经椎弓截骨矫正强直性脊柱炎后凸畸形的三维有限元分析

Three-dimensional finite element analysis of pediclesubtraction osteotomy for ankylosing spondylitis with kyphotic deformity

背景:经椎弓根椎体截骨术式矫正效果明显,且矫正度数丢失的发生率较低,一直以来都是强直性脊柱炎后凸矫正首选手术方式。目的:应用计算机辅助软件建立强直性脊柱炎后凸截骨三维有限元模型,并分析生物力学特性。方法:选取1例强直性脊柱炎后凸志愿者,拍摄脊柱全长正侧位片和磁共振扫描。建立强直性脊柱炎后凸三维模型,再生成完整的强直性脊柱炎后凸三维有限元模型。建立3种模型分别模拟3种不同截骨矫形手术方案,截骨角度分别为20°,30°,40°,并分析矫形效果及生物力学分析。结果与结论:(1)成功建立了完整强直性脊柱炎后凸截骨矫形三维有限元模型,截骨角度分别为20°,30°,40°的3种不同螺钉钛棒最大主应力分别为54.632,194.230,394.860 MPa;(2)成功模拟3种不同截骨矫形方案,模型3矫形程度最佳,但应力分布较大,位移明显,内固定后稳定性及内固定失败并发症增加,模型2在矫形程度以及应力分布适中,既获得较佳的矫形程度,同时也降低内固定失败并发症的发生。

BACKGROUND:The effect of pediclesubtraction osteotomy is obvious,and the incidence of correction degree loss is low.So,it has been the first choice for the correction of ankylosing spondylitis with kyphotic deformity.OBJECTIVE:To establish a three-dimensional finite element model of ankylosing spondylitis with kyphotic deformity by computer aided software,and to analyze the biomechanical characteristics.METHODS:A ankylosing spondylitis patient with kyphotic deformity was selected,and spinal full-length anteroposterior images were photographed,and the patient received magnetic resonance imaging.A three-dimensional model of ankylosing spondylitis with kyphotic deformity was established,and then a three-dimensional finite element model of ankylosing spondylitis with kyphotic deformity was generated.Three different types of models were established for three different surgeries at the osteotomy angle of 20°,30°and 40°.Correction effect and biomechanics were analyzed.RESULTS AND CONCLUSION:(1)A three-dimensional finite element model of ankylosing spondylitis with kyphotic deformity was successfully established at the osteotomy angle of 20°,30°and 40°.The maximum principal stresses of three different screw titanium rods were 54.632,194.230,394.860 Mpa.(2)Three different surgeries were successfully simulated.The correction degree of the model 3 was optimal,but the stress distribution was large;displacement was obvious.After internal fixation,the complications of stability and internal fixation failure increased.The model 2 had good correction degree,appropriate stress distribution,and decreased complications of fixation failure.