title: Metal-on-metal bearing surfaces.
abstract: Metal-on-metal bearing couples remain a popular option in total hip arthroplasty and are the only currently available option for surface replacement arthroplasty. In general, the intermediate-term clinical performance of metal-on-metal bearings has been favorable. There are, however, lingering concerns about the biologic consequences of metal release from these bearings in terms of both local tissue effects, including delayed-type hypersensitivity reactions in a subset of patients, and potential systemic effects as a consequence of chronic elevations in serum cobalt and chromium content. Advances in the understanding of the operant wear mechanisms in these bearings provide strategies for reducing the burden of metal released into the periprosthetic milieu, which in turn will mitigate the concerns about the biologic response to the metal debris. Continued surveillance of patients with these bearings is warranted to determine whether metal-on-metal bearing couples provide a long-term survivorship advantage over other bearing couple options and to evaluate whether chronic elevations in the body burden of cobalt and chromium is well tolerated over the long term.
authors.affiliation: Department of Orthopaedic Surgery, Rush University Medical Center, Suite 1063, 1725 West Harrison Street, Chicago, IL 60612, USA.
authors.forename: Joshua J
authors.initials: JJ
authors.lastname: Jacobs
authors.forename: Robert M
authors.initials: RM
authors.lastname: Urban
authors.forename: Nadim J
authors.initials: NJ
authors.lastname: Hallab
authors.forename: Anastasia K
authors.initials: AK
authors.lastname: Skipor
authors.forename: Alfons
authors.initials: A
authors.lastname: Fischer
authors.forename: Markus A
authors.initials: MA
authors.lastname: Wimmer
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation*; D002857:Chromium / Q000009:adverse effects / Q000097:blood / Q000652:urine; D017608:Chromium Compounds; D003035:Cobalt / Q000009:adverse effects / Q000097:blood / Q000652:urine; D006622:Hip Prosthesis / Q000009:adverse effects; D006801:Humans; D006968:Hypersensitivity, Delayed / Q000209:etiology; D008670:Metals / Q000009:adverse effects; D010710:Phosphates; D020959:Polyethylene
chemical_list: D017608:Chromium Compounds; D008670:Metals; D010710:Phosphates; D002857:Chromium; D003035:Cobalt; D020959:Polyethylene; C509369:chromic phosphate