不同终板愈合形态对椎间盘生物力学影响的有限元研究

Finite element study on the biomechanical effects of different endplate healing morphology on intervertebral disc

目的探讨软骨终板的不同愈合形态对终板本身以及椎间盘的生物力学影响。方法选取河北医科大学第三医院一名健康成年男性志愿者,计算机断层扫描受试者的T12~L2椎体,经三维重建后构建实体三维椎体模型。构建正常软骨终板、曲度增加终板、不规则愈合终板和创伤性Schmorl结节终板4种不同软骨终板模型。在进行模型有效性验证后,施加500 N垂直载荷于T12椎体上表面,获取各模型的软骨终板和椎间盘的应力分布。结果曲度增加模型髓核的应力略有增加,不规则愈合模型与创伤性Schmorl结节模型均有明显降低,分别降低38.1%和27.5%。曲度增加模型纤维环的应力略有降低,不规则愈合模型与创伤性Schmorl结节模型均有明显增加,分别增加9.8%和6.3%,且纤维环的应力集中区域较为一致,位于纤维环-髓核交界区域以及纤维环的外围。结论软骨终板的形态改变会导致椎间盘应力的重新分布,为软骨终板形态改变导致椎间盘退变提供生物力学依据。

Objective To investigate the biomechanical effects of different healing morphology of cartilage endplate on endplate itself and intervertebral disc.Methods A healthy adult male volunteer in the Third Hospital of Hebei Medical University underwent computed tomography scans from T12 to L2 vertebrae.The solid spine model was constructed after three-dimensional reconstruction.Four different cartilaginous endplate models including normal endplate,increased curvature endplate,irregular healing endplate and traumatic Schmorl node endplate were constructed.After validation of the model,500 N vertical load was applied to the upper surface of the T12 vertebral body to obtain the stress distribution of cartilage endplate and intervertebral disc in each model.Results The stress of nucleus pulposus increased slightly in increased curvature model,and decreased significantly in irregular healing model and traumatic Schmorl node model by 38.1%and 27.5%,respectively.The stress of annulus fibrosus decreased slightly in increased curvature model,and increased significantly in irregular healing model and traumatic Schmorl node model by 9.8%and 6.3%,respectively.In addition,the stress concentration of the annulus fibrosus was relatively clear,which was located in the junction area with the nucleus pulposus and the periphery of the annulus fibrosus.Conclusion The morphological changes of cartilage endplate can lead to the redistribution of stress in the intervertebral disc,which provides a biomechanical evidence for the morphological changes of cartilage endplate leading to intervertebral disc degeneration.