【作者】 张银光；

【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， 2008， 博士

【摘要】 研究背景人工膝关节外科虽然获得了极大的发展,但是目前所有的膝关节假体设计在术后都不能达到同正常膝关节相同的功能,在膝关节生理和生物力学上都不同于正常的膝关节。膝关节作为一个复杂重要的关节,各解剖亚单位之间是相互制约和共同作用的,这些解剖结构的任何改变都会对膝关节的整体功能有影响。目前除单髁假体外,几乎所有的膝关节假体设计均牺牲了前交叉韧带或前后交叉韧带。而牺牲了交叉韧带的人工膝关节设计必然导致一定程度的关节稳定性和运动生理功能的损失。目前少数国外设计的保留前叉韧带的假体,存在着关节显露困难、重新获得两条韧带的正常张力困难、假体的锚定不佳、关节线改变的不良影响等诸多问题,均未能达到预期的效果。随着人们生活水平和对健康及生活质量要求的提高,目前膝关节置换手术不仅仅只停留在单纯改善疼痛等症状,而如何获得最佳的功能及活动度以及使患者真正满意,当前成为大家都很关心的问题,因此对人工膝关节外科提出了更高更新的要求。目的设计一种能够同时保留前、后交叉韧带的表面膝关节假体,改进以往假体设计的不足,使膝关节假体解剖学、运动学及生物力学更加接近人体膝关节。方法1、通过离体尸体膝关节的测量,确定前交叉韧带在胫骨平台附着点的具体解剖学特点,结合应用现代计算机CAD技术完成本研究中双叉保留型假体的设计。2、计算机三维有限元分析:①结合应用现代计算机CAD及CAE技术,将膝关节医学影像学断层图像通过计算机建立包括骨、软骨、半月板、韧带等结构的人体膝关节和本假体置换之后的膝关节三维有限元模型,并对模型的有效性进行验证。②使用有限元分析软件ANSYS进一步分析和优化本假体的设计。主要是针对假体金属基座的优化分析:通过计算比较各种设计在不同载荷(压力负荷和扭转力矩负荷)下的力学特点,分析比较不同长短、粗细、数目、位置等设计对金属基座固定稳定性的影响。③使用有限元分析软件ANSYS分析对比本假体置换之后人工膝关节保留双叉韧带、本假体置换之后人工膝关节仅保留前叉韧带、正常完整膝关节、无前叉韧带的膝关节四种情况在不同载荷情况(压力负荷、股骨后抽屉负荷、旋转扭矩负荷)下的生物力学特点,通过有限元计算比较分析这些情况下应力应变以及位移的特点、韧带结构的力等等,以了解本保留双叉韧带型人工膝关节的生物力学。结果1、设计了一种新型的可同时保留前后交叉韧带的人工膝关节假体,在一定程度上克服了以往假体的一些缺点和不足。2、利用现代计算机技术,结合使用CAD软件、CAE软件建立的膝关节三维有限元模型和本假体置换后的三维有限元模型,形态逼真,结构完整,并且经验证其计算结果是可靠有效的。3、针对假体金属基座的优化分析:适当增加金属基座固定桩的直径、长度,固定桩位置向外侧移动都有利于提高固定的旋转稳定性;本设计同传统的单柄基座相比并未减少固定强度和固定的稳定性。4、保留双叉韧带的人工膝关节在各种负荷下的生物力学特征更接近于自然的膝关节。结论1、新型设计的双叉保留型人工膝关节假体可以最大限度地保留膝关节的正常解剖结构,同时避免了以往设计的一些不足。2、适当地固定桩的设计有利于提高假体基座的固定强度。本四桩设计的金属胫骨平台基座对于基座固定的稳定性没有明显的影响。3、保留双叉韧带的人工膝关节,使施行了人工关节置换手术之后的膝关节最大限度地保持了膝关节的生物力学功能,说明了在人工膝关节的手术中保留前叉韧带的必要性。更多还原

【Abstract】 Background: Although total knee arthroplasty(TKA) has made great progress in recent years, knee functions and biomechanics after knee arthroplasty still differ from that of natural knee. The knee joint is a very complicated system made of many subunits that undergo large loads and large relative displacements during various daily activities, and all the subunits function as a whole. So with alteration or loss of any subunits, the present knee prosthesis can lead to loss of stability and physiological dysfunction of the knee. Nowadays almost all knee prosthesis sacrifice the anterior cruciate ligament except unicompartmental knee prosthesis. Also there are many problems with the present bi-cruciate ligament retaining knee prosthesis, such as joint exposure difficulty, non-optimal anchoring, difficulty in regaining proper tension of the ligament. Along with the rapid development of modern life, TKA should not only be a procedure to relieve pain and improve function, but also a good method to improve quality of life of people. So higher requirements are needed in total knee arthroplasty.Objectives: To design a new bi-cruciate retaining knee prosthesis and overcome problems existed in present bi-cruciate ligament retaining designs, and to keep the normal function of the natural knee as much as possible.Methods: 1. Anatomical measurements were made on twenty cadaver knees in order to determine the exact attachment location of the ACL. Then with the help of modern CAD(Computer Aided Design) technology, a new bi-cruciate retaining knee prosthesis was designed. 2. The three dimensional finite element models of an intact knee joint and the knee joint with implantation of the designed prosthesis were constructed with the help of modern CAD(Computer Aided Design) and CAE(Computer Aided Engineering). Then the normal knee model was validated by comparing with previous data. After that, three dimentional finite element analysis was used in the design optimization of the tibia plate. Different kinds of tibia plate designs were compared under axial loads and rotational loads to optimize the tibia plate design. Also four conditions(including intact knee, knee without ACL, knee with implantation of the prosthesis with both cruciate ligaments and knee with implantation of the prosthesis without ACL)were compared in their biomechanical responses under axial loads, rotational loads, posterior femoral drawer forces.Results: 1. A new bi-cruciate retaining knee prosthesis was designed and this design had overcome some disadvantages of the previous bi-cruciate retaining prosthesis. 2. By the combined usage of CAD and CAE computer technology, a three dimensional finite element model of the human knee joint with cartilage, menisci, ligaments was constructed. And the model was validated to be effective and correct in predicting the biomechanical responses of the knee. Then on the basis of this model, a three dimensional finite element model of the knee with implantation of the prosthesis was also constructed. 3. Design optimization of the tibia plate suggested that properly increase of the number of pegs, the length of pegs, the diameter of pegs and placement of pegs more laterally are helpful in improving the anti-rotational ability of the tibia plate. The newly designed four pegged tibia plate with a middle cleavage to accomodate the ACL did not decrease the fixation stability compared with commonly used single post plate. 3. The biomechanics of bi-cruciate retaining total knee prosthesis was close to that of the intact natural knee.Conclusions: 1. The newly designed bi-cruciate ligament retaining knee prosthesis can preserve the normal structure of the knee maximally. 2. Proper design of the pegs in the tibial plate is helpful to achieve best fixation stability.The four pegged tibia plate with a middle cleavage to accomodate the ACL was comparable with the single post tibia plate. 3. Retaining both ACL and PCL can preserve the normal biomechanics of the knee after arthroplasty as much as possible. It is necessary to retain the ACL in total knee arthroplasty.更多还原