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

Abstract

Ballistic head injury remains a significant threat to military personnel. Studying such injuries requires a model that can be used with a military helmet. This paper describes further work on a skull-brain model using skulls made from three different polyurethane plastics and a series of skull ‘fills’ to simulate brain (3, 5, 7 and 10% gelatine by mass and PermaGel™). The models were subjected to ballistic impact from 7.62 × 39 mm mild steel core bullets. The first part of the work compares the different polyurethanes (mean bullet muzzle velocity of 708 m/s), and the second part compares the different fills (mean bullet muzzle velocity of 680 m/s). The impact events were filmed using high speed cameras. The resulting fracture patterns in the skulls were reviewed and scored by five clinicians experienced in assessing penetrating head injury. In over half of the models, one or more assessors felt aspects of the fracture pattern were close to real injury. Limitations of the model include the skull being manufactured in two parts and the lack of a realistic skin layer. Further work is ongoing to address these.

Assessment of polyurethane spheres as surrogates for military ballistic head injury

“…1a). The gelatine was allowed to set at around 17 °C for 24 h. Other work by our group has shown no difference in fracture patterns in a skull model when impacted at a series of temperatures from 4 to 25 °C [6] and no difference with the above gelatine % fills.

Fig. 1 a SYNBONE® spheres with gelatine fill; b model 6 at the range pre-shooting; c screen shot of Doppler radar read out for impact on model 6

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

“…Our recent work [ 9 ] has reported that synthetic skulls filled with 10% gelatine produced realistic fracture patterns when shot with 7.62 × 39 mm ammunition. No statistical difference was seen when the 10% gelatine was compared with 3, 5 and 7% gelatine and Permagel™.…”

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

“…The aim of this work was to attempt to replicate the injuries seen in two cases of combat-related ballistic head injury, building on our previous model development [8][9][10]16].…”

“…In order to allow comparison with our previous work [9,10,16], casualties were identified where 7.62-mm bullets were confirmed responsible for the injuries (this included 7.62 × 39, 7.62 × 51 and 7.62 × 54R mm). Seven casualties were confirmed as such.…”

“…Six head models were built from a synthetic skull [8][9][10], face and scalp. The data for the skulls comes from 3-D mapping of a human post-mortem specimen in Tai Wan.…”