Affatato Saverio, De Mattia Jonathan Salvatore, Bracco Pierangiola, Pavoni Eleonora, Taddei Paola
Laboratorio di Tecnologia Medica, Istituto Ortopedico Rizzoli, Bologna, Italy.
Laboratorio di Tecnologia Medica, Istituto Ortopedico Rizzoli, Bologna, Italy.
J Mech Behav Biomed Mater. 2016 Jun;59:418-429. doi: 10.1016/j.jmbbm.2016.02.029. Epub 2016 Mar 2.
First-generation (irradiated and remelted or annealed) and second-generation (irradiated and vitamin E blended or doped) highly crosslinked polyethylenes were introduced in the last decade to solve the problems of wear and osteolysis. In this study, the influence of the Vitamin-E addition on crosslinked polyethylene (XLPE_VE) was evaluated by comparing the in vitro wear behavior of crosslinked polyethylene (XLPE) versus Vitamin-E blended polyethylene XLPE and conventional ultra-high molecular weight polyethylene (STD_PE) acetabular cups, after accelerated ageing according to ASTM F2003-02 (70.0±0.1°C, pure oxygen at 5bar for 14 days). The test was performed using a hip joint simulator run for two millions cycles, under bovine calf serum as lubricant. Mass loss was found to decrease along the series XLPE_VE>STD_PE>XLPE, although no statistically significant differences were found between the mass losses of the three sets of cups. Micro-Raman spectroscopy was used to investigate at a molecular level the morphology changes induced by wear. The spectroscopic analyses showed that the accelerated ageing determined different wear mechanisms and molecular rearrangements during testing with regards to the changes in both the chain orientation and the distribution of the all-trans sequences within the orthorhombic, amorphous and third phases. The results of the present study showed that the addition of vitamin E was not effective to improve the gravimetric wear of PE after accelerated ageing. However, from a molecular point of view, the XLPE_VE acetabular cups tested after accelerated ageing appeared definitely less damaged than the STD_PE ones and comparable to XLPE samples.
第一代（辐照并重新熔融或退火）和第二代（辐照并与维生素E混合或掺杂）高度交联聚乙烯在过去十年中被引入，以解决磨损和骨溶解问题。在本研究中，根据ASTM F2003 - 02（70.0±0.1°C，5巴纯氧，14天）进行加速老化后，通过比较交联聚乙烯（XLPE）、维生素E混合聚乙烯XLPE和传统超高分子量聚乙烯（STD_PE）髋臼杯的体外磨损行为，评估了维生素E添加对交联聚乙烯（XLPE_VE）的影响。试验使用髋关节模拟器在小牛血清作为润滑剂的条件下运行两百万次循环进行。发现质量损失沿XLPE_VE>STD_PE>XLPE的顺序降低，尽管三组髋臼杯的质量损失之间未发现统计学上的显著差异。使用显微拉曼光谱在分子水平上研究磨损引起的形态变化。光谱分析表明，加速老化在测试过程中确定了不同的磨损机制和分子重排，这与正交晶相、非晶相和第三相内链取向和全反式序列分布的变化有关。本研究结果表明，加速老化后添加维生素E对改善PE的重量磨损无效。然而，从分子角度来看，加速老化后测试的XLPE_VE髋臼杯明显比STD_PE髋臼杯受损程度小，与XLPE样品相当。
