Differential distribution of cobalt, chromium, and nickel between whole blood, plasma and urine in patients after metal‐on‐metal (MoM) hip arthroplasty

Abstract

Evidence shows that raised cobalt (Co), chromium (Cr), and nickel (Ni) whole blood concentrations correlate with poor device outcome in patients following metal-on-metal (MoM) hip arthroplasty. To understand the local and systemic pathological effects of these raised metal concentrations it is important to define their distribution between whole blood, plasma, and urine. The metals were measured by Inductively Coupled Plasma Mass Spectrometry (ICPMS). Two hundred and five plasma, 199 whole blood, and 24 sets of urine samples were analyzed from 202 patients with Co-Cr alloy MoM hip prostheses implanted between 8 months to 12 years (mean 6.0 years) prior to analysis. Plasma Co (median 39.1 nmol/L) showed significantly positive 1:1 correlation with whole blood Co (median 45.9 nmol/L; R 2 ¼ 0.98, p < 0.001, slope ¼ 1.0). Plasma Cr (median 53.8 nmol/L) and whole blood Cr (median 40.3 nmol/L) were also correlated; however, concentrations were significantly higher in plasma indicating relatively little blood cell uptake (R 2 ¼ 0.96, p < 0.001, slope ¼ 1.6). Urinary Co was up to threefold higher than Cr (median 334.0 vs. 97.3 nmol/L respectively). Nickel concentrations in whole blood, plasma, and urine were low relative to Co and Cr. The analysis shows fundamental differences in the physiological handling of these metals: Co is distributed approximately equally between blood cells and plasma, whereas Cr is mainly in plasma, despite which, Cr had far less renal excretion than Co.

Cobalt to Chromium Ratio is Not a Key Marker for Adverse Local Tissue Reaction (ALTR) in Metal on Metal Hips

“…Cobalt is more soluble than chromium, allowing it to enter the circulation through diffusion from the joint and be measured in the serum at a higher rate [11]. Furthermore, chromium binds more readily to proteins than cobalt, allowing for chromium accumulation in local soft tissues and precipitation as chromium orthophosphate around the junctional interface [12,13]. A differential distribution of cobalt and chromium has been demonstrated in the whole blood, plasma, and urine of MoM hip arthroplasty patients [12].…”

“…Furthermore, chromium binds more readily to proteins than cobalt, allowing for chromium accumulation in local soft tissues and precipitation as chromium orthophosphate around the junctional interface [12,13]. A differential distribution of cobalt and chromium has been demonstrated in the whole blood, plasma, and urine of MoM hip arthroplasty patients [12]. These ion levels are produced from several sources: wear at the articulation, corrosion in any tapered junction, component impingement, contact between a metal liner and metal cup, abrasion of loose components, and normal body stores [14,15].…”

Molecular analysis of chromium and cobalt-related toxicity

“…Cr(III) is the most thermodynamically stable species and does not tend to reduce to Cr(II) or oxidize to Cr(VI), which are more unstable oxidation states. Cr(VI), if present could be readily reduced to Cr(III)47. Cr(III) is the form mostly observed in patients with MoM “metallosis”224849 and it often forms complexes with the ubiquitously found, negatively charged phosphate group.…”

Current Role of ICP–MS in Clinical Toxicology and Forensic Toxicology: A Metallic Profile

“…• Cobalt, chromium and other elements, for example, manganese, molybdenum, nickel and titanium, in various metal replacement joints and in dental implants have recently attracted considerable attention [60][61][62][63][64]. Owing to increased rates of revision of metal-on-metal total hip replacement, the UK's Medicines and Healthcare Products Regulatory Agency in April 2012 provided a whole blood 7 ppb guidance level for both cobalt and chromium in a medical alert [65].…”