Koseki Hironobu, Tomita Masato, Yonekura Akihiko, Higuchi Takashi, Sunagawa Sinya, Baba Koumei, Osaki Makoto
Department of Locomotive Rehabilitation Science, Unit of Rehabilitation Sciences.
Department of Orthopedic Surgery, Nagasaki University Graduate School of Biomedical Sciences, Sakamoto, Nagasaki, Japan.
Int J Nanomedicine. 2017 May 31;12:4111-4116. doi: 10.2147/IJN.S137621. eCollection 2017.
Metal-on-metal (MoM) bearings have become popular due to a major advantage over metal-on-polymer bearings for total hip arthroplasty in that the larger femoral head and hydrodynamic lubrication of the former reduce the rate of wear. However, concerns remain regarding adverse reactions to metal debris including metallosis caused by metal wear generated at the taper-head interface and another modular junction. Our group has hypothesized that carbon ion implantation (CII) may improve metal wear properties. The purpose of this study was to investigate the wear properties and friction coefficients of CII surfaces with an aim to ultimately apply these surfaces to MoM bearings in artificial joints. CII was applied to cobalt-chromium-molybdenum (Co-Cr-Mo) alloy substrates by plasma source ion implantation. The substrates were characterized using scanning electron microscopy and a 3D measuring laser microscope. Sliding contact tests were performed with a simple geometry pin-on-plate wear tester at a load of 2.5 N, a calculated contact pressure of 38.5 MPa (max: 57.8 MPa), a reciprocating velocity of 30 mm/s, a stroke length of 60 mm, and a reciprocating cycle count of 172,800 cycles. The surfaces of the CII substrates were generally featureless with a smooth surface topography at the same level as untreated Co-Cr-Mo alloy. Compared to the untreated Co-Cr-Mo alloy, the CII-treated bearings had lower friction coefficients, higher resistance to catastrophic damage, and prevented the adhesion of wear debris. The results of this study suggest that the CII surface stabilizes the wear status due to the low friction coefficient and low infiltration of partner materials, and these properties also prevent the adhesion of wear debris and inhibit excessive wear. Carbon is considered to be biologically inert; therefore, CII is anticipated to be applicable to the bearing surfaces of MoM prostheses.
金属对金属（MoM）轴承在全髋关节置换术中比金属对聚合物轴承具有显著优势，因而广受欢迎，即前者较大的股骨头和流体动力润滑可降低磨损率。然而，对于金属碎屑的不良反应，包括由锥头界面和其他模块化连接处产生的金属磨损引起的金属中毒，人们仍存担忧。我们团队推测碳离子注入（CII）可能改善金属磨损性能。本研究旨在探究CII处理表面的磨损性能和摩擦系数，最终将这些表面应用于人工关节的MoM轴承。通过等离子体源离子注入将CII应用于钴铬钼（Co-Cr-Mo）合金基底。使用扫描电子显微镜和三维测量激光显微镜对基底进行表征。使用简单几何形状的销盘磨损试验机进行滑动接触试验，试验条件为：载荷2.5 N，计算接触压力38.5 MPa（最大值：57.8 MPa），往复速度30 mm/s，行程长度60 mm，往复循环次数172,800次。CII基底表面通常无特征，表面形貌光滑，与未处理的Co-Cr-Mo合金处于同一水平。与未处理的Co-Cr-Mo合金相比，经CII处理的轴承摩擦系数更低，抗灾难性损伤能力更强，并能防止磨损碎屑的粘附。本研究结果表明，CII表面因低摩擦系数和配对材料的低渗入而使磨损状态稳定，这些特性还能防止磨损碎屑的粘附并抑制过度磨损。碳被认为具有生物惰性；因此，预计CII可应用于MoM假体的轴承表面。
