退变性腰椎侧弯单节段与双节段固定融合术后邻近节段的生物力学分析

Biomechanical analysis of adjacent segments of degenerative scoliosis treated with single and double-segment internal fixataion and bone fusion

目的利用有限元分析方法探讨单节段和双节段内固定+椎间融合术治疗退变性腰椎侧弯后对邻近节段影响的生物力学变化。方法基于一例退变性腰椎侧弯患者T12-S1上段连续的CT扫描图像,建立完整、有效的三维有限元模型。对其分别采用单节段和双节段椎管减压+椎间植骨融合+椎弓根螺钉内固定术治疗,在各种工况下对术后模型进行力学加载,比较两种治疗方法对脊柱活动度及固定邻近节段椎间盘、关节突关节的影响。结果单节段固定融合术后腰段脊柱前屈活动度增大,双节段固定融合术后腰段脊柱活动度减小,单节段固定融合术较双节段固定融合术更能增加邻近节段的活动范围;两种方法固定术后邻近节段椎间盘应力均有所集中,以邻近上节段明显,且单节段固定融合术的影响更大;两种方法固定术后对固定相邻下节段关节突关节软骨的应力影响较大,对相邻上节段影响相对较小,均以旋转运动明显,但单-双节段固定融合术对关节突关节软骨的影响无统计学差异。结论单-双节段内固定+椎间融合术后均可改变脊柱活动度并增加邻近节段活动度,且对固定邻近节段椎间盘及关节突关节的应力有所影响,有可能造成术后侧弯的加重。

Objective To investigate the biomechanical changes of adjacent segments of degenerative lumbar scoliosis treated with single-segment and double-segment internal fixation and interbody bone fusion using the finite element analysis.Methods Based on the degenerative lumbar scoliosis patient＇s CT images of the successive spinal column from T12 to superior segment of S1 and formed the integrated and effective three dimensional finite element model.Treated it with single-segment and double-segment spinal canal decompression＋interbody bone fusion＋pedicle screw internal fixation and loaded the operative model on different operating conditons.Compared the two therapeutic methods effects to spinal activity and the stress distribution of intervertebral disk and facet joints articular cartilage of adjacent segments.Results The spinal activity of anteflexion increased after single-segment internal fixation and bone fusion,the spinal activities decreased after double-segment internal fixation and bone fusion.The single-segment internal fixation and bone fusion would increase greaterly the spinal activities of adjacent segments than double-segment internal fixation and bone fusion.The stress distribution of adjacent segment intervertebral disk would concentrate after the two internal fixation and the upper segment appeared more obviously and the effects of single-segment internal fixation and bone fusion was greater.The stress of facet joints articular cartilage of lower adjacent segments appeared greatly after the two internal fixation and that ofthe upper segment appeared slightly and all appeared obviously on rotation motion.But there was no statistics difference between the two internal fixation.Conclusion Single and double-segment internal fixation＋bone fusion will change the spinal activities and increase the activities of adjacent segment and affect the stress of intervertebral disk and facet joint of adjacent segments,which may cause scoliosis aggravate.