| Summary: | 碩士 === 國立臺北科技大學 === 製造科技研究所 === 99 === There are about 70 percent of patients who accepted knee arthroplasty operation over 10 years need second surgery. That bothers them and is really a big trauma for the patients’ minds and bodies. The reasons are following: First, the setting time of bone cement is too fast, which leads to not enough time for the doctor who may place the bone cement in inappropriate time during surgery and bone cement is not to connect with bone or implant. Second, mixing bone cement will result in high temperature and destroy the tissues around the bone, which calls the phenomenon “osteonecrosis”. Third, some monomer of methyl methacrylate monomer released from the polymerization process of bone cement, and as them flow into the blood, causing harmful pulmonary embolism, heart abnormalities and other side effects. At last, the higher the compressive strength of bone cement, the probibilty of bone fractures occuring due to oppression to the bones. According to the states above, the necessary of second surgery is strongly relative to the bone cement mechanism.
In this research, one does not add supplements to market bone cement. One sets the different bone cement mixing rates of PMMA to MMA, which are tested for 1:1, 2:1 and 3:1. And with different environment, the peak exothermic, compressive stress, tensile stress, elastic modulus, setting time and dough time are measured by ASTM F451-99a in this study individually. The research then obtains the most proper prescription of reducing the probability of second surgery formation.
According to the experimental results of mixing bone cement in vacuum environment, the setting time, polymerization temperature and dough time are better than which in non-vacuum one for surgical operation. And for the higher PMMA to MMA ratio, the polymerization temperature of bone cement will be smaller, which can effectivly reduces the probibility of osteonecrosis formation.
The experimental results of dough time and compressive strength show that they decrease with the increasing of the PMMA to MMA ratio., And the elastic modulus of bone cement, regardless of using which proportion of PMMA and MMA, or testing in different environment, will not exceed the elastic modulus of a human’s skeleton. Thus, the bone fracture phenomenon will not occur.
In conclusion, the fine bone cement with 3:1 PMMA to MMA ratio and making in a vacuum enviroment is suggested in this research.
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