骨质疏松骨折椎体及相邻椎体骨水泥注入前后的有限元分析

Finite element analysis on the vertebral body and adjacent vertebrae of osteoporotic fractures before and after bone and cement injection

背景:目前有限元构建模型主要是基于医学图像的建模方法,骨水泥注入主要是人为假设的,而文章中治疗前后的数据直接来源于CT扫描,可靠性更高。目的:构建骨水泥注入前后骨质疏松性腰椎骨折椎体的三维有限元模型,分析治疗前后病椎及邻椎的应力变化。方法:选取1例75岁骨质疏松性L2椎体压缩性骨折患者,经双侧椎弓根注入少量骨水泥获得良好疗效,随访2年病椎及邻椎无新发骨折,局部无疼痛。根据其治疗前后的腰椎CT数据,构建三维有限元模型,模拟腰椎屈伸、左右侧屈、旋转等运动,统计分析治疗前后同一运动状态下的应力变化。结果与结论:建立了腰椎压缩骨折骨水泥注入前后的三维有限元模型,共生成222727个单元。骨水泥注入增加了L2椎体(病椎)屈、伸、侧屈各运动时的应力(P<0.05),对其旋转时的应力无明显影响(P>0.05);对L1,L3椎体(邻椎)在屈、伸、侧屈及旋转时的应力亦无影响(P>0.05)。提示少量骨水泥注入治疗老年骨质疏松性腰椎骨折可增加病椎强度及应力,但不改变相邻椎体应力。

BACKGROUND：At present, the establishment of finite element model mainly depends on the medical image modeling method, and bone cement injection is the artificial assumptions, while the data before and after treatment used in this study are mainly obtaind through CT scan which have a higher reliability. OBJECTIVE：To establish the three-dimensional finite element models of osteoporotic lumbar vertebral fracture before and after bone cement injection, and to analyze the stress changes of vertebral body and adjacent vertebrae before and after treatment. METHODS：A 75-year-old patient with osteoporotic vertebral compression fracture of lumbar was selected and treated by bilateral bone cement injection. Clinical curative effect was good, and 2-year fol ow-up of the vertebral body and adjacent vertebrae showed there was no new vertebral fracture and partial pain. The three-dimensional finite element model was established according to the preoperative and postoperative CT image data in order to simulate lumbar spine flexion and extension, lateral bending, rotating around movement, and then the stress changes were statistical analyzed under the same state of motion before and after treatment. RESULTS AND CONCLUSION：We have established three-dimensional finite element model of preoperative and postoperative vertebral compression fracture which had 222 727 units. Cement injection into vertebral body （disease vertebral） could increase the stress of L2 vertebral body when having the flexion and extension and lateral bending movements （P〈0.05）, and had no influence on the stress when having rotating around movement （P〉0.05）;the bone cement injection had no influence on the stress of L1 and L3 vertebral body （adjacent vertebrae） when having the flexion and extension, lateral bending and rotating around movements （P〉0.05）. Smal amount of bone cement injection for the treatment of elderly osteoporotic lumbar fracture can increase the strength and stress of the disease vertebrae without changing the stress of the adjacent vertebrae.