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Why implants loosen/fail over time

Discussion in 'Knee Replacement Pre-Op Area' started by Simon, Aug 23, 2009.

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  1. Simon

    Simon Graduate

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    Hi Folks

    I came across a summary of this article (or rather the one published in J Orthop Res but this one is easier to read) which gives a reason why implants tend to loosen over time. According to the summary I read this is why younger people are warned about the need for a replacement in 10 to 20 years.


    1: Bull NYU Hosp Jt Dis. 2009;67(2):182-8.

    Biologic effects of implant debris.

    Hallab NJ, Jacobs JJ.

    Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, IL, USA. [email protected]

    Biologic response to orthopedic implants debris is central to clinical
    performance. Eventual implant loosening due to aseptic osteolysis has been
    attributed to local inflammatory responses to wear and corrosion products that are produced by articulating implant interfaces. The response to implant debris is dominated by local immune activation, e.g. macrophages. Immune reactivity has been shown to depend on the number of particles produced or the dose (i.e., the concentration of phagocytosable particles per tissue volume, which can be characterized by knowing the size distribution and amount of debris). Elongated particles (fbers) are generally more pro-inflammatory than round particles, and there is a growing consensus that metals particles are more proinflammatory than polymers in vivo. Generally, to produce an in vitro inflammatory response, particles need to be less than 10 mum, i.e. phagocytosable. However, both soluble and particulate debris derived from Co-Cr-Mo alloy implants can induce monocyte/macrophage activation and secretion of pro-inflammatory cytokines such as IL-1beta, TNFalpha, IL-6 and IL-8 via up-regulation of transcription factor
    NFkappabeta, and activation of inflammasome danger signaling in human
    macrophages. Not only does activation of local (and systemic) inflammation result in decreased osteoblast function but osteoclast activity increases. Some people are more predisposed to implant debris induced inflammation and metal "allergy" testing services are becoming available. New pathways of implant debris-induced inflammatory reactions continue to be discovered, such as the "danger signaling" inflammasome pathway, which provides new targets for pharmaceutical intervention and improved implant performance.


    Simon
     
  2. loggon

    loggon Don

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    :pzld::sct::pzld: hummm:sigh:
     
  3. Judles

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    Wear,tear,aging and living!!! And we all pray for good luck.....that can NEVER hurt, Simon!!!! (:)0)
     
  4. Jamie

    Jamie Administrator

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    Interesting summary, Simon....thanks for posting it. It does make sense.
     
  5. Judles

    Judles Alpha

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    Really? What have you been drinking, Jame???? LOL!!! (:)0)
     
  6. JudyS

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    I need what Jamie has been drinking too.
    judy
     
  7. Linda2

    Linda2 Post-Grad

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    And that's the one that's EASY to understand!!!! :shk:
     
  8. Max Wallace

    Max Wallace Graduate

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    Our own immune system is attacking??
     
  9. Dawnie

    Dawnie Graduate

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    In ENGLISH pleaseeeeeeeeeeeee!!!!
     
  10. Judles

    Judles Alpha

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    ANY English!!! :sct::sct::sct::sct:
    :pnc:
     
  11. RickB

    RickB Member

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    Simon,
    You know, I was telling my wife the same thing the other night over dinner. I think the Dr. must have over heard me!!!!!!:hehe:
     
  12. Josephine

    Josephine NURSE DIRECTOR, BONESMART Administrator

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    The English translation is ....

    Micro loosening is when there is minute amounts of die-back around the cement. For you to understand that, let me first explain about "cement security".

    When the bone is prepared for the cement, it has to be cleansed with a power washer (not unlike the one you use on your car!) which gets rid of all the blood and fatty marrow that lies within the matrix of the spongy looking area inside the bone. This is because if any of the tiny spaces are occupied by any of these materials, the cement cannot get in. And it's important because getting the cement into these crevices is what makes it secure, or hold fast onto the bone. Additionally, if this doesn't happen, the cement sits on top of the bony spicules and quite quickly the bone will die back under the loading. Bone doesn't like being unevenly loaded, you see. So when this die-back begins, the cement loses it's grip here and there until it's loose enough to start moving tiny amounts. Strangely, when the surgeon gets in there, it'll be possible that he might not find it very easy to remove the implant and might even have to apply a little force with a kind of mini-crowbar!

    These illustrations demonstrates more clearly about the bony matrix and about cement security
    [​IMG]
    [​IMG]
     
  13. Judles

    Judles Alpha

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    Now THAT makes ALOT more sense,Jo!!!.:sct::thmb:.... Sorry, Simon! Many/most of us had trouble digesting that article but appreciate your research!!:pnc::rant::pnc::rant:
    Rick.....that must've been SOME romantic dinner you guys had last night!!!:shk::shk::shk::shk:
    :hehe::hehe::hehe::hehe::hehe:
     
  14. Josephine

    Josephine NURSE DIRECTOR, BONESMART Administrator

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    Actually, I just finished posting it on a newbie's thread and then came right here! So I copied it on.
     
  15. Linda2

    Linda2 Post-Grad

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    I also got the impression from Simon's article that the body treats any debris like an alien and goes after it with the usual arsenal, inflammation and so on. That would hasten the process. I think?
     
  16. loggon

    loggon Don

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    Thanks Jo as usual Jo to the rescue.
    Yes thank you Simon for the research, but most of us are layman and did not quite digest what the article was saying.
     
  17. RickB

    RickB Member

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    Thanks Jo, that was what I was trying to explain to the wife the other nite at dinner.:whis:
     
  18. Pat29627

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    So, though it's loosening, it's probably not really moving? But whenever it loosens in an area is when you might have bone dying back and then big problems? And if there's any cement bits or bits of the worn part, the body might attack with inflammation? It's a wonder most turn out as well as they do!!!

    Are there statistics anywhere about success rates of partials and totals?

    Pat
     
  19. Linda2

    Linda2 Post-Grad

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    After reading Jo's explanation, I think one wants a surgeon who's a bit OCD about getting out every last speck . . .
     
  20. Josephine

    Josephine NURSE DIRECTOR, BONESMART Administrator

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    Oh the pulse lavage tool does a pretty good job of clearing it all out. It would be my assumption that maybe in cases that fail, the surgeon never used one. Some don't. Incidentally, this is the tool. The two tubes are one, to apply the pressurized water jet and the other is a suction tube to take the lavage fluid away. The funnel attachment is for acetabulum and knees and the tube attachment is for the femoral shaft.

    [​IMG]

    As for the movement, it's micro-movement, meaning it is still 80-90% attached within the bone but can shift in tiny amount. You can feel the same thing with your teeth which are all capable of mico-movement. If you grasp them firmly, you can move then but they are still firmly implanted!

    Another way to explain it is that as those little spicules of bone die back, there's still a lot more that haven't!
     
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