Blast Injury and the Human Skeleton: An Important Emerging Aspect of Conflict‐Related Trauma

Recent decades have seen an accelerating trend in warfare whereby a growing proportion of conflict‐related deaths have been caused by explosions. Analysis of blast injury features little in anthropological literature. We present a review of clinical literature that includes prevalence of injury to anatomical regions and potential indicators of blast injury which can be used by forensic anthropologists. This includes high prevalence of extremity (22.8–91.2%) and facial (19.6–40%) injury in combat contexts, lower limb fractures (19–74.3%) in suicide bombing, traumatic amputation (3–43%) and diffuse fracture patterns in terrorist bombings. Potential indicators of blast trauma include blowout fractures in sinus cavities from blast overpressure, transverse mandibular fractures, and visceral surface rib fractures. Ability to recognize blast trauma and distinguish it in the skeleton is of importance in investigations and judicial proceedings relating to war crimes, terrorism, and human rights violations and likely to become increasingly crucial to forensic anthropology knowledge.     

The Erratic Behavior of Lesions in Burnt Bone

This study analyses depressed fractures (by blunt force trauma) and circular full‐thickness injuries (drill injuries and gunshot wounds) in charred bones. Fifty bovine ribs (total 104 lesions) were divided into three groups. The first group consisted in 20 depressed hammer‐produced fractures; in the second one, 60 round drill‐holes were produced (30 circular, 30 semicircular); in the third group, 12 fleshed and 12 skeletonized ribs were hit by 9‐mm bullets. Each specimen was carbonized in an electric oven up to 800°C. Morphological and metric analyses were performed before and after: morphological features were preserved, but depressed fractures showed an increase in their dimensions (p‐value < 0.05); the drilled holes shrunk (p‐value < 0.01); the charring cycle increased the number of fractures in samples with gunshot wounds differently in fleshed and defleshed ribs. This study showed the complex behavior of charred bone, for what concerns the interpretation of trauma and how caution should be applied.     

Primary and secondary skeletal blast trauma

This study examines primary (resulting from blast wave) and secondary (resulting from disintegrated, penetrating fragments) blast trauma to the skeleton. Eleven pigs were exposed to semi-controlled blast events of varying explosive type, charge size, and distance, including some cases with shrapnel. Skeletal trauma was found to be extensive, presenting as complex, comminuted fractures with numerous small, displaced bone splinters and fragments. Traumatic amputation of the limbs and cranium was also observed. Fractures were concentrated in areas nearer the blast, but there was generally no identifiable point of impact. Fractures were more random in appearance and widespread than those typically associated with gunshot or blunt force injury events. These patterns appear to be uniquely associated with blast trauma and may therefore assist forensic anthropologists and other forensic examiners in the interpretation of skeletal trauma by enabling them to differentiate between blast trauma and trauma resulting from some other cause.     

Macroscopic Analysis of Axe and Hatchet Trauma in Fleshed and Defleshed Mammalian Long Bones*

Abstract: Recently, the authors have noted that many studies involving the characterization of chopping weapon wounds have used either semi‐fleshed or defleshed bones (e.g., J Forensic Sci 2001; 46: 228). As these types of specimens do not reflect the full range of actual cases of postmortem dismemberment or perimortem trauma, 11 fresh pig (Sus scrofa) articulated hind limbs, with contiguous surrounding flesh, were inflicted with wounds using two axes and two hatchets. Defleshed humeri and femora were subjected to the same treatment. While there were no great differences found between the fleshed and defleshed specimens, characteristics observed including entrance site width and the presence of chattering were inconsistent with some aspects of Humphrey and Hutchinson’s study (J Forensic Sci 2001; 46: 228). Further, it was found that curve transverse and spiral fractures were prevalent in femora, while longitudinal fractures were prevalent in fibulae. Hence, fracture types may play a role in characterizing some wounds caused by chopping weapons.     

Examination of Hacking and Blunt Force Skeletal Trauma

Hacking trauma is prevalent in forensic cases involving genocide and dismemberment, but research into the identification of this type of trauma is lacking. The present study examines characteristics of hacking and blunt force skeletal trauma in order to determine if there is a point at which blunt force trauma becomes distinguishable from hacking trauma. Ten implements with a range of blade angles (i.e., the striking surface of the implement) were used in conjunction with a controlled-force hacking device to impact 100 limb bones of white-tailed deer (Odocoileus virginianus). Observations of the trauma included the occurrence and degree of fragmentation, the entrance widths of the impacts, and composite scores of six hacking characteristics, especially the distinctive V-shaped kerf. ANOVA tests and regression analyses were used to assess the relationships between these characteristics and the blade angles. A significant relationship (p-value = 0.011) was found between the composite hacking scores and the blade angles, indicating that blunt force and hacking trauma can be distinguished. The entrance widths of the impacts exhibited a significant relationship with the blade angles (p-value = 0.037). There was also a significant relationship between the visibility of a V-shaped kerf in the bones (p-value = 0.003), with visibility decreasing around the 60° blade angle. These data should assist in establishing guidelines to differentiate hacking and blunt force skeletal trauma in cases where the implement is on a spectrum between sharp and blunt.     

Do bone elasticity and postmortem interval affect forensic fractographic analyses?

Forensic fractographic features of bone reliably establish crack propagation in perimortem injuries. We investigated if similar fracture surface features characterize postmortem fractures. Experimentally induced peri- and postmortem fractures were used to assess if fractographic features vary as bone elasticity decreases during the postmortem interval (PMI). Thirty-seven unembalmed, defleshed human femoral shafts from males and females aged 33–81 years were fractured at varying PMIs with a drop test frame using a three-point bending setup and recorded with a high-speed camera. Vital statistics, cause of death, PMI length, temperature, humidity, collagen percentage, water loss, fracture energy, and fractography scores were recorded for each sample. Results showed that fractographic features associated with perimortem fractures were expressed in PMIs up to 40,600 accumulated degree hours (ADH), or 60 warm weather days. Hackle was the most consistently expressed feature, occurring in all fractures regardless of ADH. The most variable characteristics were wake features (78.4%) and arrest ridges (70.3%). Collagen percentage did not correlate strongly with ADH (r = −0.04, p = 0.81); however, there was a strong significant correlation between ADH and water loss (r = 0.74, p < 0.001). Multinomial logistic regression showed no association between fractographic feature expression and ADH or collagen percentage. In conclusion, forensic fractographic features reliably determine initiation and directionality of crack propagation in experimentally induced PMIs up to 40,600 ADH, demonstrating the utility of this method into the recent postmortem interval. This expression of reliable fractographic features throughout the early PMI intimates these characteristics may not be useful standalone features for discerning peri- versus postmortem fractures.     

Skeletal Trauma Resulting From Fatal Low (≤3 m) Free Falls: An Analysis of Fracture Patterns and Morphologies

The skeletal trauma resulting from fatal low (≤3 m) free falls is poorly researched and understood by forensic practitioners. The aim of this study was to identify the types of skeletal trauma resulting from low falls through investigating fracture patterns and morphologies. Skeletal trauma was analyzed using full‐body postmortem computed tomography scans of 145 individuals who died from a low free fall. Trauma was then contextualized to the variables that influence how a person falls using multiple logistic regression. Results showed fracture patterning primarily involved the axial skeleton and that there were a number of patterns significantly associated with the height fallen, pre‐existing health conditions, and age. Analysis of fracture morphologies showed 108 possible fracture types, six of which were significantly associated with the height fallen. Understanding the skeletal trauma characteristic of low free falls will further inform anthropological interpretations of trauma in cases where a fall may be considered the possible mechanism.     

An Anthropological Examination of the Types of Skeletal Fractures Resulting from Fatal High (˃3 m) Free Falls,

Fatal falls from heights (?3 m) often result in blunt force trauma (BFT) to the skeleton. The fracture patterns that result from this BFT mechanism are well understood in forensic anthropology and forensic pathology; however, details of the specific types of fractures that result remain poorly documented. The aim of this study was to provide a detailed examination of the types of fractures that may result from fatal high falls. Fractures were recorded from 95 full‐body postmortem computed tomography scans of individuals known to have died from a high fall. Trauma was then analyzed taking into account the extrinsic and intrinsic variables known to influence a fall using multiple logistic regression. A total of 339 types of fractures were classified, of which 16 were significantly associated with this BFT mechanism. Classified fracture types will augment anthropological interpretations of the circumstances of death from BFT in cases of suspected high falls.     

Applicability of Cranial Models in Urethane Resin and Foam as a Substitute for Bone: Are Synthetic Materials Reliable?

As literature is poor in functional synthetic cranial models, in this study, synthetic handmade models of cranial vaults were produced in two different materials (a urethane resin and a self‐hardening foam), from multiple bone specimens (eight original cranial vaults: four human and four swine), in order to test their resemblance to bone structure in behavior, during fracture formation. All the vaults were mechanically tested with a 2‐kg impact weight and filmed with a high‐speed camera. Fracture patterns were homogeneous in all swine vaults and heterogeneous in human vaults, with resin fractures more similar to bone fractures. Mean fracture latency time extrapolated by videos were of 0.75 msec (bone), 1.5 msec (resin), 5.12 msec (foam) for human vaults and of 0.625 msec (bone), 1.87 msec (resin), 3.75 msec (foam) for swine vaults. These data showed that resin models are more similar to bone than foam reproductions, but that synthetic material may behave quite differently from bone as concerns fracture latency times.     

A Biomechanical Evaluation of Skull–Brain Surrogates to Blunt High‐Rate Impacts to Postmortem Human Subjects

The field of forensic injury biomechanics is an emerging field. Biomechanically validated tools may assist interdisciplinary teams of investigators in assessing mechanisms of blunt head trauma resulting in skull fractures. The objective of this study is to assess the biofidelity of spherical, frangible skull–brain (SB) surrogates. Blunt impacts were conducted at 20 m/s, using an instrumented 103 g rigid impactor, to the temporo‐parietal region of four defleshed cephalic postmortem human subjects (PMHS). Force–deformation response, fracture tolerance, and fracture patterns were recorded for comparison to spherical skull–brain surrogates. Three brain substitutes were assessed: 10% gelatin, lead shot with Styrofoam and water. Force–deformation response of the skull–brain surrogates was similar to defleshed PMHS up to the point of fracture; however, none of the surrogates fractured at tolerance levels comparable to the PMHS. Fracture patterns of the skull–brain surrogates were linear and radiating, while PMHS fractures were all depressed, comminuted.     

Abusive Pediatric Thoracolumbar Fracture Due to Forced Hyperextension: Case Report,Biomechanical Considerations,and Review of the Literature

Pediatric thoracolumbar fractures are rare due to the physiological differences which afford greater resilience to the immature spine. Most pediatric thoracolumbar fractures occur as the result of high energy trauma, such as motor vehicle accidents, and modes of reasonable accidental injuries are limited by age and developmental capabilities of the child. These fractures can occur as the result of inflicted blunt force trauma and child abuse, and in most cases, the mechanism of injury to the spine is not known. We report the death of a 29-month-old man due to blunt force trauma to the back and forced hyperextension of the thoracolumbar spine causing fracture of the fourth lumbar (L4) vertebral body. A complete forensic examination revealed a previous healing fracture of the anterior aspect of the L4 vertebral body, with acute disruption of the anterior longitudinal ligament overlying the fracture site, complete fracture of the vertebral body, and fatal retroperitoneal hemorrhage. We present a review of the biomechanical considerations of the pediatric spine, a survey of pediatric spinal fractures, and a review of the literature on pediatric abusive thoracolumbar fractures. In this case, there was never a provided explanation for how the injury occurred; however, understanding the biomechanics of the pediatric spine allowed for the determination of the mechanism, force required to produce this specific pattern of abusive spinal injury, and the manner of death.     

Perimortem or Postmortem Bone Fractures? An Experimental Study of Fracture Patterns in Deer Femora*

The determination of perimortem trauma is important for forensic anthropologists. Characteristics of bone fractures such as sharp edges, presence of fracture lines, the shape of the broken ends, fracture surface morphology, fracture angle on the Z-axis, and butterfly fractures are said to differentiate perimortem from postmortem trauma. A Drop Weight Impact Test Machine was used to break 76 deer femora of various ages since death. The results of this study suggest that the characteristics listed above are unreliable at differentiating a perimortem fracture from a postmortem fracture in a forensic case. There are, however, statistically significant differences between fresh bones broken less than 4 days old and dry bones broken 44 days or 1 year old after death.     

An Examination of the Transition of Fracture Characteristics in Long Bones from Fresh to Dry in Central Florida: Evaluating the Timing of Injury

It is important to conduct timing of injury research analyzing fracture characteristics at known postmortem intervals (PMI) because bone can retain fresh characteristics throughout the PMI. Defleshed pig (Sus scrofa) long bones were fractured weekly in two environments (full sun and shade) over 14 weeks in Central Florida and fracture characteristics were categorized (N = 136) for analysis. Results of analysis of variance (ANOVA) using time in weeks (PMI) as a dependent variable indicate significant relationships between PMI and Fracture Angle (p < 0.001), Fracture Surface (p < 0.001), and Fracture Outline (p < 0.001). Fracture characteristics associated with perimortem trauma (smooth Fracture Surfaces and curved or V‐shaped Fracture Outlines) were commonly observed. Analysis of fracture characteristics for each environment demonstrated similar patterns. Overall, the loss of only fresh fracture characteristics for each bone was noted earlier in the PMI for the Central Florida region than previously reported.     

Blunt force cranial trauma in the Cambodian killing fields

In this paper we present a unique pattern of blunt force cranial trauma that was observed in 10 of a sample of 85 crania from a Cambodian skeletal collection comprised of Khmer Rouge victims. Initial examination of the trauma, which presents as substantial damage to the occipital with fractures extending to the cranial base, suggested the pattern was classifiable as a basilar or ring fracture. However, further investigation, including trauma analysis and historical research, revealed that this fracture type is distinctive from basilar and ring fractures. Historical data indicate that a particular execution method was the likely source of the trauma. Recognition of this trauma pattern is significant because it exemplifies the distinct fracture configuration resulting from an apparently categorical and methodical execution technique. Identification of this fracture type could potentially assist forensic investigators in the recognition of specific methods of murder or execution.     

Interpreting perimortem blast trauma from skeletal remains: Complications and considerations

Blast trauma results from highly variable events that can lead to similar effects in the skeleton. Clinical literature, which largely focuses on soft tissue, provides limited efficacy for interpreting fully skeletonized cases. Interpretation of skeletal blast trauma is hampered by the low number of fully skeletonized case studies and experimental replication studies, which mainly use nonhuman proxies. The purpose of this study is to discuss fracture patterns on two individuals from WWII as a means to better understand and identify fracture patterns associated with blast trauma. Existing clinical and anthropological criteria are reviewed and applied to two World War II cases, both presumed to exhibit blast trauma based on historical contexts. These case studies exhibit combinations of complicated and extensive signs of blunt-force and projectile trauma, reflecting the diversity of skeletal trauma resulting from blast-related events. This analysis emphasizes the arguably impossible task of establishing a diagnosis based on the available literature and lack of prior knowledge about specific losses. Ultimately, analysts must consider the totality of skeletal trauma, combining biomechanical theory and relevant clinical and anthropological literature to arrive at useful yet defensible assessments of trauma. However, refined criteria and additional studies are needed to assess complicated trauma from blast-related events in anthropological contexts.     

Fatal Falls from Height in Taiwan

This study conducts an investigation of fatal falls from height, examines gender differences, and compares our findings with those of Western countries. We review deaths in Taiwan caused by falls from height that underwent forensic autopsy from 1994 to 2010. Among the examined cases, 182 were suicide, 156 were accidents, and 18 were homicides. Men who fell from greater heights had a lower probability of fatal head trauma (p = 0.045), and women exhibited a lower fatal head trauma rate when falling from heights of between 10 and 25 m in accident group (p = 0.003). There was no significant difference between cases of falling from greater and lower heights within the suicide group (p = 0.834). Psychiatric illness was only reported in 20.3% and 28.8% cases in suicide and accident groups. Only in male cases was the use of psychotropic substances higher in the suicide groups than in the accident groups (p = 0.047).     

Effects of kinetic energy and firearm-to-target distance on fracture behavior in flat bones

This research implements a fractographic approach to investigate the relationships between kinetic energy, firearm-to-target distance, and various aspects of fracture behavior in gunshot trauma. Gunshot experiments were performed on pig scapulae (n = 30) using three firearms generating different muzzle (initial) kinetic energies, including a 0.32 pistol (103 J), 0.40 pistol (492 J), and 0.308 rifle (2275 J). Specimens were shot from two distances: 10 cm (n = 15) and 110 cm (n = 15). Features evaluated in fractographic analysis such as cone cracks, radiating cracks, crack branching points, and circumferential cracks could be easily identified and measured in flat bones and allowed for statistical comparison of crack propagation behavior under different impact conditions. Higher-energy bullets produced more radiating cracks, more crack branching points, and longer fracture lengths than lower-energy bullets. Distance had no significant effect on fracture morphology at the distances tested. That quantitative measures of crack propagation varied with energy affirms that kinetic energy transfer is important in determining the nature and extent of fracture in gunshot wounds and suggests it may be possible to infer relatively high- versus relatively low-energy transfer using these features. Ranges obtained with the three firearms exhibited considerable overlap, however, indicating that other variables such as bullet caliber, mass, and construction influence the efficiency of energy transfer from bullet to bone. Therefore, fracture morphology cannot be used to identify a specific firearm or to directly reconstruct the muzzle (initial) kinetic energy in forensic cases.