BACKGROUND Previous studies have revealed positive effect of Topping-off technique on upper adjacent segment after fusion surgery, while for the cases with fusion surgery on L5-S1 segment, owning maximal range of motion, and preexisting degenerated upper adjacent disc, it is necessary to clarify the superiority of Topping-ff technique and the effect exerted on the lumbar spine. METHODS A young healthy male volunteer was selected for thin-slice CT scanning. Then the image information was imported into the computer to establish the whole lumbar spine model as the health model. The medium degeneration model of intervertebral disc was established by changing the material properties of L4-S1 disc on the basis of the health model, and the fusion model and Topping-off model were respectively established on the basis of the degenerated model. The variation trend of ROM of L2-L5 and the stress changes of L4-L5 intervertebral disc, nucleus pulposus and facet joints were calculated respectively. RESULTS The L4-L5 ROM of fusion model increased significantly but the ROM of L2-L3 and L3-L4 segments did not change significantly. Compared with the degenerated model, L4-L5 activity of the Topping-off model decreased, and ROM of the L2-L3 and L3-L4 increased to some extent in the flexion and extension positions. The stress on the disc, nucleus pulposus and facet joint of the fusion model L4-L5 increased in four positions of flexion, extension, rotation and bending compared with the degenerated model, while the fiber stress on the Topping-off model decreased significantly in all four positions. CONCLUSION Topping-off technology can decrease the stress and ROM of the adjacent upper degenerated segment, and increase the ROM of other upper segments, thereby protecting the degenerated upper adjacent segments and compensating the lumbar spine mobility.

中文翻译：

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腰s顶部手术后变性邻近节段和完整腰椎的生物力学变化：三维有限元分析。

背景技术先前的研究已经显示，Topping-off技术对融合手术后的上相邻椎间盘具有积极作用，而对于融合手术的L5-S1段，拥有最大运动范围并已存在退化的上相邻椎间盘的患者，有必要进行阐明Topping-ff技术的优势以及对腰椎的作用。方法选择一名年轻健康的男性志愿者进行薄层CT扫描。然后将图像信息导入计算机，以建立整个腰椎模型作为健康模型。在健康模型的基础上，通过改变L4-S1椎间盘的材料特性，建立椎间盘的介质退化模型，并在退化模型的基础上分别建立融合模型和Topping-off模型。分别计算了L2-L5的ROM变化趋势以及L4-L5椎间盘，髓核和小关节的应力变化。结果融合模型的L4-L5 ROM明显增加，但L2-L3和L3-L4片段的ROM没有明显变化。与退化模型相比，Topping-off模型的L4-L5活性降低，屈伸位置的L2-L3和L3-L4 ROM有所增加。与退化模型相比，融合模型L4-L5的椎间盘，髓核和小关节上的应力在屈曲，伸展，旋转和弯曲四个位置上均增加，而Topping-off模型上的纤维应力在所有位置上均显着降低四个职位。