Oxidation-induced dynamic changes in morphology reflected on freeze-fractured surface of gamma-irradiated ultra-high molecular weight polyethylene components
Oxidation-induced dynamic changes in morphology reflected on freeze-fractured surface of gamma-irradiated ultra-high molecular weight polyethylene components
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DOI：
10.1002/jbm.10357
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发表时间：
2002-12-15
期刊：
影响因子：
--
通讯作者：
Moriya, H
中科院分区：
文献类型：
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作者：
Watanabe, E;Suzuki, M;Moriya, H
在空气存在的情况下通过伽马辐照灭菌导致的超高分子量聚乙烯（UHMWPE）氧化降解被认为是全关节置换术中过早磨损的主要原因之一。例如，在回收的UHMWPE胫骨平台中，不仅经常观察到粘着磨损和磨粒磨损，还经常观察到以分层和断裂为特征的疲劳磨损。在本研究中，我们检查了伽马辐照对UHMWPE胫骨平台微观结构形态的影响，并提出了严重疲劳磨损机制。对植入前在空气中接受伽马辐照灭菌的取出UHMWPE组件的冷冻断裂表面、灭菌后在货架上储存数年（5-11年）的未使用组件以及伽马辐照后接受加速老化方案的圆盘样本进行扫描电子显微镜观察。扫描电镜观察表明，这些组件的冷冻断裂表面有一个双层，这是接壤的表面以下。对边界以下的次表层进行更仔细的观察，发现了一种极其粗糙和多孔的蜂窝状结构。傅里叶变换红外分析表明，蜂窝状区域的次表面有一个高的氧化水平。根据氧化程度，将氧化UHMWPE的内部形态分为四类。根据这些结果，在空气的存在下，与γ-辐照过的HDPE的氧化降解的形态变化可以始终解释为主要的化学和物理变化，如结晶度增加，密度升高，和机械强度降低的结果。我们将表面下氧化降解引起的形态学变化与全膝关节疲劳磨损的起源位置联系起来。(C)2002 Wiley Periodicals，Inc.
Oxidative degradation of ultra-high molecular weight polyethylene (UHMWPE) attributed to sterilization by gamma-radiation in the presence of air has been cited as one of the major causes of premature wear in total joint arthroplasty. For example, in retrieved UHMWPE tibial bearings, not only adhesive and abrasive wear, but also fatigue wear characterized by delamination and fracture is frequently observed. In this study, we examined the effects of gamma radiation on the microstructural morphology of UHMWPE tibial bearings, and propose a severe fatigue wear mechanism. Scanning electron microscopic observations were conducted on freeze-fractured surface of retrieved UHMWPE components that had been sterilized with gamma radiation in air before implantation, unused components that had been stored on the shelf for several years (5-11) after sterilization, and disc specimens given an accelerated aging protocol after gamma radiation. Scanning electron microscopic observations showed that the freeze-fractured surface of these components had a double layer, which was bordered below the surface. A closer observation of the subsurface layer below the border revealed an extremely rough and porous honeycomb-like structure. Fourier transform infrared analysis demonstrated that the honeycomb-like region in the subsurface had a high oxidation level. The internal morphology of oxidized UHMWPE was classified into four categories based on the level of the oxidation. According to these results, the morphological changes with oxidative degradation of gamma-irradiated UHMWPEs in the presence of air could consistently be explained as the result of major chemical and physical changes such as increased crystallinity, elevated density, and reduced mechanical strength. We relate the morphological changes caused by oxidative degradation in the subsurface to the location of the origin of fatigue wear in total knee joints. (C) 2002 Wiley Periodicals, Inc.