Vertebroplasty and kyphoplasty affect vertebral motion segment stiffness and stress distributions - A microstructural finite-element study
Vertebroplasty and kyphoplasty affect vertebral motion segment stiffness and stress distributions - A microstructural finite-element study
复制标题
DOI：
10.1097/01.brs.0000163882.27413.01
复制
发表时间：
2005-06-01
期刊：
影响因子：
3
通讯作者：
Lieberman, IH
中科院分区：
文献类型：
--
作者：
Keller, TS;Kosmopoulos, V;Lieberman, IH
研究设计。采用有限元方法研究了骨水泥增强后胸部运动节段的力学行为。 目的。检查水泥增强对运动段刚度和载荷传递的影响。背景数据摘要。椎体成形术和椎体后凸成形术旨在硬化和强化椎体，但在不改变负载转移到相邻节段的情况下实现这些目标的最佳骨水泥体积和位置尚不清楚。方法。根据显微 CT 图像构建了椎体运动节段的微观结构有限元模型。使用弹塑性模量降低方案对椎体小梁结构内的微损伤进行建模。创建了三个运动段损伤模型：I = 18% 表观模量降低（损伤最小）、II = 45% 和 III = 85%（损伤最大）；研究了几种单节段和两节段聚甲基丙烯酸甲酯骨水泥修复策略（部分填充椎体后凸成形术，置换骨和骨髓；以及部分填充和完全填充椎体成形术，仅置换骨髓）。将平均椎间盘和骨骼应力以及运动节段表观压缩刚度与基线（未损坏和未处理）模拟结果进行比较。结果。在最大化邻近椎体的刚度和最小化应力变化以及增加运动节段表观刚度方面，我们发现，除了完全填充之外，最有效的单节段骨水泥修复策略是在覆盖椎间盘环的上节段周边进行椎体成形术（整体椎体骨应力变化<0.1％，刚度增加分别<0.1％，损坏模型III）。两节段椎体成形术（所有修复模型）将所有损伤模型中的运动节段刚度恢复到基线水平，而单节段椎体成形术（所有修复模型）仅在损伤模型 I 中将刚度恢复到基线水平。单节段和两节段椎体后凸成形术仅对模型 I 有效地将刚度恢复到基线水平。与基线模型相比，骨水泥增强降低了平均治疗节段骨应力（高达 66%，完全填充椎体成形术弹塑性模量降低模型 III），增加了平均椎间盘核应力（高达 59%，椎体后凸成形术弹塑性模量降低模型 III），并增加了平均相邻节段、终板区域应力（高达 2.8%，椎体后凸成形术弹塑性模量降低模型 II）。在椎间盘核下方的终板区域中，相邻（未经治疗）节段的峰值骨应力增加（高达 45%，后凸成形术，模型 III）。结论。损伤修复模拟表明，骨水泥增强提高了运动节段的刚度，但显着改变了治疗节段和相邻节段的骨应力分布。
Study Design. The mechanical behavior of a thoracic motion segment following cement augmentation was studied using the finite-element method.Objective. To examine effects of cement augmentation on motion segment stiffness and load transfer.Summary of Background Data. Vertebroplasty and kyphoplasty procedures are meant to stiffen and strengthen the vertebral body, but the optimal cement volume and placement to achieve these goals without altering load transfer to adjacent segments are unknown.Methods. A microstructural finite-element model of a vertebral motion segment was constructed from micro-CT images. Microdamage within the vertebral body trabecular structure was modeled using an elasto-plastic modulus reduction scheme. Three motion segment damage models were created: I = 18% apparent modulus reduction (least damage), II = 45%, and III = 85% (most damage); and several one- and two-segment polymethylmethacrylate cement repair strategies (partial fill kyphoplasty, replacement of bone and marrow; and both partial fill and complete fill vertebroplasty, replacement of marrow only) were studied. Average disc and bone stresses and motion segment apparent compressive stiffness were compared with baseline (undamaged and untreated) simulation results.Results. In terms of maximizing stiffness and minimizing stress alterations in the adjacent vertebral body and increasing motion segment apparent stiffness, we found that, other than complete fill, the most effective single-segment cement repair strategy was vertebroplasty on the periphery of the superior segment overlying the disc anulus (< 0.1% overall vertebral body bone stress alteration and 83% stiffness increase, respectively, damage Model III). Two-segment vertebroplasty (all repair models) restored motion segment stiffness to baseline levels in all damage models, while single-segment vertebroplasty (all repair models) restored stiffness to baseline levels only in damage Model I. Single- and two-segment kyphoplasty was effective in restoring stiffness to baseline levels for Model I only. Compared with the baseline model, cement augmentation decreased average treated segment bone stresses (up to 66%, complete fill vertebroplasty elasto-plastic modulus reduction Model III), increased average intervertebral disc nucleus stresses (up to 59%, kyphoplasty elasto-plastic modulus reduction Model III), and increased average adjacent segment, endplate region stresses (up to 2.8%, kyphoplasty elastoplastic modulus reduction Model II). Adjacent (untreated) segment peak bone stresses were increased (up to 45%, kyphoplasty, Model III) in endplate regions underlying the intervertebral disc nucleus.Conclusions. The damage-repair simulations indicated that cement augmentation improves motion segment stiffness but substantially alters bone stress distributions in treated and adjacent segments.