The present research examines the effects of multiple different implements on long bones to determine if there is a point at which blunt force trauma becomes distinguishable from hacking trauma. Limb bones of the white-tailed deer (Odocoileus virginianus) were used in this research as a substitute for human bone. In addition to the use of purchased tools, seven of the implements used in the present research were created and designed to imitate the size and impact angle of other surfaces possibly found in hacking and blunt force trauma. A hacking machine was used to inflict trauma on the long bones at a consistent, controlled level of force. The resulting trauma was then photographed and analyzed to determine if there is a macroscopically distinguishable point at which an implement will inflict characteristics of blunt force trauma, with no visible hacking trauma characteristics. The analytical observations of the trauma involved scoring for elements such as hacking characteristic appearance as well as the amount of fracturing and fragmentation. The author hypothesized that when the angle of the implement’s striking surface reaches 60 degrees, the trauma would consist of blunt force characteristics and not of hacking characteristics, and a V-shaped kerf would cease to appear. The author also hypothesized that there would be an increase in comminuted fractures in more blunt blade angles, while hacking trauma would exhibit more transverse and oblique fractures.
The present study found that there was a statistically significant relationship between the composite hacking scores and the blade angles (the striking surface of the implement), with a p-value of 0.011. The author concluded that blunt force trauma and hacking trauma can be distinguished by the composite hacking scores, with a score of one indicating blunt force implements and scores of three or four indicating hacking implements. The entrance widths of the impacts also had a statistically significant relationship with the implement blade angles, with a p-value of 0.037. When the elements were bisected as a result of the impact, the data generated was characterized into having bisected into three identifiable fragments or a minimum of four identifiable fragments. With regards to the data for elements with three identifiable fragments, it was found that there was a statistically significant relationship between fragmentation and the implement blade angle, with a p-value of 0.036. When examining the visibility of a V-shaped kerf in the bones, the author concluded that there is a statistically significant relationship between the blade angles and the visibility of these kerfs, with the visibility decreasing around the 60° blade angle (p-value = 0.003). With regards to the fracture patterns, there was a correlation between the appearance of transverse fractures, with a decrease in more blunt blade angles (p-value = 0.004). Additionally, the author discovered a correlation between clean cut impact site appearances and smaller blade angles, as well as with crushing and fragmentation correlating to more blunt blade angles. The data from this research should assist in establishing guidelines to determine the type of trauma inflicted in forensic cases of hacking trauma and blunt force skeletal trauma.
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