不同截骨方式修复强直性脊柱炎后凸畸形的有限元分析

Finite element analysis of kyphosis in ankylosing spondylitis treated by different osteotomy methods

背景:强直性脊柱炎后凸是一类矢状面或者冠状面失衡的脊柱畸形,目前国内外缺乏对其矫形生物力学的研究,而生物力学对矫形后重建脊柱稳定性十分重要。目的:应用计算机建模软件建立强直性脊柱炎后凸截骨三维有限元模型,并分析其生物力学特性,为临床实践提供一定的理论依据。方法:基于CT数据建立强直性脊柱炎后凸畸形三维有限元模型,测量计算L3节段预截骨角度,模拟去松质骨截骨术和全脊椎截骨术进行截骨,并分析矫形后的生物力学指标变化。结果与结论:(1)建立了完整强直性脊柱炎后凸截骨矫形三维有限元模型,并且模拟手术操作建立L3去松质骨截骨术和全脊椎截骨术2种不同术式截骨模型;(2)除S1节段外,L3去松质骨截骨术的各节段钉棒应力及截骨接触面应力均高于L3全脊椎切除术,两者差距明显;(3)综上,2种不同截骨手术方式均能重建矢状面平衡,但去松质骨截骨术的钉棒应力高于全脊椎截骨术,且差距较为明显;在相同节段,相同角度下去松质骨截骨术发生内固定失败并发症的风险高于全脊椎截骨术。

BACKGROUND： Kyphosis in ankylosing spondylitis is sagittal or coronal imbalance, but there is a lack of study on its orthopedic biomechanics, and biomechanics is of great significance for the reconstruction of spinal stability after orthopedic surgery.OBJECTIVE： To establish a three-dimensional （3D） finite element model of kyphosis in ankylosing spondylitis treated by osteotomy on software, and to analyze its biomechanical properties, thus providing theoretical basis for clinical practice.METHODS： A 3D finite element model of kyphosis in ankylosing spondylitis was established based on CT data, and the predetermined angle of the osteotomy at L2 was measured. Afterwards, vertebral column decancellation and vertebral column resection were stimulated, and then the biomechanical parameters were analyzed. RESULTS AND CONCLUSION： （1） The 3D finite element models of kyphosis in ankylosing spondylitis treated by vertebral column decancellation or vertebral column resection at L3 were established successfully. （2） The stress on the screw and contact at each segment in the vertebral column decancellation group was significantly higher than that in the vertebral column resection group except for S1. （3） To conclude, both two methods can reconstruct the sagittal balance,but vertebral column decancellation exhibits significantly higher stress on the screw. Indeed, the incidence of internal fixation failure and complications in vertebral column decancellation is higher than that in vertebral column resection at the same segment and angle.