髓芯减压空洞充填材料对股骨头应力的影响

目的探讨充填骨材料的弹性模量对股骨头内应力分布的影响。方法取成年男性正常股骨标本一具,经层厚2.0mm的螺旋CT扫描得各断面图像,输入计算机识别和提取股骨轮廓并行三维重建,导入ANSYS9.0进行前处理,依骨材料弹性模量及配比的不同,建立5种骨模型,按生理状态下股骨力载荷的三维空间分布,施加髋关节反力、外展肌力、髂腰肌力和股外侧肌力,分别计算股骨头内应力分布情况。结果植入高弹性模量的骨材料,软骨下骨板最大应力值下降;植入低弹性模量的骨材料,软骨下骨板最大应力值则上升。高、低两种弹性模量骨材料的植入都在界面产生应力集中。采用梯度法将植入材料作为功能梯度材料,按弹性模量的大小分层,界面应力集中大大下降。结论用梯度法的高弹性模量骨材料植入能有效降低软骨下骨板及骨板下松质骨的应力,大大降低分界面应力集中,从而有效防止股骨头塌陷。

Effect of Filling Materials on Femoral Head Stress Following Core Decompression

Objective To examine the effect of elastic modulus of filling materials on femoral head stress. Methods A normal femur specimen was chosen from an adult male and CT scanning was conducted at 2mm interval along cross section to get the images of cross sections. The images were then inputted into computer to get contour of femur and rebuild 3D model. The pretreatment was managed by ANSYS9. 0. Five bone models were built,and the hip joint reaction force ,the abductor muscle force , the Iliopsoas force and the vastus lateralis muscle force were applied according to the Three-dimensional space distribution of femur force under physiological state. Results The maximum subchondral bone plate stresswould decrease by using high elastic modulus filling materials,while the stress would increase by using low elastic modulus filling materials. The implantation of two kinds of filling bone materials would both cause stress concentration on the interface. By using gradient method which treated implant materials as functionally graded material and stratified implant materials according to their elastic modulus,the stress concentration on interface decreased significantly. Conclusion The gradient method and high elastic modulus implant material stratification can effectively reduce the stress on subchondral bone plate and the stress on cancellous bone under bony plate,and reduce stress concentration on the interface greatly so as to prevent femoral head collapse effectively.