有限元分析法对椎体成形术的力学评价

Mechanic evaluate the percutaneous vertebroplasty with finite element analysis

目的利用有限元方法分析椎体成形术应力变化的影响,以指导临床实践。方法在已建立的腰段骨质疏松性椎体压缩性骨折三维有限元模型(L1/L2,L2为骨折模型)上,模拟经皮穿刺椎体成形术(PVP)过程。在L2椎体中置入骨水泥,轴向加载500N状态下记录手术前后病椎椎体终板、骨小梁、骨水泥及邻近椎体终板的应力变化。结果手术前后,病椎终板的应力发生明显减少,而松质骨的应力没有明显的变化,单侧注入骨水泥与双侧注入骨水泥病椎终板的应力也不同,但相差并不大。邻近椎体终板手术前后无明显改变。结论椎体形成术,由于注入骨水泥后,病椎的应力发生了转移,终板的应力明显减少,松质骨的应力没有明显变化,而单侧注入骨水泥与双侧注入骨水泥对病椎终板的应力影响不大,手术前后对邻近椎体的应力影响不大。

Objective Mechanically evaluate the percutaneous vertebroplasty（PVP） with finite element analysis in order to guide the clinic treatment. Methods To establish L1/L2 three-dimensional finite element model of lumbar （L1/L2 ） osteoporotic vertebral compression fracture （only L2 fractured）. For simulating PVP, column-like PAMA mass was placed into L2 vertebra unilaterally and bilaterally. The von mise stress changes on endplate, cancellous bone and cement before and after the operation were analysized and recorded respectively. Results After operation, the von mise stress of the L2 vertebra endplate decreased greatly, but the cancellous bone did not show noticeable change. The von mise stress of bilateral group is a little smaller than the unilateral group. The mise stress of L1 endplate did not change with the operation. Conclusions After PVP, parts of von mise stress of the endplate tranferred to the cement, the mise stress of the endplate reduced, but mise stress of the cancellous bone did not decrease. The difference of change between unilateral group and bilateral group was so small that it almost can be neglected. PVP would not increase the mise stress of the adjacent vertebral body.