Zurich Institute of Forensic Medicine, Department of Forensic Medicine and Imaging, University of Zurich, Winterthurerstrasse 190/52, CH-8057, Zurich, Switzerland.
bpk consultancy GmbH, Forstweg 25, 3603, Thun, Switzerland.
Int J Legal Med. 2019 Sep;133(5):1429-1435. doi: 10.1007/s00414-019-02022-3. Epub 2019 Feb 21.
Blows with axes, machetes or blunt objects such as baseball bats, truncheons, etc. are often parried, resulting in typical parry injuries, or so-called nightstick fractures to the ulna. In this study, we sought to assess the impact energy required to break the ulna in such parry incidents in an experimental setting using semisynthetic and fully synthetic models. Twenty-seven sheep radii and 33 polyurethane synthetic bones were cast into gelatin prior to being fired at with missiles made of a section of an axe blade or steel rod at different firing velocities using a compressed-nitrogen cannon. Each model was then examined as to the presence of hair-line fractures or complete fractures. Sheep bones and synthetic bones displayed comparable results when struck by the axe missile; here, a clear fracture threshold was evident between 14.00 and 15.26 J. When struck by the rod missile, only the synthetic bones produced significant results, namely a fracture threshold between 20.15 and 23.59 J. In conclusion, our results show an ulnar fracture threshold of approximately 15 J when struck by an axe. The experiments regarding blows with a rod displayed a fracture threshold of around 22 J, but, as this could not be validated with biological bones, this result is questionable.
斧头、大砍刀或类似棒球棒、警棍等钝器的打击通常会被格挡，导致典型的格挡伤，或所谓的尺骨“警棍骨折”。在这项研究中，我们试图在实验环境中使用半合成和全合成模型评估在这种格挡事件中打断尺骨所需的冲击能。在使用压缩氮气炮以不同的发射速度将斧片或钢棒的一段发射到预先铸入明胶中的 27 根羊桡骨和 33 根聚氨酯合成骨之前，将其铸造。然后检查每个模型是否存在发丝状裂缝或完全裂缝。用斧片导弹撞击时，羊骨和合成骨显示出可比的结果；这里，在 14.00 到 15.26 J 之间存在明显的断裂阈值。当用杆导弹撞击时，只有合成骨产生了显著的结果，即 20.15 到 23.59 J 之间的断裂阈值。总之，我们的结果表明，用斧片撞击时尺骨的断裂阈值约为 15 J。关于用杆打击的实验显示出约 22 J 的断裂阈值，但由于无法用生物骨验证这一结果，因此值得怀疑。
