抄録
We have developed a new cementless total knee prosthesis (PCL-retention of type alumina ceramic prosthesis) . The sliding surface of the alumina ceramic femoral component has a relatively large radii in the sagital section and is partially flat in the frontal section. A space exists between the two condyles of the sliding surface for retention of the posterior cruciate ligament. The tibial component, which consists of an alumina ceramic tray with a central stem and an HDP joint surface board, has a posterior notch for the retention of the posterior cruciate ligament. The HDP joint surface is flat both in the frontal and in the sagital section, except in the anterior part. The geometry of this prosthesis allows polycentric movement, some axial rotation and a wider flexion arc between the femoral component and the tibial component.
Radiological observation of movement of the prosthesis in the knee, destruction tests under static and impact load, a fatigue test and destruction test of the knee replaced with the prosthesis were performed as in vitro tests. Radiological observation showed that the function of the PCL was maintained in the knee replaced with this type of total knee prosthesis. The results of the destruction test under static load demonstrated the average value of the ultimate strength of the femoral component to be 2913kg and that of the tibial component to be 1267kg. The results of the destruction tests under impact load showed the average value of the ultimate energy of the femoral component to be 23.8 Joule and that of the tibial component to be 18.5 Joule. The component proved to be fail safe after the fatigue test. In the destruction test of the replaced knee, only the tibia was fractured, however, the prosthesis was never damaged. These results indicated that the prosthesis would be valuable in clinical use.
