Search Results

Each year, over half of the world's 1.17 million fatalities resulting from traffic collisions are pedestrians (World Bank, 2008). Mitigation of such fatalities and serious injuries requires a thorough understanding of the common injury mechanisms that occur in pedestrian impacts. Studying the frequency of injury to each body region and how injury patterns are related may provide additional insight into pedestrian injury mechanisms, which could be used to develop additional prevention strategies. There is a wealth of information regarding pedestrian collisions within national databases that have not been extensively used to investigate these issues to date. This paper presents a review of selected databases that contain information regarding injuries to pedestrians who have been involved in a motor vehicle collision, including the strengths and weaknesses of each in performing this type of analysis.

Head injury is the most common cause of death and acquired disability in childhood. We seek to determine the influence of brain mechanical properties on inertial pediatric brain injury. Large deformation material properties of porcine pediatric and adult brain tissue were measured and represented by a first-order Ogden hyperelastic viscoelastic constitutive model. A 3-D finite element mesh was created of a mid-coronal slice of the brain and skull of a human adult and child (2 weeks old). Three finite element models were constructed: (1) a pediatric mesh with pediatric brain properties, (2) a pediatric mesh with adult tissue properties, and (3) an adult mesh with adult tissue properties. The skull was modeled as a rigid solid and an angular acceleration was applied in the coronal plane with center at C4/C5. The brain is assumed to be homogeneous and isotropic.

Computer finite element model (FEM) simulations are often used as a substitute for human experimental head injury studies to enhance our understanding of injury mechanisms and develop prevention strategies. While numerous adult FEM of the head have been developed, there are relatively few pediatric FEM due to the paucity of material property data for children. Using radiological serial images of infants (<6wks old) and recent published material property data of infant skull and suture, we developed a FEM of the infant head to study skull fracture from occipital impacts. Here we determined the relative importance of brain material properties and anatomical variations in infant suture and scalp tissue on principal stress (σp) estimates in the skull of the model using parametric simulations of occipital impacts from 0.3m falls onto concrete.

Finite element models are increasingly important in understanding head injury mechanisms and designing new injury prevention equipment. Although boundary conditions strongly influence model responses, only limited quantitative data are available. While experimental studies revealed some motion between brain and skull, little data exists regarding the base of the skull. Using magnetic resonance images (MRI) of the caudal brain regions, we measured in vivo, quasi-static angular displacement of the cerebellum (CB) and brainstem (BS) relative to skull, and axial displacement of BS at the foramen magnum in supine human subjects (N=5). Images were obtained in flexion (7° – 54°) and neutral postures using SPAMM tagging technique (N=47 pairs). Rigid body skull rotation angle from neutral posture (θ, degrees) was determined by extracting the edge feature points of the skull, and rotating and displacing the coordinates in one image until they matched those in the other.

The adult head has been studied extensively and computationally modeled for impact, however there have been few studies that attempt to quantify the mechanical properties of the pediatric skull. Likewise, little documentation of pediatric anthropometry exists. We hypothesize that the properties of the human pediatric skull differ from the human adult skull and exhibit viscoelastic structural properties. Quasi-static and dynamic compression tests were performed using the whole head of three human neonate specimens (ages 1 to 11 days old). Whole head compression tests were performed in a MTS servo-hydraulic actuator. Testing was conducted using nondestructive quasi-static, and constant velocity protocols in the anterior-posterior and right-left directions. In addition, the pediatric head specimens were dropped from 15cm and 30cm and impact force-time histories were measured for five different locations: vertex, occiput, forehead, right and left parietal region.