Kemper Andrew R, McNally Craig, Pullins Clayton A, Freeman Laura J, Duma Stefan M, Rouhana Stephen M
Virginia Tech-Wake Forest, Center for Injury Biomechanics, 114 Randolph Hall Virginia Tech Blacksburg, VA 24061, USA.
Stapp Car Crash J. 2007 Oct;51:235-73. doi: 10.4271/2007-22-0011.
The purpose of this study was to quantify both the tensile material properties and structural response of human ribs in order to determine which variables contribute to regional variation in the strength of human ribs. This was done by performing 94 matched tests on human rib specimens; 46 tension coupon tests, 48 three-point bending tests. Contralateral matched specimens were dissected from anterior and lateral regions of ribs 4 through 7 of six male fresh frozen post mortem human subjects ranging from 42 to 81 years of age. Tension coupons were taken from one side of the thorax, while three-point bending specimens were taken from the opposite side as the tension coupons at corresponding anatomical locations. The results of the tension coupon testing showed that there were no significant differences with respect to region or rib level: ultimate stress (p=0.90; p=0.53), ultimate strain (p=0.49; p=0.86), or modulus (p=0.72; p=0.81). In contrast, lateral three-point bending specimens were found to have a significantly higher peak bending moment (p<0.01), peak strain (p=0.03), modulus (p=0.05), and stiffness (p<0.01) than anterior specimens. The lateral three-point bending specimens also had a significantly larger area moment of inertia (p<0.01), larger distance to the neutral axis (p<0.01), smaller ratio of distance to the neutral axis to area moment of inertia (p<0.01), larger cortical bone area (p<0.01), and larger radius of gyration (p<0.01) than the anterior specimens. In addition, the peak moment (Ant p=0.20; Lat p=0.02), peak strain (Ant p=0.05; Lat p=0.15), and stiffness (Ant p<0.01; Lat p<0.01) were found to vary significantly with respect to rib level. Similar to anatomical region, the changes in the structural response with respect to rib level were also accompanied by significant changes in geometry. For anterior specimens, distance to the neutral axis (p<0.01), ratio of the distance to the neutral axis to area moment of inertia (p=0.02) and radius of gyration (p=0.04) were found to be significantly different with respect to rib level. For lateral specimens, the area moment of inertia (p<0.01), distance to the neutral axis (p<0.01), ratio of the distance to the neutral axis to area moment of inertia (p<0.01), the cortical bone area (p=0.01), and radius of gyration (p=0.03) were found to be significantly different with respect to rib level. These results clearly illustrate that there is variation in the structural response of human ribs with respect to anatomical region and rib level and this variation is due to changes in local geometry of each rib while the material properties remain constant.
本研究的目的是量化人类肋骨的拉伸材料特性和结构响应，以确定哪些变量导致人类肋骨强度的区域差异。这是通过对人类肋骨标本进行94次匹配测试来完成的；46次拉伸试样测试，48次三点弯曲测试。从6名年龄在42至81岁之间的男性新鲜冷冻尸体的第4至7肋的前部和外侧区域解剖对侧匹配标本。拉伸试样取自胸部一侧，而三点弯曲试样取自与拉伸试样相对的另一侧的相应解剖位置。拉伸试样测试结果表明，在区域或肋骨水平方面没有显著差异：极限应力（p = 0.90；p = 0.53）、极限应变（p = 0.49；p = 0.86）或模量（p = 0.72；p = 0.81）。相比之下，发现外侧三点弯曲试样的峰值弯矩（p < 0.01）,峰值应变（p = 0.03）、模量（p = 0.05）和刚度（p < 0.01）均显著高于前部试样。外侧三点弯曲试样的惯性矩面积（p < 0.01）、到中性轴的距离（p < 0.01）、到中性轴的距离与惯性矩面积的比值（p < 0.01）、皮质骨面积（p < 0.01）和回转半径（p < 0.01）也均显著大于前部试样。此外，发现峰值弯矩（前部p = 0.20；外侧p = 0.02）、峰值应变（前部p = 0.05；外侧p = 0.15）和刚度（前部p < 0.01；外侧p < 0.01）随肋骨水平有显著变化。与解剖区域类似，肋骨水平的结构响应变化也伴随着几何形状的显著变化。对于前部试样，发现到中性轴的距离（p < 0.01）、到中性轴的距离与惯性矩面积的比值（p = 0.02）和回转半径（p = 0.04）在肋骨水平方面有显著差异。对于外侧试样，发现惯性矩面积（p < 0.01）、到中性轴的距离（p < 0.01）、到中性轴的距离与惯性矩面积的比值（p < 0.01）、皮质骨面积（p = 0.01）和回转半径（p = 0.03）在肋骨水平方面有显著差异。这些结果清楚地表明，人类肋骨的结构响应在解剖区域和肋骨水平方面存在差异，这种差异是由于每根肋骨局部几何形状的变化，而材料特性保持不变。
