Exposure to chromium, cobalt and molybdenum from metal-on-metal total hip replacement and hip resurfacing arthroplasty.
BACKGROUND
All metal implants--and metal-on-metal bearings in particular--corrode and cause a release of metal ions. Because cobalt and chromium have been shown to be carcinogenic and mutagenic in human and animal models, systemic toxicity and cancer risk are considered to be possible disadvantages of the metal-on-metal articulation. This study was designed to investigate the serum concentration profiles of chromium, cobalt and molybdenum after implantation of a Birmingham hip resurfacing arthroplasty (BHR) and a cementless total hip replacement with a 28-mm Metasul articulation (MTHR), over the first 2 years after implantation.


METHODS
We analyzed profiles of metal ion serum levels in 111 patients implanted with a BHR, in 74 patients implanted with an MTHR, and in 130 implant-free probands control subjects using atomic absorption spectrophotometry.


RESULTS
Chromium and cobalt concentrations (in microg/L) of all BHR and MTHR patients differed significantly from those of control subjects (chromium: < 0.25; cobalt: 0.25). The median chromium and cobalt concentrations in BHR patients had increased to 5.1 and 4.3 microg/L 2 years after surgery. Concentrations in BHR patient exceeded those in the unilateral MTHR patients. Molybdenum serum concentrations hardly changed over time in either group and were not significantly different from the concentrations seen in the control subjects.


CONCLUSIONS
During the first 2 years after surgery, the Birmingham hip resurfacing arthroplasty leads to a significantly greater increase in serum chromium and cobalt levels than the 28-mm metal-on-metal MTHR. Observation of patients over a longer period will be necessary in order to evaluate any chronic adverse effects to the system due to elevated chromium and cobalt serum concentrations.
Witzleb
Wolf-Christoph
WC
Department of Orthopaedic Surgery, Universty Hospital Carl Gustav Carus, Dresden University of Technology, Dresden, Germany. Wolf-Christoph.Witzleb@uniklinikum-dresden.de
Ziegler
Joerg
J
Krummenauer
Frank
F
Neumeister
Volker
V
Guenther
Klaus-Peter
KP
D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods; D002857:Chromium / Q000009:adverse effects / Q000097:blood*; D003035:Cobalt / Q000009:adverse effects / Q000097:blood*; D005260:Female; D005500:Follow-Up Studies; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008982:Molybdenum / Q000009:adverse effects / Q000097:blood*; D011474:Prosthesis Design; D011475:Prosthesis Failure; D013054:Spectrophotometry, Atomic; D013997:Time Factors; D014131:Trace Elements / Q000097:blood
D014131:Trace Elements; D002857:Chromium; D003035:Cobalt; D008982:Molybdenum