用于骨科应力遮挡效应研究的带骨痂有限元模型设计

Design of finite element model with callus for orthopaedic stress-shielding effect analysis

目的设计带骨痂有限元模型,为骨科应力遮挡效应研究提供有效方法。方法采集正常胫骨CT扫描DICOM数据,应用Catia软件建立胫骨上段几何模型,用Solidworks软件切割出模拟骨折线,并在骨折端用计算机辅助设计(computer assisted design,CAD)制图软件导入骨痂模型,再用特征建模方法导入内固定模型,对模型进行力学有限元分析,得出不同工况和内固定方式下的骨痂应力情况,根据应力遮挡率计算公式计算应力遮挡率。结果加压固定导致的应力摭挡率为1.46%,锁定固定为0.42%,减少1个锁钉的锁定固定为0.33%,减少2个锁钉的锁定固定为0.06%。结论带骨痂有限元模型可以模拟不同条件对应力遮挡效应的影响,不同内固定方式或工况条件下应用有限元分析软件可精确计算应力遮挡率。与加压固定相比,锁定固定方法的应力遮挡率较低。

Objective To provide an effective method for stress-shielding effect analysis through designing finite element model with callus. Methods Based on DICOM data of normal tibia collected by CT scanning, the geometric model of superior segment of bibia was generated with Catia software. After simulated fracture line cut out using Solidworks software, callus model was added at the fracture part through computer assisted design （CAD） drawing software and internal fixation model was established via feature-based modeling method. Then finite element analysis on the model was carried out to obtain stress value of the model under different working conditions and different internal fixations, subsequently the stress shielding rate was calculated according to the stress shielding rate formula. Results The stress shielding rate under compression fixation was 1.46% , lock fixation 0.42%, lock fixation when reducing one locked screw 0.33%, and lock fixation when reducing 2 locked screws 0.06%. Conclusions Finite element model with callus can simulate the effects on stress shielding under different conditions or different fixations, and finite element method is an effective way to calculate stress shielding rate presicely. The stress shielding rate of lock fixation is relative low compared with those of compression fixation.