Firkins P J, Tipper J L, Saadatzadeh M R, Ingham E, Stone M H, Farrar R, Fisher J
Medical and Biological Engineering (MBE) Research Group, School of Mechanical Engineering, University of Leeds, UK.
Biomed Mater Eng. 2001;11(2):143-57.
Osteolysis and loosening of artificial joints caused by UHMWPE wear debris has prompted renewed interest in metal-on-metal (MOM) hip prostheses. This study investigated the wear and wear debris morphology generated by MOM prostheses in a physiological anatomical hip simulator for different carbon content cobalt chrome alloys. The low carbon pairings demonstrated significantly higher "bedding in" and steady state wear rates than the mixed and high carbon pairings. The in vitro wear rates reported here were up to one or two orders of magnitude lower than the clinical wear rates for first-generation MOM hip prostheses. Two methods for characterising the metal wear debris were developed, involving digestion, scanning electron microscopy and transmission electron microscopy. The metal wear particles characterised by the two methods were similar in size, 25-36 nm, and comparable to particles isolated from periprosthetic tissues from first and second-generation MOM hip prostheses. Due to the small size of the metal particles, the number of particles generated per year for MOM prostheses in vitro was estimated to be up to 100 times higher than the number of polyethylene particles generated per year in vivo. The volumetric wear rates were affected by the carbon content of the cobalt chrome alloy and the material combinations used. However, particle size and morphology was not affected by method of particle characterisation, the carbon content of the alloy or material combination.
超高分子量聚乙烯磨损碎屑导致的人工关节骨溶解和松动引发了人们对金属对金属（MOM）髋关节假体的新兴趣。本研究在生理解剖髋关节模拟器中，针对不同碳含量的钴铬合金，研究了MOM假体产生的磨损及磨损碎屑形态。低碳配对的“磨合”和稳态磨损率显著高于混合碳和高碳配对。此处报告的体外磨损率比第一代MOM髋关节假体的临床磨损率低一到两个数量级。开发了两种表征金属磨损碎屑的方法，包括消化、扫描电子显微镜和透射电子显微镜。通过这两种方法表征的金属磨损颗粒大小相似，为25 - 36纳米，与从第一代和第二代MOM髋关节假体周围组织中分离出的颗粒相当。由于金属颗粒尺寸小，估计MOM假体在体外每年产生的颗粒数量比体内每年产生的聚乙烯颗粒数量高出多达100倍。体积磨损率受钴铬合金的碳含量和所用材料组合的影响。然而，颗粒大小和形态不受颗粒表征方法、合金的碳含量或材料组合的影响。
