Volume 62, Issue 2 , Pages 90-106, May 2011
Pictorial Review of Radiographic Patterns of Injury in Modern Warfare: Imaging the Conflict in Afghanistan
Article Outline
- Abstract
- Résumé
- Part 1: Radiology in Regional Conflict, Barotauma, and Antitank Weapon Injuries
- Part 2: Improvised Explosive Devices, Mines, and Other Explosive Ordinance
- Part 3: Bullet Wounds
- Conclusion
- Acknowledgements
- References
- Copyright
Abstract
Radiographic assessment of combat injuries has been an important component of casualty care in every major conflict of the 20th and 21st centuries. The advent of multislice computed tomography scanners has provided physicians with the ability to visualize organ injury at submillimetre resolution, changing the way war wounds are treated. Modern wars are, for the most part, asymmetric conflicts where improvised explosive devices have replaced artillery as a major cause of casualties. Both bullets and explosive devices wreak distinctive patterns of injury on the human body. Being able to recognize these patterns and their potential associated morbidities will allow medical personnel to provide expert and timely care to some of the most severely injured patients on earth. This series of pictorial essays will review the radiographic patterns of combat-related injury encountered in southern Afghanistan in 2008–2009.
Résumé
L'évaluation radiographique des blessures subies au combat occupe une place importante dans les soins prodigués aux blessés des grands conflits du XXe et XXIe siècles. L'apparition des tomodensitomètres multibarrettes a permis aux médecins d'évaluer les organes blessés avec une résolution infra-milimétrique, révolutionnant ainsi le traitement des blessures de guerre. La grande majorité des guerres modernes sont, en fait, des conflits asymétriques dans lesquels la plupart des blessures sont causées par des dispositifs explosifs artisanaux et non plus par l'artillerie. Les balles et les dispositifs explosifs infligent des types distincts de blessures au corps humain. Profitant de la capacité de reconnaître ces différents types de blessure et leurs morbidités potentielles associées, le personnel médical sera alors mieux outillé pour fournir des soins plus spécialisés et en temps opportun à certains des patients les plus gravement blessés de la planète. Cette série d'articles iconographiques examine le profil radiographique des blessures subies au combat lors du conflit qui a sévi dans le sud de l'Afghanistan en 2008-2009.
Key Words: Afghanistan, Radiology, Combat injuries, Barotrauma, Antitank weapons, Improvised explosive devices, IEDs, Shrapnel, Projectiles, Bullets
Militi Succurrimus (“We hasten to aid the soldiers”)
Motto of the Canadian Forces Medical Service
Shortly after Roentgen's description in 1895, radiographs were used to evaluate foreign bodies and projectiles in patients wounded as a result of combat. By World War I, radiographic equipment was being used by the medical services of all major combatants. As equipment and power sources became increasingly portable, forward surgical units routinely used radiographs to plan the treatment of casualties during World War II. With the emergence of computed tomography (CT) and experience gained during the Lebanon War in 1982, the role of radiology has expanded from characterizing fractures and foreign-body localization to defining the extent of organ injury [1].
A 16-slice (or greater) CT scanner allows high-resolution imaging of organs and vessels down to the submillimetre level, giving wartime physicians and surgeons an unprecedented appreciation of injury extent and severity [2], [3]. As a result, one could argue that imaging and management of wartime wounds have changed more in the last decade than the weaponry used to inflict them. This pictorial review series will outline the major patterns and radiographic findings of wartime injuries encountered at the North Atlantic Treaty Organization (NATO) hospital in Kandahar, Afghanistan in 2008–2009. Part 1 will describe the medical facilities, patient population served, and “selection bias” observed at Kandahar Airfield (KAF), with a brief review of barotrauma and antitank weapon injuries. Part 2 will explore the injury patterns and radiographic findings associated with explosive devices, whether improvised and not. In Part 3, the series will deal with bullet wounds.
Part 1: Radiology in Regional Conflict, Barotauma, and Antitank Weapon Injuries
Background: KAF Medical Facilities
The NATO hospital located at KAF is the major referral centre for wounded and injured patients in the region. Although the original facility itself is primitive by North American standards (a new hospital building is nearing completion), the services offered are anything but. Multiple trauma bays, a 16-slice CT scanner, 2 operating rooms, a 5-bed intensive care unit, and a 14-bed ward were staffed by medical personnel from many countries, of which approximately half were Canadian. Two surgical teams were augmented by critical care nursing, mental health teams, a radiologist, and an intensive care specialist. The presence of a neurosurgeon and a plastic or oromaxillofacial surgeon earn the hospital its NATO Role 3 designation.
During 2008–2009, the specialist services offered by the Role 3 Multinational Medical Unit (MMU) were the only ones of their kind to be found in southwestern Afghanistan, which resulted in the transfer of patients to KAF from a large catchment area. During the summer of 2008, it was the busiest NATO hospital in either Afghanistan or Iraq [4]. Although the hospital and services provided are considered military assets, both military and local civilian populations are served. The majority of casualties treated have been Afghans, their numbers a reflection of the scale of violence in the country's most dangerous provinces. When patients arrive at the Role 3 MMU, they are all treated with the same level of dedication and care, irrespective of their nationality or status.
Selection Bias in Patients Evacuated to KAF
The mortality rate for combat injuries of US troops in the 1990–1991 Persian Gulf War was 24% (similar to that during the Vietnam War), but, by 2003–2005, the mortality rate in Iraq and Afghanistan had been reduced to 10%. Although battlefield death rates have dropped, amputation rates for US troops in these most recent conflicts have roughly doubled to 6%, in part, because of the factors outlined below [5].
The extrication of casualties from combat has never been a simple thing but is faster than ever with modern helicopters and communication systems. Evacuation times from the field of combat to the hospital at KAF ranged from minutes to several hours. However, because fighting often could delay the “scoop and run” method of transport, most casualties arrived at KAF outside the “golden hour” of Advanced Trauma Life Support (ATLS) lore. Early resuscitation and application of dressings or tourniquets were typically performed by medical technicians in the field. If a wounded patient could be quickly attended to by a field medic and those injuries were immediately survivable, then the prognosis was excellent.
Declaring injuries survivable is a subjective affair, influenced by several factors. If wounds result in rapid or massive blood loss that cannot be halted by tourniquets or “quick-clot” dressings, then the prognosis generally is poor. The body part injured proves a major determinant in survivability. NATO and coalition soldiers are provided with ballistic helmets and armor to protect the head and torso, which results in a higher proportion of extremity wounds being treated at the Role 3 MMU. Afghan soldiers, police, and civilians have less or no access to this protective equipment, which results in higher numbers of torso or head wounds in this population [5]. A torso or head wound inflicted by a modern assault weapon (ie, AK-47 or M-16 equivalent) is more likely to be lethal than those wounds caused by low-velocity shrapnel fragments entering the same body part. Finally, the kinetic energy absorbed from explosions also plays a role: no amount of body armor, timely resuscitation, or surgical skill can compensate for the detonation of stacked antitank mines or a large improvised explosive device (IED). The factors outlined above, combined with the high level of surgical and intensive care expertise available at KAF, mean that casualties have an extremely high probability of surviving their injuries once they arrive at the Role 3 hospital.
Trauma Imaging Algorithms at KAF
The role of imaging in trauma management is constantly evolving. Imaging protocols for combat injuries are less guided by randomized control studies than by recent local experience and the few articles arising from the Middle East, Iraq, and Afghanistan [3], [5]. A prime example is the emerging use of nonoperative management of penetrating torso wounds. Historically, any penetrating abdominal wound would be operatively explored, but modern CT scanners now provide surgeons with the option of safely observing selected stable patients instead of taking them to the operating room [6]. The following paragraphs outline the imaging methods typically used at KAF to investigate and manage wartime injuries.
Unless the combat-injured patient was assigned a nearly asymptomatic “walking wounded” status, some form of imaging was performed. After an initial ATLS assessment was undertaken in the trauma bay, portable radiographs were quickly obtained. Nearly all stretcher-borne patients received a supine chest radiograph. Anteroposterior (AP) pelvis views were frequently ordered, as were radiographs of fractured or projectile-ridden limbs. Cross-table lateral radiographs of the cervical spine were not universally performed; they were generally reserved for those patients not being considered for CT scanning or those patients whose head and neck wounds merited immediate attention. If there was a penetrating neck wound or concern for an osseous cervical injury, then CT was the preferred method of investigation (Figure 1).
Figure 1.
Initial radiographic assessment of a casualty in a trauma bay at the Role 3 Hospital, Kandahar Airfield.
Focused assessment with sonography for trauma (FAST) was performed by a sonographer or radiologist, or more frequently, by the emergency physician or general surgeon managing the trauma patient as an extension of their physical examination. Although FAST has been proven effective in the assessment of blunt abdominal injury, its role in penetrating trauma is less well understood. If a patient's hemodynamic status permitted, then CT remained the preferred method of defining an abdominal injury, whether the trauma sustained was blunt or penetrating. When multiple casualties presented with penetrating torso wounds, FAST was useful in prioritizing hemodynamically unstable patients for immediate operative management vs further resuscitation and investigation [3].
Once the patient had been fully assessed, vascular access obtained, and the required chest drains, splints, or additional dressings applied, the need for CT investigation was then considered. Penetrating injuries to the head, neck, chest, or abdomen-pelvis were nearly always imaged with CT, unless precluded by hemodynamic instability. Given that kinetic, penetrating, and blast injuries can occur in the same instant, the combat polytrauma patient is frequently scanned from head to pelvis. The radiologist was considered part of the trauma team and normally attended each CT performed to ensure that an appropriate and comprehensive protocol was selected for each patient. A typical protocol for acute assessment of an IED strike is shown in Figure 2.
Figure 2.
Typical computed tomography protocol for assessment of improvised explosive device strike injuries.
Peripheral CT angiographic studies were performed relatively infrequently given the number of extremity fractures and wounds encountered. Distal vessel injury is often associated with wider soft-tissue defects or severely comminuted fractures obviating the need for microvascular repair. Larger vessel repairs were usually temporary because no endovascular intervention capability existed at KAF, and surgeons were often reluctant to perform definitive vascular repair grafts in contaminated wound beds. As such, clinical assessment of distal neurovascular status and intraoperative debridement and/or washout of wounds remained the primary assessment tools in-theatre [7]. Peripheral CT angiography at KAF was typically reserved for preoperative planning of complex fracture repairs near major vessels or patients in whom the cause of uncontrolled hemorrhage was poorly defined by clinical examination or intraoperative angiography.
Complex fractures of major joints were typically imaged with a thin-slice bone algorithm during the initial CT assessment, whereas those of the wrist or foot might be delayed until other patients with higher priority wounds were investigated and surgically managed.
Mechanisms of Combat-related Injuries
The injuries treated at KAF varied enormously in type and severity. Burns, barotrauma, projectiles, and kinetic energy from either explosives or vehicle crashes were seen in isolation but were more often encountered in combination. The categorizations offered in the Parts 1, 2, and 3 of this series are grossly simplified but broadly representative of combat-related injuries treated in southern Afghanistan.
Explosive Barotrauma
Although the direct blast effects of an explosion can be lethal, the associated abrupt and often severe atmospheric pressure changes can cause injury even when the human target is protected from direct blast forces by a wall or vehicle hull or by taking cover in a trench. The larger the explosion and the closer the human target is to the explosion, the greater the pressure changes [8]. Ruptured tympanic membranes are a common cause of battlefield hearing loss and are easily diagnosed on clinical examination. In cases in which the external auditory meatus was filled with debris (often precluding otoscopic examination), that same debris often made it difficult to assess tympanic membrane integrity by CT. In our experience, mechanical disruption of the ossicles was not seen unless accompanied by basal skull fracture.
Barotraumatic injury of the intestines, stomach, or esophagus was rarely, if ever, diagnosed by CT at KAF. Although certainly possible [8], hollow visceral injuries were almost always accompanied by kinetic injury (as in motor vehicle accidents) or penetrating injury, which make it difficult to determine which was the causative insult. Widespread bowel injury or rupture may have occurred at blast sites but was presumably associated with other lethal injuries that precluded transport to the Role 3 MMU.
Pulmonary barotrauma, or “blast lung,” is a manifestation of explosive injury that may initially be clinically occult. Abrupt atmospheric pressure changes disrupt alveolar architecture and allow fluid and blood to leak into the air space; although frequently seen at KAF, the lungs are less susceptible to pressure effects than the tympanic membranes [8], [9]. Chest radiographs typically show patchy, diffuse air-space opacities, without associated rib fractures or thoracic cage injury as one would expect in cases of simple contusion. Patients with a larger proportion of lung involved can manifest clinically as hemoptysis and may require ventilatory support [8]. Pulmonary barotrauma seen at KAF was inconsistently complicated by laceration or pneumatoceles (Figure 3).
Figure 3.
Pulmonary barotrauma. Patchy air-space opacities in the right lung are easily seen on radiographs (A), but associated pneumatoceles (arrows) are better demonstrated on computed tomography (B).
Antitank Weapons
Occupants of armored vehicles are protected from minor explosions, shrapnel, and small-arms fire. Unfortunately, any amount of armor can be defeated by a suitable concentration of explosive or by dedicated antitank projectiles. The latter rely on either a shaped charge to burn a hole through a vehicle's armor or a sabot shot, which uses kinetic energy to penetrate. The effects of the projectile on the vehicle's occupants can be magnified by the enclosed space, with pressure waves and projectiles prevented from wider dispersal [8]. The broader use of composite materials in modern fighting vehicle construction can result in small filaments of carbon-fiber shrapnel, which are extraordinarily difficult to visualize with either radiograph or CT (Figure 4, Figure 5).
Figure 4.
Shrapnel wounds and pulmonary barotrauma suffered by the occupant of an armored vehicle hit by a suspected antitank weapon. (A) Despite only 1 visible shrapnel fragment in the soft tissues (circle), the orthopaedic surgeon reported innumerable carbon filaments embedded in bone and throughout the posterior compartment muscles during exploration. These could not be seen on retrospective review of the imaging. (B) A small focus of right perihilar air-space disease (arrow) is secondary to barotrauma.
Figure 5.
Widespread pulmonary barotrauma of another individual involved in the same suspected antitank weapon strike as depicted in Figure 4. Note the absence of rib fractures or pneumatoceles, despite widespread air-space involvement. Minimal hemoptysis was reported in the intensive care unit.
Summary
Both the management and imaging of combat injuries have changed in the last 2 decades. The use of CT in combat imaging has become more widespread and when available is generally performed on any patient who may (or will) require surgical management. The detailed information provided by CT allows surgeons and intensive-care teams to provide life- and limb-saving care to the combat-injured patient.
Barotraumatic injury of the tympanic membranes and lungs is frequently seen as a result of explosive events. The radiographic findings associated with the latter are of great interest to the clinical team; the extent of pulmonary involvement seen on radiographs and CT is a good indicator of the degree of ventilatory support that the patient will require. Despite the relatively low incidence of antitank projectile strikes encountered in Afghanistan, injuries suffered by the occupants of armored vehicles are frequently complicated by pulmonary barotrauma. Both the radiologist and the clinical team should be mindful that shrapnel and/or fragment projectiles arising from the hull's composite material construction can be occult on imaging.
Part 2: Improvised Explosive Devices, Mines, and Other Explosive Ordinance
In Part 1 of the series, the role of radiology in managing casualties in southern Afghanistan was reviewed as well as the factors that influenced general injury pattern and survival rates among the combat-injured patients. Barotrauma was briefly described, and the patterns of injury encountered in antitank weapon strikes were discussed. In Part 2, the radiographic patterns of injury encountered as a result of explosions will be explored in more detail.
Explosive Ordinance
IEDs and purpose-built antipersonnel or antitank mines are among the most-common weapons used by insurgent forces in southern Afghanistan. They may be remotely detonated or automatically triggered. If the device is automatically triggered, then it will be indiscriminate in its target selection. When a civilian vehicle or pedestrian is struck by an IED, the lack of vehicle or body armor can result in more-severe injuries than would be received by a military target. The end effects of explosive munitions (grenades, mortar or artillery rounds) used by NATO or coalition forces are similar, essentially differing only in their precision and method of delivery.
Wounds caused by fragment projectiles are amongst the most common injuries seen at the Role 3 Hospital at KAF. Shrapnel traditionally is defined as projectiles arising from a metal case that contains a powder charge and a large number of metal projectiles exploded in flight via a fuse. This implies the use of artillery or mortars, which is generally restricted to coalition forces in Afghanistan, or to rockets and/or missiles that are used by both sides. For the purposes of this review, shrapnel and fragment projectiles will be considered the same being, because the radiographic findings arising from them are essentially indistinguishable.
The most striking radiographic manifestation of an IED or explosive munition detonation are injuries caused by fragmented projectiles. The latter may be sourced from the device's metal casing, from purpose-designed components (metal spheres, ball bearings, or scrap metal), from the environment (gravel, building materials, or vegetation), or even body parts from another nearby casualty (animal or human). The size and number of shrapnel and/or fragment projectiles can vary enormously in the same patient, as does the velocity with which they travel. Most shrapnel and/or fragment projectiles travel at relatively low velocity, and divest less kinetic energy on the victim than would a similarly sized bullet. The projectile may be left embedded within the patient or pass through the patient. All of these variables mean that the clinician or radiologist must assess a bewildering assortment of fragments, tracts, and bone or organ injuries (Figure 6, Figure 7, Figure 8, Figure 9, Figure 10, Figure 11).
Figure 6.
Penetrating, posterior head injury by metallic fragments. Metal lies immediately adjacent to the sagittal sinus (arrow) (A), with bone fragments driven into the deep white matter of the left parietal lobe (B). The patient eventually succumbed to widespread cerebral venous infarction secondary to sagittal sinus injury.
Figure 7.
Bolts as improvised explosive device projectiles. (A) This patient was struck by several scrap metal pieces, some still recognizable as hardware on the chest radiograph (circle and arrow). (B) The computed tomography shows 1 bolt embedded in the posterior paraspinal muscles and another to have entered the pleural space from posterior; the latter passed through both diaphragm and spleen, crossing the diaphragm again, finally coming to rest as a free body in the pleural space.
Figure 8.
Gravel as projectiles. Because improvised explosive devices are often buried at the roadside, mineral fragments frequently are seen in large numbers. The density of these projectiles is less than that of metal on both radiographs (A) and computed tomography (B), but their effects on the body are much the same.
Figure 9.
Shrapnel and/or fragment injury in a pediatric patient. (A) The metal fragment lying just beneath the skin (circle) had entered the abdomen from posterior. (B) Thickened loops of small bowel (arrow) and small locules of free gas (arrowhead) are indicators of intestinal perforation, confirmed on laparotomy.
Figure 10.
Victim of an improvised explosive device blast. Traumatic bilateral lower leg amputations at the level of the knee (A, B), pubic rami fractures (C, D), sacral fracture (arrow, E), and extension teardrop fracture of C2 (arrowhead, F).
Figure 11.
This victim of an improvised explosive device blast suffered an L2 compression fracture (A, B) and severe pelvic injuries (C). Note the widened symphysis pubis and right sacroiliac joint (arrow) (C), in addition to right pubic rami and femoral fractures.
Occupants of vehicles struck by IEDs or mines often have severe lower limb and spinal fractures when explosive energy is transmitted out of the road bed and vertically through the vehicle floor and seats. The direct kinetic energy absorbed from an explosion may be compounded either by shrapnel and/or fragment projectile or by secondary kinetic injury if the victim is thrown against an object or the vehicle subsequently crashes. Although an armored vehicle hull provides enhanced protection against explosions and projectiles when compared with a civilian vehicle, the same patterns of injury may result if the explosion is large enough (Figure 12, Figure 13, Figure 14, Figure 15).
Figure 12.
Typical severe, bilateral lower limb injuries from an improvised explosive device strike on an unarmored vehicle (A, B, and C). (A) Note the application of 2 below-knee tourniquets (arrows). In North America, extensive injuries such as these might be treated with amputation and individually engineered prostheses. Because of cultural and religious beliefs, some Afghan patients refuse amputation, despite facing the prospect of death from gangrene.
Figure 13.
A victim of an improvised explosive device strike on a civilian vehicle. Severely comminuted hindfoot injuries seen on radiograph (A) and coronal computed tomography reconstructions (B). (C) Patchy air-space opacities on initial chest radiograph are from associated barotrauma.
Figure 14.
Improvised explosive device strike injuries suffered by a passenger riding in a lightly armored HUMVEE. Right supraorbital skull fracture (arrow) (A); bilateral pneumothoraces (B); thoracic spine fractures at T7 and T10 (C, D); and complex left knee injury with anterolateral tibial plateau, fibular head (arrowhead) (E), and posterior cruciate ligament avulsion fractures (open arrows) (E, F). Not shown are multiple brain contusions and superior mediastinal hematoma from venous injury.
Figure 15.
Improvised explosive device strike injuries inflicted on a soldier who was inside an armored fighting vehicle. Ankle fracture-dislocation (A), femoral fracture (B), thoracic vertebral endplate fracture (C), typical splenic laceration (arrow) (D), and right mandibular fractures (arrowheads) (E, F). Mandibular fractures may result when the head (with the added weight of a helmet) flexes forward as the body is thrust upward by the blast; the jaw makes abrupt contact with the upper edge of the body armor's ceramic breastplate.
Thermal injury is frequently seen after an explosion [8] but is better assessed clinically than by radiographs or CT. Airway burns are possible, but in our experience, demonstrated few discrete findings on CT other than mucosal thickening. In those instances in which clinical correlation between carbonaceous sputum and airway mucosal thickening suggested thermal injury, there frequently was a history of secondary vapor or liquid ignition.
The direct blast effects of an explosion can crush, break, or rip the body and limbs apart. Traumatic limb amputations seen at the Role 3 hospital, such as those shown in Figure 10, were usually at the level of the joint instead of diaphyseal. Multiple fractures could be identified in blast survivors; determining whether they were caused by the direct blast effect or by secondary kinetic injury (ie, the patient was thrown against the ground or another object) was both difficult and made little difference to management. In general, the larger the explosion and the closer the patient is to the explosion, the greater the injury severity [8]. Although the study of explosive event physics is a complex discipline, the clinician or radiologist need only recognize that such an event has occurred and maintain a high index of suspicion for deep or distant injury.
Much has been written in North America on the tagging of entry and exit wound sites and counting projectiles within the body; such a task is fruitless when dealing with explosive fragmentation wounds, which may number in the dozens in a single body part. The radiologist (and patient) is perhaps better served by searching for sites of extravasation, fractures, and direct or indirect signs of organ injury, particularly when multiple casualties are being assessed. Although surgical teams prefer to remove as many fragments as they can, there are instances in which the number of casualties and projectiles are simply too large for anything but life- or limb-saving procedures to be performed.
Summary
Explosive device injuries can be devastating, frequently combining direct blast, thermal, baraotraumatic, projectile, and kinetic forces. The effects and radiographic findings associated with each injury are briefly reviewed. Differing types of injuries can be encountered in different body parts in the same patient, thus, the radiologist and the trauma team are urged to consider the body as a whole before deciding to limit the field of imaging. Because the combat-injured patient may have numerous projectile injuries, counting entry and exit wounds, and comparing them with embedded projectile numbers is probably an activity best pursued when there is time to spare. When assessing an IED or explosive munition casualty, a thorough review of imaging for sites of active extravasation, signs of organ injury, fractures, and the location of residual fragments is suggested.
Part 3: Bullet Wounds
In Part 1 of the series, the role of radiology in managing casualties in southern Afghanistan was reviewed, as well as the factors influencing general injury pattern and survival rates among the combat-injured. Barotrauma and the patterns of injury encountered in antitank weapon strikes were discussed. In Part 2, the radiographic patterns of injury resulting from explosions were described. In Part 3, the radiographic findings associated with bullet wounds are reviewed.
Most bullet wounds imaged in North America are caused by low-velocity weapons, such as handguns or shotguns; the main exceptions are those caused by hunting rifles. Bullets fired by modern assault rifles travel at extremely high velocity, imparting large amounts of kinetic injury on tissues despite their relatively small size (kinetic energy = 1/2 mv2). Assault weapon projectiles range in calibre from 5.56 mm for the standard NATO infantry weapon to 7.62 mm for carried machine guns (squad automatic weapon or light support weapon). Even larger calibre weapons, such as 0.50-calibre sniper rifles or machine guns, combine a heavy projectile with extremely high velocities to inflict devastating injuries.
Because of bullet tumble, pressure wave, and cavitation effects on organs and vessels, central torso and head wounds inflicted by high-velocity weapons are frequently lethal [10], [11]. Patients with extremity wounds are more likely survive, but injuries can be so severe that limb salvage is not possible. Large bones can be shattered even when the projectile passes through adjacent muscle, and entire muscle compartments can be devitalized. When these high-velocity projectiles pass through the body, they may leave large exit wounds when compared with the size of the entrance site [1], [9]. These velocity- and tumble-dependant effects are not seen to the same degree in low-velocity bullet wounds.
Bullets fragment to varying degrees when they strike the human body, largely dependant upon their construction. Assault weapons used in Afghanistan may fire either fully or partially jacketed bullets; the heavier core of these bullets is encased in a harder metal layer. Bullets with a full metal jacket can remain in 1 piece as they traverse soft tissues, without leaving any metal fragments along the projectile path. Bullets with a partial metal jacket, with or without a soft metal tip, frequently deform or simply break apart on impact; these projectiles can leave a trail of metal fragments dispersed through the traversed tissues. The degree of fragmentation is generally more severe if the bullet strikes bone as it passes through the body [11].
Handguns are carried by combatants on all sides of a conflict. Bullets fired from a handgun are typically constructed of soft metal, without a metal jacket, and will deform to various degrees. A hollow-point bullet will deform more severely than a “standard” bullet, but the degree of fragmentation is again dependant upon velocity and tissue type traversed. Close-range injuries with low-velocity bullets can be fatal but as the velocity of the projectile decreases (with either distance travelled or deflection) the penetrating power of the bullet lessens. Even a high-velocity round fired from an assault rifle will eventually run out of steam. A bullet travelling at low speed (whether fired from an assault weapon or a handgun) may penetrate the skin and then tunnel beneath the subcutaneous tissues or muscular fascia before coming to rest [11].
These general ballistic principles were not strictly observed by the bullets (and the wounds resultant) seen at the Role 3 hospital at KAF and should be thought of as guidelines rather than absolutes. In addition, entry and exit wound sites can be extraordinarily difficult to see on clinical examination, because combatants may be covered in dirt and have confounding abrasions, cuts, or even additional penetrating wounds. As such, the radiologist should undertake a thorough review of all imaged tissues rather than counting on the bullet's presumed path to define injury (Figure 16, Figure 17, Figure 18, Figure 19, Figure 20, Figure 21, Figure 22, Figure 23, Figure 24).
Figure 16.
Nonsurvivable high-velocity projectile injury. The projectile grazed this patient's skull and carved a regular, superficial defect in the left frontal vertex (arrow) (A), with bone fragments driven deep into the brain (B, C). Note the associated right frontal skull fracture (arrowhead) (B) and intraventricular blood (open arrow) (D). Surgical exploration confirmed gross disruption of the anterior sagittal sinus.
Figure 17.
Spine injury caused by a high-velocity bullet wound. The projectile passed through the retroperitoneal tissues and destroyed the posterior elements at L3-4 (arrows) but left no metal fragments behind. Although the injury is below the level of the conus, the patient was left with profound lower limb neurologic deficits.
Figure 18.
Facial fractures from a high-velocity gunshot wound. The projectile passed through both maxillary sinuses (arrows) (A), between the hard palate and orbital floors (B). Although there is obvious disruption of all adjacent osseous structures, the eyes miraculously escaped injury.
Figure 19.
Nonsurvivable high-velocity projectile injury. (A) The undeformed, partially jacketed bullet is visible in the left supraclavicular soft tissues. It had entered through the left mandible (B) and fractured the C2 vertebral body (C) after it traversed the upper airway. Widespread anoxic injury (D) resulted from soft-tissue injury and airway occlusion. Metal fragments in the neck (B, C) represent dental amalgam from fractured teeth, not bullet jacket fragments.
Figure 20.
High-velocity bullet and “soft” adolescent bone. The bullet passed through the relatively soft infratrochanteric femur (circle) (A), from anterior to posterior; note the few cortical fragments at the bony exit site (arrow) (B). (C) A regular tunnel-defect carved through the femur (arrowhead) was confirmed at surgery.
Figure 21.
Femoral fracture and arterial injury by high-velocity projectile. In contrast to the patient in Figure 20, the harder adult mid femur was fractured through direct injury (A), with laceration of the distal deep femoral artery by bone fragments (arrow) (B). At surgery, devitalized muscle extended for several centimetres on either side of the projectile path.
Figure 22.
A high-velocity gunshot wound that involved the peripheral chest and abdomen. Chest radiograph and computed tomography demonstrate numerous metal fragments along the projectile's path through the right anterior ribs and thoracic cavity (arrows) (A, B). (C) The right lobe of the liver is filled with metal fragments dispersed through broad areas of nonenhancing parenchyma. (D) The large exit wound contains herniated colon, liver, and gallbladder. These images hint at the lethality of central torso injuries caused by assault weapons.
(Images courtesy of Maj L. Chapman, 1 Canadian Field Hospital - Detachment Winnipeg.)
Figure 23.
(A) Neck injury from a nearly spent rifle bullet. A computed tomography angiogram shows the bullet entered the left anterior neck (arrow) (B) and lodged against the vertebral artery (C), without injuring either the carotid or jugular vessels.
Figure 24.
A 9-mm pistol gunshot wound. The bullet's final location is easily visible on the chest radiograph (circle) (A), as is the pneumothorax. (B) The bullet initially entered the posterior midline neck (entry point was not seen on initial clinical survey), fracturing the C3 spinous process as it travelled down and anterior (arrows). (C) The bullet then fractured the clavicle (arrowhead) before deflecting inward to break the right second and third anterior ribs (not shown) before entering the chest. (D) The radiographically intact bullet in the posterior sulcus had tunneled beneath the sternocleidomastoid fascia, yet retained enough kinetic energy to break clavicle and ribs. No major vascular injury resulted.
Summary
Gunshot wounds caused by assault weapons are generally more severe than those typically encountered in North America. However, the extent of injury remains dependant upon bullet velocity, composition and/or construction, and tissue type traversed. A bullet (or fragments thereof) will frequently deflect from the initial vector once it enters the body. Radiologists and clinicians both should ensure that all potential sites of injury are adequately imaged and be mindful that the presumed bullet path may not be the real one.
Conclusion
The combat-injured patient seen at the Role 3 MMU at KAF are among the most severely injured patients on earth. The mechanisms are varied, but general patterns of injury reveal themselves on radiographs and CT. Projectiles may cause a much wider area of damage than seen in North America because of either large numbers striking a single patient or the use of high-velocity weapons. Nearly every clinician who has worked at KAF can relate a tale in which a bullet or other projectile seemed to disregard the laws of either physics or anatomy (and often both) and carve a bizarre path through the body. Injuries inflicted by explosive devices, improvised or not, are truly multifactorial; direct blast, thermal and kinetic energy, barotrauma, and projectile injuries can all be seen in the same patient.
Multislice CT scanners allow far more accurate assessment than ever before, changing the manner in which combat injuries are both investigated and treated. A working understanding of basic patterns of combat-related injuries and their potential to involve local or distant organ systems provide both the radiologist and clinician with the tools and treatment plans needed to treat the casualties of war.
Acknowledgements
The author thanks Majors N. Garraway, D. Malish, and K. Sundby (1 Canadian Field Hospital), and Dr J. Ronald (Nanaimo Regional General Hospital) for their assistance in providing clinical correlation for the cases used, and for their editorial assistance in the preparation of this article. Major L. Chapman (1 Canadian Field Hospital) also is thanked for his provision of the images used in Figure 22.
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PII: S0846-5371(10)00079-3
doi:10.1016/j.carj.2010.03.005
Crown Copyright © 2011. Published by Elsevier Inc. All rights reserved.
Volume 62, Issue 2 , Pages 90-106, May 2011
