Metal release and speciation of released chromium from a biomedical CoCrMo alloy into simulated physiologically relevant solutions

Abstract

The objective of this study was to investigate the extent of released Co, Cr(III), Cr(VI), and Mo from a biomedical high-carbon CoCrMo alloy exposed in phosphate-buffered saline (PBS), without and with the addition of 10 µM H2 O2 (PBS + H2 O2 ), and 10 g L(-1) bovine serum albumin (PBS + BSA) for time periods up to 28 days. Comparative studies were made on AISI 316L for the longest time period. No Cr(VI) release was observed for any of the alloys in either PBS or PBS + H2 O2 at open-circuit potential (no applied potential). However, at applied potentials (0.7 V vs. Ag/AgCl), Cr was primarily released as Cr(VI). Co was preferentially released from the CoCrMo alloy at no applied potential. As a consequence, Cr was enriched in the utmost surface oxide reducing the extent of metal release over time. This passivation effect was accelerated in PBS + H2 O2 . As previously reported for 316L, BSA may also enhance metal release from CoCrMo. However, this was not possible to verify due to the precipitation of metal-protein complexes with reduced metal concentrations in solution as a consequence. This was particularly important for Co-BSA complexes after sufficient time and resulted in an underestimation of metals in solution.

Can gamma irradiation during radiotherapy influence the metal release process for biomedical CoCrMo and 316L alloys?

“…A small, but statistically significant Cr enrichment and Co depletion was also observed for disks exposed to PBS + BSA (nonirradiated) as compared to PBS (both nonirradiated and irradiated), Figure (a). This is also in agreement with previous observations . Mo was statistically significant enriched in PBS + BSA as compared to PBS (for irradiated disks), Figure (a).…”

“…Upon immersion in all solutions for one hour, the surface oxide became enriched in Cr. This enrichment (coupled with a Co depletion) is expected from earlier studies . A small, but statistically significant Cr enrichment and Co depletion was also observed for disks exposed to PBS + BSA (nonirradiated) as compared to PBS (both nonirradiated and irradiated), Figure (a).…”

Comparison of the influence of citric acid and acetic acid as simulant for acidic food on the release of alloy constituents from stainless steel AISI 201

“…These findings are in agreement with previous chromium speciation measurements for released chromium from chromium-containing alloys in synthetic biological fluids (Flint et al, 2007;Hedberg et al, 2013;Hedberg and Odnevall Wallinder, 2014).…”

Failure of total hip implants: metals and metal release in 52 cases

“…Interestingly, chromium is present in both the stainless steel and CoCrMo alloys that were frequently retrieved. It is known that CoCrMo alloy implants corrode and release both chromium and cobalt ions . Finally, we found that the reasons for primary and revision surgery were comparable with registered information from the nationwide Danish Hip Arthroplasty Register (Tables and ), but acknowledge that a major proportion of these were categorized as ‘unknown’.…”