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式润滑机制的人工软骨和半月板膝关节假体的优化设计、试制和评价系统。开发了包括几何分析、试制和模拟试验在内的优化设计系统。研制了双通道膝关节模拟器，将步行运动模拟为三维模型。评价了水凝胶、聚亚安酯等人工软骨材料的摩擦学性能。采用冻融法制备了PVA(聚乙烯醇)水凝胶的摩擦试件和胫骨构件。高含水率的PVA水凝胶的摩擦力低于低含水率的水凝胶，但随着步行次数的增加，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影响。结果表明，…冻融循环5次以上是获得最高硬度、强度和最小磨损的最佳条件。在不同持续时间的静载荷作用下，柔顺材料的起始摩擦力随加载时间的延长而增大。高频交流电场对导电材料的减摩是有效的。PVA水凝胶的高含水率和聚氨酯的透明质酸溶液浸泡可以有效地降低启动摩擦。观察了几种解剖设计的回收膝关节假体的聚乙烯部件的磨损表面，其中分层和点蚀被识别为疲劳磨损。为了阐明疲劳磨损机理，将有限元方法应用于弹塑性接触分析，阐明了零件厚度和轧制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。评价了人工全膝关节置换术后膝关节线形的变化及解剖变异情况，结果表明，适中的几何设计或合适的半径，配合边界润滑能力的柔顺材料的应用，可提高膝关节的润滑性能。提出了包括拉应力对破骨细胞影响的设计方向，以供临床应用。较少

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