Moderator Berry: I think you make a really good point.
Doug let’s look at the downside of the PS knee. Virtually every big, big, big registry study shows a slight—1 or 2% at 5-10 years—advantage of cruciate retaining versus posterior stabilized knees in terms of survivorship. Do you think a cruciate retaining knee, just because it’s a little less constrained, has a slight survivorship advantage or not? And if so, does it matter?
Dr. Padgett: I think that your points are appropriate, Dan, and it’s obviously hard to tease that out of the data. It doesn’t make a lot of sense to me that the survivorship would be matched for the degree of deformity and complexity of the patients. Quite frankly, it should be different for the two groups.
Institutional data, larger registries certainly support that concept. Unclear exactly what the etiology is behind that.
Moderator Berry: Fair enough. Is there a functional difference or advantage to the type of implant that you’re advocating compared to the one your opponent is advocating? I’ll start with Michael and then we’ll go back to Doug.
Dr. Meneghini: My argument is that there is absolutely no difference. With our current metrics and the data we have to date they are equivalent. There is data that if you resect the PCL or recess the PCL in cruciate retaining knees you get better motion. But they may also have less stability.
Dr. Padgett: I’ll tell you the one functional advantage of a posterior stabilized knee is that you’re not re-operating on posterior stabilized knees because of flexion instabilities. Mike, I think you’d agree with that.
Dr. Meneghini: Doug, I know that you live in Manhattan and seeing all those skyscrapers and the posts and all those things it makes sense. But those of us in the Midwest, that makes no intuitive senses to us. You guys walk into buildings all the time. We don’t want to do that. We like smooth transitions. I would argue that that mechanical device is showing up in the registries as less durable over 10-20 years.
Moderator Berry: Doug, so let’s go back to the post for just a quick second. The post does seem like a primitive way of getting rollback, I have to admit, even though I am a posterior stabilized user. Is there anything on the horizon that’s going to move us beyond the post but still get the kind of predictable kinematics that a PS knees gives us?
Dr. Padgett: I think unless we get over the first step of the total knee replacement, which we do right now, which is quite frankly resection of the ACL, and basically having a cruciate deficient knee, then what we have to use is what’s in our armamentarium
Moderator Berry: Gentlemen, thank you very much.
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