Development of Optimum Design, Trial Production and Evaluation Systems for Knee Joint Prostheses with Artificial Cartilage and Meniscus Similar to Natural Synovial Joints

本研究的目的是开发具有自适应多模态润滑机制的人工软骨和半月板膝关节假体的优化设计、试制和评估系统。开发了包括几何分析、试制和模拟器测试在内的优化设计系统。制作了双通道膝关节模拟器，以三维模式模拟膝关节的行走运动。对水凝胶和聚氨酯等人工软骨材料的摩擦学性能进行了评价。采用冻融法制备PVA（聚乙烯醇）水凝胶摩擦试样和胫骨组分。高含水量的PVA水凝胶比低含水量的PVA水凝胶摩擦力小，但随着行走循环次数的增加，摩擦力增大。润滑剂成分，特别是透明质酸和蛋白质对柔顺材料的摩擦磨损有显著的影响。结果表明，冻融循环次数大于5次是获得最高刚度、强度和最小磨损的最佳条件。不同持续时间的静加载后，柔性材料的启动摩擦随加载时间的延长而增大。高频交流电场的应用对减少导电材料的摩擦是有效的。高含水量的PVA水凝胶和浸泡在透明质酸溶液的聚氨酯是有效的减少启动摩擦。对几种解剖设计的人工膝关节假体的聚乙烯构件的磨损表面进行了观察，并对疲劳磨损的分层和点蚀进行了区分。为了阐明疲劳磨损机理，采用有限元法进行弹塑性接触分析，阐明了构件厚度和滚动运动对塑性变形的影响。从临床角度出发，采用模式匹配法对全膝关节置换术进行运动学分析。评估全膝关节置换术后膝关节直线的变化和解剖变异。结果表明，采用较好的一致性几何设计或适当的半径设计，以及采用具有边界润滑能力的柔顺材料均可提高润滑性能。为临床应用指明了包括拉应力对破骨细胞影响在内的设计方向。少

The object of this research is to develop the systems for optimum design, trial production and evaluation of knee prostheses with artificial cartilage and meniscus, which have an adaptive multimode lubrication mechanism. The systems for optimum design including geometrical analysis, trial production and simulator testing was developed. The two-channel knee joint simulator was manufactured to simulate the walking motion as three-dimensional mode. Tribological performance of artificial cartilage materials such as hydrogels and polyurethane was evaluated. The rubbing specimens and tibial component of PVA(polyvinylalcohol) hydrogel were prepared by freezing-thawing method. PVA hydrogel with high water content exhibited the lower friction than that with low water content, but the friction increased with repetition of walking cycles. The lubricant constituents, particularly hyaluronic acid and protein had a remarkable effect on friction and wear of compliant materials. It was shown that the … More 5 cycles for freezing-thawing process was the optimum condition to attain the highest stiffness and strength and minimum wear. On the starting friction of compliant material after static loading with different duration, it increased with loading time. The application of high frequency AC electric field was effective in reduction of friction for conductive materials. High water content for PVA hydrogel and the immersion in hyaluronate solution for polyurethane were effective in reducing starting friction.The worn surfaces of polyethylene components for several retrieved knee prostheses of anatomical design were observed, where the delamination and pitting as fatigue wear were discriminated. To elucidate the fatigue wear mechanism, the finite element method was applied as elasto-plastic contact analysis, in which the influence of component thickness and rolling motion on plastic deformation was clarified. From the clinical viewpoint, the kinematic analysis of total knee arthroplasty by pattern matching method was conducted. The changes in knee alignment after total knee arthroplasty and anatomic variation were evaluated.It was shown that geometrical design with better congruity or with appropriate radius, and the application of compliant materials accompanied with boundary lubricating ability enhance the lubricating performance. The design direction including the influence of tensile stress on osteoclast was shown for clinical application. Less