Fracture patterns in diaphyseal gunshot trauma: role of the bullet's impact point and angle

Skeletal trauma assessment is an important task of forensic anthropologists and pathologists. This applies in particular to badly preserved bodies where the soft tissue cannot provide forensic evidence. Yet, the interpretation of ballistic long bone trauma can be difficult due to little conclusive data. Thus, this study explored the variability of diaphyseal fracture patterns dependent on the bullet's angle and point of impact. 20 femurs from body donors were embedded in Clear Ballistics Gel^® and divided into 4 experimental groups: 70° angled shot on the centre of the anterior shaft aspect; perpendicular shot on the centre of the lateral shaft aspect; perpendicular shot on the centre of the posterior shaft aspect; grazing shot from posterior on the margin of the medial shaft aspect. In each case, a 9-mm Luger full metal jacket projectile was shot at a distance of 2 m and an impact speed of 360 m/s. All fractures were examined macroscopically. For the trauma comparison, a fifth group (perpendicular shot on the centre of the anterior shaft aspect), previously analysed in an earlier study, was included. Although the groups revealed similar fracture characteristics, the results suggest the bullet's impact angle and location influence the fracture pattern. The most dissimilar fracture pattern was reproduced in the grazing shots, where only one defect hole was seen, instead of an entry and exit hole like in the other groups. The findings highlight the variability of ballistic fracture patterns in long bones and may serve as guidelines during the skeletal trauma assessment.