Akagi Masao, Asano Taiyo, Clarke Ian C, Niiyama Norio, Kyomoto Masayuki, Nakamura Takashi, Hamanishi Chiaki
Department of Orthopaedic Surgery, Kinki University School of Medicine, 377-2 Ohno-Higashi, Osaka-Snyama City, Osaka 589-8511, and Department of Orthopaedic Surgery, Fukui Red-Cross Hospital, Fukui, Japan.
J Orthop Res. 2006 Oct;24(10):2021-7. doi: 10.1002/jor.20223.
Severe loading and complex kinematics in total knee replacement make wear performance and toughness of the polyethylene in tibial inserts important. We investigated wear of crosslinked polyethylene using a knee simulator and measured toughness using small-punch testing. GUR1050 rods were gamma-irradiated in air at doses from 0 to 200 kGy, annealed in nitrogen, and machined into tibial inserts. The simulator was run to 4 million cycles, and wear rates determined from weight loss. Wear rate decreased by 54, 78, and 95% as radiation dose increased from 50 to 75 to 100 kGy, respectively. At every dose, toughness was significantly less after simulator testing, but the difference between control and wear-tested polyethylene, considered to be due to fatigue damage accumulation, was smallest at 50 kGy. The simulator-tested polyethylene that received 35 to 75 kGy had slightly higher toughness than equivalent material that received no irradiation. However, the toughness of simulator-tested polyethylene that received 150 and 200 kGy was lower than that of the simulator-tested polyethylene that received no irradiation. Our results suggest that an optimal irradiation dose may exist for crosslinked polyethylene for use in TKR and that the optimum dose would be less than the 100 kGy or more that are used in some current crosslinked polyethylene for hip replacement.
全膝关节置换中严重的负荷和复杂的运动学使得胫骨假体中聚乙烯的磨损性能和韧性变得很重要。我们使用膝关节模拟器研究了交联聚乙烯的磨损，并通过小冲头试验测量了韧性。将GUR1050棒材在空气中以0至200 kGy的剂量进行伽马辐照，在氮气中退火，然后加工成胫骨假体。模拟器运行至400万次循环，并根据重量损失确定磨损率。随着辐射剂量从50 kGy增加到75 kGy再增加到100 kGy，磨损率分别下降了54%、78%和95%。在每个剂量下，模拟器测试后的韧性均显著降低，但对照聚乙烯和经过磨损测试的聚乙烯之间的差异（被认为是由于疲劳损伤积累所致）在50 kGy时最小。接受35至75 kGy辐射的经过模拟器测试的聚乙烯的韧性略高于未辐照的同等材料。然而，接受150和200 kGy辐射的经过模拟器测试的聚乙烯的韧性低于未辐照的经过模拟器测试的聚乙烯。我们的结果表明，用于全膝关节置换的交联聚乙烯可能存在一个最佳辐照剂量，并且最佳剂量将低于目前一些用于髋关节置换的交联聚乙烯所使用的100 kGy或更高剂量。
