Section of Tribology, Department of Orthopedic Surgery, Rush University Medical Center, Chicago, IL 60612, USA.
Clin Orthop Relat Res. 2012 Nov;470(11):3109-17. doi: 10.1007/s11999-012-2563-5.
Although numerous in vitro studies report on the tribological performance of and, separately, on the corrosion properties of cobalt-based alloys in metal-on-metal (MoM) bearings, the few studies that take into account the synergistic interaction of wear and corrosion (tribocorrosion) have used canonical tribo-test methods. We therefore developed synergistic study using a test method that more closely simulates hip bearing conditions.
QUESTIONS/PURPOSES: (1) Is the total material loss during tribocorrosion larger than the sum of its components generated during isolated mechanical wear and isolated corrosion? (2) How is the tribocorrosive process affected by the presence of protein?
High carbon CoCrMo alloy discs (18) were subjected to corrosion and tribocorrosion tests under potentiostatic conditions in an apparatus simulating hip contact conditions. The input variables were the applied potential and the protein content of the electrolyte (NaCl solution versus bovine serum, 30 g/L protein). The output variables were mass loss resulting from wear in the absence of corrosion, mass loss resulting from corrosion in the absence of wear, and the total mass loss under tribocorrosion, from which the additional mass loss resulting from the combined action of wear and corrosion, or synergism, was determined in the presence and absence of protein.
The degradation mechanisms were sensitive to the interaction of wear and corrosion. The synergistic component (64 μg) in the presence of protein amounted to 34% of total material loss (187 μg). The presence of protein led to a 23% decrease in the total mass loss and to a considerable reduction in the mean current (4 μA to 0.05 μA) under tribocorrosion.
Synergistic effects during tribocorrosion may account for a considerable portion of MoM degradation and are affected by proteins.
The in vivo performance of some large-diameter MoM joints is unsatisfactory. The synergistic component resulting from tribocorrosion may have been missed in conventional preclinical wear tests.
虽然大量的体外研究报告了摩擦学性能和钴基合金的腐蚀性能，并且分别研究了金属对金属（MoM）轴承中的腐蚀性能，但考虑到磨损和腐蚀（摩擦腐蚀）协同作用的少数研究使用了规范的摩擦试验方法。因此，我们开发了一种协同研究方法，该方法更能模拟髋关节轴承的条件。
问题/目的：（1）在摩擦腐蚀过程中总的材料损失是否大于机械磨损和单独腐蚀产生的各组成部分的总和？（2）蛋白质的存在如何影响摩擦腐蚀过程？
高碳 CoCrMo 合金盘（18 个）在模拟髋关节接触条件的装置中，在恒电位条件下进行腐蚀和摩擦腐蚀试验。输入变量是施加的电位和电解质中的蛋白质含量（NaCl 溶液与牛血清，30g/L 蛋白）。输出变量是无腐蚀磨损产生的质量损失、无磨损腐蚀产生的质量损失以及在摩擦腐蚀下的总质量损失，从中确定了在有无蛋白质存在的情况下，磨损和腐蚀联合作用的附加质量损失，即协同作用。
降解机制对磨损和腐蚀的相互作用敏感。有蛋白质存在时的协同成分（64μg）占总材料损失（187μg）的 34%。蛋白质的存在导致总质量损失减少 23%，在摩擦腐蚀下平均电流（4μA 降至 0.05μA）大幅降低。
摩擦腐蚀过程中的协同效应可能占 MoM 降解的相当大一部分，并受蛋白质影响。
一些大直径 MoM 关节的体内性能并不令人满意。在传统的临床前磨损试验中，可能忽略了摩擦腐蚀产生的协同成分。
