Eyerer P, Ke Y C
J Biomed Mater Res. 1984 Nov-Dec;18(9):1137-51. doi: 10.1002/jbm.820180915.
In this study it is demonstrated that the combined chemical and mechanical influences of the implant situation cause property changes of ultra-high-molecular-weight polyethylene (UHMW PE) hip joint cups. Nearly 30 out of 48 loosened cups, retrieved 3 weeks to 11 years after implantation, were investigated. Density measurements show a density increase with implantation time and a dependence of these changes from implant position and loading conditions. The rate of extractable constituents also increases with course of time. An increased in vivo conditioned oxidation of the UHMW PE can be demonstrated by infrared (IR) spectrometry. The density increase can be explained by post-crystallization, which is the result of oxidative chain scission. This leads to a reduction of the average molecular weight of the PE and to an increased extractability of constituents. Since these changes have been recognized as the reasons for aging and failing of UHMW PE, the methods of material characterization used in this study for retrieved implants will help to develop suitable in vitro testing and simulating methods. They are the prerequisite for the necessary improvements of the material properties of UHMW PE.
本研究表明，植入环境的化学和机械综合影响会导致超高分子量聚乙烯（UHMW PE）髋关节杯的性能发生变化。对植入后3周至11年取出的48个松动杯中的近30个进行了研究。密度测量显示，密度随植入时间增加，且这些变化取决于植入位置和加载条件。可提取物成分的比例也随时间增加。通过红外（IR）光谱法可以证明UHMW PE在体内的条件氧化增加。密度增加可以用后结晶来解释，后结晶是氧化链断裂的结果。这导致PE平均分子量降低，成分的可提取性增加。由于这些变化已被认为是UHMW PE老化和失效的原因，本研究中用于取出植入物的材料表征方法将有助于开发合适的体外测试和模拟方法。它们是改善UHMW PE材料性能的必要前提。
