Validity to the S&N acquisition rumor?

Discussion in 'DePuy Ortho' started by anonymous, Sep 23, 2015 at 9:22 AM.

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  1. anonymous

    anonymous Guest

    Aesculap ZrN multilayer coating on CoCrMo. This is not comparable to Oxinium in terms of its adhesion to the metal substrate. Oxinium's main weakness is the softness of the metal substrate. It will wear like hell if the ZrO surface is breached by scratches. I do not necessarily advocate Oxinium. But seriously, if Aesculap ZrN coated CoCrMo is the option you refer surgeons to, DePuy has painted itself into a corner regarding femur wear.
     

  2. anonymous

    anonymous Guest

    I don't work for SN but did for a long time. I don't get the soft substrate argument that others bring up. If a scratch did occur that would breach the ZrO layer, how is that going to wear? Does the 1-2 micron scratch wear on poly? Does the Zr base layer wear away? It is in the same family as Ti, and that is used for tib trays. Do we see runaway backside wear on those?
    The scratches if they did occur (ZrO is 2x harder than CoCr) do not create peaks adjacent to scratch. Only the valley. They have done retrievals of scratched heads due to dislocation, and ran them in a simulator, and the end result is that the wear is similar to pristine CoCr heads.
    Scratch CoCr and Ox in a knee situation, and what will wear better? The ZrO will not flake off, and I worry about the Aesculab coating doing that.
    Even though I work for a competitor (not DePuy either), I still wish I had Ox in my bag. One of the few products that was fun to sell for SN.
     
  3. anonymous

    anonymous Guest

    Zr and Ti are both very reactive to oxidation and softer than steel. If the metal Zr or Ti is exposed, they wear excessively during articulation because of their hex atomic structure. Typically, Ti is nitrided in some form (TiAlN or TiN), but it is a thin brittle shell that will flake off if scratched hard enough.
     
  4. anonymous

    anonymous Guest

    I understand that Zr is softer than CoCr, but a scratch doesn't expose enough surface area to effect wear. If a head dislocates and is reduced with scratches, whether it is CoCr, ceramic, or OxZr, it will increase wear. You need a better argument against Ox. Like I said 2 posts ago...I don't sell Ox anymore, but wish I still had it in my bag.
     
  5. anonymous

    anonymous Guest

    No, I don't mean poly wear, I mean the catastrophic metal wear that only occurs with Ti and Zr when they rub against a tibial tray or acetabular shell. This is rare (e.g. when a liner separates and falls out of the shell), but for Zr metal contacting another metal, that 5 microns of ZrO disappears quickly and the amount of metallic debris product in that joint is absolutely horrendous compared to CoCrMo.

    Poly wear for Ox is fine, even in moderately scratched condition since the ZrO layer is compliant in those scratches.
     
  6. anonymous

    anonymous Guest

    so, catastrophic failure is the seed of doubt you present to docs? Zr is in the same family as Ti, meaning it is one of the most biocompatible materials on the chart of elements. So, those ions are less of a concern than say Co,Cr, or Ni. You know SN has been working on an Ox on Ox articulation for hips? The oxide layer and transition zone will be more robust, and given the wettability of Ox, should act more like a ceramic on ceramic than a Metal on Metal combo. I don't think they would continue down that path if Zr ions were toxic.

    If a CoCr femur wears through poly and rubs against a Ti tibial tray, the soft tissue will look grey/black and horrible. That is because Ti is the softer of the two, and will shed ions. Same thing can happen with a CoCr femur rubbing on a CoCr tibial tray, or Ox against any other metal.

    Still no good argument. Just buy SN and then you can sell it too.
     
  7. anonymous

    anonymous Guest

    No, if I were in sales, the seed of doubt I would present to a surgeon is about fixation. The last Ox femur retrievals I saw did not have cementless option. Perhaps this has been remedied. The last Oxinium femurs I saw did not have Zr beads because of fatigue/embrittlement issues during sintering, just like you can't fully porous coat a Ti stem because of fatigue issues.
     
  8. anonymous

    anonymous Guest

    ok, two case studies that are outliers...that's your ammo against Ox? Let's compare that to ceramic heads in the same situation...fracture probably would have occurred, and particles embedded in the soft tissue would obliterate any poly after revision. You are comparing Ox to ceramic for wear, correct? Also, didn't this discussion start regarding coatings for knees?

    In regards to sintering and beads...my understanding is that by sintering (which is done via heat), it would change the material properties of the OxZr layer, and therefore wasn't feasible. The macro textured surface failed, in my opinion, due to lack of porosity and it's rough edges, which caused a shearing effect on chamfer edges when implanted. Some did fine, others (most) failed at 1 year. They tried to come up with a porous solution, but like ceramic, how can you sinter something onto it?

    Again, arguments are not that strong, pointing to obscure catastrophic failures that you could find hundreds of ones like it with ceramic or even CoCr. I'm sure there are case studies of coated CoCr surfaces with catastrophic failures too...
    I would laugh if my surgeon brought me these concerns fed to him by a competitive rep.
     
  9. anonymous

    anonymous Guest

    I have not disparaged Oxinium by pointing out factual anecdotal failures. Overall, Oxinium is a good alternative to CoCrMo, but it simply does not beat CoCrMo in all ways all of the time. The amount of metal in these rare cases WELL exceeds that of accidental CoCrMo on CoCrMo motion. In spite of Zr's biocompatibility, the sheer volume of metal produced is still very detrimental to fixation of surrounding components. With such a defensive posture towards this product, you ignore your product's shortcomings, which are few but do exist.

    Originally, I started on DePuy for using a PVD ZrN on CoCrMo, since this is not likely to adhere long term. Oxinium's main weakness is it's underlying softness, which in rare cases can cause severe problems for the patient. It is a well engineered material for this purpose.
     
  10. anonymous

    anonymous Guest

    Again, I don't sell Ox anymore, but always had to deal with competitive reps spreading false claims about the "coating" that flakes off and turns tissue black. Sounds like you know more than any in my area, but still, there is a bit of grasping at straws with some of those rare cases. The science is there, and for the most part, there aren't many negatives. I think it was an easier discussion surrounding knees and wear than on the hip side, as all we had to go on was neck lengths without a skirt when comparing to ceramic heads.