Investigation of wound characteristics and the force associated with skull fracture due to impact by a hammer
Master Thesis
2014
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University of Cape Town
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Abstract
Death due to cranial blunt force trauma is a major issue not just in South Africa but worldwide. The vast majority of studies conducted on cranial blunt force trauma have analysed trauma to the frontal portion of the head. This is due to the involvement of the frontal portion of the head in automotive accidents. The lateral portion of the head is however no less important and is often impacted during homicidal assault. In cases involving cranial blunt force trauma, a common question asked of experts relates to the amount of force involved with a particular trauma. The goal of forensic science in general is to provide objective, repeatable results. At present, however, answering this question relies on a subjective rating scale of mild, moderate or severe force. Determining the severity of the force is also subjective, in that it relies heavily on the experience of the expert. Forensic anthropology by its nature is often subjective; however there is a need to move away from conducting analyses based predominantly on the experience of the investigator. With this in mind, this dissertation offers background information on fracture mechanics and impact biomechanics and provides a current review of the literature surrounding lateral impact to the skull. The research conducted as part of this dissertation attempts to quantify the force and energy involved with lateral impact to the skull due to a blow by a hammer, as well as describes the wound morphology associated with such impacts. Human tissue for experimentation is becoming increasingly difficult to acquire. There is therefore a need to determine suitable models for use in such testing. In the current study whole porcine heads were impacted on the fronto-parietal portion of the cranium. Half of the specimens were impacted with an implement resembling the shape and weight of a hammer. These hammer tests were conducted primarily to determine the type of trauma associated with such impacts and determine if a correlation exists between velocity or energy of impact and the level of trauma sustained. The remaining specimens were impacted with a Hopkinson pressure bar of the same diameter as the striker in the hammer tests. The Hopkinson pressure bar apparatus allows for the determination of the force of impact. The use of the Hopkinson pressure bar to determine fracture forces in whole specimens is novel. The fracture forces obtained in the current study agree considerably with the literature previously published on lateral, cranial blunt force trauma to both human and porcine specimens. The fractures produced, however, are atypical and may indicate a need to conduct further tests on other animal models.
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Mole, C. 2014. Investigation of wound characteristics and the force associated with skull fracture due to impact by a hammer. University of Cape Town.