University of Virginia, Center for Applied Biomechanics, Charlottesville, Virginia 22911, USA.
Traffic Inj Prev. 2011 Aug;12(4):377-87. doi: 10.1080/15389588.2011.583960.
The goal of the present study was to identify rib-level differences in fracture characteristics for individual ribs subjected to anterior-posterior loading.
Twenty-seven individual ribs were extracted from levels 2 to 10 from 3 postmortem human subjects (2 females and one male) and subjected to anterior-posterior loading at a quasistatic (2 mm/s) loading rate. The ribs were placed in a fixture that provided a pinned boundary condition at each extremity, and each specimen was loaded to failure. Reaction force and strains on the internal and external cortical surfaces of the ribs were measured.
Rib 2 was found to be 3 to 4 times stiffer than rib 3, whereas all other ribs were comparable in stiffness to rib 3. Fracture forces, fracture displacement, and work to fracture showed no clear rib-level trends, although the young male subject consistently exhibited higher fracture force and work values than the elderly female subjects for a given rib level. The cortical strains on the external surface of the rib remained in tension during the loading, whereas the internal surface strains were in compression. The data from the present study were compared to a similar study performed at dynamic loading rates (1.43-1.85 m/s). The quasistatic tests exhibited lower peak force and greater normalized fracture displacement than the dynamic tests, though the work was comparable between the 2 studies.
The present study is one of the few that focuses on testing the rib as an entire structure and can contribute to understanding of how the structural behavior of an individual rib contributes to the fracture tolerance of the overall thorax when undergoing frontal loading.
本研究的目的是确定个体肋骨在前-后加载下的骨折特征在肋骨水平上的差异。
从 3 具尸体（2 名女性和 1 名男性）的 2 到 10 节提取了 27 个单独的肋骨，并以准静态（2mm/s）加载速率进行前-后加载。肋骨被放置在夹具中，在每个末端提供固定边界条件，每个标本被加载至失效。测量肋骨内部和外部皮质表面的反作用力和应变。
第 2 肋被发现比第 3 肋硬 3 到 4 倍，而所有其他肋骨的刚度与第 3 肋相当。骨折力、骨折位移和断裂功没有明显的肋骨水平趋势，尽管年轻男性受试者在给定的肋骨水平上始终表现出比老年女性受试者更高的骨折力和断裂功值。肋骨外部皮质表面的应变在加载过程中保持张力，而内部表面应变则处于压缩状态。本研究的数据与在动态加载速率（1.43-1.85m/s）下进行的类似研究进行了比较。准静态试验的峰值力较低，归一化骨折位移较大，而 2 项研究的功相当。
本研究是少数专注于测试整个肋骨作为一个整体的研究之一，可以有助于理解在经受正面加载时，个体肋骨的结构行为如何对整个胸腔的骨折耐受性做出贡献。
