Su Xinlin, Shen Hao, Shi Weidong, Yang Huilin, Lv Feng, Lin Jun
Department of Orthopedic Surgery, The First Affiliated Hospital of Soochow UniversitySuzhou, Jiangsu, China.
Suzhou Nuclear Power Research InstituteSuzhou, Jiangsu, China.
Am J Transl Res. 2017 Sep 15;9(9):4036-4045. eCollection 2017.
Being beneficial in restoring stability and stiffness of osteoporotic vertebraes, cement augmentation techniques including vertebroplasty (VP) and kyphoplasty (KP) have been demonstrated to be effective for the treatment of patients with osteoporotic vertebral compressive fractures (OVCFs). However, it is unclear the influence of cement augmentation on the dynamics of pathologic and adjacent vertebraes under vibration condition. In this study, we developed a three-dimensional (3D) finite-element (FE) model of the spinal T12-Pelvis segment by using CT scan data of lumbar spine of an adult woman with no physical abnormalities. By modulating model parameters we further simulated osteoporotic conditions of the T12-Pelvis FE model with or without polymethyl methacrylate (PMMA) augmentation. Dynamic characteristics of the osteoporotic T12-Pelvis model were detected at the first order of vertical resonant frequencies (FOVRFs) under vertical vibration, which included vertical axial displacements, anteroposterior (AP) displacements and rotational angles of each vertebrae and intervertebral disc (IVD). The results showed that axial and AP displacements of both vertebraes and IVDs decreased in some point after PMMA augmentation. Axial displacements of the L4-L5 motion segment decreased most significantly and the changing ratios ranged from 20% to 30%. AP displacements of L5, D (the IVD between vertebraes L1 and L2) and D reduced most obviously after 1, 2 or 3 levels PMMA augmentation. No significant difference of axial or AP displacements of each vertebrae and IVD was observed between one-level and multilevel PMMA augmentation. Thus, we demonstrated that PMMA augmentation could reduce vertical axial and AP deformations of the osteoporotic lumbar motion segments under vertical vibration, especially for the inferior adjacent motion segments. However, the influence of the number of vertebraes with PMMA augmentation on the dynamics of osteoporotic lumbar spine was indistinctive.
骨水泥强化技术，包括椎体成形术（VP）和后凸成形术（KP），已被证明对治疗骨质疏松性椎体压缩骨折（OVCF）患者有效，有助于恢复骨质疏松椎体的稳定性和刚度。然而，骨水泥强化对振动条件下病理性椎体和相邻椎体动力学的影响尚不清楚。在本研究中，我们利用一名无身体异常成年女性腰椎的CT扫描数据，建立了脊柱T12 - 骨盆节段的三维（3D）有限元（FE）模型。通过调节模型参数，我们进一步模拟了有或没有聚甲基丙烯酸甲酯（PMMA）强化的T12 - 骨盆FE模型的骨质疏松情况。在垂直振动下，以一阶垂直共振频率（FOVRFs）检测骨质疏松T12 - 骨盆模型的动态特性，包括每个椎体和椎间盘（IVD）的垂直轴向位移、前后（AP）位移和旋转角度。结果表明，PMMA强化后，椎体和IVD的轴向和AP位移在某些点有所下降。L4 - L5运动节段的轴向位移下降最为显著，变化率在20%至30%之间。在1、2或3个节段进行PMMA强化后，L5、D（L1和L2椎体之间的IVD）和D的AP位移下降最为明显。在单节段和多节段PMMA强化之间，未观察到每个椎体和IVD的轴向或AP位移有显著差异。因此，我们证明了PMMA强化可以减少垂直振动下骨质疏松腰椎运动节段的垂直轴向和AP变形，特别是对下相邻运动节段。然而，PMMA强化椎体数量对骨质疏松腰椎动力学的影响并不明显。
