Design and Injury Assessment Criteria for Blunt Ballistic Impacts

Assessment of Less Lethal Impact Munitions Using the Facial and Ocular CountermeasUre for Safety (FOCUS) Headform

Recent social protests and gatherings in the USA have prompted law enforcement agencies to increase their use of less lethal impact munitions (LLIMs) for crowd control. Media reports and firsthand accounts have indicated that many of the LLIMs are impacting individuals in the head and neck regions. There is very little data available on the risk of injury (ROI) from LLIM impacts to these body regions. The Facial and Ocular CountermeasUre for Safety (FOCUS) surrogate headform was used to assess the ROI (fracture) from LLIM impacts. LLIMs were fired at the FOCUS headform to determine the ROI to the frontal and maxilla bones. Sixteen different LLIMs were assessed which included 12-gauge, 37-mm, and 40-mm caliber projectiles from five manufacturers. The LLIMs included bean bag style, rubber, and foam/sponge projectiles. Each LLIM was tested multiple times to determine the average ROI. The average peak resultant frontal bone force ranged from 2.0 to 7.6 kN which represented ROIs from ~ 30% up to 95%. The average peak resultant maxilla bone force ranged from 1.0 to 4.4 kN which represented ROIs from ~ 30% up to 99%. In general, 12-gauge LLIMs had a lower ROI than the larger caliber LLIMs and the rubber projectiles had a lower ROI than the bean bag style projectiles. Due to the relative thickness, the maxilla has a much lower fracture force than the frontal bone, and this was borne out in the ROIs from the maxilla impacts. Impacts to both bones showed a positive correlation between normalized energy and resultant force (p  < 0.01). The slope of the plotted resultant force against the normalized energy for the 12-gauge munitions was significantly smaller compared to larger calibers for both impact sites, frontal (p  = 0.031), and maxilla (p  < 0.001).

Effect of blast loading on the risk of rib fractures: a preliminary 3D numerical investigation

Blast is a complex phenomenon which needs to be understood, especially in a military framework, where this kind of loading can have severe consequences on the human body. Indeed, the literature lists a number of studies which try to investigate the dangerousness of such a phenomenon, both at experimental and numerical level, and the injuries that could occur when the fighters or police officers are stroke by blast wave. When focusing on primary blast effect, this paper analyses the effect of this loading on the occurrence of rib fracture, using previously developed injury risk curves.

A Special Collaborative Information System and Its Application in Kinetic Energy Impact

Although the benefits of the non-lethal kinetic energy projectiles are numerous, there is a need to assess the projectiles to assure their expected functions. In order to overcome the limitations of current research, a special collaborative information system based on Hybrid III 50th percentile male dummy (hybrid III dummy) was developed and validated to assess and predict the risk of non-lethal kinetic energy impact. Two types of non-lethal kinetic energy projectiles were used to attack the thorax region of the dummy surrogate at six levels of distance. Not only the sensors inside the dummy as a mechanics information system recorded all the kinetic energy impact measures accurately and effectively, but also other systems like acquiring and processing information system including hardware and software played their roles respectively. The acceleration response, displacement response showed consistent patterns with the kinetic energy measures. The results showed that the measurement from the special system was reliable for non-lethal kinetic energy projectiles. The maxima of displacement, viscous criterion (VC) and kinetic energy were both lower than correlative injury thresholds. Current study provided an alternative method to assess the performance of the non-lethal kinetic energy projectiles.

The traumatic potential of a projectile shot from a sling

Herein, we analyze the energy parameters of stones of various weights and shapes shot from a sling and based on this data evaluate its traumatic potential. Four police officers proficient in the use of a sling participated in the trials. The following projectile types, shot using an overhead technique at a target 100m away were: round steel balls of different sizes and weights (24mm, 57g; 32mm, 135g; 38mm, 227g); different shaped stones weighing 100-150g and 150-200g and a golf ball (47g). Our data indicated that projectiles shot from unconventional weapons such as a sling, have serious traumatic potential for unprotected individuals and can cause blunt trauma of moderate to critical severity such as fractures of the trunk, limb, and facial skull bone, depending on the weight and shape of the projectile and the distance from the source of danger. Asymmetrically shaped projectiles weighing more than 100g were the most dangerous. Projectiles weighing more than 100g can cause bone fractures of the trunk and limbs at distances of up to 60m from the target and may cause serious head injuries to an unprotected person (Abbreviated Injury Scale 4-5) at distances up to 200m from the target. Due to the traumatic potential of projectiles shot from a sling, the police must wear full riot gear and keep at a distance of at least 60m from the source of danger in order to avoid serious injury. Furthermore, given the potential for serious head injuries, wearing a helmet with a visor is mandatory at distances up to 200m from the source of danger.

Assessment of the TASER XREP blunt impact and penetration injury potential using cadaveric testing

TASER International's extended range electronic projectile (XREP) is intended to be fired from a shotgun, impact a threat, and apply remote neuromuscular incapacitation. This study investigated the corresponding potential of blunt impact injury and penetration. Forty-three XREP rounds were deployed onto two male human cadaver torsos at impact velocities between 70.6 and 95.9 m/sec (232 and 315 ft/sec). In 42 of the 43 shots fired, the XREP did not penetrate the abdominal wall, resulting in superficial wounds only. On one shot, the XREP's nose section separated prematurely in flight, resulting in penetration. No bony fractures were observed with any of the shots. The viscous criterion (VC), blunt criterion (BC), and energy density (E/A) were calculated (all nonpenetrating tests, average ± 1 standard deviation: VC: 1.14 ± 0.94 m/sec, BC: 0.77 ± 0.15, E/A: 22.6 ± 4.15 J/cm(2)) and, despite the lack of injuries, were generally found to be greater than published tolerance values.

Sturdivan's formula revisited: MRI assessment of anterior chest wall thickness for injury risk prediction of blunt ballistic impact trauma

BACKGROUND

The thickness and composition of the chest wall are important quantities in multiparametric trauma models for the assessment of injury severity due to blunt ballistic chest impact. While ballistic parameters of non-penetrating projectiles can routinely be measured with high accuracy, data on the thickness of the anterior chest wall is unreliable. Therefore, it is the aim of this work to provide data on the thickness and composition of the anterior chest wall based on MRI examinations of healthy volunteers and to compare these measurements with different empirical estimation rules for the chest wall thickness.

METHODS

The study encompassed consecutive male patients from an ongoing population-based cohort study. Each subject underwent standardized whole-body MRI (1.5Tesla). Thickness of total chest wall (CWT) and of adipose tissue (AT) were measured by two independent readers at ten anatomic locations on two cross-sectional planes over the centre of the left ventricle and over the tracheal bifurcation. For each subject, chest wall thickness was estimated based on ten different empirical estimation rules and percent errors were calculated.

RESULTS

The study encompassed 250 male volunteers (average age 55.5 years, range 21-84 years, SD 13.6 years). Mean intraclass correlation coefficient of the two readers was 0.90 (range 0.59-1.0, SD 0.08). Average CWT was 31.2mm (range 17.3-51.6mm, SD 5.8mm) while average thickness of AT was 13.1mm (range 3.6-26.7mm, SD 4.6mm). Relative adiposity was 0.41 on average (range 0.19-0.61, SD 0.09). There was significant correlation between CWT and body weight and between CWT and body mass index. Sturdivan's approximation formula showed strong correlation with the measured values (percent error 3.58%, SD 16.26%).

CONCLUSION

In this population, Sturdivan's equation formula which is based on the individual's body weight provides valid approximation values for the chest wall thickness and may be used for the optimal design of protective devices and personal body armor as well as for the development of anthropomorphic based test methodologies.

Blunt Criterion trauma model for head and chest injury risk assessment of cal. 380 R and cal. 22 long blank cartridge actuated gundog retrieval devices

BACKGROUND

Blunt ballistic impact trauma is a current research topic due to the widespread use of kinetic energy munitions in law enforcement. In the civilian setting, an automatic dummy launcher has recently been identified as source of blunt impact trauma. However, there is no data on the injury risk of conventional dummy launchers. It is the aim of this investigation to predict potential impact injury to the human head and chest on the basis of the Blunt Criterion which is an energy based blunt trauma model to assess vulnerability to blunt weapons, projectile impacts, and behind-armor-exposures.

METHODS

Based on experimentally investigated kinetic parameters, the injury risk of two commercially available gundog retrieval devices (Waidwerk Telebock, Germany; Turner Richards, United Kingdom) was assessed using the Blunt Criterion trauma model for blunt ballistic impact trauma to the head and chest.

RESULTS

Assessing chest impact, the Blunt Criterion values for both shooting devices were higher than the critical Blunt Criterion value of 0.37, which represents a 50% risk of sustaining a thoracic skeletal injury of AIS 2 (moderate injury) or AIS 3 (serious injury). The maximum Blunt Criterion value (1.106) was higher than the Blunt Criterion value corresponding to AIS 4 (severe injury). With regard to the impact injury risk to the head, both devices surpass by far the critical Blunt Criterion value of 1.61, which represents a 50% risk of skull fracture. Highest Blunt Criterion values were measured for the Turner Richards Launcher (2.884) corresponding to a risk of skull fracture of higher than 80%.

CONCLUSION

Even though the classification as non-guns by legal authorities might implicate harmlessness, the Blunt Criterion trauma model illustrates the hazardous potential of these shooting devices. The Blunt Criterion trauma model links the laboratory findings to the impact injury patterns of the head and chest that might be expected.

When backyard fun turns to trauma: risk assessment of blunt ballistic impact trauma due to potato cannons

Although potato cannons are an area of great interest among internet users, they are almost completely unknown in the medical community. These simple ballistic devices are made from plastic plumbing pipes and are powered with propellant gas from aerosol cans. By combustion of the gas-oxygen mixture, a high pressure is produced which propels the potato chunks through the barrel. It is the aim of this study to investigate the hazardous potential of these shooting devices. Test shots were performed using three illegally manufactured potato cannons that were confiscated by police authorities. Velocity, impulse, kinetic energy, and energy density were calculated. The risk of head and chest injuries was investigated by using Sturdivan's Blunt Criterion (BC), an energy based five parametric trauma model assessing the vulnerability to blunt weapons, projectile impacts, and behind-body-armor exposures. The probability of lethality due to blunt impact trauma to the chest was assessed using Sturdivan's lethality model. For potential head impacts, all test shots far exceeded the critical BC (head) value which corresponds to a 50% risk of skull fracture. The risk of injury with regard to chest impacts was similar. All but two test shots far exceeded the critical BC (chest) value corresponding to a 50% risk of sustaining a thoracic skeletal injury of Abbreviated Injury Scale 2 or 3. The probability of a lethal injury due to blunt chest impact was as high as 20%. To conclude, this work demonstrates that potato cannons should be considered dangerous weapons rather than as toys used by adventurous adolescents.

Tolerance of the skull to blunt ballistic temporo-parietal impact

Less-lethal ballistic projectiles are used by police personnel to temporarily incapacitate suspects. While the frequency of these impacts to the head is low, they account for more serious injuries than impacts to any other body region. As a result, there is an urgent need to assess the tolerance of the head to such impacts. The focus of this study was to investigate the tolerance of the temporo-parietal skull to blunt ballistic impact and establish injury criteria for risk assessment. Seven unembalmed isolated cadaver heads were subjected to fourteen impacts. Specimens were instrumented with a nine-accelerometer array as well as strain gages surrounding the impact site. Impacts were performed with a 38 mm instrumented projectile at velocities ranging from 18 to 37 m/s. CT images and autopsies were performed to document resulting fractures. Peak fracture force for the seven resulting fractures was 5633+/-2095 N. Peak deformation for fracture-producing impacts was 7.8+/-3.2 mm. The blunt criterion (BC), peak force and principal strain were determined to be the best predictors of depressed comminuted fractures. Temporo-parietal tolerance levels were consistent with previous studies. An initial force tolerance level of 2346 N is established for the temporo-parietal region for blunt ballistic impact with a 38 mm diameter impactor.

Penetrating injury to the chest by an attenuated energy projectile: a case report and literature review of thoracic injuries caused by "less-lethal" munitions

We present the case of a patient who sustained a penetrating injury to the chest caused by an attenuated energy rubber bullet and review the literature on thoracic injuries caused by plastic and rubber "less-lethal" munitions. The patient of this report underwent a right thoracotomy to extract the projectile as well as a wedge resection of the injured lung parenchyma. This case demonstrates that even supposedly safe riot control munition fired at close range, at the torso, can provoke serious injury. Therefore a thorough investigation and close clinical supervision are justified.

The Trauma Bay Chest Radiograph in Stable Blunt-Trauma Patients: Do We Really Need It?

The current study evaluates the need for trauma bay chest radiographs (CXR) in stable blunt-trauma patients who are scheduled for chest computed tomography (CCT). A retrospective review of 157 randomly selected, stable, adult blunt-trauma patients who were admitted to a level I trauma center between 2000 and 2002, who underwent both CXR and CCT (GE Light-Speed Scanner), was performed. Stable patients were defined as unintubated, normotensive (SBP >100 mm Hg), and without hypoxia (O2 saturation >90%). No interventions were conducted in the trauma bay based on chest radiograph findings. Among 95 patients with a “normal” CXR, 38 patients (40%) were found on CCT to have traumatic injuries. Among 62 patients with an “abnormal” CXR, 18 (29%) were found to be normal on CCT. Of the remaining 44 patients, 34 had additional findings on CCT. In 32 patients, CCT led to changes in management. CCT was more sensitive in diagnosing thoracic injuries and led to significant changes in management. We feel that CXR could be safely eliminated in favor of CCT in stable blunt-trauma patients.