Using CT scans to determine the optimal sizes of hard armour plates to protect the torso for UK female Armed Forces personnel.

INTRODUCTION: Hard armour plates provide coverage to essential anatomical structures in the torso that, if injured, would likely be responsible for death before damage control surgery can be undertaken. Existing front and rear OSPREY plates in conjunction with Mark 2 plates used at the sides in current UK Armed Forces personal armour systems are provided in a single size, used by both female and male users. METHODS: CT scans of 45 female UK military personnel were analysed. Distances between anatomical structures representing threshold (absolute minimum) and objective (the maximum level of coverage beyond which there is limited further benefit) coverage of the torso were determined and compared with OSPREY and Mark 2 plate dimensions. Sample characteristics were compared with the 2006/2007 UK Armed Forces Anthropometric Survey. RESULTS: No statistical difference was found between sample means for stature (p=0.131) and mass (p=0.853) from those of the anthropometric survey in this sample. The height of both the front OSPREY plates exceeded the threshold coverage (suprasternal notch to lower border of the 10th rib) for all women studied. The height of the Mark 2 plate exceeds the objective coverage from the side for all women studied. CONCLUSIONS: Based on a plate height providing threshold coverage of all women up to the 50th percentile, the height of the front and rear OSPREY plates could be reduced by 36mm and 31mm respectively. Based on a presumption that a side plate should cover up to the 95th percentile, the Mark 2 plate achieves the objective height and width for the female population studied. Strong evidence was found to support the UK Ministry of Defence requirement for procurement of new front and rear plates of multiple heights for both female and male users.

Injury modelling for strategic planning in protecting the national infrastructure from terrorist explosive events.

Terrorist events in the form of explosive devices have occurred and remain a threat currently to the population and the infrastructure of many nations worldwide. Injuries occur from a combination of a blast wave, energised fragments, blunt trauma and burns. The relative preponderance of each injury mechanism is dependent on the type of device, distance to targets, population density and the surrounding environment, such as an enclosed space, to name but a few. One method of primary prevention of such injuries is by modification of the environment in which the explosion occurs, such as modifying population density and the design of enclosed spaces. The Human Injury Predictor (HIP) tool is a computational model which was developed to predict the pattern of injuries following an explosion with the goal to inform national injury prevention strategies from terrorist attacks. HIP currently uses algorithms to predict the effects from primary and secondary blast and allows the geometry of buildings to be incorporated. It has been validated using clinical data from the '7/7' terrorist attacks in London and the 2017 Manchester Arena terrorist event. Although the tool can be used readily, it will benefit from further development to refine injury representation, validate injury scoring and enable the prediction of triage states. The tool can assist both in the design of future buildings and methods of transport, as well as the situation of critical emergency services required in the response following a terrorist explosive event. The aim of this paper is to describe the HIP tool in its current version and provide a roadmap for optimising its utility in the future for the protection of national infrastructure and the population.

Torso body armour coverage defined according to feasibility of haemorrhage control within the prehospital environment: a new paradigm for combat trauma protection.

Developments in military personal armour have aimed to achieve a balance between anatomical coverage, protection and mobility. When death is likely to occur within 60 min of injury to anatomical structures without damage control surgery, then these anatomical structures are defined as 'essential'. However, the medical terminology used to describe coverage is challenging to convey in a Systems Requirements Document (SRD) for acquisition of new armour and to ultimately translate to the correct sizing and fitting of personal armour. Many of those with Ministry of Defence responsible for the procurement of personal armour and thereby using SRDs will likely have limited medical knowledge; therefore, the potentially complex medical terminology used to describe the anatomical boundaries must be translated into easily recognisable and measurable external landmarks. We now propose a complementary classification for ballistic protection coverage, termed threshold and objective, based on the feasibility of haemorrhage control within the prehospital environment.

Comparing the medical coverage provided by four contemporary military combat helmets against penetrating traumatic brain injury.

INTRODUCTION: Modern military combat helmets vary in their shapes and features, but all are designed to protect the head from traumatic brain injury. Recent recommendations for protection against energised projectiles that are characteristic of secondary blast injury is to ensure coverage of both the brain and brainstem. METHOD: Graphical representations of essential coverage of the head (cerebral hemispheres, cerebellum and brainstem) within an anthropometrically sized model were superimposed over two standard coverage helmets (VIRTUS helmet, Advanced Combat Helmet (ACH)) and two 'high-cut' helmets (a Dismounted Combat Helmet (DCH)) and Combat Vehicle Crewman (CVC) helmet), both of which are designed to be worn with communications devices. Objective shotline coverage from representative directions of projectile travel (-30 to +30 degrees) was determined using the Coverage of Armour Tool (COAT). RESULTS: VIRTUS and ACH demonstrated similar overall coverage (68.7% and 69.5%, respectively), reflecting their similar shell shapes. ACH has improved coverage from below compared with VIRTUS (23.3% vs 21.7%) due to its decreased standoff from the scalp. The 'high-cut' helmets (DCH and CVC) had reduced overall coverage (57.9% and 52.1%), which was most pronounced from the side. CONCLUSIONS: Both the VIRTUS and ACH helmets provide excellent overall coverage of the brain and brainstem against ballistic threats. Coverage of both would be improved at the rear by using a nape protector and the front using a visor. This is demonstrated with the analysis of the addition of the nape protector in the VIRTUS system. High-cut helmets provide significantly reduced coverage from the side of the head, as the communication devices they are worn with are not designed to provide protection from ballistic threats. Unless absolutely necessary, it is therefore recommended that high-cut helmets be worn only by those users with defined specific requirements, or where the risk of injury from secondary blast is low.

Sizing of ballistic arm protection for the VIRTUS body armour and load carriage system.

INTRODUCTION: Severe haemorrhage from the arm that is unresponsive to direct pressure necessitates the application of a tourniquet. Detachable arm protection, referred to as brassards, are used by the UK Armed Forces to protect the upper arm from fragmentation threats. However, the coverage they originally provided was based on limited medical evidence. Medical consensus has determined that the dimensions of arm protection should in future be related to how far up the arm a tourniquet can be applied. METHOD: CT scans of 120 male Armed Forces personnel were analysed to ascertain the vertical distances from acromion process to the point at which a tourniquet can applied, equating to the anterior axillary fold. These values were statistically compared with those derived from the 2007 UK Military anthropometric survey using a paired t-test. Additional distances were added to account for tourniquet width and slippage, with the total value compared with VIRTUS brassard length. RESULTS: No significant difference (p<0.01) was found in mean acromion to axilla length (114 mm) compared with that found in the anthropometric survey confirming sample validity. The deltoid insertion lay 24 mm below the axillary fold for the 50th percentile value from CT. Essential arm coverage for the 99th percentile male in this study was calculated as 201 mm. CONCLUSIONS: Based on this research, a single new brassard for the VIRTUS body armour and load carriage system was recommended and manufactured based on the 99th percentile. This is over 30% shorter than the existing VIRTUS brassard, reducing the overall weight burden for the soldier and improving heat dispersion, integration and interoperability. The new brassard has been issued to Armed Forces personnel since October 2018. The reduced mass of ballistic protective material in conjunction with requiring only a single size of brassard has already saved the Ministry of Defence £20 000 in procurement costs.

Determining the optimum anatomical coverage of side plates for the VIRTUS body armour and load carriage system.

INTRODUCTION: Side plates are worn by UK Armed Forces as part of the VIRTUS body armour and load carriage systems to protect the thorax and abdomen from high-velocity threats. The VIRTUS project has provided the impetus to objectively demonstrate the anatomical coverage provided by side plates. METHOD: CT scans of 120 male UK Armed Forces personnel were analysed to ascertain the vertical distance between the anterior axillary fold and iliac crest, and horizontal distance between anterior and posterior borders of the liver, delineating the boundaries of essential medical coverage from the side aspects. The percentage of shot-lines intersected by the existing Enhanced Combat Body Armour (ECBA) plates as well as an optimised plate based on the maximum potential dimensions of essential coverage was determined in the Coverage of Armour Tool. RESULTS: ECBA plates were 101 mm shorter and 4 mm narrower than a plate with dimensions providing essential medical coverage for the 50th percentile subject (157×315 mm). Coverage increased by 35% when using two ECBA plates as side coverage in addition to using the front and rear OSPREY plates in the VIRTUS vest. Two side plates with dimensions providing essential medical coverage for the 50th percentile increased anatomical coverage by a further 16%. CONCLUSIONS: This analysis has provided strong evidence that ECBA plates are already optimised for side protection, despite not being originally designed for this purpose. They are correctly positioned within the VIRTUS soft body armour vest and the width of the ECBA plate is only 3% less than what would be optimum size for the 50th percentile. Although the height of the plate could be increased to further enhance the anatomical coverage, it is unlikely that this would be acceptable in terms of the human factors, equipment integration or additional mass.

Defining the medical coverage of ballistic protection to the pelvis and thigh.

INTRODUCTION: Pelvis, lower limb and associated genital injury caused by explosive devices was responsible for mortality and considerable long-term morbidity for the UK Armed Forces during combat operations in Afghanistan, resulting in the issue of a pelvic protection system in 2010. The aim of this current research was to determine the medical coverage of the pelvis and thigh and to define the vertical dimensions of ballistic protective material for future pelvic protection (PP). METHOD: CT scans from 120 male UK Armed Forces personnel were analysed to identify the anthropometric landmarks and vertical boundaries of coverage for the pelvis and thigh. Pelvic height was the vertical distance between the upper border of the iliac crest in the midaxillary plane to the most inferior point of the ischial tuberosity of the pelvis. Upper thigh height was proposed as a 100 mm fixed distance below the ischial tuberosities, enabling a tourniquet to be reproducibly applied. These distances were compared with the ballistic component of the five sizes of tier 1 PP using a paired t-test. RESULTS: The vertical components of coverage measured using CT scans were all significantly less (p<0.01) compared with all five sizes of tier 1 PP; for example, the ballistic component of the smallest size of tier 1 PP measured 410 mm, which was larger than the 99th percentile male, which measured 346 mm on CT scans. CONCLUSIONS: While all sizes of tier 1 PP provide coverage to the pelvis and upper thigh structures, there is an opportunity to optimise future PP. For example, comparing the large size of tier 1 PP to the 50th percentile male demonstrated an opportunity to reduce the ballistic protective component by 31%. Reducing the quantity of material used will improve heat dissipation and user comfort and reduce material mass and acquisition costs.