踇外翻微创截骨术后绷带和Herbert螺钉固定截骨端生物力学的三维有限元分析

3D finite element analysis of the biomechanics of bandage and Herbert screw fixation after hallux valgus osteotomy

目的:比较踇趾外翻微创截骨术后截骨端用绷带和Herbert螺钉两种方式的固定强度和稳定性。方法:招募1位中度踇外翻女性病人,对其左足行CT扫描获得数据,导入三维有限元软件,初步建立踇外翻三维有限元模型,模拟微创截骨术后采取绷带固定和Herbert螺钉固定,分析足部跖屈位截骨端最大位移及应力分布情况,Herbert螺钉的应力分布情况。结果:绷带固定截骨端最大等效应力为7.8615 MPa,Herbert螺钉固定截骨端最大等效应力为8.3156 MPa。绷带固定截骨端总位移为0.268960 mm,Herbert螺钉固定截骨端总位移为0.029195 mm。螺钉在截骨端附近的最大应力为46.404 MPa。结论:在截骨端固定强度和稳定性上,Herbert螺钉固定优于绷带固定,但绷带固定微动范围未超过有害距离,对断端愈合无不利影响;Herbert螺钉本身在截断近端处应力较高,这种应力集中对早期维持骨折断端的稳定有着非常重要的作用。

Objective:To compare the fixation strength and stability between bandage and Herbert screw fixation after hallux valgus osteotomy.Methods:A female patient with moderate hallux valgus was selected,and the left foot of patient was scanned using spiral CT,the data were imported into the finite element software to construct the 3D finite element model of hallux valgus,which was used to simulate the bandage and Herbert screw fixation after hallux valgus osteotomy.The maximum displacement and stress distribution of osteotomy end in the metatarsal flexion of foot,and stress distribution of Herbert screw were analyzed.Results:The maximum equivalent stress of the osteotomy end fixed with bandage and Herbert screw were 7.8615 MPa and 8.3156 MPa,respectively.The total displacement of osteotomy ends fixed with bandage and Herbert screw were 0.268960 mm and 0.029195 mm,respectively.The maximum stress of the screw near the osteotomy end was 46.404 MPa.Conclusions:Herbert screw fixation is better than that of bandage fixation in terms of strength and stability of osteotomy ends,but the range of bandage fixation does not exceed the harmful distance,and has no adverse effect on the healing of broken end.Moreover,the Herbert screw has a high stress at the near end of the truncation,and this stress concentration plays an important role in maintaining the stability of the fracture end in the early stage.