Friday, March 25, 2011

Interesting tidbits from the 12 videos on Depuy hip/metal ion issues by Dr. Michael McCabe, Toxicologist.


(1)   Dr. McCabe seems to be well qualified to comment on the metal ion issues.  While he is not a medical doctor, he is a Phd and Toxicologist.  His specialty is the effects of heavy metal on the Immune response, aka Immunotoxicology.
a.       The first time I heard about the potential relationship between this hip and the Immune issues is from the Toxicologist I went to see last week.

(2)   He claims that it has been shown in the literature that chromium 3 (the non toxic trivalent form) can produce carcinogenic mechanisms by stimulating the immune response through   inflammation.   If the inflammation goes unchecked, then this can contribute to the development of the cancer etc. The literature is all environmental evidence and not evidence that shows a link between the hip and cancer.  The one fact is that inflammation is known as a progressive factor in causing cancers environmentally.  (from video number 8 of 12)

Interesting because this suggests to me that if the MRI shows any level of inflammation regardless of whether you are experiencing pain, this is yet one additional piece of critical information that should be considered in combination of other issues in making a revision decision.

(3)   He reiterates that the three things to look at for cobalt toxicity with the hip are:
a.       Cardiomyopathy-swelling of the heart
b.      Hypothyroidism
c.       Some neurotoxic issues (not sure what these are but will look into it.)

(4)   He reiterates that if you are exposed to over 5 parts per billion of cobalt, the environmental FDA regulations are such that you should be removed from the exposure.  No one knows what it means re the hip however, I like his approach which is to say:  how might the environmental observations inform us as to how we might view the hip.  I think that is a good way to look at this.  Many physicians seem to dismiss the environmental observations (inhalation, dermatitis) and I don’t know that this is a reasonable thing to do.  I think it is a data point that should not be dismissed out of hand but rather considered in the big picture.

(5)   Elevated cobalt level is not cumulative but is coming from an active source which is from wear debris from the hip.  If the hip is removed, cobalt will decrease over time…red blood cells will turn over every 3 months.  In approximately 3 months those levels should decrease if the hip is removed.   You are not completely out of the woods however,  even after revision because you have the potential to stimulate immune response..  long term immunological issues still exist post revision.

(6)   Do high Co and Cr levels cause cancer?  Both in vitro and in vivo studies suggest there is imunogenisis in the DNA etc.  There are no epidemiological studies to close that loop and solidify the claim that the changes in DNA (chromosomal changes) cause cancer.    Given there are health consequences (heart/hypothyroidism/ neurotoxic issues), there are potentially carcinogenic issues that might surface.

He is quite sympathetic with the position the orthopedic surgeons are in as the symptom complex is complicated and we seem to have no direct data that proves anything.  The physicians are left in a really bad position as are the patients to have to interpret things without a lot of information.  My orthopedic surgeon summarized this whole thing in 3 words:  It’s all murky!

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