Determining Fracture Timing from Histological Characteristics of Cortical Bone

Determining if an injury occurred before death (antemortem), around the time of death(perimortem) or after death (postmortem) is typically straightforward if the soft tissues are present but becomes more challenging as remains skeletonize. Postmortem changes may mask or mimic skeletal trauma, and even when skeletal trauma is present, it may not be possible to discern perimortem definitively from postmortem events. Bones may receive postmortem damage that resembles perimortem trauma if it occurs when soft tissues are still intact, and/or the bone is still elastic. Depending on environmental circumstances, bone may maintain elasticity for days, weeks, even months after death. Due to this prolonged perimortem interval in bone, macroscopic evaluation of fractures is limited in the ability to discern true perimortem events from postmortem damage unless other indicators are present to support the analysis. Numerous studies have demonstrated that our current practice of examining macroscopic fracture characteristics is limited and unreliable for determining fracture timing with scientific certainty, particularly during the transitional period between wet and dry bone. A more reliable method is needed, as this has significant implications in a court of law. The primary goal of this research is to characterize microscopic features able to discern the timing of traumatic events more effectively than current methods using human cortical bone in a controlled experimental environment. The bones are heated for varying times at low temperatures in a gravity convection oven to simulate postmortem dehydration and collagen degradation in a controlled temperature and humidity environment. Next, a 1 cm section is removed to determine the amount of collagen present and approximate elasticity. Then, the bones are fractured using a drop test frame using a 3-point bending setup to simulate blunt trauma. Blunt trauma is used as the mechanism of trauma because the fracture patterns from blunt trauma are most problematic when distinguishing perimortem trauma from postmortem damage. Finally, scanning electron microscopy (SEM) is used to identify microscopic characteristics of the fracture surfaces. These characteristics will be analyzed and correlated to the bone elasticity and postmortem interval. SEM is used widely in forensic investigations, and advances in microscopy have led to much progress in the forensic sciences. Our preliminary study has produced promising results, and this research will further those investigations. The use of digital imaging is key, as we anticipate future solutions will involve the use of artificial intelligence and pattern recognition programs to assess fracture characteristics. Note: This project contains a research and/or development component, as defined in applicable law, and complies with Part 200 Uniform Requirements - 2 CFR 200.210(a)(14). CA/NCF