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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 effect of augmented cancellous granule and polymethylmethacrylate (PMMA) on the vertebral biomechanics of the treated and adjacent non-treated segments by using the three-dimensional finite element model of the lumbar spine. Methods: The osteoporosis finite element model of three-dimensional spinal functional units of L1-L2 was established with a normal adult male spine specimen in the range of L1-L2. Simulated percutaneous kyphoplasty (PKP) process in the L2 vertebral body were placed in the cancellous bone pellets and PMMA, analysis of axial compression, flexion and extension after three kinds of loading state before and after treatment of the treatment segment and Changes of vertebral stress and strain in adjacent non-treated segments. Results: Both cancellous bone pellets and PMMA had little effect on the biomechanics of adjacent vertebral bodies. However, the changes of stress and stress distribution in the vertebral enhancement area were obvious. CONCLUSIONS: Three-dimensional finite element analysis of the mechanics shows that both materials enhance the overall strength and stiffness of the treatment segment and are conducive to the reconstruction of vertebral body function. However, the increase of cancellous bone granule was better than that of polymethylmethacrylate (PMMA) in restoring the stress level inside the treatment segment.