Interfacial compliance, energy dissipation, frequency effects, and long‐term fretting corrosion performance of Ti‐6Al‐4V/CoCrMo interfaces

Abstract

Fretting corrosion in modular orthopedic implants is a well‐documented process that may be associated with adverse local tissue reactions, pain, and revisions. Engineering modular junction interfaces to withstand applied fretting motion without surface abrasion could prevent implant degradation and surface damage. Previous work on geometrically modified Ti‐6Al‐4V/CoCrMo interfaces with increased compliance showed reduced fretting currents and surface damage during short term, variable‐load in vitro testing. This study assesses the same interfaces under long‐term conditions using an in vitro pin‐on‐disk fretting corrosion test apparatus. Preliminary variable‐load frequency testing of typical control pin geometries showed a frequency‐dependent current response, with underlying contact conditions of metal–metal interfaces that remained unchanged. One‐million‐cycle testing showed diminished fretting currents in all groups by 5 × 105 cycles, but consistently lower currents in the high‐compliance group. Corresponding fretting currents and work of fretting measurements of high‐compliance pins confirmed that minimal fretting was experienced at the interface, with elastic bending of the pin accounting for almost all applied displacement. Debris generated during testing were composed of titanium and chromium oxides, small amounts of cobalt and molybdenum oxides, and sodium and phosphate originating from the surrounding test solution. Post‐test analyses of sample surfaces revealed substantially more surface damage on CoCrMo disks than Ti‐6Al‐4V pins, thought to be a result of adhesive wear of mixed oxide debris on the pin and abrasion of the disk by the oxide debris layer. Surface damage to high‐compliance pins suggests some abrasion is unavoidable with geometric modifications.

Corrosion Passivation in Simulated Body Fluid of Ti-Zr-Ta-xSn Alloys as Biomedical Materials

“…Ti-based alloys are significant for many different applications in addition to biomedicine, for example, in the automotive and aerospace industries. Their outstanding biocompatibility, extraordinary corrosion resistance, and high mechanical strength allow these alloys to be successfully used in biomedical applications [ 5 , 6 , 7 , 8 , 9 , 10 ].…”

Temperature-Dependence Corrosion Behavior of Ti6Al4V in the Presence of HCl

“…However, there is increasing evidence to demonstrate that Ti implants do corrode in the body under specific conditions (Addison et al, 2012;Nelson et al, 2020). The combination of multiple crevice environments (metal-metal; metal-bone, metal-soft-tissue) may produce significant changes in the chemistry of the local solution which are not predicted by standard pre-clinical testing regimens (Liu et al, 2021;Smith and Gilbert, 2021). Direct evidence of Ti corrosion in vivo has been reported in the orthopaedic literature associated with cemented femoral stems and Morse taper connections (Jacobs et al, 1998a;Jacobs et al, 1998b;Hallam et al, 2004).…”