A link between the tribology and corrosive degradation of metal-on-metal THRs

Abstract

The degradation of Metal-on-Metal (MoM) Total Hip Replacements (THRs) is a complex mix of tribological, corrosive phenomena and their synergistic processes. Previous links between the corrosion of these devices and their sliding conditions over a cycle have been observed in simulator studies instrumented with a three-electrode electrochemical cell. This study further quantifies that link; demonstrating clear repeating periodicity in the anodic current transients of a 28 mm diameter MoM bearing under a standard ISO-14242 walking profile. A simplified 2D model and an expression of the Hamrock-Dowson equation was utilised to estimate the Theoretical Minimum Film Thickness (h min ) over a cycle, which was shown to match closely to the measured anodic current in both shape and magnitude.

Adverse loading effects on tribocorrosive degradation of 28 mm metal-on-metal hip replacement bearings

“…These peaks have been noted previously to coincide with the lubrication regime over the course of a cycle. 29 As shown in Figure 6 a general trend of increased anodic current with higher inclination was observed. This varied cycle to cycle however, and the peaks were often of a similar magnitude of between approximately 5 to 8 µA.…”

“…This agreed with the steady-state values demonstrated both in Figure 6 and as reported previously. 28,29 Upon increasing the inclination to 40°the anodic currents immediately increased to 20-40 µA and again to 40-60 µA at 45°. At the final 50°inclination the anodic current increased to 60-70 µA for the first repeat and continued to climb to over 120 µA by the third repeat.…”

“…Little has been added to the pre-clinical analysis of metal-on-metal bearings that fully elucidates the degradation mechanisms or goes beyond simple wear comparisons to metal-on-polymer bearings. 28,29 Doing so will be critical going forward not only to ensure the degradation of devices with metallic sliding interfaces are fully understood, but to inform treatment of patients with such devices already implanted. This study therefore aimed to investigate the corrosive degradation of the bearing surface of metal-on-metal devices under increased acetabular inclination; a common adverse loading scenario for hip simulation.…”

Role of tribochemistry reactions of B4C on tribofilm growth at a PEEK–steel interface in simulated body fluids

“…In this case, fresh metal is exposed to the electrolyte and consequently, the metal is dissolved by anodic polarization, combined with increased roughness, causing aggravated corrosion and wear, i.e., tribocorrosion. 19,50 With respect to the sliding against PEEK/B 4 C, the current increases moderately at the beginning of the sliding, and then it gradually decreases over time most probably due to the growth of a resilient tribolm. Tribolm formed on the steel surface rubbed with PEEK/B 4 C serves as a barrier between metal and electrolyte, and thus strengthens passivation.…”

High Temperature Tribology under Linear Oscillation Motion

“…As medical technology advances, certain procedures such as total hip joint replacements (THRs) are made possible. However, the materials of the THRs will start to wear over time and a study by Beadling et al [16] focuses on the tribological aspects of the metal-on-metal wear and degradation of THRs in order to reduce repeated revisions. In this study, the process of understanding the "tribocorrosive contact" was investigated using simplified 2D models and taking into account simple walking data.…”