The sensitivity of chest X-ray (CXR) for the detection of significant thoracic injury in children exposed to blast.

INTRODUCTION: Thoracic trauma is an important cause of morbidity and mortality in children exposed to blast and early recognition of these injuries is vital. While numerous studies have investigated the sensitivity of chest X-ray (CXR) for the detection of chest injury in blunt trauma, none have evaluated its performance in paediatric blast injury. METHODS: CXR and Computed Tomography (CT) thorax findings were compared for 105 children who were injured by blast and presented to the UK Role 3 Hospital, Camp Bastion, Helmand Province, during the recent conflict in Afghanistan from 2011 to 2013. CXR performance was evaluated compared to the 'gold standard' of CT for the detection of significant thoracic injuries, defined as pneumothorax, haemothorax, aortic or great vessel injury, 2 or more rib fractures, ruptured diaphragm, sternal fracture, penetrating fragments and pulmonary contusion or laceration. RESULTS: The sensitivity of CXR for the detection of significant injuries was: pneumothorax 43%, haemothorax 40%, contusion 44%, laceration 100%, blast lung 80% and subdermal metallic fragments 75%. CXR missed all cases of diaphragm injury, ≥2 rib fractures, clavicle fracture and pleural effusion, although numbers of each were small. Specificity for CXR injury detection was 94% for contusion and 93% for fragment, and 100% otherwise. The sensitivity and specificity of CXR for identifying an abnormality that would prompt CT imaging was 72% (95% CI 55-85%) and 82% (95% CI 70-90%). CONCLUSIONS: CXR has a poor sensitivity for the identification of significant thoracic injury in children exposed to blast. We argue that, given the challenge of clinical assessment of injured children and the potential for serious adverse consequences of missed thoracic injuries, there should be a low threshold for the use of CT chest in the evaluation of children exposed to blast.

Injuries in Underbody Blast Fatalities: Identification of Five Distinct Mechanisms of Head Injury.

Previous research has shown that injuries to the head and neck were prevalent in 73% of all mounted fatalities of underbody blast. The mechanisms that cause such injuries to the central nervous system (CNS) are not yet known. The aim of this study was to identify the head and spinal injuries in fatalities due to underbody blast (UBB) and then develop hypotheses on the causative mechanisms. All U.K. military fatalities from UBB with an associated head injury that occurred during 2007-2013 in the Iraq and Afghanistan conflicts were identified retrospectively. Computed tomography post-mortems (CTPMs) were interrogated for injuries to the head, neck, and spine. All injuries were documented and classified using a radiology classification. Pearson's chi-square and Fisher's exact tests were used to show a relationship between variables and form a hypothesis for injury mechanisms. There were 50 fatalities from UBB with an associated head injury. Of these, 46 had complete CTPMs available for analysis. Chi-square and Fisher's exact tests showed a relationship between lateral ventricle blood and injuries to the abdomen and thorax. Five partially overlapping injury constellations were identified: 1.multiple-level spinal injury with skull fracture and brainstem injury, 2.peri-mesencephalic hemorrhage, 3.spinal and brainstem injury, 4.parenchymal contusions with injury to C0-C1, and 5.an "eggshell" pattern of fractures from direct impact. These injury constellations can now be used to propose injury mechanisms to develop mitigation strategies or clinical treatments.

Assessment of the potential impact of embedded radioactive fragments following the use of a crude radiological dispersal device ('dirty bomb').

This work was undertaken to understand what would happen if a high-activity radioactive fragment became embedded in an individual following the use of a crude radiological dispersal device ('dirty bomb'). Two areas were addressed: how would a high-activity fragment be viewed on modern digital x-ray imaging systems; and, what would be the impact on medical management for the patient? A set of experimental trials were undertaken using an iridium-192 source and a DRagon mobile x-ray set equipped with a Canon CXDI-50G portable flat panel digital detector plate. In addition, the potential doses to a surgical team were calculated and potential doses to a patient were assessed using a Monte Carlo code, in which a radioactive point source of nil volume was located within a limb of an anthropomorphic voxel phantom. Three distinct effects on the digital imaging systems were observed, referred to in this paper as a localised 'bloom' effect, a 'discontinuity' effect towards the middle of the image and 'fogging' across the entire image. The first two of these effects were unexpected, and possible reasons for their appearance are discussed. The Monte Carlo modelling showed that the patient exposure can potentially lead to very high localised absorbed doses, which may result in symptoms associated with acute radiation syndrome. While the dose clearly depends upon the activity of the fragment and the length of time that the fragment is present inside the patient, it is clear that radiation necrosis of bone, muscle and other tissues may threaten the medium term viability of the limb. The dose rates associated with high-activity fragments may also restrict the time a surgeon has to operate, leading to challenging ethical and surgical decisions. Low-activity fragments allow for conventional surgical management to be considered with appropriate control measures.

Pelvic injury patterns in blast: Morbidity and mortality.

BACKGROUND: Pelvic trauma has emerged as one of the most severe injuries to be sustained by the victim of a blast insult. The incidence and mortality due to blast-related pelvic trauma is not known, and no data exist to assess the relative risk of clinical or radiological indicators of mortality. METHODS: The UK Joint Theater Trauma Registry was interrogated to identify those sustaining blast-mediated pelvic fractures during the conflicts in Iraq and Afghanistan, from 2003 to 2014, with subsequent computed tomography image analysis. Casualties that sustained more severe injuries remote to the pelvis were excluded. RESULTS: One hundred fifty-nine casualties with a 36% overall mortality rate were identified. Pelvic vascular injury, unstable pelvic fracture patterns, traumatic amputation, and perineal injury were higher in the dismounted fatality group (p < 0.05). All fatalities sustained a pelvic vascular injury. Pelvic vascular injury had the highest relative risk of death for any individual injury and an associated mortality of 56%. Dismounted casualties that sustained unstable pelvic fracture patterns, traumatic amputation, and perineal injury were at three times greater risk (relative risk, 3.00; 95% confidence interval, 1.27-7.09) to have sustained a pelvic vascular injury than those that did not sustain these associated injuries. Opening of the pubic symphysis and at least one sacroiliac joint was significantly associated with pelvic vascular injury (p < 0.001), and the lateral displacement of the sacroiliac joints was identified as a fair predictor of pelvic vascular injury (area under the receiver operating characteristic curve, 0.73). CONCLUSION: Dismounted blast casualties with pelvic fracture are at significant risk of a noncompressible pelvic vascular injury. Initial management of these patients should focus upon controlling noncompressible pelvic bleeding. Clinical and radiological predictors of vascular injury and mortality suggest that mitigation strategies aiming to attenuate lateral displacement of the pelvis following blast are likely to result in fewer fatalities and a reduced injury burden. LEVEL OF EVIDENCE: Prognostic, level III.

Preliminary effect of projectile yaw on extremity gunshot wounding in a cadaveric animal model: a serendipitous study.

Gunshot wounding (GSW) is capable of causing devastating tissue injuries by delivering kinetic energy (KE) through the contact surface area of a projectile. The contact surface area can be increased by yaw, deformation and fragmentation, all of which may be caused by any intermediate layers struck by the projectile prior to entering its target. This study aims to describe whether projectile yaw occurring before penetration of a cadaveric animal limb model causes greater damage with or without clothing layers present using 5.45 × 39 mm projectiles. In total, 12 fallow deer hind limbs were shot, further divided into 4 with no clothing layers (Cnil), 4 with a single clothing layer (Cmin) and 4 with maximum clothing layers (Cmax) as worn on active duty by UK military personnel. Contrast computed tomography (CT) of limbs was used to measure permanent cavity size and the results were compared using analysis of variance (ANOVA). No significant differences were found among clothing states for each series of measurements taken, with greater cavity sizes noted in all clothing states. This is in contrast to previous work looking at symmetrically flying projectiles in the same model, where a larger permanent cavity was found only with Cmax present. Projectile yaw is therefore likely to be a key variable with regard to causation of damage within this extremity wound model.

Ballistic research techniques: visualizing gunshot wounding patterns.

There are difficulties associated with mapping gunshot wound (GSW) patterns within opaque models. Depending on the damage measurement parameters required, there are multiple techniques that can provide methods of "seeing" the GSW pattern within an opaque model. The aim of this paper was to test several of these techniques within a cadaveric animal limb model to determine the most effective. The techniques of interest were flash X-ray, ultrasound, physical dissection, and computed-tomography (CT). Fallow deer hind limbs were chosen for the model with four limbs used for each technique tested. Quarantined 7.62 × 39 mm ammunition was used for each shot, and each limb was only shot once, on an outdoor range with shots impacting at muzzle velocity. Flash X-ray provided evidence of yaw within the limb during the projectile's flight; ultrasound though able to visualise the GSW track, was too subjective and was abandoned; dissection proved too unreliable due to the tissue being cadaveric so also too subjective; and lastly, CT with contrast provided excellent imaging in multiple viewing planes and 3D image reconstruction; this allowed versatile measurement of the GSW pattern to collect dimensions of damage as required. Of the different techniques examined in this study, CT with contrast proved the most effective to allow precise GSW pattern analysis within a cadaveric animal limb model. These findings may be beneficial to others wishing to undertake further ballistic study both within clinical and forensic fields.

Shooting through windscreens: ballistic injury assessment using a surrogate head model-two case reports.

A synthetic head model developed to reproduce military injuries was assessed in two different scenarios involving shooting through intermediate targets (a laminated vehicle windscreen in scenario 1 and a military helicopter windscreen in scenario 2) with 7.62 × 39-mm mild steel core (MSC) ammunition. The injury patterns resulting from the two scenarios were assessed by a military radiologist and a forensic pathologist with combat injury experience and found to be clinically realistic.

The effect of military clothing on gunshot wound patterns in a cadaveric animal limb model.

The majority of injuries in survivors of gunshot wounds (GSW) are typically to the extremities. Novel wound ballistic research is encouraged to try and capture corporate knowledge on the management of these injuries gained during recent conflicts and understand the wounding patterns seen. With recent work examining the effect of UK military clothing on extremity GSW patterns in a synthetic model, a model with greater biofidelity is needed for ballistic testing. The aim of this study was to assess the effect of UK military clothing on GSW patterns within a cadaveric animal limb model using two types of ammunition commonly used in recent conflicts-7.62 × 39 mm and 5.45 × 39 mm. In total, 24 fallow deer hind limbs were shot, 12 by 7.62 mm projectiles and the remaining 12 shot by 5.45 mm projectiles, further divided into four with no clothing layers (Cnil), four with a single clothing layer (Cmin) and four with maximum clothing layers (Cmax) as worn on active duty by UK military personnel. Limbs were analysed after ballistic impact using contrast CT scanning to obtain measurements of permanent cavity damage, and results were compared using analysis of variance (ANOVA). Results showed significantly different damage measurements within limbs with Cmax for both ammunition types compared with the other clothing states. This may result in GSWs that require more extensive surgical management, and invites further study.

Forensic reconstruction of two military combat related shooting incidents using an anatomically correct synthetic skull with a surrogate skin/soft tissue layer.

Six synthetic head models wearing ballistic protective helmets were used to recreate two military combat-related shooting incidents (three per incident, designated 'Incident 1' and 'Incident 2'). Data on the events including engagement distances, weapon and ammunition types was collated by the Defence Science and Technology Laboratory. The models were shot with 7.62 × 39 mm ammunition downloaded to mean impact velocities of 581 m/s (SD 3.5 m/s) and 418 m/s (SD 8 m/s), respectively, to simulate the engagement distances. The damage to the models was assessed using CT imaging and dissection by a forensic pathologist experienced in reviewing military gunshot wounds. The helmets were examined by an MoD engineer experienced in ballistic incident analysis. Damage to the helmets was consistent with that seen in real incidents. Fracture patterns and CT imaging on two of the models for Incident 1 (a frontal impact) were congruent with the actual incident being modelled. The results for Incident 2 (a temporoparietal impact) produced realistic simulations of tangential gunshot injury but were less representative of the scenario being modelled. Other aspects of the wounds produced also exhibited differences. Further work is ongoing to develop the models for greater ballistic injury fidelity.

Analysis of isolated transverse process fractures sustained during blast-related events.

BACKGROUND: Personnel have sustained a range of devastating blast injuries during recent conflicts. Previous studies have focused on severe injuries, including to the spine; however, no study has specifically focused on the most common spinal injury-transverse process (TP) fractures. Although their treatment usually requires limited intervention, analysis of TP fractures may help determine injury mechanisms. METHODS: Data were collected from victims with spinal fractures who were injured in improvised explosive device attacks, from the UK's Joint Theatre Trauma Registry. The level and side of each TP fracture were recorded, as well as associated injuries, whether they were mounted or dismounted, and outcome (survivor or fatality). RESULTS: Most (80%) of the TP fractures were lumbar. More bilateral (both left and right fractures at the same level), and L5 TP fractures, were seen in fatalities than survivors. In the mounted group, lumbar TP fractures were statistically significantly associated with fatality, head injury, noncompressible torso hemorrhage, pelvic injury, and other spinal injuries. In the dismounted group, thoracic TP fractures were associated with head, chest wall, and other spinal injuries; and lumbar TP fractures were associated with pelvic and other spinal injuries. CONCLUSIONS: Different injury mechanisms of the TP in the mounted and dismounted groups are likely. Inertial forces acting within the torso due to rapid loading being transferred through the seat, or high intra-abdominal pressures causing the tensile forces acting through the lumbar fascia to avulse the TPs are likely mechanisms in the mounted group. Blunt trauma, violent lateral flexion-extension forces, or rapid flail of the lower extremities causing tension of the psoas muscle, avulsing the TP, are likely causes in the dismounted group. Isolated lumbar TP fractures can be used as markers for more severe injuries, and fatality, in mounted blast casualties. LEVEL OF EVIDENCE: Prognostic and epidemiological, level III.

Ballistic impacts on an anatomically correct synthetic skull with a surrogate skin/soft tissue layer.

The aim of this work was to further develop a synthetic model of ballistic head injury by the addition of skin and soft tissue layers to an anatomically correct polyurethane skull filled with gelatine 10% by mass. Six head models were impacted with 7.62 x 39 mm full metal jacket mild steel core (FMJ MSC) bullets with a mean velocity of 652 m/s. The impact events were filmed with high-speed cameras. The models were imaged pre- and post-impact using computed tomography. The models were assessed post impact by two experienced Home Office pathologists and the images assessed by an experienced military radiologist. The findings were scored against real injuries. The entry wounds, exit wounds and fracture patterns were scored positively, but the synthetic skin and soft tissue layer was felt to be too extendable. Further work is ongoing to address this.

Identifying Spinal Injury Patterns in Underbody Blast to Develop Mechanistic Hypotheses.

STUDY DESIGN: A retrospective case series of UK victims of blast injury. OBJECTIVE: To identify the injury patterns in the spine caused by under-vehicle blast, and attempt to derive the mechanism of those injuries. SUMMARY OF BACKGROUND DATA: The Improvised Explosive Device has been a feature of recent conflicts with frequent attacks on vehicles, leading to devastating injuries. Vehicle design has evolved to reduce the risk of injury to occupants in underbody blast, where the device detonates beneath the vehicle. The mechanism of spinal injury in such attacks is not well understood; understanding the injury mechanism is necessary to produce evidence-based mitigation strategies. METHODS: A Joint Theatre Trauma Registry search identified UK victims of blast between 2008 and 2013. Each victim had their initial scan reviewed to classify spinal fractures. RESULTS: Seventy-eight victims were identified, of whom 53 were survivors. There were a total of 284 fractures, including 101 thoracolumbar vertebral body fractures and 39 cervical spine fractures. Most thoracolumbar fractures were wedge compression injuries. Most cervical spine fractures were compression-extension injuries.The most common thoracic and lumbar body fractures in this group suggest a flexed posture at the time of injury. Most cervical spine fractures were in extension, which might be compatible with the head having struck another object. CONCLUSION: Modifying the seated posture might reduce the risk of thoracolumbar injury, or allow the resulting injury patterns to be controlled. Cervical spine injuries might be mitigated by changing vehicle design to protect the head. LEVEL OF EVIDENCE: N/A.

Blast Injury in the Spine: Dynamic Response Index Is Not an Appropriate Model for Predicting Injury.

BACKGROUND: Improvised explosive devices are a common feature of recent asymmetric conflicts and there is a persistent landmine threat to military and humanitarian personnel. Assessment of injury risk to the spine in vehicles subjected to explosions was conducted using a standardized model, the Dynamic Response Index (DRI). However, the DRI was intended for evaluating aircraft ejection seats and has not been validated in blast conditions. QUESTIONS/PURPOSES: We asked whether the injury patterns seen in blast are similar to those in aircraft ejection and therefore whether a single injury prediction model can be used for both situations. METHODS: UK military victims of mounted blast (seated in a vehicle) were identified from the Joint Theatre Trauma Registry. Each had their initial CT scans reviewed to identify spinal fractures. A literature search identified a comparison population of ejected aircrew with spinal fractures. Seventy-eight blast victims were identified with 294 fractures. One hundred eighty-nine patients who had sustained aircraft ejection were identified with 258 fractures. The Kruskal-Wallis test was used to compare the population injury distributions and Fisher's exact test was used to assess differences at each spinal level. RESULTS: The distribution of injuries between blast and ejection was not similar. In the cervical spine, the relative risk of injury was 11.5 times higher in blast; in the lumbar spine the relative risk was 2.9 times higher in blast. In the thoracic spine, the relative risk was identical in blast and ejection. At most individual vertebral levels including the upper thoracic spine, there was a higher risk of injury in the blast population, but the opposite was true between T7 and T12, where the risk was higher in aircraft ejection. CONCLUSIONS: The patterns of injury in blast and aircraft are different, suggesting that the two are mechanistically dissimilar. At most vertebral levels there is a higher relative risk of fracture in the blast population, but at the apex of the thoracic spine and in the lower thoracic spine, there is a higher risk in ejection victims. The differences in relative risk at different levels, and the resulting overall different injury patterns, suggest that a single model cannot be used to predict the risk of injury in ejection and blast. CLINICAL RELEVANCE: A new model needs to be developed to aid in the design of mine-protected vehicles for future conflicts.

Identifying future 'unexpected' survivors: a retrospective cohort study of fatal injury patterns in victims of improvised explosive devices.

OBJECTIVES: To identify potentially fatal injury patterns in explosive blast fatalities in order to focus research and mitigation strategies, to further improve survival rates from blast trauma. DESIGN: Retrospective cohort study. PARTICIPANTS: UK military personnel killed by improvised explosive device (IED) blasts in Afghanistan, November 2007-August 2010. SETTING: UK military deployment, through NATO, in support of the International Security Assistance Force (ISAF) mission in Afghanistan. DATA SOURCES: UK military postmortem CT records, UK Joint Theatre Trauma Registry and associated incident data. MAIN OUTCOME MEASURES: Potentially fatal injuries attributable to IEDs. RESULTS: We identified 121 cases, 42 mounted (in-vehicle) and 79 dismounted (on foot), at a point of wounding. There were 354 potentially fatal injuries in total. Leading causes of death were traumatic brain injury (50%, 62/124 fatal injuries), followed by intracavity haemorrhage (20.2%, 25/124) in the mounted group, and extremity haemorrhage (42.6%, 98/230 fatal injuries), junctional haemorrhage (22.2%, 51/230 fatal injuries) and traumatic brain injury (18.7%, 43/230 fatal injuries) in the dismounted group. CONCLUSIONS: Head trauma severity in both mounted and dismounted IED fatalities indicated prevention and mitigation as the most effective strategies to decrease resultant mortality. Two-thirds of dismounted fatalities had haemorrhage implicated as a cause of death that may have been anatomically amenable to prehospital intervention. One-fifth of the mounted fatalities had haemorrhagic trauma which currently could only be addressed surgically. Maintaining the drive to improve all haemostatic techniques for blast casualties, from point of wounding to definitive surgical proximal vascular control, alongside the development and application of novel haemostatic interventions could yield a significant survival benefit. Prospective studies in this field are indicated.

Frequency and relevance of acute peritraumatic pulmonary thrombus diagnosed by computed tomographic imaging in combat casualties.

BACKGROUND: Posttraumatic pulmonary embolism is historically diagnosed after clinical deterioration within the first week after injury. An increasing prevalence of immediate and asymptomatic pulmonary embolism have been reported in civilian and military trauma, termed hereafter as acute peritraumatic pulmonary thrombus (APPT). The objective of this study was to define the frequency of APPT diagnosed by computed tomographic (CT) imaging in wartime casualties. An additional objective was to identify factors, which may be associated with this radiographic finding METHODS: A 1-year retrospective cohort analysis conducted using the US and UK Joint Theater Trauma Registries performed to determine the prevalence of and risk factors for the diagnosis of APPT in casualties admitted to Bastion Hospital, Afghanistan. APPT imaging characteristics were collected, and demographics, injury severity and mechanism, and risk factors were included in the analysis. Logistic regression was used to identify factors independently associated with APPT. RESULTS: APPT was found in 66 (9.3%) of 708 consecutive trauma admissions, which received a CT chest with intravenous contrast as part of their initial evaluation. Diagnosis of APPT at the time of injury was made in 23 patients (3.2%), while thrombus was detected in 43 additional patients (6.1%) at the time of reexamination of CT images. Of the APPTs, 47% (n = 31) were central, 38% (n = 25) were segmental, and 15% (n = 10) were subsegmental. Forty-seven percent (n = 31) had bilateral APPT. Logistic regression found presence of deep venous thrombosis on admission (odds ratio, 5.75; 95% confidence interval, 2.44-13.58; p < 0.0001) and traumatic amputation (odds ratio, 2.53; 95% confidence interval, 1.10-5.85; p = 0.030) to be independently associated with APPT. All APPTs were felt to be incidental and likely would not have required interventions such as anticoagulation or vena caval interruption. CONCLUSION: This report is the first to characterize acute, peritraumatic pulmonary thrombus in combat injured. Nearly 1 in 10 patients with severe wartime injury has findings of pulmonary thrombus on CT imaging, although many instances require repeat examination of initial images to identify the clot. APPT is a phenomenon of severe injury and associated with deep venous thrombosis and lower-extremity traumatic amputation. Additional study is needed to characterize the natural history of peritraumatic pulmonary thrombus and the indications for anticoagulation or vena cava filter devices.

Primary blast lung injury prevalence and fatal injuries from explosions: insights from postmortem computed tomographic analysis of 121 improvised explosive device fatalities.

BACKGROUND: Primary blast lung injury (PBLI) is an acknowledged cause of death in explosive blast casualties. In contrast to vehicle occupants following an in-vehicle explosion, the injury profile, including PBLI incidence, for mounted personnel following an external explosion has yet to be as well defined. METHODS: This retrospective study identified 146 cases of UK military personnel killed by improvised explosive devices (IEDs) between November 2007 and July 2010. With the permission of Her Majesty's Coroners, relevant postmortem computed tomography imaging was analyzed. PBLI was diagnosed by postmortem computed tomography. Injury, demographic, and relevant incident data were collected via the UK Joint Theatre Trauma Registry. RESULTS: Autopsy results were not available for 1 of 146 cases. Of the remaining 145 IED fatalities, 24 had catastrophic injuries (disruptions), making further study impossible, leaving 121 cases; 79 were dismounted (DM), and 42 were mounted (M). PBLI was noted in 58 cases, 33 (79%) of 42 M fatalities and 25 (32%) of 79 DM fatalities (p < 0.0001). Rates of associated thoracic trauma were also significantly greater in the M group (p < 0.006 for all). Fatal head (53% vs. 23%) and thoracic trauma (23% vs. 8%) were both more common in the M group, while fatal lower extremity trauma (7% vs. 48%) was more commonly seen in DM casualties (p < 0.0001 for all). CONCLUSION: Following IED strikes, mounted fatalities are primarily caused by head and chest injuries. Lower extremity trauma is the leading cause of death in dismounted fatalities. Mounted fatalities have a high incidence of PBLI, suggesting significant exposure to primary blast. This has not been reported previously. Further work is required to determine the incidence and clinical significance of this severe lung injury in explosive blast survivors. In addition, specific characteristics of the vehicles should be considered.

Computed tomography can improve the selection of fragment simulating projectiles from which to test future body armor materials.

INTRODUCTION: Ballistic protective materials used in body armor are tested with fragment simulating projectiles (FSPs). The type of FSP used has historically been made by choosing fragments representative of those produced by controlled explosions, which may not be representative of those fragments actually injuring soldiers. METHOD: 75 cylindrical FSPs of three different sizes were fired into six euthanized pigs, imaged using computed tomography (CT) and the wound tracks dissected. Skin entry wound locations, as determined by surface-shaded CT, were compared to clinical photographs. FSP dimensions and depth of penetration derived from CT were compared to surgical dissection using a Mann-Whitney U test. RESULTS: Skin entry wound locations derived from CT were identical to that seen clinically. FSP dimensions were consistently 15% to 19% larger than the true measurements, reflecting the magnifying effect associated with metallic artifact. No statistical difference (p = 0.26) was found between depth of penetration measured radiologically compared to dissection when a projectile did not hit bone but there was a statistical difference when bone was hit (p < 0.05). CONCLUSIONS: CT has the potential to accurately ascertain values required to improve the selection of representative FSPs from which future ballistic protective materials are tested.

Outcomes of IED foot and ankle blast injuries.

BACKGROUND: Improvements in protection and medical treatments have resulted in increasing numbers of modern-warfare casualties surviving with complex lower-extremity injuries. To our knowledge, there has been no prior analysis of foot and ankle blast injuries as a result of improvised explosive devices (IEDs). The aims of this study were to report the pattern of injury and determine which factors are associated with a poor clinical outcome. METHODS: U.K. service personnel who had sustained lower leg injuries following an under-vehicle explosion from January 2006 to December 2008 were identified with the use of a prospective trauma registry. Patient demographics, injury severity, the nature of the lower leg injury, and the type of clinical management were recorded. Clinical end points were determined by (1) the need for amputation and (2) ongoing clinical symptoms. RESULTS: Sixty-three U.K. service personnel (eighty-nine injured limbs) with lower leg injuries from an explosion were identified. Fifty-one percent of the casualties sustained multisegmental injuries to the foot and ankle. Twenty-six legs (29%) required amputation, with six of them amputated because of chronic pain eighteen months following injury. Regression analysis revealed that hindfoot injuries, open fractures, and vascular injuries were independent predictors of amputation. At the time of final follow-up, sixty-six (74%) of the injured limbs had persisting symptoms related to the injury, and only nine (14%) of the service members were fit to return to their preinjury duties. CONCLUSIONS: This study demonstrates that foot and ankle injuries from IEDs are associated with a high amputation rate and frequently with a poor clinical outcome. Although not life-threatening, they remain a source of long-term morbidity in an active population.

FASS is a better predictor of poor outcome in lower limb blast injury than AIS: implications for blast research.

OBJECTIVES: Due to the absence of clinical blast data, automotive injury data using the abbreviated injury score (AIS) has been extrapolated to define current North Atlantic Treaty Organisation (NATO) injury thresholds for anti-vehicle mine tests. We hypothesized that AIS, being a marker of fatality rather than disability, would be a worse predictor of poor clinical outcome compared with the lower limb-specific foot and ankle severity score (FASS). METHODS: Using a prospectively collected trauma database, we identified UK Service Personnel sustaining lower leg injuries from under-vehicle explosions from January 2006 to December 2008. A full review of all medical documentation was performed to determine patient demographics and the severity of lower leg injury, as assessed by AIS and FASS. Clinical endpoints were defined as (1) need for amputation or (2) poor clinical outcome (defined as amputation or ongoing clinical problems). Statistical models were developed to explore the relationship between the scoring systems and clinical endpoints. RESULTS: Sixty-three UK casualties (89 limbs) were identified with a lower limb injury after under-vehicle explosion. The mean age of the casualty was 26.0 years. At 33.6 months follow-up, 29.1% (26 of 89) required an amputation and 74.6% (67 of 89) having a poor clinical outcome. Only 9 (14%) casualties were deemed medically fit to return to full military duty. Receiver operating characteristic analysis revealed that both AIS = 2 and FASS = 4 could predict the risk of amputation, with FASS = 4 demonstrating greater specificity (43% vs. 20%) and greater positive predictive value (72% vs. 34%). In predicting poor clinical outcome, FASS was significantly superior to AIS. Probit analysis revealed that a relationship could not be developed between AIS and the probability of a poor clinical outcome. CONCLUSIONS: Our study clearly demonstrates that AIS is not a predictor of long-term clinical outcome and that FASS would be a better quantitative measure of lower limb injury severity.

The modern "deck-slap" injury--calcaneal blast fractures from vehicle explosions.

BACKGROUND: Anti-vehicle mines and improvised explosive devices remain the most prevalent threat to coalition troops operating in Iraq and Afghanistan. Detonation of these devices causes rapid deflection of the vehicle floor resulting in severe injuries to calcaneus. Anecdotally referred to as a "deck-slap" injury, there have been no studies evaluating the pattern of injury or the effect of these potentially devastating injuries since World War II. Therefore, the aim of this study is to determine the pattern of injury, medical management, and functional outcome of UK Service Personnel sustaining calcaneal injuries from under-vehicle explosions. METHOD: From January 2006 to December 2008, using a prospectively collected trauma registry (Joint Theater Trauma Registry), the records of all UK Service Personnel sustaining a fractured calcaneus from a vehicle explosion were identified for in-depth review. For each patient, demographic data, New Injury Severity Score, and associated injuries were recorded. In addition, the pattern of calcaneal fracture, the method of stabilization, local complications, and the need for amputation were noted. Functional recovery was related to the ability of the casualty to return to military duties. RESULTS: Forty calcaneal fractures (30 patients) were identified in this study. Mean follow-up was 33.2 months. The median New Injury Severity Score was 17, with the lower extremity the most severely injured body region in 90% of cases. Nine (30%) had an associated spinal injury. The overall amputation rate was 45% (18/40); 11 limbs (28%) were amputated primarily, with a further 3 amputated on return to the United Kingdom. Four (10%) casualties required a delayed amputation for chronic pain (mean, 19.5 months). Of the 29 calcaneal fractures salvaged at the field hospital, wound infection developed in 11 (38%). At final follow-up, only 2 (6%) were able to return to full military duty with 23 (76%) only fit for sedentary work or unfit for any military duty. CONCLUSION: Calcaneal injuries following under-vehicle explosions are commonly associated with significant multiple injuries including severe lower limb injury. The frequency of associated spinal injuries mandates radiologic evaluation of the spine in all such patients. The severity of the hindfoot injury is reflected by the high infection rate and amputation rate. Only a small proportion of casualties were able to return to preinjury military duties.