椎体骨皮质强化差异对骨质疏松性椎体压缩性骨折生物力学的影响

Effect of differences in vertebral cortical bone reinforcement on biomechanics of osteoporotic vertebral compression fractures

背景:骨质疏松性椎体压缩性骨折经皮椎体成形过程中骨水泥在椎体内的骨皮质强化区域对脊柱生物力学及临床疗效有重要影响,但以往研究大多局限于二维层面。目的:采用有限元分析法探讨经皮椎体成形过程中骨水泥在椎体三维层面内骨皮质强化差异对骨质疏松性椎体压缩性骨折椎体、邻近椎间盘及终板生物力学分布的影响,以评估其效果。方法:建立T12椎体骨质疏松性压缩性骨折行经皮椎体成形治疗的有限元模型,从横断面、矢状面、冠状面对骨水泥有无皮质强化情况进行分组分析,研究不同体位变化下,骨皮质强化对T12椎体松质骨、皮质骨、T11/T12椎间盘、T12/L1椎间盘、T11下终板、L1上终板生物力学的影响。结果与结论:(1)在垂直压缩力作用下,经皮椎体成形过程中有或无骨水泥皮质强化在不同体位变化下除伤椎皮质骨以外结构应力变化均不明显;(2)伤椎皮质骨Von Mises应力值在人体前屈、左/右侧弯和左/右轴向旋转时差异显著,同一平面内骨皮质完全强化组较无骨皮质强化组最大Von Mises应力值明显变小,随着骨皮质强化越广泛Von Mises应力值整体呈下降趋势;(3)提示行经皮椎体成形治疗时,横断面内骨水泥应尽量广泛对称水平分布于椎体骨皮质边缘,矢状面内骨水泥应广泛纵向分布且靠近上下终板及前后壁,冠状面内骨水泥应广泛分布于中线两侧同时对称接触上下终板及侧壁,可有效避免伤椎再骨折风险且不增加邻椎骨折、残留盘源性疼痛风险。

BACKGROUND:The cortical bone reinforcement area of bone cement in the vertebral body during percutaneous vertebroplasty for osteoporotic vertebral compression fractures has an important influence on spinal biomechanics and clinical efficacy,but previous studies were mostly limited to the two-dimensional level.OBJECTIVE:To investigate the effect of the difference in cortical bone reinforcement of bone cement in the three-dimensional plane of the vertebral body on the biomechanical distribution of the vertebral body,adjacent intervertebral disc and endplate in osteoporotic vertebral compression fractures by finite element analysis during percutaneous vertebroplasty,so as to evaluate its effect.METHODS:The finite element model of percutaneous vertebroplasty for osteoporotic vertebral compression fractures of T12 vertebrae was established.The presence or absence of cortical reinforcement of bone cement was analyzed in groups from the transverse,sagittal and coronal planes.The effects of cortical reinforcement on the biomechanics of T12 vertebral cancellous bone,cortical bone,T11/T12 intervertebral disc,T12/L1 intervertebral disc,T11 lower endplate,and L1 upper endplate under different body position changes were studied.RESULTS AND CONCLUSION:(1)Under the effect of vertical compression force,percutaneous vertebroplasty cortical reinforcement with or without bone cement had no significant changes in structural stress except for the injured vertebral cortical bone.(2)The Von Mises stress value of the injured cortical bone was significantly different in human forward flexion,left/right bend,and left/right axial rotation.The maximum Von Mises stress value in the best group of cortical reinforcement was significantly smaller than that in the non-cortical reinforcement group.The Von Mises stress value showed a downward trend with extensive cortical reinforcement in the same plane.(3)It is indicated that when percutaneous vertebroplasty is performed,bone cement should be distributed as broadly and symmetrically horizontally along the cortical edge of the vertebral body as far as possible in cross section.Bone cement in sagittal plane should be widely distributed longitudinally near the upper and lower endplates and the anterior and posterior walls.Bone cement in coronal plane should be widely distributed on both sides of the midline while symmetrically touching the upper and lower endplates and lateral walls.It can effectively avoid the risk of refracture of the injured vertebra and does not increase the risk of adjacent vertebral fracture and residual discogenic pain.