Fragmentation characteristics of long bones resulting from impact of different ammunition sizes
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Abstract
The present study examined differences in fragmentation and trauma characteristics on long bones caused by two ammunition types. White-tailed deer (Odocoileus virginianus) tibiae (n = 50) were encased in 10% ballistic gelatin, and 9 mm ammunition from a handgun and 5.56 mm ammunition from an assault rifle were fired from a distance of 3 yards. Due to the higher muzzle velocity, it is anticipated that tibiae impacted by 5.56mm ammunition will exhibit a greater degree of fragmentation and obscure fracture patterns. Conversely, fragmentation patterns from 9 mm ammunition are expected to be more discernible, given the lower energy transfer and smaller caliber, allowing for easier classification of fracture patterns including drill-hole, impaction and false butterfly. A Kolmogorov-Smirnov test indicated the number of fragments for each ammunition type followed a normal distribution (Df(25) = 0.139, p = 0.200) for 9 mm and (Df(25) = 0.090, p = 0.200) for5.56 mm ammunition. A Mann-Whitney U-test revealed 5.56 mm ammunition caused more fragmentation than 9 mm (p = 0.002). Of the examined-for fracture patterns, only false butterfly fractures were observed, in 48% of the 9 mm sample and 4% of the 5.56 mm sample. Chi-square tests for independence showed that all but stepped breakout (x2(1) = 1.299, p = 0.254) had a statistical association with an ammunition type. The present study found significant differences between the frequency of observed ballistic characteristics and ammunition type offering a potential method for identifying ammunition types in future cases of ballistic trauma where no projectile is present.
Description
2025