Medical College of Wisconsin, Milwaukee, WI, USA; Zablocki Veterans Affairs Medical Center, Milwaukee, WI, USA; Marquette University, Milwaukee, WI, USA.
Medical College of Wisconsin, Milwaukee, WI, USA; Zablocki Veterans Affairs Medical Center, Milwaukee, WI, USA.
J Forensic Leg Med. 2022 Aug;90:102395. doi: 10.1016/j.jflm.2022.102395. Epub 2022 Jul 6.
Buried blast explosions create small projectiles which can become lodged in the tissue of personnel as far away as hundreds of meters. Without appropriate treatment, these lodged projectiles can become a source of infection and prolonged injury to soldiers in modern combat. Human cadavers can be used as surrogates for living humans for ballistic penetration testing, but human cadavers are frozen during transport and storage. The process of freezing and thawing the tissue before testing may change the biomechanical properties of the tissue. The goal of the current study was to understand penetration threshold differences between fresh, refrigerated, and frozen tissue and investigate factors that may contribute to these differences. A custom-built pneumatic launcher was used to accelerate 3/16″ stainless steel ball bearings toward porcine legs that were either tested fresh, following refrigerated storage, or following frozen storage. A generalized linear mixed model, accounting for within-animal dependence, owing to repeated observations, was found to be the most appropriate for these data and was used for analysis. The "generalized" model accommodated non-continuous observations, provided a straight-forward way to implement the repeated measures, and provided a risk estimate for projectile penetration. Both storage condition (p = 0.48) and leg (p = 0.07) were shown to be not significant and the confidence intervals for those variables were overlapping. As all covariates were found to be non-significant, a single model containing all impacts was used to develop a V, or velocity at which 50% of impacts are expected to penetrate. From this model, 50% probability of penetration occurs at 137.3 m/s with 95% confidence intervals at 132.0 and 144.0 m/s. In this study, the fresh legs and previously frozen legs allowed penetration at similar velocities indicating that previously frozen legs were acceptable surrogates for fresh legs. This study only compared the penetration threshold in tissues that had been stored in differing conditions. To truly study penetration, more conditions will need to be studied including the effects of projectile mass and material, the effects of projectile shape, and the effects of clothing or protective layers on penetration threshold.
掩埋爆炸产生的小型弹丸可能会嵌入数百米远的人员组织中。如果没有适当的治疗，这些嵌入的弹丸可能成为现代战场上士兵感染和长期受伤的根源。人类尸体可以用作活体人类进行弹道穿透测试的替代品，但人类尸体在运输和储存过程中会被冷冻。在测试之前，冷冻和解冻组织的过程可能会改变组织的生物力学特性。本研究的目的是了解新鲜、冷藏和冷冻组织之间的穿透阈值差异，并研究可能导致这些差异的因素。一个定制的气动发射器被用来加速 3/16 英寸不锈钢滚珠轴承向猪腿射击，这些猪腿要么是新鲜测试的，要么是冷藏后测试的，要么是冷冻后测试的。一个广义线性混合模型，考虑到动物内部的依赖性，由于重复观察，被发现是最适合这些数据的，并且用于分析。“广义”模型可以容纳非连续的观察结果，为实施重复测量提供了一种简单的方法，并为弹丸穿透提供了风险估计。存储条件（p=0.48）和腿部（p=0.07）都没有显示出显著差异，并且这些变量的置信区间重叠。由于所有协变量都被发现没有显著意义，因此使用包含所有冲击的单个模型来开发 V 或预计 50%的冲击穿透的速度。从该模型中，可以得出 50%的穿透概率发生在 137.3 m/s，95%置信区间为 132.0 和 144.0 m/s。在这项研究中，新鲜的腿部和之前冷冻的腿部允许以相似的速度穿透，这表明之前冷冻的腿部是新鲜腿部的可接受替代品。本研究仅比较了在不同条件下储存的组织中的穿透阈值。要真正研究穿透，需要研究更多的条件，包括弹丸质量和材料的影响、弹丸形状的影响以及服装或防护层对穿透阈值的影响。
