经皮骨移植增强对椎体生物力学性能的影响

目的 利用腰椎三维有限元模型,评价经皮骨移植增强(Optimesh(R))的生物力学性能.方法 L1～L2的三维脊柱功能单位的有限元模型由脊柱尸体标本CT扫描后形成.功能脊柱单元有限元模型有23446实体单元和310纤维单元组成,共36009个节点.模拟经皮骨移植增强(Optimesh(R))过程在L2椎体中置入松质骨粒,分析轴向压缩、前屈和后伸3种加载状态下手术前后椎体应力和应变的变化.结果 在压缩、前屈和后伸3种加载状态下,松质骨粒增强模型强化区最大的Von Mises应力分别为0.333、0.436、0.321 MPa,应变分别为0.335%、0.438%、0.322%;骨质疏松模型相应区域最大的Von Mises应力分别为0.174、0.239、0.161 MPa,应变0.512%、0.709%、0.474%.与术前(骨质疏松)模型相比,松质骨粒增强模型强化区最大的Von Mises应力增加1倍,应变下降1/3左有.结论 经皮骨移植增强(Optimesh(R))能有效地恢复椎体的生物力学性能,可为临床提供一种新的经皮椎体成型术方法.

Biomechanics of percutaneous vertebral augmentation with bone graft: a finite element evaluation

Objective To investigate the biomechanical effects of percutaneous vertebral augmentation with bone graft (Optimesh) using three-dimensional finite element model of lumbar. Methods Three-dimensional, anatomically detailed finite element (FE) models of the L1-L2 functional spinal unit (FSU) were developed on the basis of cadaver computed tomography (CT) scans. As a result, the finite element model of the functional spinal unit L1-L2 was developed, consisting of 23 446 solid elements, 310cable elements and a total of 36 009 nodes. For simulating Optimesh, cancellous bone granules were placed into L2 vertebra. The changes in stress and strain on vertebral bodies were analyzed before and after the operation of cancellous bone granule augmentation under following loading conditions: compression,flexion and extension. Results Under compression, flexion and extension loading conditions evaluated in the current study, the maximum yon Mises stress and strain within the reinforcement material plug in the treated level due to the presence of morcelized cancellous bone were 0. 333, 0. 436, 0. 321 MPa and 0. 335%, 0. 438%, 0. 322% respectively, whereas the maximum yon Mises stress and strain within corresponding area in the osteoporotic, untreated model were 0. 174, 0.239, 0. 161 MPa and 0.512%,0. 709%, 0. 474% respectively. Compared to the untreated model, the maximum von Mises stress and and strain within the reinforcement area in the treated model were approximately double and two-thirds those in the osteoporotic model respectively. Conclusion Percutaneous vertebral augmentation with bone graft ( Optimesh(R) ) can improve the biomechanical strength of vertebral body, and can be used as a new method in the percutaneous vertebroplasty operation.