Development of a skull/brain model for military wound ballistics studies

Abstract

Reports on penetrating ballistic head injuries in the literature are dominated by case studies of suicides; the penetrating ammunition usually being .22 rimfire or shotgun. The dominating cause of injuries in modern warfare is fragmentation and hence, this is the primary threat that military helmets protect the brain from. When helmets are perforated, this is usually by bullets. In combat, 20% of penetrating injuries occur to the head and its wounding accounts for 50% of combat deaths. A number of head simulants are described in the academic literature, in ballistic test methods for helmets (including measurement of behind helmet blunt trauma, BHBT) and in the 'open' and 'closed' government literature of several nations. The majority of these models are not anatomically correct and are not assessed with high-velocity rifle ammunition. In this article, an anatomically correct 'skull' (manufactured from polyurethane) and 'brain' (manufactured from 10%, by mass, gelatine) model for use in military wound ballistic studies is described. Filling the cranium completely with gelatine resulted in a similar 'skull' fracture pattern as an anatomically correct 'brain' combined with a representation of cerebrospinal fluid. In particular, posterior cranial fossa and occipital fractures and brain ejection were observed. This pattern of injury compared favourably to reported case studies of actual incidents in the literature.

Does preliminary optimisation of an anatomically correct skull-brain model using simple simulants produce clinically realistic ballistic injury fracture patterns?

“…Smith et al [10] found that spheres filled with ballistic gelatine produced damage patterns that compared well with published examples of real gunshot trauma, similar to the findings of both Thali et al [7] using spheres and Carr et al [11] using synthetic skulls. In this present work, the overall fracture patterns in 23 of the 39 skulls (59%) were considered close to reality by at least one of the five assessors.…”

“…A thin low-density polyethylene bag was inserted into the base of the skull and gelatine, 10% by mass, poured into the bag to fill the cranial cavity. The gelatine was allowed to set for 24 h at 17 °C (laboratory temperature) and then conditioned at 4 °C for a further 24 h [11]. …”

“…Preliminary work to develop a suitable anatomically correct skull brain model for ballistic studies incorporating a helmet have been reported [11]. This model consisted of an anatomically correct polyurethane skull with a 10% gelatine brain (by mass; 4 °C) impacted with 7.62 × 39 ammunition (M43 ball, Chinese, mild steel core, Factory 71, 1984) at a mean velocity of 675 m/s.…”

Forensic reconstruction of two military combat related shooting incidents using an anatomically correct synthetic skull with a surrogate skin/soft tissue layer

“…and 7.62 mm calibres) were noted to 'compare favourably with published examples of modern cranial gunshot injury' [7]. Carr et al [8] reported similar findings using an anatomically correct skull model which has been the basis for our subsequent experiments [9,10].…”

Understanding blunt force trauma and violence in Neolithic Europe: the first experiments using a skin-skull-brain model and the Thames Beater

“…Cranial sutures (the joints between the bones of the skull) are able to absorb force, and can stop the progression of fractures across the surface of the cranium (Lovell 1997: 155; Wedel & Galloway 2014: 135). The skull is also buttressed with arched areas of thicker bone; fractures follow the path of least resistance and can be influenced by these patterns of strong and weak bone in the skull (Lovell 1997: 155; Kasrai et al 1999: 238; Wedel & Galloway 2014: 141; Carr et al 2015: 508).…”