Ceramic Physics Laboratory and Research Institute for Nanoscience, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, 606-8585 Kyoto, Japan.
Acta Biomater. 2011 Mar;7(3):1150-9. doi: 10.1016/j.actbio.2010.10.014. Epub 2010 Oct 18.
The response to applied strain of EtO-sterilized and γ-irradiated polyethylene materials belonging to tibial inserts has been studied by polarized Raman spectroscopy. Initial calibrations on as-received samples from three different makers were employed to clarify the rearrangement of molecular chains under strain, expressed in terms of Euler angular displacements in space and orientation distribution functions. This body of information was then applied to a quantitative analysis of four tibial inserts (from the same three makers of the unused samples) retrieved after in vivo exposures ranging between 7 months and 5 years 8 months. The main results of the Raman analysis can be summarized as follows: (i) γ-irradiated samples experienced lower texturing on the molecular scale compared to EtO-sterilized samples, likely due to a higher strain recovery capability; and (ii) independent of sterilization method, the amount of plastic strain was mainly developed early after in vivo implantation, whereby out-of-plane molecules rotated under load onto planes parallel to the sample surface until saturation of angular displacements was reached.
通过偏振拉曼光谱研究了属于胫骨插入物的经环氧乙烷灭菌和γ辐照的聚乙烯材料对施加应变的响应。最初对来自三个不同制造商的接收样品进行校准，以阐明应变下分子链的重排，以欧拉角位移和取向分布函数表示。然后将这方面的信息应用于对从同三个制造商回收的四个胫骨插入物（来自未使用样品）进行定量分析，这些插入物在体内暴露的时间从 7 个月到 5 年 8 个月不等。拉曼分析的主要结果可以概括如下：（i）γ辐照样品在分子尺度上的织构化程度低于环氧乙烷灭菌样品，这可能是由于较高的应变恢复能力所致；（ii）与灭菌方法无关，在体内植入后的早期，塑性应变的量主要发展，此时，分子在负载下从垂直于样品表面的平面旋转，直到达到角位移的饱和。
