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

Tom Stevenson,Sarah A Stapley,Debra J Carr,Iain E Gibb

doi:10.1007/s00414-020-02271-7

Abstract

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.

Highlights

Wound ballistics study can be challenging to the modern researcher
With prior research from this group having modelled extremity gunshot wounding (GSW) to test the effects of UK military clothing on wounding patterns, key variables such as velocity, engagement distance and yaw have been previously controlled [9, 10]
Where gelatine is validated against live porcine thighs [14, 18], and it is known that porcine tissues have a thicker skin and subcutaneous tissues compared with human [28], the authorship of this work required the use of a human tissue surrogate more biofidelic and representative of a healthy military population

Summary

Introduction

Wound ballistics study can be challenging to the modern researcher. With the variables that require control in order to preserve objectivity and scientific rigour, reproducing highquality experiments is arduous for any researcher. With prior research from this group having modelled extremity GSW to test the effects of UK military clothing on wounding patterns, key variables such as velocity, engagement distance and yaw have been previously controlled [9, 10]. With regard to wounding potential, the greater the contact surface area of a projectile (i.e. its shape, stability and integrity e.g. deforming or fragmenting) with its target will mean a greater amount of kinetic energy (KE) delivered over a fixed distance by a known velocity and mass of the projectile [12,13,14,15,16,17,18,19] Under these circumstances, the property of interest is kinetic energy density (KED). One study by Wen et al in 2017 describes the effect of preliminary yaw from a computer model using 7.62 × 39 mm projectiles based on a gelatine model

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