3D技术设计的带前弓股骨长柄假体的有限元分析和生物力学研究

The number of total hip revision (THR) is increasing year by year. During these operations, femoral defect (Paprosky I,II,IIIA type) and femoral periprosthetic fracture (Vancouver B2,B3 type) are usually reconstructed with long stem prosthesis. However, there is an anterior bow in the middle upper part of the femur. The long femur stems are designed either without this anterior bow or designed according to the femur anatomy of Caucasus race. This would cause stress concentration and occlusion, thus increasing the failure risk of femur reconstruction. This team was the first one to measure the femoral anterior bow precisely and anatomically with method of extracting three-dimensional centerline of the femoral medullary cavity. Homogeneous finite element analysis and biomechanical experiments were conducted on anterior bow stem and normal stem tentatively with the standardized femur model for the first time, the results revealed anterior bow stem can reduce stress concentration of distal femur and occlusion of proximal femur, the overall stress distribution is better. On this basis, we will establish anistrope finite element models and biomechanical bone models for different types of femoral defect and femoral periprosthetic fracture, the biomechanical characteristic of both normal stem and anterior bow stem are compared in various models. This study may illustrate stress mechanism between the long stem and the femur in different pathological state of THR. At the meantime, theoretical basis may be provided for the design and clinical application of the long stem with the femoral anterior bow.

髋关节翻修手术数量呈逐年递增状态，术中PaproskyI、II、IIIA型的股骨缺损及VancouverB2、B3型股骨假体周围骨折主要用长柄假体进行重建。而股骨中上段存在向前的解剖弯曲，即股骨前弓。当前长柄假体无前弓角度，或前弓角度根据高加索人种进行设计，与国人股骨匹配不佳，股骨重建失败率高。本课题组前期采集中国北方人群CT数据，率先采用三维提取股骨髓腔中心线方式精准测量前弓；据此设计出带前弓股骨长柄假体；并使用正常股骨对其进行了均质有限元分析及生物力学实验对比，发现前弓假体相较于直柄假体，可明显减少远端应力集中与近端应力遮挡，整体受力环境更佳。本次课题拟在此基础建立不同分型的股骨缺损和假体周围骨折的非均质有限元模型和生物力学骨模型，比较前弓假体和常规假体模拟植入后的生物力学特点。本课题有望阐明髋关节翻修术中不同病理状态下长柄假体生物力学机制，为带前弓长柄假体设计和使用提供理论依据。

国内髋关节翻修手术数量呈逐年递增状态，术中Paprosky I、II、IIIA型股骨缺损及Vancouver B、C型股骨假体周围骨折主要应用长柄假体进行股骨侧重建，而股骨中上段存在向前的解剖弯曲，即股骨前弓。以往长柄假体多无合适前弓角度，与国人股骨匹配不佳。课题组采集中国北方人群CT数据，采用抽取髓腔中心线的方式获得了精准可靠股骨前弓曲率并据此设计出带前弓股骨长柄假体；课题组使用正常股骨对该假体进行了均质有限元分析及生物力学实验对比，发现前弓假体相较于直柄假体，可明显减少远端应力集中与近端应力遮挡，整体受力环境更佳。本次课题在此基础上建立了Paprosky I、II、IIIA型股骨骨缺损和Vancouver B、C型股骨假体周围骨折下的股骨非均质有限元模型，并模拟髋关节翻修手术植入前弓长柄假体和常规直柄假体。在假体周围骨折情况下重点分析了骨折线及两侧应力分布、骨折线远近端微动、股骨截面应力分布，发现带前弓长柄假体相比常规直柄假体可以降低应力屏蔽，有利于骨折的愈合。在股骨骨缺损情况下重点分析缺损边缘应力分布、远近端应力分布变化、近端松动位移，发现带前弓长柄假体组中，应力屏蔽现象降低，骨吸收风险降低，且在Paprosky IIIA分型下应用常规直柄会降低假体在股骨中的稳定性。本课题证实了带前弓长柄假体相比常规直柄假体在解剖上更符合髓腔的形状，有利于应力的传导，可减少应力屏蔽，相比直柄假体更加有助于骨折的愈合和骨吸收风险的降低，为带前弓长柄假体的设计、选择和临床应用提供了较为可靠的理论依据。在上述工作基础上，本课题组在本课题经费支持下运用相关技术发表SCI论文19篇，获得前弓假体实用新型专利一项，获批髋关节医疗器械注册证及3D打印个体化定制髋关节备案许可证。本次课题的实施促进了长柄假体的改进和临床应用，加深了课题组对3D打印医工交互理念的理解和运用，为以后课题组进行3D打印个体化定制假体的研发及其生物力学研究积累了丰富技术经验。