经皮椎间孔镜髓核摘除术后椎间盘生物力学改变的有限元分析

Finite element analysis of intervertebral disc biomechanical changes after percutaneous transforaminal endoscopic discectomy

目的探讨经皮椎间孔镜髓核摘除术后椎间盘生物力学的变化,以及摘除不同位置和大小的椎间盘对术后椎间盘应力的影响。方法基于CT扫描数据,建立L4-L5椎间盘部分摘除术后腰椎及椎间盘的三维有限元模型,施加载荷后模拟人体7个运动方向(直立、前屈、后伸、左右侧弯、左右旋转),记录并分析椎间盘的应力变化。结果髓核去除的6组与正常组比较,不同体位下椎间盘的应力均升高。除旋转体位下,椎间盘应力的改变为A2组>A1组>B2组>B1组,A1组均大于去除面积是其两倍的B2组。左旋转体位下,椎间盘应力增加明显,B2组>B1组>A2组>A1组>正常组。在除了侧弯的5种体位下,C2组椎间盘应力为所有组中最高,且C1组应力大于A1组和B1组。结论腰椎前屈时应力最大。在相同位置,去除椎间盘的大小和其术后应力改变成正相关。椎间盘切除过宽会使其应力增加较大。MSU分型为C型(外侧或极外侧椎间盘突出),术后椎间盘应力增加最多,是椎间盘去除术后退变的高风险型,B型(旁中央型椎间盘突出)术后椎间盘应力增加最小,是术后的相对稳定型。

Objective To investigate the biomechanical changes of intervertebral disc after percutaneous intervertebral foramen and nucleus pulposus resection.Methods Based on CT scan data,three-dimensional finite element models of lumbar spine and intervertebral disc after partial discectomy were established by software,and the changes of stress distribution in 7 motion directions(upright,forward bending,backward extension,left and right lateral bending,and right and left rotation)were recorded,compared with normal intervertebral disc to analyze the changes of stress.Results Compared with the normal group,the stress of intervertebral disc in the 6 groups with nucleus pulposus removal was higher than that in the normal group.Except for the rotation position,the change of disc stress was A2>A1>B2>B1,which was larger than B2 group with twice the removal area.In the left rotation position,the stress of intervertebral disc increased significantly,B2>B1>A2>A1>normal group.The stress of intervertebral disc in group C2 was the highest in all groups except lateral bending,and the stress in group C1 was higher than that in group A1 and B1.Conclusion At the same location,the size of the disc was positively correlated with the change of stress after discectomy.After the removal of lateral and extreme lateral disc herniation,the stress effect was the greatest,followed by central disc herniation,and the smallest was paracentral disc herniation.In the case of narrow disc removal,the effect of depth of disc removal on disc mechanics is relatively small.