Relation of Kinetic Energy to Contact Wounds of the Head by Centerfire Rifles and Shotgun Slugs

Wounds of high‐energy centerfire rifles and shotguns represent distinctive injuries of forensic importance. Previous studies of contact wounds have shown variability in the potential of these weapons to produce bursting wounds of the head. The present study analyzed contact head wounds owing to 26 centerfire rifles and nine shotgun slugs and compared them with respect to weapon, ammunition, entry wound site, and projectile kinetic energy. The bursting effect, defined for this study as disruption of at least 50% of the head, occurred in 25/35 of cases and was related to kinetic energy. Bursting was associated with energies <2700 ft‐lbs in 12/22 cases and energies >2700 ft‐lbs in 13/13 cases. The volume of gunpowder gas injected into the wound was considered as contributing to the bursting phenomenon. There was no relation of bursting to the specific entrance wound site, type of ammunition, or projectile fragmentation.     

Problems in biomechanics of life-time intracranial injuries

Discusses the impact of kinetic energy and number of head movements during falling from a standing posture on one's back for various variants of falling on the formation of subdural hematomas, subarachnoidal hemorrhages, and brain concussions in the areas of the stroke, contralateral to the stroke, and intermediate. Discloses the correlations between the area and volume of injury and changes in energy parameters of stroke impact. Demonstrates the relationship between the severity of atherosclerotic involvement of the vessels and the volume and type of intracranial injury.     

Mechano- and morphogenesis of gunshot fractures in the flat bones

Gunshot fractures in flat bones, bullet defects in the continuum were studied in experiment. The laws of gunshot fracture formation were formulated. In far distance, bullet has a direct and radial blow action. The direct blow induces comminution and disintegration of the bone tissue with dislocation of bone fragments; radial blow potentiates bone destruction. Morphological characteristics of gunshot fractures of flat bones depend on the force of the direct and radial impact action and can be used for estimation of the far shot distance, kinetic energy and shape of the head of the shell.     

Fracture Characteristics of Entrapped Head Impacts Versus Controlled Head Drops in Infant Porcine Specimens,,

In many forensic cases, the job of forensic pathologists and anthropologists is to determine whether pediatric death is due to an abusive act or an accidental fall. The goal of this study was to compare the cranial fracture patterns generated on the parietal bone of a developing, infant porcine (pig, Sus scrofa) model by a controlled energy head drop onto a plate versus previous data generated by blunt force impact at the same energy onto the head constrained to a plate. The results showed that blunt force impacts on a head constrained to a rigid plate produces more fracture, but the same general pattern, as that for a head dropped onto the plate with the same level of impact energy. The study suggests that head constraint may be an important factor to consider in the evaluation of death causation for blunt force impacts to the pediatric skull.     

Forensic-medical significance of the characteristics of gunshot perforating fractures of the skull bones

The study was made of gunshot perforating fractures of calvarial bones in cases of lethal perforating head wounds in long distance shots from a 9-mm Makarov gun. Morphological characteristics of inlet and outlet perforating fractures and bone fragments were found to differ. Gunshot fractures in calvarial bones inflicted by bullets from a 9-mm Makarov gun were studied in experiments with different kinetic energy. In low kinetic energy, bullets make oval holes on the outer table of the skull and round holes on the inner table with radial prominences on the walls of bullet channels, large bone fragments; in moderate kinetic energy--make round holes in the outer table and oval on the inner table with skew prominences on the walls of the outlet part of the channels, large and middle-sized flat bone fragments; in high kinetic energy injuries on both tables were round, prominences were cross, bone fragments were flat, small and middle-sized.     

二次溅落状血迹形态的模拟实验观察

目的观察二次溅落状血迹的形态特征,探讨其形成机理及与行为方式的关系。方法建立室内现场环境,用10mL血液,以单滴连续滴落或一次性倾倒方式,从10～160 cm高度以10 cm为间隔,制作二次溅落状血迹模型;用棍棒打击及撞击方式制作低位打击及头部撞击溅落血迹模型。观察各种血迹分布,并分析比较其形态差异。结果二次溅落状血迹和头部撞击溅落状血迹在垂直面上均形成倒三角形空白区域的分布形态,但前者分布面积较后者小;低位打击溅落在垂直面上的血迹无此特征,且打击飞溅血滴的飞行角度大于二次溅落血迹。结论利用二次溅落状血迹的形态特征,对于鉴别低位溅血、分析行为方式、证实相关证词具有重要价值。     

Classification of Porcine Cranial Fracture Patterns Using a Fracture Printing Interface,,

Distinguishing between accidental and abusive head trauma in children can be difficult, as there is a lack of baseline data for pediatric cranial fracture patterns. A porcine head model has recently been developed and utilized in a series of studies to investigate the effects of impact energy level, surface type, and constraint condition on cranial fracture patterns. In the current study, an automated pattern recognition method, or a fracture printing interface (FPI), was developed to classify cranial fracture patterns that were associated with different impact scenarios documented in previous experiments. The FPI accurately predicted the energy level when the impact surface type was rigid. Additionally, the FPI was exceedingly successful in determining fractures caused by skulls being dropped with a high‐level energy (97% accuracy). The FPI, currently developed on the porcine data, may in the future be transformed to the task of cranial fracture pattern classification for human infant skulls.     

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.     

Pontomedullary lacerations in falls from a height--a retrospective autopsy study

Brainstem pontomedullary laceration (PML) in falls from a height appears as isolated cases and usually in feet-first impacts with a ring fracture. The aim of this study was to determine the frequency of PML in falls from a height, as well as the frequency of concomitant head and neck injuries. Out of 261 cases, PML was present in 40. An impact to the chin, as well as a feet- or buttocks-first impact, most often led to PML owing to transmission of the impact force. Also, a lateral, frontal, or posterior head impact, with subsequent hinge fracture, as well as the frontoposterior hyperextension of the head associated with an upper spine fracture, could be possible mechanisms of PML in falls from a height. The jawbone and other facial bones act as shock absorbers, and their fracture diminishes energy transfer toward the skull and protects the brain and brainstem from injury.     

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.     

Impact-induced intracranial pressure caused by an accelerated motion of the head or by skull deformation; an experimental study using physical models of the head and neck, and ones of the skull

An impact incurred by the movable head may bring about a change in intracranial pressure and this change may play an important part in the occurrence of the cerebral contusion. We have carried out the following experiments to determine whether the intracranial pressure change was attributed to an accelerated motion of the head or to a skull deformation. In the blow experiment in which the head was accelerated, a positive peak in the intracranial pressure was recorded immediately after impact at the impact site and a negative one at a site opposite the impact. In the one in which the skull could be deformed, the intracranial pressure curves at both sites contained harmonics. The modal analysis revealed an inbending in the frontal and occipital regions of the skull and an outbending in the parietal and temporal regions immediately after impact, followed by a reverse deformation. Regarding the intracranial pressure change, positive pressures were recorded in the frontal and occipital regions immediately after impact, followed by a negative one. This study demonstrated that the positive and negative peaks were caused by the accelerated motion of the head, and that the curve of the intracranial pressure changes contained harmonics which were caused by the deformation of the skull.     

Differences in the intracranial pressure caused by a 'blow' and/or a 'fall'--an experimental study using physical models of the head and neck

In cases of a severe head injury caused by a fall, coup contusions are either absent or very minor, in contrast to presence of extensive contre-coup damage. In cases of a severe blow to head, however, the reverse occurs, with contre-coup lesions a rarity and coup damage extensive. To investigate this further, head injuries caused by a 'blow' or a 'fall' have been studied, using physical human models of the head and neck, both filled with distilled, degassed water and fixed onto a dummy torso. An impact of a constant magnitude was applied to the midoccipital region in 'blow' and 'fall' experiments, and the acceleration of the head and changes in the intracranial pressure were measured, with the resulting data analyzed by a computer. In both experiments, the peak amplitude of the acceleration pulse were almost the same. Similarly, the intracranial pressure curve at the impact site consisted of a positive pulse that hardly differed, nor did the peak amplitude of that pulse vary significantly. In the 'blow' experiment, however, the intracranial pressure curve at the site opposite the impact consisted of a negative pulse, whereas in the 'fall' experiment, the intracranial pressure recorded at the same area was negative but of a longer duration, with an absolute value that was slightly greater. Our results indicate that an impact to the head triggers a different response in the intracranial space, dependent on whether that impact force was caused by a 'blow' or a 'fall'.     

Position paper on fatal abusive head injuries in infants and young children

This article represents the work of the National Association of Medical Examiners Ad Hoc Committee on shaken baby syndrome. Abusive head injuries include injuries caused by shaking as well as impact to the head, either by directly striking the head or by causing the head to strike another object or surface. Because of anatomic and developmental differences in the brain and skull of the young child, the mechanisms and types of injuries that affect the head differ from those that affect the older child or adult. The mechanism of injury produced by inflicted head injuries in these children is most often rotational movement of the brain within the cranial cavity. Rotational movement of the brain damages the nervous system by creating shearing forces, which cause diffuse axonal injury with disruption of axons and tearing of bridging veins, which causes subdural and subarachnoid hemorrhages, and is very commonly associated with retinal schisis and hemorrhages. Recognition of this mechanism of injury may be helpful in severe acute rotational brain injuries because it facilitates understanding of such clinical features as the decrease in the level of consciousness and respiratory distress seen in these injured children. The pathologic findings of subdural hemorrhage, subarachnoid hemorrhage, and retinal hemorrhages are offered as "markers" to assist in the recognition of the presence of shearing brain injury in young children.     

Destruction of the skull during compression

The article contains the results of an experimental modeling of the destruction of the head of a bio-mannequin by compressing it between two blunt objects with the hard, flat and broad surfaces and by using a mechanical press (with slow motion) and freely falling object (with fast motion). The obtained results were compared with two opposite-direction blows by a similar object. The author studied the main regularities of fractures of the skull of the main shapes, i.e. ellipsoid or ovoid as well as spheroid and rhomboid shapes, at different directions of its compression (sagittal, lateral, diagonal, vertical or moving). A comparison of local, constructional and local-and-constructional zones of the inflicted fractures made it possible to establish the succession in the formation of the destruction of the skull at the static and dynamic compression types.     

Computer Simulations to Investigate the Consequence of Blunt Head Impact

Blunt head impact as sustained in falls or punches against the head can result in rupture of bridging veins. Computer simulations were performed to simulate three different types of falls and punches against the head. The relative brain‐skull motion was recorded. The falls resulted in impact on the backside of the head, whereas the punches struck the face. The maximum resultant translational and rotational acceleration, the Head Injury Criterion (HIC), and the characteristics of the relative brain‐skull motion, as well as the coup and contre‐coup regions were determined. The maximum resultant translational acceleration was found to be between 2982 and 3541 m/s² for falls and between 814 and 942 m/s² for punches. The maximum resultant rotational acceleration reached 632–1000 rad/s² for falls and 252–620 rad/s² for punches. The HIC for falls was found to be at least 1357 and at most 130 for punches. The major brain‐skull displacement calculated for falls and punches was 6.6 and 4.2 mm, respectively. The results of this study suggest that falls are associated with a higher risk for bridging vein ruptures than punches and that cerebral contusions at the contre‐coup side are more serious.     

Measurement of kinetic energy dissipation with gelatine fissure formation with special reference to gelatine validation

Various methods for calculating the amount of kinetic energy dissipated by a bullet into ballistic gelatine have been suggested in literature. These methods were compared using the results of thirteen 9 mmx19 mm pistol and five 7.62 mmx 39 mm rifle bullets shot into 10% ballistic gelatine. The Wound Profile Method gave the highest correlation, 0.89, with the measured amounts of dissipated kinetic energy. The Fissure surface area and total crack length method gained 0.51 and 0.52, respectively. The experimental results were also compared with those from pig tests with the same bullet types. Using the z-test at 95% level of confidence no difference between impact velocity normalized bullet decelerations could be determined for the 9 mm bullet used. The same test showed significant difference for 7.62 mm bullets. That, however, can be considered to be the result of the bullet's tendency to tumble in non-homogenous living tissue causing significant dispersion of observed deceleration values. The results add further evidence supporting the validity of 10% gelatine at +4 degrees C as wound ballistic tissue simulant. The study also introduces the use of an elastic "shroud" to hold the gelatine in place, to some extent reduce the effects of asymmetric expansion of the gelatine and to simulate the expansion suppression effect of surrounding tissues.     

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

The forensic literature suggests that when adolescents fall onto edged and pointed surfaces, depressed fractures can occur at low energy levels. This study documents impact biomechanics and fracture characteristics of infant porcine skulls dropped onto flat, curved, edged, and focal surfaces. Results showed that the energy needed for fracture initiation was nearly four times higher against a flat surface than against the other surfaces. While characteristic measures of fracture such as number and length of fractures did not vary with impact surface shape, the fracture patterns did depend on impact surface shape. While experimental impacts against the flat surface produced linear fractures initiating at sutural boundaries peripheral to the point of impact (POI), more focal impacts produced depressed fractures initiating at the POI. The study supported case‐based forensic literature suggesting cranial fracture patterns depend on impact surface shape and that fracture initiation energy is lower for more focal impacts.     

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.     

The shaking trauma in infants - kinetic chains

The findings in three children who died as a consequence of shaking and those in another child who survived are presented. In the three fatal cases, a combination of anatomical lesions were identified at autopsy which appear to indicate the sites where kinetic energy related to the shaking episodes had been applied thus enabling the sequence of events resulting in the fatal head injury to be elucidated. Such patterns of injuries involved the upper limb, the shoulder, the brachial nerve plexus and the muscles close to the scapula; hemorrhages were present at the insertions of the sternocleidomastoid muscles due to hyperextension trauma (the so-called periosteal sign) and in the transition zone between the cervical and thoracic spine and extradural hematomas. Characteristic lesions due to traction were also found in the legs. All three children with lethal shaking trauma died from a subdural hematoma only a few hours after the event. The surviving child had persistant hypoxic damage of the brain following on massive cerebral edema. All the children showed a discrepancy between the lack of identifiable external lesions and severe internal ones.