有限元分析用于水平截骨颏成形术固定方式的生物力学研究

Biomechanical study of finite element analysis in the fixation of horizontal osteotomy genioplasty

目的:应用三维重建和有限元分析的方法探究不同内固定方式对水平截骨颏成形术的影响,寻找生物力学最佳的固定方式。方法:采集1例小颏畸形患者头颅螺旋CT数据,通过Mimics、Geomagic Studio、Solidworks、Ansys Workbench等软件重建下颌骨三维模型和内固定装置,模拟手术截骨,并分别采用4种内固定方法(单纯H形钛板固定、3根拉力螺钉固定、H形钛板联合双侧直形钛板固定、H形钛板联合双侧拉力螺钉固定)进行固定,通过有限元分析测试在相同载荷条件下各固定方式的形变和应力分布差异。结果:H形钛板联合双侧拉力螺钉固定的效果最均衡,整体位移小(0.0332 mm),内固定材料和游离骨段应力集中小(分别为59.79 MPa和4.69 MPa),区域应力小[内固定材料等效应力组间比较时,除与3根拉力螺钉固定方式相近(P>0.05)外,明显小于另2种固定方式(P<0.01);游离骨段等效应力组间比较时,除与单纯H形钛板固定方式相近(P>0.05)外,明显小于另2种固定方式(P<0.05)]。结论:水平截骨颏成形术使用H形钛板联合双侧拉力螺钉固定的方法形变小,不易导致固定材料变形断裂和骨吸收,力学性能优越,相对更适合在临床推广。

Objective Three-dimensional reconstruction and finite element analysis were used to investigate the outcomes of different fixation methods on horizontal osteotomy genioplasty and to identify the fixation method with best biomechanics.Methods The skull spiral CT data of a patient with chin deformity were collected.The mandible three-dimensional model and internal fixation devices were reconstructed by Mimics,Geomagic Studio,Solidworks and Ansys Workbench software.The surgical osteotomy and four internal fixation methods(simple H-shaped titanium plate;3 lag screws;H-shaped titanium plate combined with bilateral straight titanium plates;H-shaped titanium plate combined with bilateral lag screws)were simulated.The difference of deformation and stress distribution in each fixation under the same load were tested by finite element analysis.Results The results of H-shaped titanium plate combined with bilateral lag screws fixation were the most balanced,the overall displacement was minimal(0.0332 mm),the stress concentration of fixation material and free bone was 59.79 MPa and 4.69 MPa,respectively,and the regional stress was small[comparison of the equivalent stress of fixation material between groups,except that it was similar to the three lag screw fixation methods(P>0.05),it was significantly smaller than the other two fixation methods(P<0.01);comparison of the equivalent stress of free bone segment between groups,except that it was similar to the simple H-shaped titanium plate fixation method(P>0.05),it was significantly smaller than the other two fixation methods(P<0.05)].Conclusion The method of H-shaped titanium plate combined with bilateral lag screws fixation in horizontal osteotomy genioplasty has small deformation,which is not easy to cause deformation and fracture of fixation materials,and has superior mechanical properties.It is an appropriate method for clinical application.