Abstract
The purpose of this study was to investigate the difference in mandibular trauma caused by two mechanisms for the delivery of missile injuries: firearms and improvised explosive devices (IEDs). The data investigated included sex, age, mechanism of injury, and other clinical and radiographic manifestations. Seventy consecutive patients, predominantly male, with a mean age of 28.6 ± 14 years (range 2–60 years) were enrolled: 38 patients (54.3%) sustained mandibular fractures caused by bullet injuries and 32 patients (45.7%) had mandibular fractures caused by IED explosion injuries. The study revealed that the differences in most of the investigated variables were not statistically significant; the only significant differences were the incidence of trauma to other body regions and the presence of retained foreign bodies. The effect on the mandible of IED explosion resembles that of bullets. Bullet injuries are associated with a relatively higher number of mandibular sites involved and more bilateral fractures, in addition to more extensive bone loss. IEDs, on the other hand, cause more multisystem injuries and result in more retained foreign bodies.
Missile injuries represent a major problem that is growing worldwide . These injuries can inflict severe disruption to the tissues, presenting a great challenge to the attending surgeons. Such injuries in the maxillofacial region result in a complex pattern of trauma, with comminution, loss of bone, and soft tissue avulsion being common manifestations . Traditionally these injuries are categorized as penetrating, perforating, or avulsion injuries depending on the energy transfer of the missile (being either high or low) and on the anatomical structures involved .
The two main mechanisms for the delivery of missile injuries are firearms, such as handguns and rifles, and explosives, among which are improvised explosive devices (IEDs). IEDs are defined as bombs fabricated in an improvised manner to destroy or incapacitate military personnel or civilians . They have been reported to be responsible for increased morbidity and mortality during the last decade , and are considered vital weaponry in the current ongoing armed conflict and terrorist actions in Iraq. These devices have incurred a new class of casualty involving multiple organ systems . IEDs were the most common cause of injury for coalition soldiers during the Iraqi insurgency in 2006 . Three major types of IED have been used in Iraq: package-type, vehicle-borne, and suicide bomb IEDs .
Being an exposed part of the body, the maxillofacial region is a common location for missile injuries , and the mandible is the most frequently injured bone. Injuries to the mandible are difficult to classify . The bone comminution associated with mandibular missile injuries occurs with little relation to the calibre of the missile or its velocity .
There appear to have been no studies comparing the patterns of mandibular fracture between bullet injuries and IED injuries. Therefore the purpose of this study was to investigate these patterns in terms of the clinical manifestations, radiographic findings, and associated morbidity and mortality, and to compare these parameters in such injuries.
Materials and methods
This retrospective study included patients who sustained mandibular fractures caused by missile injuries in the form of bullets or IED explosions during the period extending from September 2013 to December 2015. Most of the patients received their preliminary care in the emergency department of the same hospital, while a few received their primary care elsewhere but were ultimately referred to this hospital for definitive care. Plain radiographs and/or computed tomography (CT) scans were used to determine the extent of the bone injury for all of the patients.
The data included in the analysis were sex, age, mechanism of injury (whether bullets or an IED explosion, as reported by the patient when conscious, or by their escorts), and clinical and radiographic findings, including the anatomical sites of the mandible involved, the pattern of the mandibular trauma (whether linear fractures, comminuted fractures, bone loss leading to continuity defects, or a combination thereof), the laterality of the trauma (unilateral or bilateral fractures), and whether a single site or multiple mandibular sites were involved. The data recorded also included the accompanying soft tissue injuries, injuries in other body regions, the presence of retained foreign bodies, and the mortality rate.
The statistical analysis was performed using GraphPad Prism version 6 for Windows (GraphPad Software, La Jolla, CA, USA). For the descriptive analysis, percentages or the mean ± standard deviation (SD) were recorded. All investigated variables were analyzed statistically using the Student t -test for two independent means, the χ 2 test, or Fisher’s exact test. The differences were considered significant at P ≤ 0.05.
This study was exempted from institutional review board approval due to its retrospective nature.
Results
During the study period, 70 consecutive patients were admitted and treated for missile injuries. They had a mean age of 28.6 ± 14 years (range 2–60 years). Fifty-seven patients (81.4%) were male and 13 patients (18.6%) were female. During the immediate phase of treatment, nine patients (12.9%) required a tracheostomy to secure the airway.
Thirty-eight patients (54.3%) sustained mandibular fractures caused by bullet injuries. Their mean age was 27.5 ± 14.3 years (range 5–60 years); 31 were male and seven were female, giving a male to female ratio of 4.4:1. Thirty-two patients (45.7%) had mandibular fractures caused by IED explosion injuries. Twenty-six were male and six were female, giving a male to female ratio of 4.3:1, and their mean age was 29.9 years (range 2–60 years). There was no statistically significant difference in mean age or sex distribution between the two groups ( P ≤ 0.05). Both groups showed a similar age group distribution, with the most frequently affected age group being 20–29 years, followed by 30–39 years. The least involved were patients in their seventh decade of life. Of note is that 26.3% of patients in the bullet injury group were under 20 years of age compared to 18.8% in the IED injury group.
In the bullet injury group, the total number of mandibular sites involved was 68; the distribution of the mandibular anatomical sites of injury is summarized in Table 1 . The main characteristics of the injuries in this group are shown in Table 2 . Seventeen patients (44.7%) had facial wounds that required repair, 10 of whom had avulsed exit wounds with soft tissue loss that were repaired by undermining and advancement of the remaining tissues. The remaining patients had small wounds that were not sutured; most of these wounds were bullet entrance wounds. Three patients had a facial nerve injury.
