Forensic/ Bioarchaeology Anthropology

Blunt Force Trauma

Deaths from blunt force trauma on the head are some of the most common cases investigated by practicing forensic pathologists. Usually, recovery of skeletal remains with signs of trauma on the skull is likely to involve crime or homicide. Previous studies indicate that inflicting pain on the head of the victim is one of the most effective methods of murder. According to Sulaiman, Osman, & Hamzah (2014), assailants often select this region because it is unprotected and easy to make severe injuries with less effort. Along with that, blunt force trauma on the head is also present in accident or suicide cases. In fact, blunt force trauma is one of the most common causes of death in traffic accidents or falls from high levels. Importantly noted, the presence of a fracture indicates the severity of force, thus, it is logical to assume the presence of the blunt object outline. Consequently, Sulaiman et al., highlight that the severity of a trauma depends on two factors. The factors include one, characteristics of the blunt object that has been used, and the site of impact, and two the amount and thickness of hair, scalp, and skull at the site of impact. In essence, this is to mean that a higher velocity of impact produced by a smaller surface area of object used is likely to lead to severe damage as opposed to a blunt object used on a wide head. Consistent with the field of interest, we review different studies on blunt force trauma on skeletons to get a comprehensive overview of the different types of BFT. We further explore the connection between the timings of injuries and cause of death, the etiology of blunt force trauma, and current practices used by forensic anthropologists and pathologists to detect BFT.

Types of Blunt Force Trauma

Abrasions

Abrasions are also referred to as scratches, grazes, or scrapes and often result from a blunt object meeting the surface of the skin with disruption (Prahlow  & Byard, 2012). Usually, they are only present at the site of impact, and not necessarily from blunt object impact. Usually, when examining dead bodies, abrasions are often overlooked, especially if the affected area does not show evidence of an injury. Consequently, abrasions get lost easily and are seldom present in surviving trauma victims. Under special circumstances, scrapes can be indicative of a special type of trauma such as seat belt marks after road traffic accidents or bite marks.

Contusions

Contusions usually occur when extravasations of red blood cells escape from ruptured vessels and spread to the surrounding tissues. Mostly, as Prahlow and Byard (2012) note, when a contusion or bruise occurs, an outline showing the impact of the blunt object is visible. As compared to abrasions, contusions arise at the site of impact and the sites around the area of impact as blood spreads through the tissues. People who sustain contusions are often victims of blunt force violence. Consequently, it is important to note that in darkly pigmented individuals, it is hard to identify contusions using the naked eye and use of infrared may be necessary to diagnose subcutaneous blood extravasations.

Lacerations

Lacerations are tears that appear on the skin or internal organs resulting from blows from blunt objects, the impact from vehicles, fall on the ground, or impact from heavy footwear (Prahlow & Byard, 2012). Just like contusions, lacerations often occur at the site of impact and sometimes extend to the area surrounding the area due to stretching tissue. Usually, lacerations occur on regions where the integument provides a firm bony base. When force is applied to the skin, the subcutaneous tissue is pressed so hard in such a way the integument is crushed and split sideways.

Head Injuries

The head remains a common target by assailants with blunt objects. Head injuries are also a common cause of death in traffic accidents, falls from high levels, or from self-inflicted harm. Usually, head injuries can be detected through marked swelling, excoriation, and or laceration, especially if the impact was severe (Prahlow & Byard, 2012). However, other times the injuries are not visible particularly if the area is covered by hair or in case the impact came from a flat surface. Consequently, head injuries are classified into various categories, which include skull fractures, intracranial hemorrhages, and cerebral injuries.

Chest Injuries

Blunt objects force can damage the thoracic walls or chest organs when they come into contact with the chest area. The injuries can be sustained through two ways; one a localized force applied and breaks the underlying ribs, and two the impact fractures the ribs due to chest compression. Usually, as Horst, Simon, and Pfeifer (2016) note, a fracture in the rib is considered fatal and can be dangerous to the victim, especially if there is a presence of several fractures, which may lead to the ribs losing their rigidity leading to paradoxical respiration. Sharp and pointed ends are likely to penetrate the pleura and lacerate the lungs causing bleeding in the chest cavity.  Additionally, a leak in the visceral pleura allows entry of air into the pleural cavity forcing lung collapse. Consequently, a blunt force applied to the chest is likely to lead to heart or lung rapture, which can be life-threatening to the victim.

Abdominal Injuries

Abdominal injuries are often sustained as a result of blunt force from traffic and work accidents, criminal assaults or suicidal falls from high levels. Normally, the solid liver and spleen are one of the abdominal organs that are most vulnerable to trauma. Substantial injuries to these two organs are life-threatening to the individual, especially if rapid surgical treatment is not available.

Skeletal Injuries

Forensic anthropology is a complementary discipline of forensic pathology, concerned with examining skeletal remains to establish their potential association with the cause of death (Kranioti, 2015). Normally, depending on their location, skeletal injuries are classified into two; cranial and postcranial injuries. Further classification considers the nature of the injuries such as ballistic trauma, blunt force, or sharp force. Consistent with the field of interest, blunt force trauma often comes from a blunt object with a low-velocity impact. It is the responsibility of forensic anthropologists to examine dead bodies carry out trauma analysis to identify trauma patterns and possible association with the cause of death.

Timing of Injuries

In skeletal injuries, the most important task for forensic pathologists is to determine whether they coincide with the time of death. The mechanical interpretation of bone trauma allows anthropologists to reconstruct the biomechanics of trauma and develop knowledge on possible causes of death consistent with the manner of the injury (Scheirs, Malgosa, & Sanchez-Molina, 2016). The procedure often allows the forensic anthropologists to complement the work of forensic pathologists during the assessment of injuries. Virtually, to get a comprehensive overview, the process involves an analysis of the antemortem, perimortem, and postmortem trauma. Antemortem trauma is indicated with evidence of healing and involves the presence of remodeling or healing of the bones before the occurrence of death. Importantly noted, while the healing process starts immediately after sustained injuries, it often takes between one to three weeks for the signs to be seen. In bones, the healing process is in the form of osteoblastic and osteoclastic responses, with lines of demarcation. Consequently, although bones develop a callus formation as part of their healing, the skull requires the development of bony ridges between the fractured fragments. Accordingly, the absence of these signs points to the presence of a perimortem or postmortem damage. As Kranioti (2015) points out, distinguishing the two damages is dependent on the pattern of the fracture. On the other hand, postmortem usually involves a presence of taphonomic alteration and scavenging, with squared or sharp-edged right-angled patterns at the surface of the bone. The damage is also likely to result in massive fragmentation.  Similarly, it should be stressed that, in postmortem damages, there is a presence of rough or bump preponderant texture and blunt edges or irregular preponderant outline. In post-mortem damages, injuries are often obtuse or acute fractured with a smooth and preponderant texture and regular line. Nonetheless, perimortem is often ambiguous and takes into consideration at or around the time of death (Bartelink, 2015). The term is often problematic because bones retain significant moisture content after death and are likely to exhibit the same biomechanical properties as skeletal tissues that are alive. Similarly, distinguishing between perimortem and postmortem is not easy. On both perimortem and postmortem injuries, there is no presence of a healing process.

Etiology of Blunt Force Trauma

Blunt force trauma has long been considered as one of the most common mechanical causes of death. According to Kranioti (2015), the condition is caused by a number of factors such as interpersonal violence such as assault. The condition is also associated with the cause of death in road accidents or self-inflicted injury from jumping from high places. Scholars have noted that cranial injuries are more likely a result of interpersonal violence.  

Best Practices

Essentially, blunt force trauma is one of the most common types of injury found in autopsies. The head is also the most targeted part, especially in homicide cases. Therefore, as Kranioti (2015) notes, it is important for a forensic pathologist to conduct a careful analysis of the injuries on the skin and soft tissue. Usually, forensic pathologists use a series of techniques to examine head trauma. Such procedures include the use of radiographic to examine the body, macroscopic and microscopic in the examination of the skin and soft tissue as a dissection of the skull. Where possible, CT scans imaging analysis is used to inspect the endocranial surface of the skull without using anatomical dissection. However, in the absence of soft tissue, the analysis requires challenging procedures, such as removing the soft tissue remnants for manipulation. In multiple cranial fragments, the parts are fixed together using non-permanent glue, photographed, and sketched. This is to capture the fracture lines from various views and draw conclusions on the nature of injuries.

The impact of a blunt force is determined by the velocity of force applied to the area, contact surface area, and the pressure transferred from the object to the site of impact. High pressure translates to severe blunt force trauma. In the field of forensic anthropology, understanding blunt force trauma is an important yet challenging task. More importantly, understanding the difference between perimortem and postmortem trauma is critically significant to help in determining the cause of death in victims during investigations.

References

Bartelink, E. J. (2015). Blunt force trauma patterns in the human skull and thorax: a case study from northern California. 56-73.

Horst, K., Simon, T. P., Pfeifer, R., Teuben, M.,  Almahmoud, K., Zhi, Q.,  Aguiar Santos, S.,  Castelar Wembers, C., …Hildebrand, F. (2016). Characterization of blunt chest trauma in a long-term porcine model of severe multiple trauma. Scientific Reports, 6(39659), 1-13.

Kranioti, E. (2015). Forensic investigation of cranial injuries due to blunt force trauma: current best practice. Research and Reports in Forensic Medical Science, 25, 25-37

Prahlow, J. A., & Byard, R. W. (2012). Atlas of forensic pathology. New York: Springer.

Scheirs, S., Malgosa, A., Sanchez-Molina, D., Ortega-Sánchez, M., Velázquez-Ameijide, J., Arregui-Dalmases, C., Medallo-Muñiz, J., … Galtés, I. (2016). New insights in the analysis of blunt force trauma in human bones. Preliminary results. International Journal of Legal Medicine, 131(3), 867-875.

Sulaiman, N. A., Osman, K., Hamzah, N. H., & Amir, H. S. P. A. (2014). Blunt force trauma to skull with various instruments. The Malaysian Journal of Pathology, 36, 1, 33-40.