Monday, January 9, 2012

Comment Solicitation: If you are a revision patient, did the Surgeon remove the Taper/Stem?

Last week I was speaking with the hospital Path department who are responding to requests to have the explants sent for examination.  When I asked what parts she had of my explant, I expected her to say:
  • Ball
  • Acetablum
  • Taper/Stem/trunion (I think these are all the same.)
She left out the Taper/Stem.  I was kind a curious as to why that didn't get replaced when the MRI had shown some issues with the tissue surrounding the stem.  I have to ask my surgeon when I see him.  The lady in the path lab said quite a few of the explants did have the stem/taper removed so of course I was curious about that comment as well.

I do know that most of these stems limit the options  of which Acetablum and Ball can be chosen for the revision as they are not apparently interchangable between companies?  Many have revised to the Pinnacle from the ASR Depuy because the Pinnacle can accept the existing Taper/Stem. ( I think I understand that to be so.)

Curious as to how many of you had all 3 parts replaced vs just two of the parts?

Anyone have feedback on this?

Thanks!

6 comments:

  1. Had all three parts removed,the stem had loosened and the surgeon was able to "pull it out with his hands".I go back in March to have my remaining ASR removed,I have some fear about keeping the stem because I just have no confidence in DePuy equipment.But this one seems to to be well knit into my femur,and the removal process sounds brutal.

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  2. I have only had the cup, acetabulum, and ball changed on both sides. It may be the reason why I continue to be in constant pain and have major swelling 14 months post op. Thanks for the heads up!! 5 different doctors have told me that I shouldn't have pain, but have major pockets of fluid showing on MRI. I'll post back.

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  3. Hi Connie, Anonymous from above. Since this earlier post I have been all over the interenet looking for a diagram of the ASR. I can't find a BOM, parts list or a good diagram of the complete device. Moriarty (sp) law group has a drwg that shows what looks to be a completely assembled ASR but it doesn't state all components. I question if there are 3 parts or more. I know there's the aceptabular cup, ball and S-rom femorial stem but here's my question. Is there a spacer or trunion on the top of the stem. My thought is that DePuy may have designed the top of the pin, utilizing a spacer or "trunion" to allow for differnent size balls. I know that the ASR was intended to use a larger ball and cup that allowed for more range of motion and load. It would make sense that to allow for a larger range of ball and cup sizes, they would change the ID of the ball attachement hole. Have you ever come across a diagram or bill of material (BOM) for the ASR showing all parts involved. I know that I only received the Aceptabular cup and ball after my surgeries.

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  4. The market as a whole seems to continue to think that the metal debris comes only from the friction between the ball and the acetablum. The more recent literture seems to be looking at the micromotion at the stem, neck area which is why I brought this up in the first place.

    You can see the stem/ neck clearly in the photos of this jounal article:

    J Biomech. 2011 Jun 3;44(9):1747-51. Epub 2011 Apr 30.

    Influence of material coupling and assembly condition on the magnitude of micromotion at the stem-neck interface of a modular hip endoprosthesis.

    Jauch SY, Huber G, Hoenig E, Baxmann M, Grupp TM, Morlock MM.

    You would have to go to a medical library to get this paper or you can buy it on line.

    Hope this helps.

    Connie

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  5. The video says Chromium 3 is released from the devices not Chromium 6. But if chromium 6 were present it would be reduced to Chromium 3 and the reduction process is the catalyst for cancer. There is no reduction of Chromium 3 to 6.

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  6. Hi,

    I think you meant to attach this the HoT topic article but in any event, the reference this physcian uses was for an article done by CP case. Just thought I would give you a sense of what CP Case talks about re the influence of these metal on metal hips (these are all publications of CP Case and his colleagues):

    -Thresholds for indirect DNA damage across cellular barriers for orthopaedic biomaterials

    -Metal-specific differences in levels of DNA damage caused by synovial fluid recovered at revision arthroplasty

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

    -Changes in the proportions of peripheral blood lymphocytes in patients with worn implants

    -Tumors around implants.

    -Preliminary observations on possible premalignant changes in bone marrow adjacent to worn total hip arthroplasty implants

    -Systemic distribution of wear debris after hip replacement. A cause for concern?

    etc....

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