Recent evidence suggests that both the accepted mechanism of blast-mediated traumatic amputation (TA) (shockwave then blast wind exposure) and the link with fatal shockwave exposure merit review. Searching UK military prospectively gathered trauma registry data and post mortem CT (PM-CT) records identified casualties from August 2008 to August 2010 with blast-mediated TAs. TA level and associated injuries were recorded. Data on pre-debridement osseous and soft tissue injuries were only consistently available for fatalities through PM-CT imaging. 146 Cases (75 survivors and 71 fatalities) with 271 TAs (130 in survivors and 141 in fatalities) were identified. Through-joint TA rate in fatalities was 34/141 (24.1%). PM-CT analysis demonstrated only 9/34 through joint TAs with contiguous fractures in the immediately proximal long bone/limb girdle. 18/34 had no fracture, and 7/34 had a non-contiguous fracture. The previously reported link between TA and blast lung injury was not present, calling into question the significance of shockwaves in generating blast-mediated TAs. Furthermore, contemporary blast injury theory cannot account for the high prevalence of through joint TAs (previously published rate 1.3%). The proportion of through joint TAs with no associated fracture or a non-contiguous fracture (74%) is supportive of pure flail as a mechanism for blast-mediated TA.

Current military conflicts are characterised by the use of the Improvised Explosive Device (IED). Improvements in personal protection, medical care and evacuation logistics have resulted in increasing numbers of casualties surviving with complex musculoskeletal injuries, often leading to life-long disability. Thus, there exists an urgent requirement to investigate the mechanism of extremity injury caused by these devices in order to develop mitigation strategies. In addition, the wounds of war are no longer restricted to the battlefield; similar injuries can be witnessed in civilian centres following a terrorist attack.

Key to mitigating such injuries is the ability to deconstruct the complexities of an explosive event into a controlled, laboratory-based environment. In this study, an anti-vehicle underbelly injury simulator, capable of recreating in the laboratory the impulse from an anti-vehicle (AV) explosion, is presented and characterised. Tests were then conducted to assess the simulator's ability to interact with human cadaveric legs. Two mounting conditions were assessed, simulating a typical seated and standing vehicle passenger using instrumented cadaveric lower limbs.

This experimental device, will now allow us (a) to gain comprehensive understanding of the load-transfer mechanisms through the lower limb, (b) to characterise the dissipating capacity of mitigation technologies, and (c) to assess the biofidelity of surrogates.

The defining weapon of the conflicts in Iraq and Afghanistan has been the Improvised Explosive Device (IEDs). When detonated under a vehicle, they result in significant axial loading to the lower limbs, resulting in devastating injuries. Due to the absence of clinical blast data, automotive injury data using the Abbreviated Injury Score (AIS) has been extrapolated to define current NATO injury thresholds for Anti-vehicle (AV) mine tests. We hypothesized that AIS, being a marker of fatality rather than disability would be a worse predictor of poor clinical outcome compared to the lower limb specific Foot and Ankle Severity Score (FASS).

Using a prospectively collected trauma database, we identified UK Service Personnel sustaining lower leg injuries from under-vehicle explosions from Jan 2006–Dec 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 (i) need for amputation or (ii) poor clinical outcome. Statistical models were developed in order to explore the relationship between the scoring systems and clinical endpoints.

63 UK casualties (89 limbs) were identified with a lower limb injury following under-vehicle explosion. The mean age of the casualty was 26.0 yrs. At 33.6 months follow-up, 29.1% (26/89) required an amputation and a further 74.6% (41/89) having a poor clinical outcome (amputation or ongoing clinical problems). Only 9(14%) casualties were deemed medically fit to return to full military duty. ROC 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 32%). In predicting poor clinical outcome, FASS was significantly superior to AIS (p<0.01). Probit analysis revealed that a relationship could not be developed between AIS and the probability of a poor clinical outcome (p=0.25).

Foot and ankle injuries following AV mine blast are associated with significant morbidity. 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. There is a requirement to reassess the current injury criteria used to evaluate the potential of mitigation technologies to help reduce long-term disability in military personnel. Our study highlights the critical importance of utilising contemporary battlefield injury data in order to ensure that the evaluation of mitigation measures is appropriate to the injury profile and their long-term effects.

Recent advances in combat casualty care have enabled survival following battlefield injuries that would have been lethal in past conflicts. While some injuries remain beyond our current capability to treat, they have the potential to be future ‘unexpected’ survivors. The greatest threat to deployed coalition troops currently and for the foreseeable future is the improvised explosive device (IED) Therefore, the aim of this study was to conduct an analysis of causes of death and injury patterns in recent explosive blast fatalities in order to focus research and mitigation strategies, to further improve survival rates.

Since November 2007, UK Armed Forces personnel killed whilst deployed on combat operations undergo both a post mortem computed tomography (PMCT) scan and an autopsy. With the permission of the coroners, we analysed casualties with PMCTs between November 2007 and July 2010. Injury data were analysed by a pathology-forensic radiology-orthopaedic multidisciplinary team. Cause of death was attributed to the injuries with the highest AIS scores contributing to the NISS score. Injuries with an AIS < 4 were excluded. During the study period 227 PMCT scans were performed; 211 were suitable for inclusion, containing 145 fatalities due to explosive blast from IEDs. These formed the study group. 24 cases had such severe injuries (disruptions) that further study was inappropriate. Of the remaining 121, 79 were dismounted, and 42 were mounted (in vehicles).

Leading causes of death were head CNS injury (47.6%), followed by intra-cavity haemorrhage (21.7%) in the mounted group, and extremity haemorrhage (42.6%), junctional haemorrhage (22.2%) and head CNS injury (18.7%) in the dismounted group.

The severity of head trauma in both mounted and dismounted IED fatalites would indicate that prevention and mitigation of these injuries is likely to be the most effective strategy to decrease their resultant mortality. Two thirds of dismounted fatalities have haemorrhage implicated as a cause of death that may have been amenable to prehospital treatment strategies. One fifth of mounted fatalites have haemorrhagic trauma which currently could only be addressed surgically. Maintaining the drive to improve all haemostatic techniques for combat casualties from point of wounding to definitive surgical proximal control alongside development and application of novel haemostatics could yield a significant survival benefit.

The mechanism of traumatic amputation (TA) from explosive blast has traditionally been considered to be a combination of blast wave induced bone injury – primary blast - followed by limb avulsion from the blast wind – tertiary blast. This results in a transosseous TA, with through joint amputations considered to be extremely rare. Data from previous conflicts has also suggested that this injury is frequently associated with a non-survivable primary blast lung injury (PBLI), further linking the extremity injury to the primary blast wave. However, our current experience in the Middle East would suggest that both the mechanism of TA and the link with fatal primary blast exposure need to be reconsidered. The aim of this study was to analyse the injury profile of the current cohort of TA fatalities to further investigate the underlying blast injury mechanism and to allow hypotheses on injury mechanisms to be developed for further analysis.

With the permission of the coroners, 121 post-mortem CT (PMCT) scans of UK Armed Forces personnel who died following an IED blast were analysed. All orthopaedic injuries were identified, classified and the anatomical level of any associated soft tissue injury noted. PMCT evidence of PBLI was used as a marker of significant primary blast exposure.

75/121 (62%) sustained at least 1 TA, with 138 TAs seen in total. 31/138 (22%) were through joints, with through knee amputations most common (23/31, 74%). Only 7/31(23%) through joint amputations had an associated fracture proximal to and contiguous with the amputation site. The soft tissue injury profile of through joint and transosseous TAs were not significantly different (p=0.569). When fatality location was considered (i.e. mounted or dismounted), no overall relationship between PBLI and TA was evident. The two pathologies were not seen to consistently occur concurrently, as has been previously reported.

The accepted mechanism for traumatic amputation following explosive blast does not adequately explain the significant number of through joint TAs presented here. The previously reported link between TA and PBLI in fatalities was not supported by this analysis of modern combat blast fatalities. Lack of an associated fracture with the majority of through joint TAs in conjunction with a lesser contribution of primary blast may implicate flail and periarticular soft tissue failure as a potential injury mechanism. Analysis of through joint TA incidence and associated injuries in survivors is now indicated. Case studies within the fatality dataset may facilitate generation of injury mechanism hypotheses. To further investigate the injury mechanism, work is required to understand osseous, ligamentous and other soft tissue behaviour and failure at high strain rates. This should allow characterisation and modeling of these injuries and inform mitigation strategies.

Background

Tears of the rotator cuff are a common pathology and poorly understood. Achieving a good functional outcome for patients may be difficult, and the degree of fat infiltration into the muscle is known to be a major determining factor to surgical repair and post operative function. It is the hypothesis of this study that the degree of retraction of the common central tendon as seen on MRI corresponds to the amount of fat infiltration classified according to the Goutallier grading System.