退变性脊柱侧凸短节段固定融合术后椎间盘的应力变化

目的 探讨短节段固定融合术治疗退变性脊柱侧凸(DS)后椎间盘的应力变化.方法 基于DS患者T12～S1上段连续的CT扫描图像,赋予模型特定的材料属性,建立完整、有效的DS三维有限元模型.对其采用短节段(单节和双节)椎管减压+椎间植骨融合+椎弓根螺钉内固定术治疗,在前屈、后伸、左侧弯、右侧弯、左旋转、右旋转6种工况下对术后模型进行加载,计算和分析两种治疗方法对各椎间盘的应力分布变化,并与术前DS模型进行比较.结果 短节段固定融合术后固定相邻节段椎间盘应力均较术前DS模型有所增加,旋转运动对相邻上节段椎间盘影响较大,后伸运动对相邻下节段椎间盘影响较大.单节段固定术后相邻上、下节段椎间盘应力(平均值分别为6.03、4.58 MPa)增加均大于双节段固定术后(平均值分别为5.24、4.47 MPa),但两者比较差异无统计学意义(P＞0.05).结论 短节段固定融合术可使DS固定邻近节段椎间盘应力增加,其中单节段固定融合术对相邻上、下节段椎间盘应力的影响大于双节段固定融合术；短节段固定融合术治疗DS,术后应避免旋转及后伸运动.

The stress changes of intervertebral disk of degenerative scoliosis after treatment with shortsegment internal fixation and fusion

Objective To investigate the stress changes of intervertebral disk of degenerative scoliosis (DS) after treatment with short-segment internal fixation and fusion.Methods Based on the DS patient's CT images of the successive spinal column from T12 to superior segment of S1,assigning special material attributes to the model and forming the integrated and effective three dimensional finite element model of DS.Treated with the short-segment (one-segment and two-segment) spinal canal decompression +intervertebral bone fusion+pedicle screw internal fixation.Loading the model on the following postures:anteflexion,postextension,left lateral inclination,right lateral incliniation,left rotation and right rotation.Calculating and analyzing the stress distribution of intervertebral disk and comparing to that of the preoperative normal DS model.Results The stress of intervertebral disk after the short-segment internal fixation and fusion was increased than that of preoperation.The rotation motion affected greater to the upper intervertebral disk of fixation segment and the extension motion affected greater to the inferior intervertebral disk of fixation segment.The increase of stress of upper and inferior intervertebral disk of fixation segment treated with one-segment fixation and fusion(average was 6.03,4.58 MPa,separately) was greater than that of the two-segment fixation and fusion (average was 5.24,4.47 MPa,separately),but there was no statisticdifference (P ＞ 0.05).Conclusions The short-segment intemal fixation can increase the intervertebral disk stress of adjacent segment fixation of DS.The effect on the stress of upper and inferior intervertebral disk of fixation segment of one-segment fixation and fusion is greater than that of two-segment fixation and fusion.And the patient should avoid the rotation and extension movements after treated with the short-segment internal fixation and fusion.