REFERENCE: Herrmann NP, Bennett JL. The differentiation of traumatic and heat-related fractures in burned bone. J Forensic Sci 1999;44:(3)461–469. ABSTRACT: Interpretations of antemortem and perimortem trauma are complicated when dealing with cases involving extreme exposure to fire. This investigation attempts to discern the signa- tures of perimortem trauma from heat related trauma. Femora of do- mestic pig, sus scrofa, with minimal soft tissue and articulated patellae were subjected to varying traumatic forces. Skeletal ele- ments were impacted with blunt and sharp forces, cut with varying instruments, subjected to torsional forces or shot. Bones were burned in various situations in conjunction with Knox County Rural/Metro Fire Department training exercises con- ducted in Knox County, Tennessee. Following recovery, fragments were subjected to radiographic, macroscopic, and microscopic anal- yses. Skeletal elements were reconstructed to permit accurate com- parison with pre-fire visual records. In addition, fracture surfaces were examined under both transmitted light and scanning electron microscopy in an attempt to discern surface signatures of the causal fracture (trauma, heat, or situational). Results indicate that signatures of sharp force trauma remain ev- ident following incineration. Furthermore, radiopaque spatter was not observed in any shot specimen. However, these initial findings suggest that the interpretation of blunt force and torsional trauma re- quires a rigorous examination and comparison of fracture patterns in conjunction with surface morphology. KEYWORDS: forensic science, forensic anthropology, burned bone, fracture morphology, perimortem trauma The accurate interpretation of perimortem trauma is crucial to anthropological and pathological analyses. However, such deter- minations are complicated when dealing with cases involving ex- treme exposure to fire. Burned skeletal elements typically exhibit severe fragmentation and fracturing limiting interpretations of an- temortem and perimortem trauma. Although the effects of fire upon skeletal material have been considered by numerous re- searchers (1–10), these investigations were not designed to address traumatic interpretation. These archaeologically inspired works provide useful information concerning the intensity and duration of heating as well as data on structural changes. This research, how- ever, does little to aid forensic or contemporary interpretations of burned human remains. Recently, limited examinations and analy- ses have been advanced towards isolating and recognizing heat in- duced trauma (11–13). Nevertheless, more specific investigations are necessary to formulate criteria with which to accurately differ- entiate between perimortem fractures (i.e., traumatically induced) and heat-related fractures as well as situational fracturing. Situa- tional fractures occur during post-fire recovery or as a result of physical forces impacting the skeletal remains late in the fire episode. It is important to note that these fractures are not directly heat-induced. Forensic anthropologists and pathologists commonly classify traumatic events as resulting from sharp forces, gunshot or blunt forces (see 14–17). Through the documentation and interpretation of traumatic signatures, the forensic anthropologist can infer details concerning the manner of death. Sharp force trauma traditionally includes cutmarks, sawmarks, and stab wounds evidenced by sharp margins, blade striae, kerf walls and sheering of cortical and can- cellous bone surfaces (15,18–22). Gunshots are characterized by beveling, radiating fractures, concentric fractures and is often con- firmed by the presence of lead spatter (17,23,24). Blunt force trauma is commonly associated with diverse fracture patterns and is often evidenced by an impact point (11,12,16,25–28). Each of these forces generates unique skeletal attributes that are usually readily identifiable in unmodified remains, however, exposure to heat can significantly blur traumatic signatures. The aim of the pre- sent study is to investigate which, if any, markers of skeletal trauma remain visible following incineration. Heat Induced Fractures Bone is a resilient yet fragile structure predominantly comprised of collagen, which provides tensile strength, and hydroxyapatite crystals which provide compressive strength or hardness (28). With extreme heat, the dehydration of collagen decreases the elasticity of bone which dramatically alters the structural integrity causing shrinkage, distortion, and deformation. Descriptions of heat in- duced fractures have been generated by anthropologists as a result of investigations of archaeological cremations and experimentally burned bone (1–3). Commonly defined by location and direction of propagation, heat induced fractures are classified as longitudinal, curved transverse, straight transverse, patina and delamination (see 13). Fractures that follow the long axis of the bone and usually propagate with the grain are recognized as longitudinal fractures. Curved transverse fractures occur in a stacked arc formation across the grain of the bone and are commonly associated with the reduc- tion of soft tissue during incineration. They are traditionally re- ferred to as thumbnail fractures, and are considered a unique prod- uct of heat exposure as they do not resemble defects attributable to trauma. Straight transverse or step fractures extend from the mar- 461 Nicholas P. Herrmann, M.A. 1 and Joanne L. Bennett, M.A. 1 The Differentiation of Traumatic and Heat-Related Fractures in Burned Bone* 1 Department of Anthropology, The University of Tennessee, Knoxville, TN 37996. * Presented in part at the 49th Annual Meeting, American Academy of Foren- sic Sciences, New York, NY, February 1997. * This study was supported by a Lucas Research Grant from the Forensic Sci- ences Foundation. Received 11 June 1998; and in revised form 31 Aug. 1998; accepted 31 Aug. 1998.