase recline of the restraint, and/or support the head, trunk and pelvis. Three padding materials were tested: cloth toweling, soft foam, and expanded polystyrene (EPS). The influence of padding on head excursion, peak 3 ms head acceleration, HIC15, peak 3 ms chest acceleration and chest deflection were analyzed. Results The influence of padding varied depending on the location of use. Padding used under the restraint to increase the recline angle increased head injury metrics. Toweling in multiple locations which included behind the head increased head excursion and chest injury metrics. There was minimal effect on injury risk measures with additional padding to support the sides of the head or the pelvis position. Rigid EPS foam, as recommended in Australian standards and guidelines, had minimal effect on injury metrics when used inside the restraint, as did tightly rolled or folded toweling secured to the restraint at single locations around the body of the child. Conclusions This study does not support the use of postural support padding to increase recline of a forward-facing restraint or padding behind the head. Recommendations in published standards and guidelines to not use foam that is spongy, soft or easily compressed, with preference for secured firm foam or short-term use of tightly rolled or folded toweling under the child restraint cover is supported. This study also highlights the importance of considering the whole context of child occupant protection when using additional padding, particularly the change in the child’s seated position when adding padding in relation to the standard safety features of the restraint.