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目的:应用三维有限元模型探讨椎体成形术治疗老年骨质疏松椎体压缩性骨折对邻近节段生物力学的影响。方法:选取1例老年骨质疏松椎体(T12)压缩性骨折女性患者的术前、球囊扩张后凸成形术(KP)术后CT片,范围为T11～L1(包括病椎、邻近椎体和邻近椎间盘),分别建立术前、术后的三维脊柱功能单元的有限元模型。对T11上终板垂直向下加载300N的力矩和10N·m的旋转力矩,分析在垂直载荷、前屈、后伸、侧屈及旋转的情况下,手术前后病变椎体的变化以及椎体皮质骨、松质骨、相邻椎间盘、终板的应力改变情况。结果:成功建立术前、术后脊柱功能单元的三维有限元模型,术前T12椎体前、中缘高度分别为13.1mm和10.9mm,术后分别为15.2mm和12.6mm,明显增高(P<0.05)。在垂直载荷应力下,邻近椎体上下终板(T11下终板和L1上终板)所受应力无显著变化,但在前屈、后伸、侧屈、轴向旋转时T11/12椎间盘所受压力分别增加0.66、0.88、2.25、0.85MPa;T12/L1椎间盘所受压力分别增加1.56、1.60、0.50、2.35MPa,与术前比较均有显著性差异(P<0.05)。结论:球囊扩张后凸成形术有效改善了脊柱功能单位的生物力学性能,并未对邻近椎体产生较大的影响,但可能会加速邻近椎间盘的退变。
OBJECTIVE: To investigate the effect of vertebroplasty on the biomechanics of adjacent segments by vertebroplasty in elderly patients with osteoporotic vertebral compression fractures. Methods: One patient with compression fractures of the elderly with osteoporotic vertebral body (T12) underwent preoperative and postoperative kyphoplasty (KP) of postoperative CT. The range of T 1 1 to L 1 (including diseased vertebrae and adjacent vertebrae Body and adjacent disc), respectively, to establish the preoperative and postoperative three-dimensional finite element model of spinal functional unit. T300 on the end plate vertical load torque of 300N and torque of 10N · m, analysis of vertical load, flexion, extension, lateral flexion and rotation, changes in vertebral body before and after surgery and vertebral cortex Bone, cancellous bone, adjacent disc, end plate stress changes. Results: The three-dimensional finite element model of preoperative and postoperative spine functional units was successfully established. The anteroposterior and medial edge height of preoperative T12 vertebrae were 13.1mm and 10.9mm, respectively. The postoperative were 15.2mm and 12.6mm respectively (P <0.05). Under vertical load stress, there was no significant change in the stress on the upper and lower endplates of the vertebral bodies (T11 and L1). However, in the flexion, extension, lateral flexion and axial rotation, the T11 / 12 intervertebral disc The pressure increased 0.66,0.82,2.25,0.85MPa; T12 / L1 intervertebral disc pressure increased by 1.56,1.60,0.50,2.35MPa, compared with the preoperative were significant differences (P <0.05). CONCLUSION: Balloon kyphoplasty can effectively improve the biomechanical properties of spinal functional units without affecting the adjacent vertebral bodies, but may accelerate the degeneration of adjacent vertebral discs.