Biomechanics of Frontal Skull Fracture

Abstract

The main purpose of the present study was to investigate whether an energy failure level would apply to the skull fracture mechanics in unembalmed post mortem human heads under dynamic frontal loading conditions. A double-pendulum set-up was used to conduct frontal impact tests on specimens from eight unembalmed post mortem human subjects. The specimens were isolated at the occipital condyle level and pre-test computed tomography images were obtained. The specimens were rigidly attached to an aluminum pendulum in an upside down position and obtained a single degree of freedom, allowing motion in the plane of impact. A steel pendulum delivered the impact and was fitted with a flat-surfaced, cylindrical aluminum impactor, which distributed the load to a force sensor. The relative displacement between the two pendulums was measured using a laser sensor and used as a measure for the deformation of the specimen in the plane of impact. Two impact velocity conditions were created: low (3.60±0.24 m/s) or high (5.18±0.04m/s) velocity. Computed tomography and dissection techniques were used to detect pathology. If no fracture was detected, repeated tests on the same specimen were performed with higher impact energy until fracture occurred. Eventually all specimens were fractured. Peak force, displacement and energy variables were used to describe the biomechanics. These preliminary data suggest a positive correlation between impact velocity and energy to fracture. Further experiments are necessary to elucidate the possibility of an energy criterion for skull fracture in head impacts.