改良内踝截骨术的3种不同固定方式的有限元分析

Finite element analysis of modified medial malleolus osteotomy with three different fixation methods

目的本研究旨在通过有限元分析评估本团队设计的改良内踝截骨术中3种不同固定方式的优劣。方法创建改良内踝截骨模型,每种固定方式使用2个同样配置的螺钉(3 mm空心双头加压螺钉)固定,以此建立了3种不同的固定方式:双螺钉垂直交叉固定、双螺钉由内向外平行固定及双螺钉由前向后平行固定。使用1200 N的垂直载荷作用于模拟单腿站立的模型上。分析截骨块及螺钉的Von-Mises应力,截骨块在X(向前)、Y(向内)、Z(向上)方向的位移及螺钉的整体位移。结果双螺钉垂直交叉固定组的截骨块在X、Y、Z方向上的位移及螺钉的整体位移(16.895μm、20.491μm、0.746μm、43.888μm)及螺钉Von-Mises峰值应力(50.084 N)最小。结论由双螺钉垂直交叉螺钉固定的改良内踝截骨术减少了截骨块的滑动及分离,螺钉更不容易被折断,是较稳定的固定方式。

Objective The purpose of the present study was to evaluate different fixation techniques in modified methods of medial malleolus osteotomy by finite element analysis.Methods Modified medial malleolus osteotomy models were created.The steotomy was fixed with two screws(3 mm hollow double-headed compression type)having the same configuration.Three new internal fixation schemes were considered:double screw vertical cross fixation,double screws fixed in parallel from inside to outside and double screws fixed in parallel from front to back.A vertical load of 1200 N was applied to each model,simulating a fixed ankle standing on one leg.The Von-Mises stresses on the osteotomy block and screws,the displacement of the osteotomy block in the X(forward),Y(inward)and Z(upward)directions,and the total deformation of the screw were calculated.Results The minimum displacement of the block in the X,Y,and Z directions(16.895μm、20.491μm、0.746μm),the minimum total deformation of the screws(43.888μm),and the minimum Von-Mises stress on the screws(50.084 N)were observed when the modified medial malleolus osteotomy technique with two vertical cross-fixed screws was used.Conclusion The fixation method of the two vertically cross-fixed screws reduce the sliding and separation of the osteotomy block,and the sorewsare less likely to break.We conclud that the modified medial malleolus osteotomy with two vertical cross-fixed screws is the most stable model.