Saturday, June 18, 2011

Systemic effects of metal debris (7e 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.

First piece of evidence:

J Bone Joint Surg Br. 2001 Sep;83(7):1075-81.

Increased chromosome translocations and aneuploidy in peripheral blood lymphocytes of patients having revision arthroplasty of the hip.


Bristol Implant Research Centre and the University Department of Orthopaedic Surgery, England.


The long-term biological effects of wear debris are unknown. We have investigated whether there is any evidence of cumulative mutagenic damage in peripheral blood lymphocytes of patients undergoing revision arthroplasty of predominantly metal-on-plastic total hip replacements compared with those at primary arthroplasty. There was a threefold increase in aneuploidy and a twofold increase in chromosomal translocations which could not be explained by the confounding variables of smoking, gender, age and diagnostic radiographs. In the patients with TiVaAl prostheses there was a fivefold increase in aneuploidy but no increase in chromosomal translocations. By contrast, in patients with cobalt-chrome prostheses there was a 2.5-fold increase in aneuploidy and a 3.5-fold increase in chromosomal translocations. In six patients with stainless-steel prostheses there was no increase in either aneuploidy or chromosomal translocations. Our results suggest that future epidemiological studies of the putative long-term risks of joint replacement should take into account the type of alloy used in the prosthesis.

[  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

So, this journal article above which was examined by the committee says yes, in patients with cobalt-chrome prostheses there was a 2.5-fold increase in aneuploidy and a 3.5-fold increase in chromosomal translocations.]

The committee who reviewed this paper published in 2001 concluded: 
  • The patient sample was small and  it would not be possible to draw any definite conclusions re differences between different types of Metal on Metal devices.
  • The procedures used in testing the blood metal levels were done appropriately
  • The evaluation of these two gene mutations mentioned above had been adequately reported
  • Members wanted to see the full details of the tests.

You can draw your own conclusion from the above.  I am eager to see the next 4 papers.

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