Cortical and trabecular load sharing in the human vertebral body
Cortical and trabecular load sharing in the human vertebral body
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DOI：
10.1359/jbmr.051027
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发表时间：
2006-02-01
影响因子：
6.2
通讯作者：
Keaveny, TM
中科院分区：
文献类型：
--
作者：
Eswaran, SK;Gupta, A;Keaveny, TM
导读：在评估骨质疏松性椎体骨折的风险和治疗效果时，一个基本但鲜为人知的问题是小梁骨和皮质壳在椎体承载能力中的作用。材料和方法：为13个老年人椎骨（年龄范围：54-87岁；74.6 +/- 9.4岁）开发了基于mu ct的高分辨率有限元模型，并进行了参数研究（有终板和没有终板），以确定壳与小梁骨的作用以及模型假设的影响。结果：椎骨皮质壳的平均厚度仅为0.38 +/- 0.06 mm，而不包括终板的壳质量分数（壳质量/总骨量）范围为0.21至0.39。在最窄的截面上，壳体所承受的最大载荷分数在0.38 ~ 0.54之间变化。骨小梁承受的最大载荷分数在各椎骨之间的变化范围为0.76 ~ 0.89，发生在终板附近。无论是最大壳载荷分数还是最大小梁载荷分数都不依赖于椎体的任何密度或形态特性，这表明载荷分担机制的复杂性。尽管这些模型捕获了椎骨内的总体趋势，但移除终板显著改变了椎体间壳承载能力的变化。结论：薄皮质壳在椎体中的生物力学作用是巨大的，在中横切面约占45%，但在靠近终板处低至15%。由于负荷分担的复杂性，仅取样中部小梁骨作为强度替代物错过了重要的生物力学信息。一种结合皮质骨和小梁骨的结构作用的更综合的方法可以改善体内椎体骨强度的无创评估。
Introduction: A fundamental but poorly understood issue in the assessment of both osteoporotic vertebral fracture risk and effects of treatment is the role of the trabecular bone and cortical shell in the load-carrying capacity of the vertebral body.Materials and Methods: High-resolution mu CT-based finite element models were developed for 13 elderly human vertebrae (age range: 54-87 years; 74.6 +/- 9.4 years), and parameter studies-with and without endplates-were performed to determine the role of the shell versus trabecular bone and the effect of model assumptions.Results: Across vertebrae, whereas the average thickness of the cortical shell was only 0.38 +/- 0.06 mm, the shell mass fraction (shell mass/total bone mass)-not including the endplates-ranged from 0.21 to 0.39. The maximum load fraction taken by the shell varied from 0.38 to 0.54 across vertebrae and occurred at the narrowest section. The maximum load fraction taken by the trabecular bone varied from 0.76 to 0.89 across vertebrae and occurred near the endplates. Neither the maximum shell load fraction nor the maximum trabecular load fraction depended on any of the densitometric or morphologic properties of the vertebra, indicating the complex nature of the load sharing mechanism. The variation of the shell load-carrying capacity across vertebrae was significantly altered by the removal of endplates, although these models captured the overall trend within a vertebra.Conclusions: The biomechanical role of the thin cortical shell in the vertebral body can be substantial, being about 45% at the midtransverse section but-as low as 15% close to the endplates. As a result of the complexity of load sharing, sampling of only midsection trabecular bone as a strength surrogate misses important biomechanical information. A more integrative approach that combines the structural role of both cortical and trabecular bone should improve noninvasive assessment of vertebral bone strength in vivo.