Blast-mediated traumatic amputation: evidence for a revised, multiple injury mechanism theory

Pattern of upper limb amputation associated with lower limb amputation: the UK military experience from Iraq and Afghanistan

INTRODUCTION

The conflicts in Iraq and Afghanistan resulted in large numbers of personnel sustaining extremity injuries. In the context of polytrauma, partial hand amputation is often unrecorded. The aim of this work was to quantify the burden of upper limb (UL) amputation at any level occurring concurrently with a major (ankle and proximal) lower limb (LL) amputation. Knowledge of this cohort could aid in prosthetic modification to further improve quality of life outcomes in a population with dexterity loss.

METHOD

A trauma database search was undertaken for all UK military LL amputees from the conflicts in Iraq and Afghanistan. A manual search method was employed to identify from the major LL amputees those who had a concurrent UL amputation at any level (including isolated finger amputation). Demographics, level of amputation, and injury profile data were recorded.

RESULTS

Sixty-eight individuals were identified; the most prevalent population was bilateral LL with a unilateral UL amputation (60%). Most UL amputations were partial hand (75%). The was no statistically significant difference between left or right side (p=0.13). On the left side, correlation was found between amputation of the thumb and third digit (rho=0.34; p=0.005) not seen on the right.

CONCLUSION

We have determined the rate of UL amputation at any level, in combination with LL amputation as a result of blast injury. Knowledge of these combinations enables further research to support anecdotal evidence that there is a need for tailored prosthetics in the context of potential dexterity loss making donning and doffing problematic.

The Injury Mechanism of Traumatic Amputation

Traumatic amputation has been one of the most defining injuries associated with explosive devices. An understanding of the mechanism of injury is essential in order to reduce its incidence and devastating consequences to the individual and their support network. In this study, traumatic amputation is reproduced using high-velocity environmental debris in an animal cadaveric model. The study findings are combined with previous work to describe fully the mechanism of injury as follows. The shock wave impacts with the casualty, followed by energised projectiles (environmental debris or fragmentation) carried by the blast. These cause skin and soft tissue injury, followed by skeletal trauma which compounds to produce segmental and multifragmental fractures. A critical injury point is reached, whereby the underlying integrity of both skeletal and soft tissues of the limb has been compromised. The blast wind that follows these energised projectiles completes the amputation at the level of the disruption, and traumatic amputation occurs. These findings produce a shift in the understanding of traumatic amputation due to blast from a mechanism predominately thought mediated by primary and tertiary blast, to now include secondary blast mechanisms, and inform change for mitigative strategies.

Development of a rodent high-energy blast injury model for investigating conditions associated with traumatic amputations

AIMS

In recent conflicts, most injuries to the limbs are due to blasts resulting in a large number of lower limb amputations. These lead to heterotopic ossification (HO), phantom limb pain (PLP), and functional deficit. The mechanism of blast loading produces a combined fracture and amputation. Therefore, to study these conditions, in vivo models that replicate this combined effect are required. The aim of this study is to develop a preclinical model of blast-induced lower limb amputation.

METHODS

Cadaveric Sprague-Dawley rats' left hindlimbs were exposed to blast waves of 7 to 13 bar burst pressures and 7.76 ms to 12.68 ms positive duration using a shock tube. Radiographs and dissection were used to identify the injuries.

RESULTS

Higher burst pressures of 13 and 12 bar caused multiple fractures at the hip, and the right and left limbs. Lowering the pressure to 10 bar eliminated hip fractures; however, the remaining fractures were not isolated to the left limb. Further reducing the pressure to 9 bar resulted in the desired isolated fracture of the left tibia with a dramatic reduction in the fractures to other sites.

CONCLUSION

In this paper, a rodent blast injury model has been developed in the hindlimb of cadaveric rats that combines the blast and fracture in one insult, necessitating amputation. Experimental setup with 9 bar burst pressure and 9.13 ms positive duration created a fracture at the tibia with total reduction in non-targeted fractures, rendering 9 bar burst pressure suitable for translation to a survivable model to investigate blast injury-associated diseases. Cite this article: Bone Joint Res 2021;10(3):166-172.

Belgium experience in disaster victim identification applied in handling terrorist attack at Brussels Airport 2016

The Belgian disaster victim identification (DVI) team is involved in many investigations in our country. Indeed, this specialized team of the federal police oversees searching for and investigating criminally buried dead bodies, identification of unknown putrefied corpses, and more. The Belgian DVI team also assists with the identification of victims of mass disasters (natural, accidental, and mass murders). In this article, we consider the contributions of different teams (forensic pathology, anthropology, and odontology, federal police, and crime scene investigation) both on the scene of the attack at the Brussels National Airport (Zaventem) and in the laboratory work (autopsies, sample studies).

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.

A New Understanding of the Mechanism of Injury to the Pelvis and Lower Limbs in Blast

Dismounted complex blast injury (DCBI) has been one of the most severe forms of trauma sustained in recent conflicts. This injury has been partially attributed to limb flail; however, the full causative mechanism has not yet been fully determined. Soil ejecta has been hypothesized as a significant contributor to the injury but remains untested. In this study, a small-animal model of gas-gun mediated high velocity sand blast was used to investigate this mechanism. The results demonstrated a correlation between increasing sand blast velocity and injury patterns of worsening severity across the trauma range. This study is the first to replicate high velocity sand blast and the first model to reproduce the pattern of injury seen in DCBI. These findings are consistent with clinical and battlefield data. They represent a significant change in the understanding of blast injury, producing a new mechanistic theory of traumatic amputation. This mechanism of traumatic amputation is shown to be high velocity sand blast causing the initial tissue disruption, with the following blast wind and resultant limb flail completing the amputation. These findings implicate high velocity sand blast, in addition to limb flail, as a critical mechanism of injury in the dismounted blast casualty.

Restricting Lower Limb Flail is Key to Preventing Fatal Pelvic Blast Injury

Pelvic vascular injury in the casualty of an explosive insult is a principal risk factor for increased mortality. The mechanism of injury has not previously been investigated in a physical model. In this study, a small-animal model of pelvic blast injury with a shock-tube mediated blast wave was utilised and showed that lower limb flail is necessary for an unstable pelvic fracture with vascular injury to occur. One hundred and seventy-three cadaveric mice underwent shock-tube blast testing and subsequent injury analysis. Increasingly displaced pelvic fractures and an increase in the incidence of pelvic vascular injury were seen with increasing lower limb flail; the 50% risk of vascular injury was 66° of lower limb flail out from the midline (95% confidence intervals 59°–75°). Pre-blast surgical amputation at the hip or knee showed the thigh was essential to result in pelvic displacement whilst the leg was not. These findings, corroborated by clinical data, bring a paradigm shift in our understanding of the mechanism of blast injury. Restriction of lower limb flail in the human, through personal protective equipment, has the potential to mitigate the effects of pelvic blast injury.

The burden of gunshot wounding of UK military personnel in Iraq and Afghanistan from 2003-14

INTRODUCTION

Gunshot wounding (GSW) is the second most common mechanism of injury in warfare after explosive injury. The aim of this study was to define the clinical burden of GSW placed on UK forces throughout the recent Iraq and Afghanistan conflicts.

METHODS

This study was a retrospective review of data from the UK Military Joint Theatre Trauma Registry (JTTR). A JTTR search identified records within the 12 year period of conflict between 19 Mar 2003 and 27 Oct 2014 of all UK military GSW casualties sustained during the complete timelines of both conflicts. Included cases had their clinical timelines and treatment further examined from time of injury up until discharge from hospital or death.

RESULTS

There were 723 casualties identified (177 fatalities, 546 survivors). Median age at the time of injury was 24 years (range 18-46 years), with 99.6% of casualties being male. Most common anatomical locations for injury were the extremities, with 52% of all casualties sustaining extremity GSW, followed by 16% GSW to the head, 15% to the thorax, and 7% to the abdomen. In survivors, the rate of extremity injury was higher at 69%, with head, thorax and abdomen injuries relatively lower at 5%, 11% and 6% respectively. All GSW casualties had a total of 2827 separate injuries catalogued. A total of 545 casualties (523 survivors, 22 fatalities) underwent 2357 recorded surgical procedures, which were carried out over 1455 surgical episodes between admission to a deployed medical facility and subsequent transfer to the Royal Centre for Defence Medicine (RCDM) in the UK. This gave a median of 3 (IQR 2-5) surgical procedures within a median of 2 (IQR 2-3) surgical episodes per casualty. Casualties had a combined length of stay (LoS) of 25 years within a medical facility, with a mean LoS in a deployed facility of 1.9 days and 14 days in RCDM.

CONCLUSION

These findings define the massive burden of injury associated with battlefield GSW and underscore the need for further research to both reduce wound incidence and severity of these complex injuries.

Perioperative management of traumatic limb amputations due to civilian trauma: current practice and future directions

Traumatic limb amputations are serious injuries. They require urgent multidisciplinary management and emergency surgical intervention to save life and, where possible, preserve limb function. It is therefore vital that perioperative management follows established evidence-based principles to optimise outcomes. In recent years a vast quantity of research on traumatic amputations in the military setting has been published, but civilian injuries, which often have strikingly different mechanisms, have been neglected. This article reviews existing information on epidemiology, pathophysiology, perioperative management strategies, outcomes and future directions in the field.