title: Cobalt deposition in mineralized bone tissue after metal-on-metal hip resurfacing: Quantitative μ-X-ray-fluorescence analysis of implant material incorporation in periprosthetic tissue.
abstract: Most resurfacing systems are manufactured from cobalt-chromium alloys with metal-on-metal (MoM) bearing couples. Because the quantity of particulate metal and corrosion products which can be released into the periprosthetic milieu is greater in MoM bearings than in metal-on-polyethylene (MoP) bearings, it is hypothesized that the quantity and distribution of debris released by the MoM components induce a compositional change in the periprosthetic bone. To determine the validity of this claim, nondestructive µ-X-ray fluorescence analysis was carried out on undecalcified histological samples from 13 femoral heads which had undergone surface replacement. These samples were extracted from the patients after gradient time points due to required revision surgery. Samples from nonintervened femoral heads as well as from a MoP resurfaced implant served as controls. Light microscopy and µ-X-ray fluorescence analyses revealed that cobalt debris was found not only in the soft tissue around the prosthesis and the bone marrow, but also in the mineralized bone tissue. Mineralized bone exposed to surface replacements showed significant increases in cobalt concentrations in comparison with control specimens without an implant. A maximum cobalt concentration in mineralized hard tissue of up to 380 ppm was detected as early as 2 years after implantation. Values of this magnitude are not found in implants with a MoP surface bearing until a lifetime of more than 20 years. This study demonstrates that hip resurfacing implants with MoM bearings present a potential long-term health risk due to rapid cobalt ion accumulation in periprosthetic hard tissue. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1855-1862, 2017.
authors.affiliation: Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, D-22529, Hamburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Hahn
authors.affiliation: Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, D-22529, Hamburg, Germany.
authors.forename: Björn
authors.initials: B
authors.lastname: Busse
authors.affiliation: IFG-Institute for Scientific Instruments, D-12489, Berlin, Germany.
authors.forename: Mathias
authors.initials: M
authors.lastname: Procop
authors.affiliation: Institute of Bone Pathology, University Medical Center Hamburg-Eppendorf, D-22529, Hamburg, Germany.
authors.forename: Jozef
authors.initials: J
authors.lastname: Zustin
authors.affiliation: Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, D-22529, Hamburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Amling
authors.affiliation: ORTHOCLINIC Hamburg, D-22457, Hamburg, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Katzer
mesh_terms: D000069343:Bone-Implant Interface / Q000473:pathology*; D003035:Cobalt / Q000493:pharmacokinetics*; D005260:Female; D005270:Femur Head / Q000378:metabolism / Q000473:pathology; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D013052:Spectrometry, X-Ray Emission; D013997:Time Factors
chemical_list: D003035:Cobalt
keywords: hip implants; metal alloys; micro-X-ray fluorescence; microanalysis; orthopedic pathology