Ion release in stable hip arthroplasties using metal‐on‐metal articulating surfaces: A comparison between short‐ and medium‐term results

Abstract

The use of metallic heads articulating with metallic cups could solve the problem of polyethylene (PE) wear in total hip replacement (THR) with metal-on-PE bearings. A conspicuous release of metal ions from new models of metal-on-metal bearings has been found in the short-term, but it is yet unclear whether the medium-term corrosion rate is high or, on the contrary, it becomes negligible, because of the continuous surface finishing. Our purpose was to compare the serum ion values (nanograms per milliliter) in 15 patients with metal-on-metal stable prosthesis (Group A), in the short-term (subgroup A(1); mean follow-up: 24 mo) and medium-term (subgroup A(2); mean follow-up: 52 mo), in order to determine whether the ion release decreased with time of implant. Chromium (Cr), cobalt (Co), molybdenum (Mo) and aluminum (Al) were analyzed. Twenty-two presurgical patients were used for comparison (Group B). The reference range was obtained from a population of 27 healthy subjects (Group C). Co and Cr levels in the medium-term (subgroup A(2)) were not decreased in comparison with the short-term values (subgroup A(1)) and were significantly higher (p < 0.001) than presurgical and reference values. Otherwise, Mo and Al concentrations were not significantly increased in comparison with reference values. In conclusion, despite the apparent advantage of metal-on-metal coupling, especially in younger patient populations, there is a major concern about the extent and duration of the relevant "internal" exposure to Cr and Co ions. This exposure should be carefully monitored, in order to clarify the biologic effects of ion dissemination and, consequently, to identify risks concerning long-term toxicity of metals.

Serum metal ion levels after rotating-hinge knee arthroplasty: comparison between a standard device and a megaprosthesis

“…The authors interpreted their findings as suggesting a negative influence on the immune system. Savarino et al [13] reported haematological and immuno- logical alterations in patients with metal-on-metal or metalon-polyethylene arthroplasty, whereas these effects could not be observed in patients with ceramic-on-ceramic prostheses. These findings led on to the hypothesis that metal ions, especially Co and Cr, might have a toxic effect on myelopoesis and the immune system.…”

“…Imanishi et al [9], Back et al [6], Daniel et al [5], Engh et al [10], Antoniou et al [11], Witzleb et al [12] and Savarino et al [7,13] demonstrated that the levels of Co and Cr ions increase within the first three months to two years following metal-on-metal THA. In the study of Imanishi et al [9], there was no significant additional increase of serum metal ion concentration at the one year follow-up, whereas Back et al [6] and Daniel et al [5,14] observed a decreasing trend of serum concentration between one and six years.…”

Does Ion Release Differ Between Hip Resurfacing and Metal-on-metal THA?

“…Although the clinical use of MOM THA is increasing in popularity, concerns remain regarding wear and corrosion of the bearing surfaces and the consequent increase in metal ion serum levels [10,26,31,32,35]. It is certain that metal ions are released because of the combined effect of corrosion of the implant surface and wear particles.…”

Levels of systemic metal ions in patients with intramedullary nails

“…Despite this variability, however, the levels of serum chromium reported for patients with metalon-metal hip arthroplasties have been reasonably consistent, averaging 2.0 µg/L (Jacobs et al 1996, Brodner et al 1997, MacDonald et al 2003, Savarino et al 2003, MacDonald 2004, Dunstan et al 2005, Heisel et al 2005. Despite the recent interest in metal ion release from arthroplasty, few studies dealing with metal ion release from fracture fixation devices have been published.…”