Cobalt and Chromium Concentrations in Patients With Metal on Metal Total Hip Replacements

The John Charnley Award: Metal-on-Metal Hip Resurfacing versus Large-diameter Head Metal-on-Metal Total Hip Arthroplasty

“…By having identical articulations in the two groups, the only plausible explanation for the markedly elevated serum cobalt and chromium levels relates to the two areas of modularity for the attachment of the femoral head to the stem. It is well-known that the head-neck junction is a source of release of metal ions due to fretting and corrosion [19]. In the large-head MOM THA group in this study, the two modular junctions and mismatch of metals between the titanium stem and the Cr-Co alloy adaptor, could account for the elevated metal ion levels seen [13,19,20].…”

“…It is well-known that the head-neck junction is a source of release of metal ions due to fretting and corrosion [19]. In the large-head MOM THA group in this study, the two modular junctions and mismatch of metals between the titanium stem and the Cr-Co alloy adaptor, could account for the elevated metal ion levels seen [13,19,20]. In the literature, one article has addressed metal ions in largehead metal-on-metal total hips [3].…”

“…The rationale for the use of metal-on-metal articulation is that it produces less volumetric wear debris than metal-on-polyethylene and therefore may result in a decreased incidence of osteolysis-induced failure, particularly in young active patients who are expected to have a long life expectancy [12,27]. The widespread acceptance of metal-on-metal articulations has been tempered by concerns of increased metal ion production from these devices compared to standard total hip arthroplasty [14,18,19,25,31]. To date, there are no published clinical data to suggest that there are adverse health consequences related to the type of ion production associated with these devices; however, a recent paper suggest that pseudotumors may result from a reaction to high metal wear debris [29].…”

Investigating the Immunologic Effects of CoCr Nanoparticles

“…Therefore, CoCr nanoparticles can inhibit Signal 1-and 2-dependent T cell proliferation and, importantly, this effect occurred at sublethal concentrations of CoCr. Hart et al [12] reported a reduction in CD8+ T cells in patients with elevated CoCr levels after M/M hip resurfacing, although how this effect is mediated has not been described [15]. Our data suggest antigen-specific stimulation is necessary for CoCr to have effects on T cell function and number, although where, when, and what antigen stimulus is necessary remains unclear.…”

“…The modern era of M/M hip arthroplasties began in 1991, when, as reported by Willert [31], Heinz Wagner introduced his system based on the Metasul TM wrought-forged, CoCr alloy bearing. The reintroduction was based on good long-term results associated with McKee-Farrar THAs (M/M coupling used in 1960s), which had excellent results even at 20 years' followup [15,16,20,27]. After a rapid wear rate for the first year after implantation, as a result of an initial conditioning phase, most M/M arthroplasties have a constant low wear rate [28].…”