Moderator Berry: Would both of you agree that the biggest problems with the ceramic-ceramic bearing remain a risk of fracture of the liner, probably usually due to impingement or mal-seating, and risk of squeak?
Dr. Lee: Yes, I would. Fracture of the liner is probably mal-seating and occurs at surgery.
Moderator Berry: Mal-seating or impingement due to mal-positioning of the cup?
Dr. Lee: Yes.
Moderator Berry: Steve, would you agree with those 2 points?
Dr. MacDonald: I agree those are 2 drivers. I think cost, honestly, is a pretty significant driver.
Moderator Berry: I’m just talking about failure reasons, not drivers of use. There’s agreement on that. Secondly, what are the potential benefits of ceramic-on-ceramic? Gwo has shown that ceramic-on-ceramic is not, right now, beating ceramic-on-crosslinked polyethylene in most registries at 15 years. Do you agree with that point? Do you want to rearticulate your argument?
Dr. Lee: I would agree in part with those statements. I don’t agree that at 15 years ceramic-on-polyethylene is beating ceramic-on-ceramic. The Australian Registry for patients under 55, at 16 years the cumulative revision rate is actually 10%, whereas for that population ceramic-on-ceramic it is only 7.7%.
Moderator Berry: Steve, is the data you presented slightly biased by having all comers rather than looking at a very young population?
Dr. MacDonald: It could be. Really, whether the patient is 65 or 40, you’re still 15 years out. So, we could debate that back and forth. As the registries get longer out, we have more patients, we’ll be able to make better conclusions.
Moderator Berry: Steve, what’s going to happen in 20, 30, 40 years for the really ultra-young patient. Do you feel that you have confidence that crosslinked polyethylene is going to keep performing well out to that length of time? Or do you think that eventually you’re going to see the curves cross over?
Dr. MacDonald: Well, if you look at the behavior of polyethylene, you get a linear wear over time and cumulative and that’s a burden. We’re not seeing that with highly crosslinked polyethylene. It’s not like at 15 years we’re now seeing a 10% or 15% wear or lysis, so we’re really sort of still at ground zero at 15 years. We’d have to have a very strange behavior to all of a sudden start falling apart at 20-25 years.
Moderator Berry: Before we close, let’s go back to this question about squeaking. So, Gwo has this problem gone away or is it still there and we just don’t want to talk about it?
Dr. Lee: It’s not gone away. It’s something I discuss with my patients when I offer a ceramic-on-ceramic bearing. I tell them that I have no idea what causes it. They have to weigh the potential for squeaking against the potential for excellent durable and longevity.
Moderator Berry: Steve, can I just come back with a quick closing question. If you knew that it would never impinge and was perfectly positioned would you think that ceramic-on-ceramic would outperform crosslinked polyethylene?
Dr. MacDonald: In my heart of hearts I don’t believe that. A number of papers have looked at squeaking and cup position and they’re not predictive. Even if we know the target, we’re not eliminating the complication.
Moderator Berry: Ladies and gentlemen, please join me in thanking the two speakers for an excellent session.
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I am 57 years old. I’ve been active in sports and outdoor activities all my life. I have had three orthopedic surgeon tell me I need a hip replacement because it is bone on bone. I have stopped running because of the pain. I still work out on an eliptical. I am considering as hip replacement using ceramic on ceramic. I live in southern Missouri about 4 hours South of St.Louis. Are there any surgeons relatively close to me that use the ceramic on ceramic material? I’ve seen on surgeon in New York, that uses ceramic on ceramic, but that’s a long way from home.
Thanks,
Darrell Brewer