Wear of CoCrMo alloys used in metal-on-metal hip joints: A tribocorrosion appraisal

Abstract

a b s t r a c tA good biocompatibility, excellent mechanical properties and high corrosion resistance characterize CoCrMo alloys. Therefore they are widely used for artificial joints in biomedical implants. However, the degradation of the implants during service life leads to the release into the body of toxic ions and wear particles. This continuous degradation is of concern for long-term stability of the implants. Published literature has highlighted the relevance of lubrication as well as metallurgical and contact mechanical factors on the degradation of CoCrMo implant alloys. Recent experimental investigations have proposed tribocorrosion, i.e., the interplay of mechanical wear and corrosion by the body fluids, as one of the crucial degradation mechanism of implants. Tribocorrosion is sub-discipline of tribology and corrosion that recently made significant progresses in mechanistic understanding and modelling. The present work aims at evaluating published results on the degradation of CoCrMo alloys using existing tribocorrosion concepts. Results show that wear accelerated corrosion due to mechanical removal of the passive film during sliding is a major contribution to the overall degradation. Further, a transition from low (10 À 6 N/mm 3 m) to high (10 À 4 N/mm 3 m) wear coefficients was found at a threshold electrode potential close to 0.2 V SHE These findings clearly show that electrochemical phenomena play a key role on the tribological behaviour of biomedical CoCrMo alloy implants.

Tribocorrosion behavior and ions release of CoCrMo alloy coated with a TiAlVCN/CN multilayer in simulated body fluid plus bovine serum albumin

“…For these reasons, we can conclude that the multilayer coating provides protection from pitting and general corrosion. The surface semiquantitative analysis of the pit area A selected is described in section 3.5. passive film on the sample surface was locally removed thus exposing bare metal to the solution and therefore the rubbed areas experienced an increase in metal oxidation rate because the loss of passivity [7]. Furthermore, an important surface degradation on the CoCrMo substrate is observed on the wear rate, as is shown in Figure 10.…”

“…Tribocorrosion, defined as the conjoint action of any mechanical wear under load and corrosive attack of the material surface [6], has been shown to shorten the life of prostheses. Moreover, corrosion during reciprocating movement is accelerated by the synergistic effect of the wear [7]. This phenomenon is highly relevant to the field of biomedical joint implants in general, and specifically to hip and knee joints [7,8].…”

“…Moreover, corrosion during reciprocating movement is accelerated by the synergistic effect of the wear [7]. This phenomenon is highly relevant to the field of biomedical joint implants in general, and specifically to hip and knee joints [7,8]. The damage is restricted mostly to the local movement site, while the generated debris act as abrasive particles.…”

Analysis of Run-in-Stage Wear Behavior and Contact Mechanics of Metal-on-Metal Hip Joint Bearings with Different Radial Clearances

“…1) CoCr-MOM bearings exhibit extremely high survival rates over 510 years of service 2,3) owing to their excellent mechanical properties and extremely low wear rate, 47) and they are expected to serve for longer life than the present ones for younger, active patients. Despite of these encouraging results, recent reports also indicated that unexpected high failure rates for large head MOM bearings and debris detachment from the rubbing surfaces, which led to an alert from the Medicines and Healthcare products Regulatory Agency prompting an urgent review of all MOM articulations.…”

“…Despite of these encouraging results, recent reports also indicated that unexpected high failure rates for large head MOM bearings and debris detachment from the rubbing surfaces, which led to an alert from the Medicines and Healthcare products Regulatory Agency prompting an urgent review of all MOM articulations. 8) The debris enter the blood, serum, and urine of recipients, cause a high incidence of adverse reaction to metal debris (ARMD) 3,911) known as periprosthetic soft tissue reactions and systemic genotoxicity.…”