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.

Effects of police body armour on overmatching ballistic injury.

Overmatching occurs when body armour that has been designed to resist perforation by a specified projectile is perforated by a greater threat. This may result in wounding to the body armour wearer. In this work, overmatching of two types of police body armour was studied using two types of ammunition. The use of a 250-mm-long gelatine block to represent the depth of the human torso combined with armour panels mounted on the anterior and posterior of the block allowed for a more realistic simulation to be completed. There was some evidence to suggest that overmatching events could lead to increased levels of damage during a survivable incident compared with no body armour being present. This information is of interest to armour designers and medical personnel that might treat such wounds.

UK military helmet design and test methods.

The aim of this paper was to provide the military medical community with an expert summary of military helmets used by HM Armed Forces. The design of military helmets and test methods used to determine the fragmentation and non-ballistic impact protection are discussed. The helmets considered are Parachutist, Combat Vehicle Crewman, Mk6, Mk6A, Mk7 and VIRTUS. The helmets considered provide different levels of fragmentation and non-ballistic impact protection dictated by the materials available at the time of the helmet design and the end-user requirement. The UK Ministry of Defence defines the area of coverage of military helmets by considering external anatomical features to provide protection to the brain and the majority of the brainstem. Established test methods exist to assess the performance of the helmet with respect to the threats; however, these test methods do not typically consider anatomical vulnerability.

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.

The effect of military clothing on gunshot wounding patterns in gelatine.

With no two gunshot wounds (GSW) being the same, novel research into wound ballistics is challenging. It is evident that the majority of previous wound ballistic research has been conducted without the presence of clothing. Whilst the effect of clothing on wound contamination has been explored, there is a paucity of literature examining the effect of clothing on GSW patterns. The aim of this study was to test the effect of Multi-Terrain Pattern (MTP) UK military clothing on GSW patterns within calibrated blocks of 10% by mass gelatine, using two types of ammunition commonly used in recent conflicts-7.62 × 39 mm and 5.45 × 39 mm. In total, 36 blocks were shot, 18 by each projectile type, further divided into 6 with no clothing layers (Cnil), 6 with a single clothing layer (Cmin) and 6 with maximum clothing layers (Cmax) worn on active duty. Blocks were analysed with high-speed video and dissection to capture measurements of damage, and results compared using analysis of variance (ANOVA). Results showed significantly different damage measurements within blocks with Cmax for both ammunition types compared to the other clothing states. This may result in GSWs that require more extensive surgical management, inviting further study.

A preliminary study into injuries due to non-perforating ballistic impacts into soft body armour over the spine.

The UK Home Office test method for ballistic protective police body armours considers anterior torso impacts to be the worst-case scenario and tests rear armour panels to the same standards as front panels. The aim of this paper was to examine the injuries from spinal behind armour blunt trauma (BABT) impacts. This study used a cadaveric 65 kg, female pig barrel and 9 mm Luger ammunition (9 × 19 mm, FMJ Nammo Lapur Oy) into HG1/A + KR1 soft armour panels over the spine. Injuries were inspected and sections removed for x-radiography and micro-CT assessment. All shots over the spine resulted in deep soft tissue injuries from pencilling of the armour and the shirt worn under the armour. The wounds had embedded fabric debris which would require surgery to remove resulting in increased recovery time over injuries usually seen in anterior torso BABT impacts, which are typically haematoma and fractured ribs. The shot with the deepest soft tissue wound (41 mm) also resulted in a fractured spinous process. Shots were also fired at the posterior and anterior rib area of the pig barrel, for comparison to the spine. Similar wounds were seen on the shots to the posterior rib area while shallower, smaller wounds were seen on the anterior and one anterior rib shot resulted in a single, un-displaced rib fracture. The anatomical differences between pigs and humans would most likely mean that injury to a human from these impacts would be more serious.

The effect of helmet materials and simulated bone and tissue layers on bullet behaviour in a gelatine model of overmatch penetrating head injury.

The aim of this work was to simulate an overmatch ballistic event against a head wearing a helmet. The experiments were designed to understand how layers of bone (or synthetic bone), synthetic skin and currently used helmet materials influence the behaviour of full metal jacket mild steel core (FMJ MSC) 7.62 × 39 mm bullets, impacting on targets with a mean velocity of 650 m/s. Bullet behaviour within 10% (by mass) gelatine blocks was assessed by measurements made of the temporary cavity within the blocks using high-speed video and of the permanent cavity by dissecting blocks post firing. While ANOVA did not find significant difference at the 0.05 level in the mean values of most of the measurements, there was a significant difference in neck length within the gelatine blocks. The addition of material layers did produce greater variability in the temporary cavity measurements under some of the conditions. One of the synthetic bone polymers with a synthetic skin layer produced similar results within the gelatine blocks to the horse scapulae (with residual tissue) and may be suitable for future ballistic experiments.

A systematic review of military head injuries.

INTRODUCTION: This commissioned review discusses military head injuries caused by non-ballistic impacts, penetrating fragments and bullets (including parts of bullets) and behind helmet blunt trauma (BHBT). METHOD: A systematic review of the literature was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses method. The openly accessible literature was reviewed to investigate military head injuries and their severity. RESULTS: Fifty-four sources were identified that included pertinent openly accessible information relevant to this topic. Limited injury data exist for non-ballistic head injuries for UK forces, although some international data exist for parachutists. The majority of fatal head injuries are due to projectiles penetrating through the face rather than through the area of the head covered by the helmet. Penetrating head injuries are primarily caused by fragments, but helmets are more commonly perforated by high-energy rifle bullets than by fragments. No reports of a BHBT injury have been located in the literature. CONCLUSIONS: The description of body segment varies among articles and this makes comparisons among datasets difficult. There is a lack of detail regarding the precise position and severity of injuries, and long-term outcome for casualties. It is demonstrated that wearing military helmets reduces fatalities on and off the battlefield. The risk of BHBT injuries is widely referred to, but evidence of their occurrence is not provided by the authors that describe the risk of BHBT occurring. Further research into the causes and severity of head injuries would be useful for designers of military helmets and other associated personal protective equipment, particularly as advances in materials technology means lighter, thinner and more protective helmets are achievable.

Drip bloodstain appearance on inclined apparel fabrics: Effect of prior-laundering, fibre content and fabric structure.

The interaction of blood and fabrics is currently a 'hot topic', since the understanding and interpretation of these stains is still in its infancy. A recent simplified perpendicular impact experimental programme considering bloodstains generated on fabrics laid the foundations for understanding more complex scenarios. Blood rarely impacts apparel fabrics perpendicular; therefore a systematic study was conducted to characterise the appearance of drip stains on inclined fabrics. The final drip stain appearance for 45° and 15° impact angles on torso apparel fabrics (100% cotton plain woven, 100% polyester plain woven, a blend of polyester and cotton plain woven and 100% cotton single jersey knit) that had been laundered for six, 26 and 52 cycles prior to testing was investigated. The relationship between drop parameters (height and volume), angle and the stain characteristics (parent stain area, axis 1 and 2 and number of satellite stains) for each fabric was examined using analysis of variance. The appearance of the drip stains on these fabrics was distorted, in comparison to drip stains on hard-smooth surface. Examining the parent stain allowed for classification of stains occurring at an angle, however the same could not be said for the satellite stains produced. All of the dried stains visible on the surface of the fabric were larger than just after the impacting event, indicating within fabric spreading of blood due to capillary force (wicking). The cotton-containing fabrics spread the blood within the fabrics in all directions along the stain's circumference, while spreading within the polyester plain woven fabric occurred in only the weft (width of the fabric) and warp (length) directions. Laundering affected the formation of bloodstain on the blend plain woven fabric at both impact angles, although not all characteristics were significantly affected for the three impact conditions considered. The bloodstain characteristics varied due to the fibre content and fabric structure for both impact angles investigated. It is therefore necessary to consider the age of the fabric (which is fabric specific), the fibre type (including blends) and the fabric structure, before interpreting bloodstain patterns. An understanding of this simplified inclined drip stain interaction has been investigated to generate a basis for more complex interactions, such as spatter bloodstains.

Is behind armour blunt trauma a real threat to users of body armour? A systematic review.

INTRODUCTION: Behind armour blunt trauma (BABT) has been defined as a non-penetrating injury caused by the rapid deformation of body armour. There has been an increasing awareness of BABT as an injury mechanism in both the military and civilian worlds; whether BABT results in serious injuries is debatable. METHOD: A systematic review of the openly accessible literature was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses method to investigate those injuries classified as BABT and their severity. RESULTS: 50 sources were identified that included pertinent information relevant to this systematic review on BABT injuries. Typical injuries reported included skin contusion, laceration and penetration, rib fracture and contusions to lungs, kidneys, spleen and (rarely) the heart. No evidence of fatal injuries due to BABT was identified. CONCLUSIONS: Whether BABT can lead to life-threatening injuries when small-arms ammunition impacts body armour components designed to stop that ammunition is debatable. It should be emphasised that other data may be available in government reports that are not openly available. Further research should be considered that investigates developments in body armour, including initiatives that involve reducing burden, and how they affect BABT.

Systematic investigation of drip stains on apparel fabrics: The effects of prior-laundering, fibre content and fabric structure on final stain appearance.

Bloodstain pattern analysis is the investigation of blood deposited at crime scenes and the interpretation of that pattern. The surface that the blood gets deposited onto could distort the appearance of the bloodstain. The interaction of blood and apparel fabrics is in its infancy, but the interaction of liquids and apparel fabrics has been well documented and investigated in the field of textile science (e.g. the processes of wetting and wicking of fluids on fibres, yarns and fabrics). A systematic study on the final appearance of drip stains on torso apparel fabrics (100% cotton plain woven, 100% polyester plain woven, blend of polyester and cotton plain woven and 100% cotton single jersey knit) that had been laundered for six, 26 and 52 cycles prior to testing was investigated in the paper. The relationship between drop velocity (1.66±0.50m/s, 4.07±0.03m/s, 5.34±0.18m/s) and the stain characteristics (parent stain area, axes 1 and 2 and number of satellite stains) for each fabric was examined using analysis of variance. The experimental design and effect of storing blood were investigated on a reference sample, which indicated that the day (up to five days) at which the drops were generated did not affect the bloodstain. The effect of prior-laundering (six, 26 and 52 laundering cycles), fibre content (cotton vs. polyester vs. blend) and fabric structure (plain woven vs. single jersey knit) on the final appearance of the bloodstain were investigated. Distortion in the bloodstains produced on non-laundered fabrics indicated the importance of laundering fabrics to remove finishing treatments before conducting bloodstain experiments. For laundered fabrics, both the cotton fabrics and the blend had a circular to oval stain appearance, while the polyester fabric had a circular appearance with evidence of spread along the warp and weft yarns, which resulted in square-like stains at the lowest drop velocity. A significant (p<0.001) increase in the stain size on laundered blend fabric was identified. Bloodstain characteristics varied due to fibre content (p<0.001) and fabric structure (p<0.001). Blood on polyester fabric, after impact, primarily moved due to capillary force and wicking of the blood along the fibres/yarns, while for the cotton fabrics wicking was accompanied by movement of blood into the fibres/yarns. This study highlights the importance for forensic analysts of apparel evidence to consider the age, the fibre type and the fabric structure before interpreting bloodstain patterns.

Clothing increases the risk of indirect ballistic fractures.

BACKGROUND: Current literature has shown the mechanism of how indirect fractures occur but has not determined what factors increase the risks of such fractures. The objective of this study is thus to determine the effect of clothing and soft tissue thickness on the risk of indirect fracture formation. METHODS: Twenty-five fresh red deer femora embedded in ballistic gelatine were shot with varying distances off their medial cortex with a 5.56 × 45 mm North Atlantic Treaty Organization (NATO) bullet while being filmed with a slow-motion video. We compared the effect of two different gelatine depths and the effect of denim cloth laid onto the impact surface of the moulds. RESULTS: Bullet passage in thinner moulds failed to cause fracture because the bullet exited the mould before a large expanding temporary cavity was produced. Clothing dramatically altered the size and depth of the expanding cavity, as well as increased lateral pressures, resulting in more severe fractures with greater bullet distances from the bone that can cause fracture. CONCLUSIONS: Clothing increases the risk of indirect fracture and results in larger, more superficial temporary cavities, with greater lateral pressures than are seen in unclothed specimens, resulting in more comminuted fractures. Greater tissue depth affords the 5.56 × 45 mm NATO a chance to yaw and thus develop an enlarging temporary cavity that is sufficient to cause fracture.

Remote ballistic fractures in a gelatine model--aetiology and surgical implications.

BACKGROUND: Remote ballistic femoral fractures are rare fractures reported in the literature but still debated as to their existence and, indeed, their treatment. This study aimed to prove their existence, understand how they occur and determine which ammunition provides the greatest threat. In addition, fracture patterns, soft tissue disruption and contamination were assessed to aid in treatment planning. METHOD: We filmed 42 deer femora embedded in ballistic gelatine and shot with four different military (5.56 × 45 mm, 7.62 × 39 mm) and civilian (9 × 19 mm, .44 in.) bullets, at varying distances off the bone (0-10 cm). RESULTS: Two remote ballistic fractures occurred, both with .44 in. hollow-point bullets shot 3 cm off the bone. These fractures occurred when the leading edge of the expanding temporary cavity impacted the femur's supracondylar region, producing a wedge-shaped fracture with an undisplaced limb, deceivingly giving the appearance of a spiral fracture. No communication was seen between the fracture and permanent cavity, despite the temporary cavity encasing the fracture and stripping periosteum from its base. CONCLUSION: These fractures occur with civilian ammunition, but cannot prove their existence with military rounds. They result from the expanding temporary cavity affecting the weakest part of the bone, creating a potentially contaminated wedge-shaped fracture, important for surgeons considering operative intervention.

An integrated approach towards future ballistic neck protection materials selection.

Ballistic protection for the neck has historically taken the form of collars attached to the ballistic vest (removable or fixed), but other approaches, including the development of prototypes incorporating ballistic material into the collar of an under body armour shirt, are now being investigated. Current neck collars incorporate the same ballistic protective fabrics as the soft armour of the remaining vest, reflecting how ballistic protective performance alone has historically been perceived as the most important property for neck protection. However, the neck has fundamental differences from the thorax in terms of anatomical vulnerability, flexibility and equipment integration, necessitating a separate solution from the thorax in terms of optimal materials selection. An integrated approach towards the selection of the most appropriate combination of materials to be used for each of the two potential designs of future neck protection has been developed. This approach requires evaluation of the properties of each potential material in addition to ballistic performance alone, including flexibility, mass, wear resistance and thermal burden. The aim of this article is to provide readers with an overview of this integrated approach towards ballistic materials selection and an update of its current progress in the development of future ballistic neck protection.