螺钉、克氏针内固定治疗距骨颈骨折的三维有限元分析

摘要

目的 利用三维有限元法分析克氏针、螺钉内固定治疗距骨颈骨折的稳定性,为临床上研究距骨颈骨折内固定最佳力学环境提供生物力学理论依据.方法 获取健康男性志愿者左足及胫腓骨远端骨CT扫描信息,利用Mimics软件对距骨行三维建模；所有数据以点云格式输出到Geomagic软件编辑,得到模型实体,把所有数据以IGES格式输出；之后导入到Ansys软件中,利用该软件对克氏针、螺钉造模并模拟距骨颈骨折模型,分别用空心螺钉、克氏针对骨折进行固定,而后分别对模型赋予单元类型和属性建立有限元模型.在模型的胫距关节的距骨关节面垂直施加2100N的压力进行非线性分析.结果 后侧入路内固定骨折面接触压力最大为7.23 MPa,骨折间隙最小为0.199 451 mm;前侧入路内固定分别为6.991 MPa、0.249 261 mm.螺钉内固定的骨折面接触压力最大为7.23 MPa,骨折间隙最小为0.199451 mm;克氏针分别为6.958 MPa、0.242006 mm.多根固定的骨折面接触压力最大为7.23 MPa,骨折间隙最小为0.199 451 mm;单根固定分别为6.976 MPa、0.243 946 mm.结论 利用三维有限元法可对克氏针、螺钉内固定治疗距骨颈骨折的稳定性进行对比分析,得出最适用于距骨颈骨折内固定的最佳力学环境；双螺钉由后向前固定治疗距骨颈骨折的稳定性优于其他固定方式.%Objective To analyze the stability of talar neck fracture treated by screw fixation and Kiischner wire (k-wire) internal fixation using the finite element analysis, so to provide biomechanical theoretical basis for the clinical study of the best mechanical environment after internal fixation of talar neck fracture. Methods CT images of the left distal tibia and fibula from healthy male volunteers were analyzed in order to build three-dimensional models of talar by Mimics software. All the data were output in point cloud style and then input into Geomagic software to build model entities which were output in IGES form. Finally, the data were input in Ansys software to simulate talar fracture and establish treatment models of screw fixation and k-wire internal fixation. Finite element models were built following unit type and property were given to these models. Nonlinear analysis was performed in these models under the same load (2 100 N) at the same point of the talar articular surface of the tibiotalar joint. Results The max fracture surface contact pressure of the posterior approach fixation treatment model was 7.23 Mpa, the min fracture gap of the posterior approach fixation treatment model was 0. 199 451 mm; the anterior approach fixation were 6.991 Mpa, 0. 249 261 mm. The screw fixation treatment model were 7.23 Mpa, 0. 199 451 mm, and the k-wire fixation treatment model were 6.958 Mpa, 0. 242 006 mm. The multiple fixation treatment model were 7. 23 Mpa, 0.199 451 mm, and the single fixation treatment model were 6.976 Mpa, 0. 243 946 mm. Conclusion Using the finite element method to analyze the stability of talar neck fracture treated by screw fixation and k-wire internal fixation, it could conclude the best mechanical environment to the talar neck fracture. The fixation stability of the double posterior-to-anterior screws fixation is better than the others.