Hip spica casts (or body casts) are commonly applied to young pediatric trauma and hip dysplasia patients. The greatest hip stability in the cast is achieved via fixed hip flexion or abduction and fixed knee flexion. Unfortunately, this fixed position causes difficulties in restraining children for transport because the child cannot typically accommodate their body to the child car seat geometry. The objectives of the current study were to identify a range of reasonable seating options for casted children. These positions were then studied in frontal crash tests to identify the relative injury exposure for the different positions. A revised casting technique was also investigated in an effort to address head-to-cast contact identified during the course of the study.
The current study assessed the ability for different child seats and the vehicle seat belts to accommodate casted 1-year-old and 3-year-old crash test dummies. The restrained dummies were then subjected to frontal 30-mph crash tests with uncasted dummies serving as a control.
In general, traditional child seats were able to accommodate both children; however, the child’s body shifted anteriorly in the cast when the belts were tightened. This shift produced concerns for pulmonary function and the potential for elevated pressure on the superior mesenteric artery. This anterior shift of the chest was reduced when the dummies were restrained by a special hip spica child seat or solely by the vehicle seat belts. When considering all restraint types, the addition of the cast increased the majority of the injury metric magnitudes. For the 3-year-old dummy these increases were determined to be related to the casting technique; an alternative technique significantly reduced the injury metrics.
This study demonstrates that there are anticipated variable effects on basic physiologic function for body-casted children based on the method of restraint. Restraint modalities which place the child forward facing with the face in proximity to the anterosuperior cast overlying the chest should be avoided.
From the Department of Mechanical Engineering (G.O., P.A.), Kettering University; and Department of Orthopaedics (J.Z., J.S., N.W., P.A.), McLaren Regional Medical Center, Flint, Michigan.
Submitted for publication January 9, 2008.
Accepted for publication March 10, 2009.
Supported by a grant from the Kettering Crash Safety Center, the McLaren Research Panel, and a grant from the McLaren Foundation, Flint, Michigan.
Presented, in part, at the annual Michigan Orthopaedics Society meeting, June 2007.
Address for reprints: Patrick J. Atkinson, PhD, Kettering University, Mechanical Engineering Department, 1700 W. Third Avenue, Flint, MI 48504; email: firstname.lastname@example.org.