椎体成形术填充剂最优化分布模式三维有限元分析

Three-dimensional finite element analysis of optimal distribution model of fillers in vertebroplasty

目的:通过建立骨质疏松三维有限元模型,模拟液体流动进入椎体,研究不同状态骨水泥灌注量及分布条件下经皮椎体成形术术后伤椎刚度恢复及相邻椎体应力分析。方法:选取男性健康志愿者一名,从T11到L2之间使用CT扫描,采用Mimics 15.0以及ABAQUS 6.11等软件提取CT图像,建立骨质疏松性骨折椎体模型,将模拟流动物理场与传导和扩散物理场二者耦合,模拟骨水泥注入椎体骨折模型的过程及分布,注入骨水泥量分别为2、4、6 ml。在图像上模拟出骨水泥弥散范围,获得骨水泥注入后模型。在模型上表面均匀施加垂直向下、前倾、后伸各300 N压力,模拟椎体活动。计算不同状态下上下椎体及病椎应力变化。结果:(1)骨折前后3种状态下T12下终板VonMises应力最大。(2)骨折后椎间盘及各终板VonMises应力明显高于骨折前水平,当应用经皮椎体成形术后,随着骨水泥注入量的增加,相邻椎体终板VonMises应力呈上升趋势;而相对于病椎,随着骨水泥量的增加而椎体终板VonMises应力呈下降趋势。结论:应用CT扫描数据通过软件模拟可以建立可靠的腰椎骨折生物力学模型,椎体骨折以及椎体成形术后将引起上下相邻椎体生物力学改变,随着骨水泥量的注入增加,生物力学改变的影响明显升高,相邻椎体骨折可能性更高。经皮椎体成形术比较合适的骨水泥注入量为4 ml。

Objective:To establish a three-dimensional finite element model of osteoporosis and to study the stiffness recovery of injured vertebrae and stress analysis of adjacent vertebrae after percutaneous vertebroplasty under different perfusion and distribution conditions by simulating fluid flow into the vertebral body.Methods:A male healthy volunteer was selected.CT scans were performed from T11 to L2.Mimics 15.0 and ABAQUS 6.11 software were used to extract CT images.The vertebral model of osteoporotic fracture was established.The flow physical field and conduction and diffusion physical field were coupled to simulate the process and parts of the injection of bone cement into the vertebral fracture model.The amount of bone cement injected into the vertebral fracture model was 2 ml,4 ml,6 ml respectively.The diffusion range of bone cement was simulated on the image,and the post-injection model of bone cement was obtained.Vertical downward,forward and backward pressure of 300 N were applied on the surface of the model to simulate vertebral movement.The stress changes of upper and lower vertebrae and diseased vertebrae under different conditions were calculated.Results:(1)The VonMises stress of T12 inferior endplate was the largest in the three states before and after fracture.(2)The VonMises stress of the intervertebral disc and each endplate after fracture was significantly higher than before fracture.When percutaneous vertebroplasty was applied,as the amount of bone cement injection increases,the VonMises stress of the adjacent vertebral endplates increases.In the diseased vertebrae,as the amount of bone cement increases,the VonMises stress of the vertebral body endplate showed a downward trend.Conclusion:Reliable biomechanical model of lumbar vertebral fracture can be established by using CT scanning data through software simulation.Vertebral fracture and vertebroplasty will cause biomechanical changes of adjacent vertebral bodies.With the increase of bone cement injection,the influence of biomechanical changes will increase significantly.Neighbouring vertebral fractures are more likely.For this experiment,percutaneous vertebroplasty has a suitable amount of cement injection of 4 ml.