Optimum Design of Knee Prostheses with High Performance Similar to Natural Knee Joints

本研究的目的是开发出与自然膝关节相似的高性能膝关节假体的优化设计方法。我们的目标是建立自适应多模式润滑。膝关节接触条件的三维分析通过在润滑剂中加入铝粉，实现了人工软骨等柔韧材料与透明板材之间流体膜形成的光学可视化。利用CCD摄像机和图像处理系统分析了流体膜的轮廓和接触区。以明胶溶液为润滑剂的明胶模型，可以观察到凝胶膜的低摩擦行为。膝关节模拟器为了评价行走状态下膝关节假体内液体膜的形成情况，研制了膝关节模拟器，用于测量股骨和胫骨假体之间的电阻和摩擦。在由高粘度润滑剂润滑的弹性体胫骨假体的膝关节假体中，即使在加载站立阶段，也相当程度地形成了弹流动态膜。实验结果表明，采用聚乙烯胫骨假体或低粘度润滑剂的膝关节假体需要采用自适应多模式润滑，以保证假体的长期使用寿命。四种非骨水泥型人工膝关节假体的临床效果从几何设计、器械和术后界面固定的角度进行了评价。

The object of this research is to develop the approaches for the optimum design of knee prostheses with high performance similar to natural knee joints. What we are aiming at is to establish the adaptive multimode lubrication.The following methods were carried out.1. Three-dimensional analysis for the contact conditions in knee jointsThe optical visualization of fluid film formation between compliant material as artificial cartilage and transparent plate was carried out by mixing aluminium particles into lubricants. The fluid film profiles and contact zones were analyzed by means of CCD camera and image processing system. The low frictional behavior of gel film was observed for gelatin models lubricated with gelatin solution.2. Knee joint simulator testTo evaluate the fluid film formation in knee prostheses under walking condition, the knee joint simulator was developed and used for the measurement of electric resistance and friction between femoral and tibial components. In a knee prosthesis with an elastomeric tibial component lubricated with high visosity lubricatns, the elastohydrodynamic film was considerably formed even during the loading stance phase. It is suggested from the experimental results that the adaptive multimode lubrication is required to establish the long durability of the knee prosthesis with polyethylene tibial component, or lubricated with low viscosity lubricants.3. Clinical optimization in total knee replacementThe clinical results of four types of uncemented total knee prostheses were evaluated from the viewpoint of the geometrical design, instrumentations and postoperative fixation at the interface.