以三维有限元分析多孔钽块植入治疗股骨头缺血性坏死的生物力学改变

Biomechanical study and three-dimension finite element analysis on the treatment of the iscbemic necrisis of the femoral head using piece of tantalum

目的对比研究3种治疗成人股骨头缺血性坏死方法的生物力学行为;总结最合适的钽块大小、植入位置和植入试验股骨头模型后防止塌陷的效果。方法选择健康成人右侧股骨为研究对象,经层厚2.0mm的螺旋CT扫描得各断面图象,输入计算机识别和提取股骨轮廓并行三维重建。按生理状态下股骨力载荷的三维空间分布,施加髋关节接触力1620N,外展肌合力1061N,髂胫束力1720N。对股骨头三维有限元模型进行计算,求出股骨头受力模型在3种不同处理方法下,不同直径和形状钽金属植入股骨头模型后股骨头负重区表面的塌陷值。结果髓芯减压+植骨+钽块植入组防止股骨头塌陷效果较髓芯减压+植骨组、髓芯减压+植骨+钽棒植入组有明显改善,而髓芯减压+植骨组与髓芯减压+植骨+钽棒植入组随坏死角度增大后无明显差异。结论植入钽金属块后尽可能靠近负重区关节面对股骨头予以支撑,能有效阻止和限制坏死继续进展;植骨加钽棒植入在小范围坏死时尚有一定的支撑作用,当坏死范围增大后不能增加股骨头的机械支撑力;钽金属块植入组治疗股头缺血性坏死明显优于钽金属棒植入组;钽块的最佳植入位置在股骨头负重区正下方软骨板下0～3mm。

Objective To study the biomechanics for the treatment of vascular necrosis of the femoral head by 3 different methods and to determine the most proper diameter and implant site.Methods Choose the right femur healthy adults as the research object,adult and CT scanning was conducted by 2mm interval to get the images of cross sections.The images were then inputted into computer to get contour of femur and rebuild 3D mode1.The hip joint reaction force of 1620N,the abductor muscle force of 1061N,the vastus lateralis muscle force of 1720N were applied according to the 3D space distribution of femur force under physiological state.The collapse areas of the weigh loading site femoral head models with pieces of Tantalum in different diameters in differernt implant sites were calculated.Results The stiffness of femoral head after memorial pieces of Tantalum planting was larger than that of goup 1（core decomprssion with bone grafting）and group 2（core decomprssion with bone and metal Tantalum great grafting）.But there was not significant different between group 1 and group 2 with the increasing Angle necrosis.Conclution The piece of Tantalum implanting can increase mechanical support and ducrease the stress for femoral head.It can promise revascularization and new boen formation for necotic femoral head;With great implant bone graft in small range tantalum necrosis fashion has certain support functions,while larger necrosis after the femoral head cannot increase mechanical support;Tantalum metal piece of implant treatment group head of avascular necrosis obviously better than the metal tantalum implant group;The best diameter of tantalum use to treat ischemic necrosis of the femoral head is 0.5mm,The best position in the femoral head directly under loading the area cartilage board is located 0～3mm.