Monday, June 20, 2011

Systemic effects of metal debris (7f of 7); excerpts from the Committee on Mutagenicity

Excerpts and commentary based on the 6/4 post-Metal on Metal Bearings, The Evidence So Far

Genotoxic issues surrounding systemic effects of metal debris (continued from prior posts)

The committee on mutagenicity has reported that internal exposure to orthopedic metals is associated with increased genotoxicity.

This is a series of commentary from the committee on mutangenicity evidence based on the the key journal articles examined by that committee. I think you will find the results really interesting if you are concerned about the systemic effects of the metal.

Second piece of evidence:

J Arthroplasty. 2004 Dec;19(8 Suppl 3):78-83.

Changes in metal levels and chromosome aberrations in the peripheral blood of patients after metal-on-metal hip arthroplasty.


University of Bristol, Orthopaedic Surgery, BIRC-Bristol Implant Research Center, Bristol, UK.


A prospective study was performed to investigate changes in metal levels and chromosome aberrations in patients within 2 years of receiving metal-on-metal hip arthroplasties. There was a statistically significant increase of cobalt and chromium concentrations, with a small increase in molybdenum, in whole blood at 6, 12, and 24 months after surgery. There was also a statistically significant increase of both chromosome translocations and aneuploidy in peripheral blood lymphocytes at 6, 12, and 24 months after surgery. The changes were generally progressive with time, but the change in aneuploidy was much greater than in chromosome translocations. No statistically significant correlations were found in secondary analyses between chromosome translocation indices and cobalt or chromium concentration in whole blood. Although the clinical consequences of these changes, if any, are unknown, future epidemiological studies could usefully include direct comparisons of patients with implants of different composition.

[ Notes below added by connie //
First: What is aneuploidy and what is chromosomal tranlocations?
Aneuploidy is an abnormal number of chromosomes, and is a type of chromosome abnormality. Some cancer cells have abnormal numbers of chromosomes.[1] Aneuploidy occurs during cell division when the chromosomes do not separate properly between the two cells...The question is what is the relationship between the metal on metal hip and long term systemic effects with things like cancer?
In genetics, a chromosome translocation is a chromosome abnormality caused by rearrangement of parts between nonhomologous chromosomes. A gene fusion may be created when the translocation joins two otherwise separated genes, the occurrence of which is common in cancer.
This study supports the claim of genotocity associated with metal on metal implants.]
The committee who reviewed this paper published in 2004, concluded the following:
  •  The increase in the number of chromosomes was much greater than that of chromosome abnormality and both were progressive over time.
  • Many more patients were studied this time around compared to the Doherty study that I reviewed on Saturday the 18th of June.
  • The blood measurements had been adequately taken
  • the evaluation of chromosome aberrations had been adequately undertaken and reported
  • Further information should be reviewed on the question of the agents that resulted in cell division
  • The members concluded that the evidence from these tow studies supported the involvement of released Chromium and cobalt in the observed chromosomal effects associated with MoM hip replacement although, it was not possible to to conclude whether this was due to release of soluble ions or particulate metals.

Gee, I can't wait to see the last 3 studies! 

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