Implant Research Center, School of Biomedical Engineering, Science, and Health Systems, Drexel University, and Exponent, Inc, 3401 Market Street, Suite 300, Philadelphia, PA 19104, USA.
Clin Orthop Relat Res. 2011 Aug;469(8):2278-85. doi: 10.1007/s11999-010-1728-3.
Highly crosslinked and thermally treated polyethylenes were clinically introduced to reduce wear and osteolysis. Although the crosslinking process improves the wear performance, it also introduces free radicals into the polymer that can subsequently oxidize. Thermal treatments have been implemented to reduce oxidation; however, the efficacy of these methods with regard to reducing in vivo oxidative degradation remains to be seen. Polyethylene oxidation is a concern because it can compromise the ultimate strength and ductility of the material.
QUESTIONS/PURPOSES: We analyzed the oxidation, oxidation potential, and mechanical behavior of thermally treated highly crosslinked polyethylene retrieved acetabular liners.
Three hundred seven acetabular liners were collected from consecutive revision surgeries at six institutions over a 10-year period. Twenty-four were sterilized using nonionizing methods, 43 were sterilized in an inert environment, 80 were highly crosslinked and annealed, and 160 were highly crosslinked and remelted. Oxidation and oxidation potential were assessed by Fourier transmission infrared spectroscopy. Mechanical behavior was assessed by the small punch test.
Oxidation and hydroperoxide (oxidation potential) indices were elevated in the annealed and gamma inert sterilized groups compared with those of the remelted liners and uncrosslinked gas sterilized controls, particularly at the rim. We also detected an increase in oxidation over time at the bearing surface of the remelted group. Ultimate strength of the polyethylene at the bearing surface was negatively correlated with implantation time for the annealed liners.
Within the first decade of implantation, the clinical outlook for first-generation highly crosslinked polyethylene remains promising. However, ongoing research continues to be warranted for first-generation highly crosslinked polyethylene bearings to monitor the implications of elevated oxidation at the rim of annealed liners as well as to better understand the subtle changes in oxidation at the bearing surface of remelted liners that occur in vivo.
高度交联和热处理的聚乙烯在临床上被引入以减少磨损和骨质溶解。虽然交联过程改善了耐磨性，但它也会在聚合物中引入自由基，这些自由基随后会氧化。已经实施了热疗来减少氧化；然而，这些方法在减少体内氧化降解方面的效果仍有待观察。聚乙烯的氧化是一个问题，因为它会影响材料的最终强度和延展性。
问题/目的：我们分析了从六个机构的连续翻修手术中回收的热交联高度交联聚乙烯髋臼衬垫的氧化、氧化电位和力学性能。
在十年期间，从六个机构的连续翻修手术中收集了 307 个髋臼衬垫。24 个采用非电离方法进行消毒，43 个在惰性环境中消毒，80 个高度交联和退火，160 个高度交联和重熔。通过傅里叶传输红外光谱评估氧化和氧化电位。通过小冲孔试验评估力学性能。
与重熔衬垫和未交联气体消毒对照相比，退火和γ惰性消毒组的氧化和过氧化物（氧化电位）指数升高，尤其是在边缘。我们还在重熔组的轴承表面检测到氧化随时间的增加。退火衬垫轴承表面的聚乙烯极限强度与植入时间呈负相关。
在植入的最初十年内，第一代高度交联聚乙烯的临床前景仍然乐观。然而，仍需要对第一代高度交联聚乙烯轴承进行持续研究，以监测退火衬垫边缘氧化升高的影响，并更好地了解重熔衬垫轴承表面体内氧化的细微变化。
