Browsing by Subject "Head"

Traumatic injuries are the leading cause of death to children between the ages of one to nineteen years in the United States. The primary source of these traumatic injuries is motor vehicle traffic, with the head being the primary region of the body to suffer injury. While the pediatric neck is also prone to injury, it is particularly notable since it governs head excursion and acceleration, thus influencing head impacts and injuries. Pediatric fatalities can be prevented through safety improvements to vehicle compartments and child restraints by way of advanced biofidelic pediatric anthropomorphic testing devices (ATDs) and a more complete understanding of pediatric biomechanics. Computer models of the pediatric head and neck provide a valuable tool to combine results from pediatric postmortem human specimen (PMHS), radiological, and human volunteer studies to investigate the dynamics of the pediatric head and neck. The current study produced the first validated computer model of the pediatric head and neck which were created using the framework of a validated adult model. Radiology studies were conducted to determine pediatric cervical muscle cross sectional areas, vertebral anthropometry, and vertebral inertial properties. The results of these studies were combined with available pediatric PMHS properties to create the six and ten year old models. The models were validated against pediatric volunteer low speed frontal impacts and were then used to simulate higher rate and injurious inducing loading scenarios. The six and ten year old flexion bending stiffnesses were found to be 36% and 45% of the adult bending stiffness, respectively. The pediatric tensile stiffnesses were found to be 67% and 76% of the adult tensile stiffness. The tensile failure tolerance of the six year old was between 1490 and 2300 N and of the ten year old between 2040 and 3170 N. The adult and pediatric Hybrid III ATDs were found to be on average 2.5 times stiffer in flexion bending than the computer models. Biofidelity corridors were created with the models to be used to guide future ATD designs. Overall, the pediatric models provide a general tool that can be used to assess the safety of children during motor vehicle crashes.

Child head injury is a very costly problem, both in terms of morbidity/mortality and direct medical costs. In fact, it is the leading cause of death and disability for those in the United States under age 18-years-old. Currently, head injury in children ages newborn to 19-years-old is responsible for 7500 deaths per year--30% of all childhood deaths in the United States. Given its importance and effect on the population, the study of pediatric head injury is greatly hindered by the lack of available pediatric post mortem human specimen (PMHS) data. As a substitute for PMHS testing, anthropometric test devices (ATDs) and finite element models (FEMs) have been developed to model the head. However, there is a dearth of data for the design and validation of these models.

The goal of this study was to use pediatric PMHSs to both advance the study of pediatric head injury and to provide validation data for ATD and finite element head models. 14 pediatric heads, 8 adult heads, and 6 ATD heads were studied to obtain geometrical, inertial, structural stiffness, and impact properties. The computational tomography (CT) method was used on pediatric heads to get inertial properties, and clinical CT scans were used to develop average head and skull contours for 12 different age groups. To obtain impact properties, the heads were dropped onto a rigid plate from 15cm and 30cm, and the acceleration-time pulses were analyzed to obtain acceleration HIC and other impact properties. The heads were then placed between two aluminum plates and compressed at four different rates to obtain structural stiffness values. Using the PMHS results, the ATD heads were compared against age-matched human heads, and the scaling rules used for ATD production were tested for accuracy.

The study found that between the ages of 5-months-old and 22-months-old, the human head was susceptible to fracture from drops as low as 15cm. The structural stiffness of the human head was shown to increase by three orders of magnitude from neonate to adult. For the impact properties, the human head's peak acceleration and head injury criteria increased with age, while the human head's pulse duration and coefficient of restitution decreased with age. The 50th percentile Hybrid III head was found to adequately model the response of the adult head for multiple head impact locations, while the 3-year-old Q3 child ATD was found to be too stiff during impact. Overall, this study provides novel data that can be directly applied to pediatric head injury curves, and pediatric ATD and finite element head models.