Characteristics of Ballistic and Blast Injuries




Abstract


Ballistic injury patterns to the craniomaxillofacial region present a unique, and challenging, dilemma for the facial trauma surgeon. The tissue disruption associated with ballistic injury to the head and neck region can be daunting, and the identification of normal anatomic planes, potentially lost within bleeding, destroyed soft and hard tissues, can challenge the skills of even the most experienced facial trauma specialist. While classically considered to be under the purview of the military trauma surgeon, ballistic and blast injuries are routinely treated by the civilian surgeon due to the incidence of intentional and unintentional firearm injuries and industrial accidents. Unfortunately, as evidenced by the recent surge of terrorist attacks in locales such as Paris, France and Orlando, Florida, the civilian craniomaxillofacial trauma surgeon must have not only a working knowledge of the management of ballistic wounds to the craniofacial region, but also an understanding of the staging and timing of the treatment of these injuries. A basic understanding of the definitions and characteristic clinical findings of ballistic and blast wounds should be an important tool in the armamentarium of the practicing craniomaxillofacial trauma surgeon.




Keywords

facial, maxillofacial, ballistic, blast, soft tissue injury, bone injury

 




Introduction


Ballistic injury patterns to the craniomaxillofacial region present a unique, and challenging, dilemma for the facial trauma surgeon. The tissue disruption associated with ballistic injury to the head and neck region can be daunting, and the identification of normal anatomic planes, potentially lost within bleeding, destroyed soft and hard tissues, can challenge the skills of even the most experienced facial trauma specialist. While classically considered to be under the purview of the military trauma surgeon, ballistic and blast injuries are routinely treated by the civilian surgeon due to the incidence of intentional and unintentional firearm injuries and industrial accidents. Unfortunately, as evidenced by the recent surge of terrorist attacks in locales such as Paris, France and Orlando, Florida, the civilian craniomaxillofacial trauma surgeon must have not only a working knowledge of the management of ballistic wounds to the craniofacial region, but also an understanding of the staging and timing of treatment in these injuries. A basic understanding of the definitions and characteristic clinical findings of ballistic and blast wounds should be an important tool in the armamentarium of the practicing craniomaxillofacial trauma surgeon.




Background


Any introduction to the study of ballistic injuries should provide a review of commonly used terms. Box 1.20.1 provides the necessary background information to recognize the terminology associated with ballistics, and how those components correlate to an understanding of ballistic injuries:



Box 1.20.1

Terminology of Ballistics


Components of Ammunition















Cartridge/Round A unit of firearm ammunition
Projectile The component of the round that is expelled towards the target, sometimes referred to as the “bullet”
Magnum A cartridge loaded with either a greater volume or more powerful propellant than the original cartridge design, imparting greater velocity to the projectile


Components of Weapon















Rifling Helical grooves in the barrel of a weapon, which imparts spin along the long axis of the projectile
Caliber The internal diameter of the barrel of a weapon, usually measured in millimeters or fractions of an inch
Gauge/Bore The total number of round lead balls that would fill the diameter of the barrel and weigh 1 pound


Associated Terms Seen in Ballistic Literature





















Yaw Movement along the longitudinal access of the projectile
Precession Rotation of the projectile around the center of mass
Nutation Small circular movement along the projectile tip
Magnus Effect Lateral crosswind effect of a spinning projectile in flight
Coriolis Effect Spherical shape and rotational properties of the Earth, and its orbit, as it applies to the projectile



As historical concepts of ballistics teach that impact kinetic energy is equal to one half the mass of the projectile times velocity squared (KE = MV 2 ), one would wrongly assume caliber (size) of the projectile and velocity are the sole components of injury calculation. Actually, the increased energy transmitted from a high-velocity projectile does not necessarily translate to increased wounding capacity, as will be noted throughout the remainder of this chapter, and the physical properties of the projectile, and its fate upon striking the victim, are more important than the caliber. Caliber alone has no alteration to the surgical treatment of the injury, and primarily serves to satisfy the curiosity of the attending medical staff. By understanding the basic mechanical properties of the projectile expelled towards the target, the correlation of velocity and subsequent energy transfer, and the anatomical properties of the head and neck, the craniomaxillofacial trauma surgeon will have a better understanding of the consequences of ballistic injury to the facial skeleton (see Box 1.20.2 ).



Box 1.20.2

Factors Affecting Energy Transfer Between a Projectile and Body Tissue





  • Velocity



  • Profile



  • Shape



  • Stability



  • Fragmentation



  • Expansion



  • Secondary impact




Yaw, precession, and nutation are frequently referenced when initially studying ballistics. Yaw and precession decrease as the distance of the bullet from the barrel increases, and along with nutation, are terms generally associated with shooting from a distance, as seen in military grade artillery weaponry ( Fig. 1.20.1 ). Illustrative examples of yaw are exaggerated in excess of 30 degrees for graphic representation, while in actuality the degree of yaw is generally less than 1–2 degrees, affording tight control of the projectile in flight and allowing the projectile to hit what the firearm is aimed towards. Should the yaw be as exaggerated as seen in most artistic renderings, the projectile would be uncontrollable due to tumbling along the path of fire. A clear clinical example of the effects of yaw and precession is the fact that when examined on a shooting range, projectile holes in targets are consistently circular in nature, indicating the spherical shape of the projectile, not a ragged opening consistent with “tumbling ” or excessive yaw. Of interest, projectiles do tumble within the body of the target causing increased damage after striking hard tissue, or with deformation of the projectile. While these terms have practical applications in weaponry, the clinical significance of these items in craniomaxillofacial ballistic trauma is negligible at best.




Fig. 1.20.1


Yaw, precession, and nutation.


The Magnus and Coriolis Effects are also frequently referenced in the discussion of ballistics, but again are isolated to the military applications of projectile flight, as well as the recreational aspects of long-range firing for hunting or competitive shooting. As the overwhelming majority of ballistic injuries to the head and neck region occur within relatively short distances, well within the effective range of the weapon and projectiles, these definitions and concepts have minimal to no correlation to the remainder of this chapter, or for the surgical management of these ballistic injuries.




Components of Ballistic Missiles


As previously described, the cartridge or round describes a unit of firearm ammunition. Each round consists of the following components ( Fig. 1.20.2A–B ):




  • Projectile



  • Casing



  • Propellant



  • Primer




Fig. 1.20.2


(A) Cross-sectional analysis of a cartridge and shotgun shell. (B) Cross-section of a full metal jacketed rifle cartridge. (C) Photograph of the projectile changes associated with hollow-point ammunition after they strike resistance (i.e., tissue) in flight






The components of a round provide a basic understanding of the principles of firearm injury. The projectile is the portion of the bullet that is expelled and strikes the target. The compositional makeup of the projectile (soft lead, hollow point, full copper covering, or multiple pellets as seen in shotguns) has a direct correlation on the wounding potential of the weapon. As a projectile deforms after striking the victim, either as a result of metallurgic composition during manufacturing, or as a direct consequence of striking the underlying bone, the energy transfer to the victim, and potential injury to associated tissues, is increased ( Fig. 1.20.2C ). As noted earlier, the actual projectiles expelled by firearms are limited in type only by the imagination of the manufacturers and firearm enthusiast. The casing is the container packaging the projectile, propellant (gunpowder or cordite) and primer as a single unit for placement into the firing mechanism of the weapon. The propellant, such as gunpowder or cordite, is the accelerant that actually allows for expulsion of the projectile from the weapon. The more propellant in a cartridge, as is seen in Magnum and rifle rounds, the greater velocity the projectile exhibits. Wadding, or wads , are generally plastic frameworks with a paper or felt insert that hold the various pellets (projectiles) together in relation to the propellant, allowing for accurate and safe release of all the projectiles simultaneously from the barrel in scattershot and shotgun cartridges. Without the presence of wadding, the gas produced by the propellant would push through the pellets, and not propel them as a unit. The primer is the only portion of the bullet with an explosive charge. As the primer is struck by the firing pin of the weapon, the explosive charge is activated, igniting the propellant and sending the projectile on its flight. Some cartridges are referred to as rimfire as the priming mechanism is contained within the rim of the base rather than a separate primer in the center of the base. Generally, rimfire cartridges are less powerful and cannot be reloaded, while centerfire cartridges can have the primer replaced and reloaded with another projectile.


Rifles, handguns, and machine guns have rifled barrels – essentially, spiral grooves cut into the length of the interior of the bore of the barrel. The grooves impart spin upon the projectile, stabilizing it in flight and allowing the projectile to travel in a controlled manner to the target. The grooves are separated by segments of metal, called lands, which project into the middle of the barrel. The diameter of the barrel measured between the lands represents the caliber of the projectile. Caliber specifications based on nomenclature used in the United States can be difficult to comprehend, and utterly confusing to the healthcare team. The .30-06 and the Winchester .308 cartridges are both loaded with bullets that have a diameter of .308 inches. The “06” in this term describes the year, 1906, when the cartridge was introduced to the market. The term “grains” originally was applied to black powder charges and refers to the weight of the powder in the cartridge, not the number of granules contained in the cartridge case. A .30-30 cartridge has a .308 inch diameter bullet propelled by 30 grains of smokeless powder. As newer forms of gunpowder were developed, this powder charge was no longer used, but the terminology persists to this day. Additional misperceptions regarding caliber exist because the North Atlantic Treaty Organization (NATO) and United States military projectiles are described using the metric system (7.62 mm or 9 mm rounds), while United States civilian firearm munitions are generally referred to in measurements relating to inches (.357 or .38). Unfortunately, no uniform mechanism exists for the description of firearm cartridges and manufacturers continue to inundate the market with further descriptions to add to the confusion, such as velocity, country of manufacture, number of grains of propellant, year of manufacture, etc. ( Fig. 1.20.3 ). As noted earlier, the question regarding caliber is commonly asked in the management of ballistic injury. In reality, caliber has minimal practical impact on the care of the patient as the surgical management of a wound caused by a .357 projectile is no different from a wound caused by a 9 mm round, and should be directed to the specific anatomical anomaly created by the projectile not the weapon used. Experienced surgical providers cannot accurately determine the caliber of a weapon by visual examination of the wound alone, and would never alter the required treatment based on the diameter of the projectile.




Fig. 1.20.3


Photograph of the tremendous variety of caliber, projectile composition or construction, and variable volumes of propellant and casings available for the modern firearm.

(From Powers DB, Delo RI. Maxillofacial ballistic and missile injuries. In Fonseca RJ, Walker RV, Betts NJ, et al., editors. Oral and maxillofacial trauma, 4th ed. St. Louis, MO; 2012.)


Handguns are handheld firearms, with a barrel length generally inches or less, which usually fire projectiles of a lower velocity and caliber. Handgun injuries generally have a tendency to “push-away,” or stretch soft tissues, including vessels or nerves as opposed to avulsive loss. The characteristic low-velocity wound has a small rounded, or slightly ragged entrance wound, causing fragmentation of teeth and bony comminution, often exhibiting no exit wound ( Figs. 1.20.4A–C ). If an exit wound does occur, it is generally slit-shaped or stellate. Rifles are long guns with barrel lengths generally more than 24 inches. At distance, rifle wounds create a low-energy transfer similar to those seen with handguns. At close range the wounding characteristics are different due to the increased potential injury associated with velocity and high-energy transfer ( Figs. 1.20.4D–H ). The presence of an exit wound is usually found, which may be stellate and larger than the entry wound. The existence of avulsive soft/hard tissue wounds and significant fragmentation of the bone can be characteristic findings of rifle wounds. A shotgun is a long gun that may fire a single pellet, or numerous pellets, at a relatively low velocity. The gauge of the shotgun is classified as the number of lead balls/pellets placed together equaling the interior diameter of the barrel, which would weigh one pound. For contact with close range injuries, the effect of the gas that is discharged under pressure into the wound also needs to be considered. This scenario is extremely important in shotgun and improvised explosive blast wounds due to the higher degree of contamination and presence of propelled gas and shock waves. Powder gases are expelled from the muzzle of the weapon after combustion of the gunpowder and follow the projectile out of the barrel. When the muzzle of the weapon is in contact with the target, this can be an additional source of tissue displacement, injury, and thermal burning.




Fig. 1.20.4


(A) Characteristic clinical appearance of low-energy/low-velocity gunshot wound to the anterior mandible. No exit wound was detected. (B) 3-Dimensional reconstruction of computed tomography scan indicating the degree of comminution associated with this gunshot wound. 3-D reconstructions provide superior visualization, and localization, of anatomic variants in the management of ballistic injuries to the craniomaxillofacial unit. (C) Application of a modern external fixator for the management of a low-energy/low-velocity gunshot wound to the mandible. (D) High-energy/high-velocity rifle wound to the anterior maxilla with complete avulsion of the nasal complex. Note the significant difference in the wounding characteristics of the high-energy weapon, as the patient was shot in the face at a distance by an assailant with a rifle. Reconstruction shows utilization of calvarial bone to reconstruct the vertical pillars of support for the maxilla. (E) High-energy gunshot wound to the anterior mandible. Note the presence of soft tissue disruption as the projectile exited the patient’s mouth and then tracked along the soft tissues of his anterior maxilla. (F) 3-Dimensional reconstruction of computed tomography scan indicating the degree of comminution and avulsive bone loss associated with this gunshot wound. (G) Initial stabilization of the patient was accomplished with an external fixator. (H) Definitive reconstruction with open reduction and internal fixation with a reconstruction plate.

(Panel (D) from Powers DB, Delo RI. Maxillofacial ballistic and missile injuries. In: Fonseca RJ, Walker RV, Betts NJ, et al., editors. Oral and maxillofacial trauma, 4th ed. St. Louis, MO; 2012. Panels (E–H) from Powers DB, Delo RI. Characteristics of ballistic and blast injuries. Atlas Oral Maxillofac Surg Clin North Am 2013; 21;15–24.)
















Shotgun pellet injuries essentially depend completely on the distance the weapon is from the target at the time of discharge. Sherman and Parrish devised a classification system to describe shotgun wounds in relation to the distance from the target. Type I injury occurs from a distance longer than 7 yards; Type II injury is sustained when the discharge is within 3–7 yards; Type III injury is within 3 yards. Type III injuries usually sustain dramatic soft and hard tissue injuries and avulsion of tissue, whereas Type I injuries may be minimal ( Figs. 1.20.5A–D ). Because victims often have difficulty in determining how far away the shotgun was at the time of discharge, Glezer and colleagues revised this classification system and directed their attention to the size of the pellet scatter. Type I injuries occur when pellet scatter is within an area of 25 cm 2 ; Type II injuries are within 10 cm 2 to 25 cm 2 ; Type III injuries have pellet scatter less than 10 cm 2 . Although the Glezer classification originally was developed for abdominal injuries, the information is transferable to other areas of the body, and determinations of tissue injury can be correlated directly to the size of the pellet scatter. Intuitively, the closer the shotgun is to the patient, the more dramatic the hard and soft tissue damage. For rifles and handguns, the practical clinical difference in whether the weapon was 10 feet, 100 feet, or 1000 feet away from the patient otherwise has no bearing on surgical and medical treatment.


Sep 22, 2019 | Posted by in Aesthetic plastic surgery | Comments Off on Characteristics of Ballistic and Blast Injuries
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