The effect of longitudinal loading under weight-bearing conditions on ballistic long bone fracture patterns – an experimental study on porcine femora

To examine the effect of longitudinal load on ballistic bone fracture patterns, sixteen porcine femurs embedded in ordnance gelatine were subjected to a compressive load of 100 N. The lengths of anterior fractures and the amount of radial fractures and concentric fractures, as well as the displacement of the fragments seen after being hit by 9 mm full metal jacketed (FMJ, n = 4) and by 5.56 mm Swiss projectiles (n = 4), were compared to those of equal groups struck by the same ammunition but not subjected to longitudinal load. The amount and lengths of fractures seen in these scenarios differed somewhat, with a slight trend towards an increase in the load groups, especially when hit by 5.56 mm Swiss bullets; however, no overall clear-cut increase or decrease could be detected. The dispersal of fragments was distinct; although only the 9 mm FMJ ammunition led to an increase in anterior fragment displacement under loading, the bones hit by 5.56 mm Swiss bullets showed a strong increase in fragment displacement distances under load. This insight may help understand bone damage in shooting incidents.