The Frequency of Cranial Base Fractures in Lethal Head Trauma

The interpretation of cranial base injuries has never been investigated from a purely anthropological perspective. Very little exists in forensic literature in order to interpret the significance of cranial base fractures. We analyzed 296 cases of deaths due to skull–brain injuries. The frequency of vault fractures was 75.7% and that of base fractures was 91.9%. We observed the distribution of cases of death according to manner of death and manner of injury and number of fossae involved. These observations were analytically compared to different variables (age, sex, manner of injury, and mode of injury). The study presented the proportion of base fractures associated with vault fractures, and the frequency of absence of base fracture in subjects with no vault fractures. Interesting associations of base fractures to age and manner of death are shown.     

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.     

Novel Classification System of Rib Fractures Observed in Infants

Rib fractures are considered highly suspicious for nonaccidental injury in the pediatric clinical literature; however, a rib fracture classification system has not been developed. As an aid and impetus for rib fracture research, we developed a concise schema for classifying rib fracture types and fracture location that is applicable to infants. The system defined four fracture types (sternal end, buckle, transverse, and oblique) and four regions of the rib (posterior, posterolateral, anterolateral, and anterior). It was applied to all rib fractures observed during 85 consecutive infant autopsies. Rib fractures were found in 24 (28%) of the cases. A total of 158 rib fractures were identified. The proposed schema was adequate to classify 153 (97%) of the observed fractures. The results indicate that the classification system is sufficiently robust to classify rib fractures typically observed in infants and should be used by researchers investigating infant rib fractures.     

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.     

Traumatic Injury Pattern Analysis in a Light Rail Transit Death: A Retrospective Case Study

Within the context of medical examiner's offices, forensic anthropologists are increasingly being asked to assist with the interpretation of traumatic skeletal injury. This case study presents an example of trauma analysis performed by forensic anthropologists at the Maricopa County Forensic Science Center in Phoenix, Arizona. The primary goal of this study is to document an uncommon pattern of traumatic injury—severe grinding abrasions of the lower appendage that macroscopically resemble sharp force trauma, especially as observed in dismemberment cases—resulting from an individual being dragged beneath a Light Rail train for c. 1.7 miles. The abraded skeletal elements include a femoral shaft fragment, a femoral head portion, and the right foot. Second, this study aims to illustrate the efficacy of forensic anthropological analysis of patterned skeletal trauma. Finally, this study demonstrates the critical importance of analyzing scene information before drawing conclusions as to the etiology of a traumatic injury pattern.     

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.     

Microscopic Pattern of Bone Fractures as an Indicator of Blast Trauma: A Pilot Study

The assessment of fractures is a key issue in forensic anthropology; however, very few studies deal with the features of fractures due to explosion in comparison with other traumatic injuries. This study focuses on fractures resulting from blast trauma and two types of blunt force trauma (manual compression and running over), applied to corpses of pigs; 163 osteons were examined within forty fractures by the transmission light microscopy. Blast lesions showed a higher percentage of fracture lines through the Haversian canal, whereas in other types of trauma, the fractures went across the inner lamellae. Significant differences between samples hit by blast energy and those runover or manually compressed were observed (p < 0.05). The frequency of pattern A is significantly higher in exploded bones than in runover and compressed. Microscopic analysis of the fracture line may provide information about the type of trauma, especially for what concerns blast trauma.     

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.     

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.     

The Role of Interface on the Impact Characteristics and Cranial Fracture Patterns Using the Immature Porcine Head Model

The role of impact interface characteristics on the biomechanics and patterns of cranial fracture has not been investigated in detail, and especially for the pediatric head. In this study, infant porcine skulls aged 2–19 days were dropped with an energy to cause fracturing onto four surfaces varying in stiffness from a rigid plate to one covered with plush carpeting. Results showed that heads dropped onto the rigid surface produced more extensive cranial fracturing than onto carpeted surfaces. Contact forces generated at fracture initiation and the overall maximum contact forces were generally lower for the rigid than carpeted impacts. While the degree of cranial fracturing from impacts onto the heavy carpeted surface was comparable to that of lower‐energy rigid surface impacts, there were fewer diastatic fractures. This suggests that characteristics of the cranial fracture patterns may be used to differentiate energy level from impact interface in pediatric forensic cases.     

The Power of Contextual Effects in Forensic Anthropology: A Study of Biasability in the Visual Interpretations of Trauma Analysis on Skeletal Remains

The potential for contextual information to bias assessments in the forensic sciences has been demonstrated, in several forensic disiplines. In this paper, biasability potential within forensic anthropology was examined by analyzing the effects of external manipulations on judgments and decision‐making in visual trauma assessment. Three separate websites were created containing fourteen identical images. Participants were randomly assigned to one website. Each website provided different contextual information, to assess variation of interpretation of the same images between contexts. The results indicated a higher scoring of trauma identification responses for the Mass grave context. Furthermore, a significant biasing effect was detected in the interpretation of four images. Less experienced participants were more likely to indicate presence of trauma. This research demonstrates bias impact in forensic anthropological trauma assessments and highlights the importance of recognizing and limiting cognitive vulnerabilities that forensic anthropologists might bring to the analysis.     

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 Proposed Scheme for Classifying Pediatric Rib Head Fractures Using Case Examples

Pediatric rib head fractures are typically described as “posterior” or “costovertebral,” terms lacking specificity. To resolve this issue, a scheme was developed to describe the location of rib head fractures observed in a pediatric forensic population. The scheme uses three anatomical landmarks, terminus (tip), tubercle, and costovertebral articular surface to divide the rib head into two subregions, costovertebral and costotransverse. Examples of five cases of infants with rib head fractures are presented using this scheme. Forty‐eight rib head fractures were observed in these infants with the following frequencies: 56% (three infants) at the terminus; 21% (three infants) in the costovertebral subregion; 21% (one infant) at the costovertebral articular facet; and 2% (one infant) in the costotransverse subregion. Due to the small number of cases assessed, statistical analyses could not be performed; however, the data demonstrate the variation in distribution of pediatric rib head fractures.     

An unusual blunt force trauma pattern and mechanism to the cranial vault: Investigation of an atypical infant homicide

This case report presents an unusual fracture pattern in the cranium of a four-month-old infant indicative of child abuse. Upon postmortem examination, the infant presented with numerous bilateral linear cranial fractures running perpendicular to the sagittal suture with depressed and curvilinear fractures apparent on the supra-auricular surfaces of the cranium. Histological evidence indicates multiple traumatic events to the cranium. In addition, the stair-step pattern of a parietal fracture may represent multiple contiguous fractures from repeated loading of the head at different times with variation of the focal points of compressive force. Additionally, the left humerus, left radius, and left ulna have healing metaphyseal fractures, and the left ulna also has an antemortem diaphyseal fracture which resulted in the distal metaphysis being rotated 45 degrees medially. Integration of autopsy, anthropological, and neuropathological reports for this case suggest multiple inflicted injury episodes with a repeated atypical mechanism(s) to the cranial vault of the infant. During investigative interviews, the caretaker admitted to squeezing the infant's head and neck on multiple occasions to quiet the child. This reported abusive mechanism is consistent with the pattern of symmetric cranial fractures and soft tissue injuries indicating asphyxiation. This case report provides forensic investigators with a potential trauma mechanism to explore in cases when a similar pattern of cranial trauma is observed and highlights the need for greater research on fracture propagation and fracture healing in the infant cranium.     

Injuries of the Head from Backface Deformation of Ballistic Protective Helmets Under Ballistic Impact

Modern ballistic helmets defeat penetrating bullets by energy transfer from the projectile to the helmet, producing helmet deformation. This deformation may cause severe injuries without completely perforating the helmet, termed “behind armor blunt trauma” (BABT). As helmets become lighter, the likelihood of larger helmet backface deformation under ballistic impact increases. To characterize the potential for BABT, seven postmortem human head/neck specimens wearing a ballistic protective helmet were exposed to nonperforating impact, using a 9 mm, full metal jacket, 124 grain bullet with velocities of 400–460 m/s. An increasing trend of injury severity was observed, ranging from simple linear fractures to combinations of linear and depressed fractures. Overall, the ability to identify skull fractures resulting from BABT can be used in forensic investigations. Our results demonstrate a high risk of skull fracture due to BABT and necessitate the prevention of BABT as a design factor in future generations of protective gear.     

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.     

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.     

Suicide by blasting caps: a case study of rare cranial trauma

Suicide is a deliberate act of ending one's life. Suicide by use of any explosive device, when not involved in a terrorist act, is quite rare in occurrence when compared with other methods routinely utilized. In this paper, we present to the medicolegal community a case of an adult male who committed suicide with blasting caps and the subsequent extensive damage to the cranial hard tissue. Although the cause and manner of death were relatively straightforward, consultation with forensic anthropologists was requested for an anthropological trauma assessment of the highly fragmented skull. After the skull was cleaned and reconstructed, the analysis revealed similarities between blasting cap trauma to the head and high velocity gunshot trauma to the head. Therefore, in a case where some evidence may have been removed or destroyed, forensic analysis involving trauma of this magnitude could result in a misinterpretation of the true mechanism responsible for the osseous damage. In this case, cooperation among the law enforcement agency, coroner's investigators, the forensic pathologist, and forensic anthropologists provided a comprehensive death case analysis.     

Bone Mineral Density Adult Age Estimation in Forensic Anthropology: A Test of the DXAGE Application

Estimating age‐at‐death of individuals represented only by skeletonized human remains is a fundamental aspect of forensic anthropological casework. Recently, several researchers have proposed that bone mineral density (BMD) is a useful predictor of age‐at‐death in forensic contexts. Navega et al. (JFS 63(2):497–503) developed an online application called DXAGE for calculating age‐at‐death from BMD parameters. This study tests the utility of DXAGE by utilizing data from the National Health and Nutrition Examination Survey (NHANES). BMD data from a female subsample (n = 470) of the NHANES 2007–2008 dataset were analyzed, and the relationship between predicted age and real age was examined. Inaccuracy was 14.25 years, and bias was ?7.20 years. Results show that there is a weak correlation between predicted and actual age (r = 0.47) using the DXAGE application. While BMD data are potentially useful for predicting age age‐at‐death, the DXAGE application should be used cautiously in forensic anthropological contexts.     

Interpreting Injury Mechanisms of Blunt Force Trauma from Butterfly Fracture Formation

According to biomechanics of fracture production during blunt impact, tubular bones are subject to compressive (impact site) and tensile (opposite impact site) forces; this causes bones to break in tension before compression, producing Y-shaped fracture patterns with breakaway (butterfly) fragments. In current forensic models, the side of the bone exhibiting the breakaway fragment is designated the impact side, with initial breakage occurring opposite. Fracture production and patterning of blunt impacts to 255 sheep femora were analyzed. Contra the existing model, only 60% of complete butterfly fractures exhibited impact side breakaway fragments. Although fractures initiated on the tension, nonimpact side, butterfly fragments formed on either compression or tension sides. Using newly defined breakaway fragment shape criteria, impact side was estimated with 98% accuracy for both complete and partial butterfly fractures. Furthermore, the results suggest that the impact site is the located on one of the Y-fracture's arms, not the butterfly fragment's center, as previously modeled.