【作者】 张强；

【导师】 王岩； 郑诚功；

【作者基本信息】 中国人民解放军军医进修学院 ， 骨科学， 2009， 博士

【摘要】 研究背景对于人工髋关节置换,随着生物力学的发展及假体设计的不断改善,过去常见的近期假体失败,如假体断裂、脱位等已很少见,只要植入正确,不论在短期或长期的随访研究中都取得了极高的成功率,远期无菌性松动成为假体失效的主要原因。从假体外形设计考虑增加假体和骨的密合度、降低初期微动,增加远期骨长入是实现远期固定的必由的路。而这一密合程度由髓腔形态与假体外形共同决定,因此股骨髓腔形态必须纳入假体设计的考量的中,而研究各种影响髓腔形态的因素就极具价值和意义。许多研究提示股骨头缺血性坏死患者无论是年龄分布还是骨质特征都比较特殊。目的探索AVN患者股骨近端髓腔的特点,证实AVN髓腔形态的特殊改变,针对其特点设计一款AVN特异股骨柄,使其与此种疾病患者的髓腔形态更加匹配,并建立AVN股骨置换的有限元模型,对该假体效果进行评价。方法1、通过研究AVN患者标准X线正、侧位片127例(179髋),获得股骨近端的解剖学数据,利用荟萃分析的方法比较AVN患者股骨近段髓腔特征平面(LT+20,LT,LT-20)及CFI的改变与以往研究数据的差异,并利用创伤性FNF患者资料代替正常人股骨数据进一步比较髓腔前、后、内、外四条曲线段上的差异。2、通过结合现代CAD技术,将内、外、前、后曲线拟合到AVN柄的外形上,选用短柄假体设计,近段设计利用AVN患者骨髓腔CT相对应位置的断面进行修正,设计AVN人工股骨柄。3、计算机三维有限元分析:①使用CAD软件SolidWorks和有限元软件Ansys所建立的髋关节股骨侧假体置换后的三维有限元模型。②使用有限元分析软件Ansys进一步分析AVN柄特点,主要包括髓腔填满程度、适合程度及截面应力情况。③与另两种常用假体进行比较研究,包括髓腔填满程度、股骨近端内侧皮质应力、最大微动量及微动面积百分比等。结果1、丰富了以AVN疾病分类的解剖学数据,AVN疾患股骨近段髓腔特征平面(LT+20,LT,LT-20)的改变,无论相对于以往西方人数据还是国人的数据都有统计学差异,比较创伤性FNF和AVN证实存在髓腔曲线段上的统计差异,因此,为AVN患者设计特异性假体具有科学意义和现实的市场需求。2、通过CAD技术,成功将正位片上的内、外两条曲线,侧位片上的前、后两条曲线全部或部分拟合到AVN柄的外形上,选用短柄假体设计,近段设计利用AVN患者骨髓腔CT相对应位置的断面进行修正,最终形成了特点鲜明的AVN人工股骨柄设计。3、通过使用CAD软件SolidWorks和有限元软件Ansys所建立的髋关节股骨侧假体置换后的三维有限元模型,形态逼真,结构完整,模拟加载,可以很好地用于人工常用股骨柄的生物力学评估及新假体设计的验证。通过模拟AVN股骨例置换的有限元分析,AVN柄表现出了良好的股骨近端匹配(fit &fill),优于Zimmer的Versys假体,在fill的某些平面上不如Zimmer的新型短柄假体Fitmore。在内侧皮质应力分析上,Fitmore虽然近端2cm表现出比AVN柄更高的应力,自收敛部达到应力最高值后没有很好的回落,在后续的微动试验中Fitmore最大微动量已经超过150微米,而且微动出现在假体内侧的远近端的4.5%的面积,61.2%面积的骨长入不可靠,而AVN柄微动面积则均未超过150微米,更易获得初期稳定,利于远期骨长入。结论1、丰富了以AVN疾病分类的解剖学数据。2、为AVN患者设计特异性假体具有科学意义和现实的市场需求。3、使用CAD软件SolidWorks和有限元软件Ansys所建立的髋关节股骨侧假体置换后的三维有限元模型可以很好地用于人工股骨柄的生物力学评估及新假体设计的验证。4、有限元结果证实AVN柄近端匹配性能优于长柄设计Versys股骨假体,应力分布比Fitmore假体更合理,微动量更小,更有利于骨长入获得假体长期固定,适合AVN患者股骨特征。更多还原

【Abstract】 Background:With the development of biomechanics and continuous improvement of prosthetic design in THA,the common failures of prosthesis in the past,such as prosthesis fracture and dislocation,rarely occurred.As long as the implant procedure is correctly done,high success rates can be achieved either in short term or long term follow-ups.Aseptic loosening of prosthesis has become the main reason for failure. From the prospect of prosthesis design,increasing the prosthesis and bone adaptation to reduce the initial micromotion and increase long term bone ingrowth is the only way to achieve long term fixation.This kind of adaptation is determined by both the shapes of medullary cavity and prosthesis.Therefore it must incorporate the shape of femoral medullary cavity into prosthesis design considerations.Research for the factors which affect variety of medullary cavity has become a valuable and scientific trend.In addition, many studies of patients with AVN showed plenty of special characteristics,such as age distribution and bone quality.Objective:To study the geometric features of proximal femur for the Chinese AVN population,in order to prove the existence of special characteristic of proximal femur for the disease and then develop an AVN-specialized stem evaluated by a validated finite element analysis(FEA).Methods:1.The author investigated the standard X-ray data of 127 cases(179 hips) with definite diagnosis of AVN to provide anatomical references for this disease.At the same time,we conducted a meta-analysis of anatomical studies of normal proximal femur data,including the section of LT+20,LT,LT-20 and CFI to identify the potential difference between AVN and normal population.Furthermore,the author also performed a comparison of proximal femur canal curve between AVN and traumatic FNF(as a substituent of normal population).2.With the help of modern CAD technology,the stem was designed by the medial,lateral,anterior,posterior canal curves and consummated by the CT scanning data.3.In this FEA study:①A validated FEM was set up by CAD software SolidWorks and FE software Ansys,②the features of stem was evaluated in respects of fill,fit and section stress distribution,③the comparison study among AVN stem and another two common-used prostheses, including fill status,stress distribution of medial proximal femur,max micromotion and percentage at critical micromotion point.Results:1.The author gained a large series data of AVN proximal femur and indentified the changes of AVN population at the plane of LT+20,LT,LT-20. Furthermore,the difference of canal cures was found in comparison of traumatic FNF and AVN.As a result,a developed stem special for AVN patient does not only posses scientific meaning but also meet the demand of market.2.A novel AVN stem was designed with the characteristics of canal curve.3.A validated FEM of stem replacement was set up in realistic form,integritive structure to simulate the load for artificial hip stems,so that it can be well used to assess and verify the biomechanical characteristics of the new prosthesis design.AVN stem showed a better match feature(fit & fill) than the Versys prosthesis,but the fill status of AVN stem did not overweigh Fitmore prosthesis at some plane.In the stress analysis of medial cortex,Fitmore showed higher stress than AVN stem in the proximal 2 cm area,but the stress did not drop back quickly after it achieved the highest value.In the following fretting test,the largest micromotion of Fitmore was more than 150 microns,and the area with micromotion over 150 microns occupied 4.5%in the medio-proximal and medio-distal part of stem.Over 61.2%of bone ingrowth area is not reliable,while AVN stem is more likely to gain the initial stability and more beneficial to long term bone ingrowth with no micromotion over 150 microns.Conclusions:1.This study enriches the data for proximal femur anatomic parameters of AVN population.2.Newly designed AVN-specialized stem does not only posses scientific meaning but also meets the demand of market.3.A validated FEM of stem replacement was established,it is beneficial to assess and verify the biomechanical characteristics of the new stem design.4.The AVN stem confirmed by FEA was especially adaptive for AVN patient with features of good match and stress distribution in the proximal femur,which predicted better initial stability and long term bone ingrowth.更多还原