Dr. Callaghan: Leo and I have been friends for a long time. Just like he said, I was president of the AAOS and when someone wrote me an irate letter, I just said, “I appreciate your perspective.” And I’ve always appreciated Leo’s perspective and even more so today.
So, my disclosures are that I have designed both knee and hip implants. And believe it or not both cementless and cemented knee implants.
One might say that long-term data is irrelevant to today—and I would agree with that. Why? Because the demographics of patients today are totally different. They’re younger and heavier.
The devices are improved. The capture mechanisms are improved. Polyethylene is markedly improved. Kinematics improved. Patellofemoral joints and fixation are improved.
And the one thing with 20-year follow-up is that most of those patients were over 65, and very few of them are living out to 20 years.
So, when you look at some meta-analysis—this happens to be by Michael Mont—cemented versus cementless looks pretty close. Ten years, same survivorship. Twenty years—Leo would probably say that 5% is a little different. The good thing is as he pointed out, they do better with screws.
And that brings me to Leo’s scab theory.
A scab, if you pick on it, it is not going to last. So, since I heard this for the first time this fall in Paris, I started looking for the scab theory. So, in a 22-year follow-up X-ray, I still can’t see the scab.
Why should one consider using cement to fix the total knee?
It works, it’s durable, it provides predictable clinical results.
The prosthesis I use today is really a variant of the prosthesis that was used over 20 years ago. We had the opportunity to review mobile bearing LCS knees and I still believe in a mobile bearing and maybe that’s why the scab doesn’t quite come as frequently.
Our 20-year results show no loosening. Our results have been corroborated by many other investigators using many other cemented designs. Sculco with 8.3% revision at 20 years with the Total Condylar knee. Kinematic I knees out to 15 years. CR knees working just as well.
Ritter, as he said, with cementless they did well, but his cemented results were just as well as his cementless results. And the IB results at 10 years, and in younger patients, had 92% success.
So, Leo’s scab theory of cement does not hold out at least at 20 years as far as I can see.
We should always go to registries to find the real data. In the Australian Registry—the cement curve always outdoes the cementless design out to 15 years.
I don’t think there’s really a need to change. I haven’t seen it yet, or I didn’t think I did. But we are starting to see some failures in patients with poor bone, large patients who are caving in medially. And today, in big, huge people I’m actually using a long cemented stem, and I’m a little bit uncomfortable with that, but that’s what I’m doing to try to prevent that caving effect.
So, for this reason and for all the success that Leo’s reported with cementless TKAs, after the New Year I’m going to embark on a prospective study evaluating a contemporary, cementless total knee design. And the best part about that is Seth will never be able to make me debate Leo anymore because I’m going to be in his camp.
Zebra’s do change occasionally. I thank you for your attention.
Thought you might find this of interest.
I have been using cementless total knees for almost 14 years now. I admit I don’t do the large numbers as the presenters, but I have had great results. The only ones I had to revised was due to surgeon’s error. I placed too small a tibial component and it settled. I have used cementless in 90 year old female and a 95 year old male and 400lb males.