(1) He strongly preferred the Depuy Pinnacle for the revision. Why?
- He had personally placed over 1000 Pinnacle cups in his practice
- He had a very small revision number due to infection but none due to loosening, excessive wear, liner issue or metal debris.
- He does not use metal on metal in that line
- His recommendation:
- Pinnacle Cup (made of titanium...see post from yesterday where I address this metal.
- Marathon poly liner.
- Ceramic head
The one comment that was completely utterly fascinating is this one: "The literature suggests that when wear debris is generated from contemporary metal on metal bearings, some hexavlaent chromium is generated, but it is quickly reduced inside the body's cells to trivalent."
I definitely need to pursue this comment post surgery... You know why? I have spent considerable time looking at this very issue (see prior posts by typing hexavalent or trivalent chromium in the search box or type in chromium 3 or chromium 6.) If this is correct, we need to explore the relevancy of "quickly reduced to trivalent".
(1) Is this an acknowledgement that chromium 6 (the carcinogenic chromium) is in fact present in the the hip?...something I have suspected for a very long time. If you ask any surgeon what Chromium version is in the hip, the answer will always be Chromium 3, the alleged non carcinogenic form. Chromium 3 can generate carcinogenic chromosomes but not to the extent that chromium 6 can.
(2) Does it matter how long the the Chromium 6 is in your body before it oxidizes to chromium 3? I don't know. Kinda sounds like an "almost pregnant" analogy. By that I mean, pregnancy is binary. You either are or you are not. I think the same is true for oxidation. It either happened and changed the chromosomes or it didn't. This is something I will definitely look at. My understanding is that you can get abnormal cells generated merely from the oxidation process (having 6 turn to 3.) I could be wrong but I want to know this. Abnormal chromosomes (in number or size) have the possibility of becoming carcinogenic. This statement above suggests that generating abnormal chromosomes is not binary but progressive or something???
Here is a copy of the pertinent information from an earlier blog post I wrote:
Oxidative Damage / exerpts from Acta Orthopaedica 2008 79 (6) 734-747 University of Oxford
//Metal-induced intracellular effects
1. Reactions with metal ions can lead to generation of free radicals: reactive oxygen species (ROS) and reactive nitrogen species (RNS) which in , cause cellular dysfunction.
2. Inside the cells, Cr 6 is oxidized to Cr 3 in a series of steps that generate free radicals.
3. Free radicals catalyze the oxidation of protein and phospholipids.
4. That process leads to the formation of malondialdeyde which can react with DNA bases to form DNA protein cross links
5. Permanet modification of genetic material resulting from this oxidative damage represents the first step in mutagenesis and carcinogenesis.
6. Direct binding of Cr 3 to DNA is well documented.
7. In cells , two main processes exist to correct DNA aberrations to restore the integrity of the genome.
8. Under stimulation by Cobalt 2 and Chromium 6, both of these mechanisms are inhibited.
9. Landon (2004) investigated changes in metal ion levels and chromosome aberrations in patients within two years of receiving metal on metal atheroplasties.
10 The authors noted an increase in chromosome translocations and aneuploidy in peripheral blood lymphocytes at 6, 12, 24 months after surgery.
- Aneuploidy is an abnormal number of chromosomes, and is a type of chromosome abnormality. Some cancer cells have abnormal numbers of chromosomes. 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.
11. The authors noted the changes were progressive.
12. The authors didn't find any statistically significant correlations over those short time frames between chromosomal translocations and Co and Cr concentrations in the whole blood.
following are some summary steps of this oxidation process. A bit technical but helpful:
- Different pathways are used by metal ions to enter the cells
- Chromium 6 can cross the cell membrane
- Chromium 6 undergoes rapid metabolic reduction to form Chromium 5, chromium 4 and then chromium 3.
- At each step of the Cr 6 reduction, ROS and RNS are generated (see above for definition of these terms)
- Cr 3 can cross the cell membrane and participate in alteration of DNA.
so...... pretty interesting hugh?
In any event, my surgeon's note was quite helpful to me and provided me with peace of mind which is all I was interested in hearing.