Wu Tongge, Bonnheim Noah B, Pendleton Megan M, Emerzian Shannon R, Keaveny Tony M
Department of Mechanical Engineering, University of California, Berkeley, CA, USA.
Department of Orthopaedic Surgery, University of California, San Francisco, CA, USA.
Comput Methods Biomech Biomed Engin. 2024 Aug;27(10):1278-1286. doi: 10.1080/10255842.2023.2239415. Epub 2023 Jul 28.
In this study, we used micro-CT-based finite element analysis to investigate the biomechanical effects of radiation on the microstructure and mechanical function of murine lumbar vertebrae. Specifically, we evaluated vertebral microstructure, whole-bone stiffness, and cortical-trabecular load sharing in the L5 vertebral body of mice exposed to ionizing radiation 11 days post exposure (5 Gy total dose; = 13) and controls ( = 14). Our findings revealed the irradiated group exhibited reduced trabecular bone volume and microstructure ( < 0.001) compared to controls, while cortical bone volume remained unchanged ( = 0.91). Axially compressive loads in the irradiated group were diverted from the trabecular centrum and into the vertebral cortex, as evidenced by a higher cortical load-fraction ( = 0.02) and a higher proportion of cortical tissue at risk of initial failure ( < 0.01). Whole-bone stiffness was lower in the irradiated group compared to the controls, though the difference was small and non-significant (2045 ± 142 vs. 2185 ± 225 vs. N/mm, irradiated vs. control, = 0.07). Additionally, the structure-function relationship between trabecular bone volume and trabecular load fraction differed between groups ( = 0.03), indicating a less biomechanically efficient trabecular network in the irradiated group. We conclude that radiation can decrease trabecular bone volume and result in a less biomechanically efficient trabecular structure, leading to increased reliance on the vertebral cortex to resist axially compressive loads. These findings offer biomechanical insight into the effects of radiation on structure-function behavior in murine lumbar vertebrae independent of possible tissue-level material effects.
在本研究中，我们使用基于微型计算机断层扫描（micro-CT）的有限元分析来研究辐射对小鼠腰椎微观结构和力学功能的生物力学效应。具体而言，我们评估了暴露于电离辐射11天后（总剂量5 Gy；n = 13）的小鼠L5椎体的椎骨微观结构、全骨刚度和皮质-小梁负荷分担情况，并与对照组（n = 14）进行比较。我们的研究结果显示，与对照组相比，辐照组的小梁骨体积和微观结构减少（P < 0.001），而皮质骨体积保持不变（P = 0.91）。辐照组的轴向压缩负荷从小梁中心转移至椎骨皮质，这表现为较高的皮质负荷分数（P = 0.02）以及较高比例的有初始失效风险的皮质组织（P < 0.01）。与对照组相比，辐照组的全骨刚度较低，尽管差异较小且无统计学意义（2045 ± 142 vs. 2185 ± 225 N/mm，辐照组 vs. 对照组，P = 0.07）。此外，两组之间小梁骨体积与小梁负荷分数之间的结构-功能关系存在差异（P = 0.03），表明辐照组的小梁网络生物力学效率较低。我们得出结论，辐射可减少小梁骨体积并导致生物力学效率较低的小梁结构，从而增加对椎骨皮质抵抗轴向压缩负荷的依赖。这些发现为辐射对小鼠腰椎结构-功能行为的影响提供了生物力学见解，而不受可能的组织水平材料效应的影响。
