Limited experimentation has been conducted on fractography of fresh versus dry bones. The present project examined the presence of select fractographic features on wet and dry bone specimens over a time interval of 15 months. The experimental remains consisted of a total of 81 white-tailed deer (Odocoileus virginianus) long bones as a proxy for human long bones. A subsample of 15 long bones that were defleshed of most external soft tissue was subjected to blunt force trauma every 30 days for a total of three months. After these three months passed, a subsample of 15 bones was subjected to blunt force trauma every 90 days for the remaining 12 months. Following fracturing, the long bones were macerated and the fractures on the long bones were inspected, and observations were recorded and photographed. The author hypothesized that the presence (or absence) of fractographic features including hackle patterns, bone mirror, cantilever curls, and arrest ridges, on the fractured long bones would differ on fresh versus dry bones. Therefore, the difference in fractographic features found on the fresh versus dry bones would allow greater separation of perimortem from postmortem fractures. Other fracture characteristics such as fracture angle, fracture surface texture, fracture jaggedness, number of fragments produced, and type of fracture produced were also observed as part of the data collected in this research to potentially confirm the findings and results of previous studies conducted on differentiating between perimortem and postmortem trauma on bone.
This study disproved the hypothesis by concluding that the presence (or absence) of fractographic features is not greatly affected by time exposure and therefore, does not aid in distinguishing between fresh bone and dry bone fractures. Fractographic features were present and absent on bone specimens during all postmortem intervals. The only statistically significant difference discovered was that bone hackle patterns are more commonly observed than cantilever curls on bones with a later PMI. Other general trends observed were that the number of bones showing bone hackle patterns increased over time and the number of bones showing bone mirror decreased over time.
In addition, the results of the study revealed that the only fracture characteristic that showed a slightly significant difference with time of exposure was the fracture surface texture produced. The probability of a bone showing intermediate fracture surfaces is statistically significantly higher than a bone showing rough fracture surfaces when the represented PMI is fresh. The probability of a bone showing intermediate fracture surfaces is statistically significantly higher than a bone showing smooth fracture surfaces when the represented PMI is dry.
The present study showed that the fracture characteristics including fracture angle, fracture type, number of fragments produced, and fracture jaggedness were not greatly influenced by exposure of time but, certain patterns and trends were recognized. The number of bones showing sharp fracture angles increased over time, while the number of bones showing intermediate fracture angles stayed stagnant. Bones showing comminuted fractures also increased with the progression of drying time. The average number of fragments produced were high during both fresh and dry PMIs and low throughout the transitional postmortem intervals. Bones showing jagged, intermediate, and not jagged broken ends increased with the progression of time however, not jagged broken ends only began to appear in the sample starting at a PMI of 90 days.
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