Ballistic variables and tissue devitalisation in penetrating injury—establishing relationship through meta-analysis of a number of pig tests

Abstract

Assessment of the injury potential is central to ascertaining that a law enforcement bullet does not cause unjustified and excessive injuries. There seems to prevail an understanding that tissue devitalisation correlates with kinetic energy dissipated into the tissue. Other views exist too. The purpose of the study was to find out whether such a correlation can be found and at what level of confidence. A number of reported tests done with live pigs with sufficient primary data have first been brought to the same temporally comparable level and then analysed. The tests comprise of 140 shots. To maintain consistency tests with other animals were excluded. The best correlation was obtained between excised muscle tissue and dissipated kinetic energy per millimetre of wound channel. An equation describing the relationship between dissipated energy E(d) and devitalised tissue m(deb) is presented as a regression function m(deb)=44.575xE(d)+10.319 with R2=0.293. An experimental method for estimating the energy used for bullet deformation of controlled deformation bullets is also presented. A method for using the regression function for obtaining tissue destruction figures for any point of wound channel formed in tissue simulant is presented. The figures are intended for meaningful comparison of the injury potential of various bullets and not for forecasting actual tissue injuries. The documentation of the ballistic properties in animal tests also seems somewhat lacking. Some changes in documenting firearms injuries are proposed in order to validate the methods and further enhance the fidelity of simulant testing.