骨质疏松椎体经皮骨移植增强的有限元研究

Percutaneous osteoporosis vertebral augmentation with bone graft using a three-dimensional finite element analysis

目的:利用骨质疏松腰椎三维有限元模型,探讨松质骨粒和聚甲基丙烯酸甲酯(PMMA)增强后对治疗节段和相邻非治疗节段椎体生物力学影响。方法:选取青壮年男性正常人体脊柱标本一具,范围为L1-L2,建立L1-L2的三维脊柱功能单位的骨质疏松有限元模型。模拟经皮穿刺椎体后凸成形术(PKP)过程在L2椎体中分别置入松质骨粒和PMMA,分析轴向压缩、前屈和后伸3种加载状态下手术前后治疗节段和相邻非治疗节段椎体应力和应变的变化。结果:松质骨粒和PMMA均对邻近椎体生物力学的影响极小,但治疗节段椎体增强区域的应力增加和应力分布变化明显。结论:三维有限元力学分析表明两种材料均增强治疗节段的总体强度和刚度水平,有利于椎体功能的重建。但松质骨粒的增强对恢复治疗节段内部的应力水平要优于聚甲基丙烯酸甲酯(PMMA)。

Objective： To investigate the biomechanical effects of cancellous bone granules and polymethylmethacrylate （PMMA） augmentation on treated and adjacent nontreated vertebral bodies using three-dimensional finite element model of osteoporotic lumbar. Methods： L1-L2 motion segment data of the cadaver of an young man who had no abnormal findings on roentgenograms were obtained from computed tomography （CT） scans. Three-dimensional model of L1-L2 was established with Mimics software, and finite element model of osteoporosis L1-L2 functional spinal unit （FSU） was established by Ansys 11.0 software. For simulating percutaneous kyphoplasty, cancellous bone granules and PMMA were respectively placed into L2 vertebra. The changes in stress and strain on treated and adjacent nontreated vertebral bodies was analyzed before and after the operation of cancellous bone granules and PMMA augmentation under following loading conditions： compression, anteflexion and retroextension. Results： The FSU study suggested that changes in stress and strain at adjacent levels were minimal but stresses within the reinforcement material plug were increased and their distribution was obviously changed. Conclusions： Three-dimensional finite element model analysis suggests that both cancellous bone granules and PMMA could increase the total strength and stiffness level of treated vertebral bodies and benefit to the reconstruction of vertebral function. However at the point of stress level recovery of treated vertebral body, the cancellous bone granules is better than PMMA augmentation.