“If I can do an osteointegrated total knee and I can choose the one I want and I do the operation myself then I will guarantee it for a lifetime, ’ says Leo Whiteside. John Callaghan: “Lifetime guarantees are dangerous in ALL aspects of life. Look at Vegas…marriage capital of the world…50% of those don’t work out. Death and taxes are the only guarantees.”
This week’s Orthopaedic Crossfire® debate is “The Cementless TKA: Lifetime Guarantee on Parts and Labor.” For the proposition is Leo Whiteside, M.D. of Missouri Bone and Joint Center in St. Louis, Missouri; against the proposition is John Callaghan from the University of Iowa. Moderating is William J. Maloney, III, M.D. from Stanford University in California.
Dr. Whiteside: “If I can do an osteointegrated total knee and I can choose the one I want and I do the operation myself then I will guarantee it for a lifetime. But it depends on the design, porous technology, instruments, and technique. We’re trying to improve upon the knee that gradually worsens over time—and that’s the typical cemented total knee replacement.”
“Ranawat’s data from 1993 shows that this failure begins at about five years in the more challenging patients. You see the same thing in Dr. Callaghan’s data…that after ten years falloff begins to occur. These interfaces are crucial…the bone-cement interfaces are crucial and the cement-metal interface is a big issue. We continue to see reports that have failure at the interface between the metal and the cement. It doesn’t always show up on cement, but when you get in you find that the implants are loose in the cement and the cement is broken up underneath those implants.”
“Bone ingrowth offers advantages. Early reports were not favorable, primarily due to inadequate design and engineering. Inadequate fixation with little pegs made the PCA (porous coated anatomic) fail at a higher rate. The terrible metal-backed patellar components…gamma radiated poly with flat implants was a bad idea…poorly locked polyethylenes…all coincided with starting cementless technology.”
“Porous coating technologies are a big issues. Patch porous coating leads to osteolysis and failure in many cases. But reliable technology has been here since 1980. An alignment system and a tibial finishing system that allows you to fix the implant tightly to bone and have it be stable. You want a reliable stem with peripheral porous coating and peripheral capture…and in situations where you don’t have hard bone, it’s good to have a stem extender that allows you to make it tight, make it fit, and get it fixed in virtually every case.”
“An article by Bartel and Burstein from 1989 was spot on: a stem with peripheral capture leads to loading of that bone. My clinical results confirm that. When we looked at that type of technology over the past ten years we found—in 256 patients—was one case of loosening. We continued to follow these patients out further to 18 and then 20 years. We found a loosening rate of well under half of 1%. And their pain didn’t worsen.”
“As for osteointegration the question is how to do it right. Full porous coating is an extremely important part of this design, and an anterior radiolucent line can occur routinely. If you give them an anterior porous coating very seldom do you have trouble. You must have excellent instrumentation that guides the saw and you must be able to redo the tibia if necessary. A stem is a crucial part of tibial fixation. My survivorship results with this in a Profix knee at 12 years were nearly 99%; none were revised for loosening. Aaron Hofmann’s study also found no loosening at ten years.”
“I now use a thin saw blade—not a big change from 1980—and the same sort of cutting blocks, but just less bone burning. I use a strong implant that is rigidly fixed with a high tech porous coating on the femur and the tibia. As it goes in I’m determining whether I need screws. I remove the initial driver and finish off with a mobile driver that ensures that this thing is going to be seated. For the one out of one hundred that doesn’t have good fixation I use screws. I use a secure locking/sealing mechanism that makes sure that the poly doesn’t fall apart.”
“When I see osteointegration at the tip of the stem I am happy. A ceramic that’s made of space age material and fixes well…smoother than metal and much less reactive…and can be put in with a technique that works every time.”
Dr. Callaghan: “So why are lifetime guarantees dangerous in ALL aspects of life? I think you can start right here in Vegas…marriage capital of the world, but 50% of those don’t work out. Death and taxes are the only guarantees.”
“Recently, as part of the knee replacement industry’s direct to consumer marketing campaigns there have been suggestions that knee replacements should last a lifetime…or at least 30 years. I’ve done a lot of wear simulation studies and what happens in the lab is often different from what happens in humans. While some ads contain a lifetime knee warranty, it’s important to read the fine print. The ‘limited lifetime warranty’ contains caveats such as ‘for the life of the patient, but one-time free replacement of parts; free replacements of components only.’ And they reserve the right to modify or withdraw the warranty at any time without notice. It doesn’t sound like a lifetime knee guarantee.”
“The real problem with cementless knee replacement is that we already have a problem with patient satisfaction. And for those patients who don’t bone ingrow their surfaces…and some of those other designs that Leo said that don’t work well with cementless, you don’t know what to do with those people.”
“I do give Leo credit that the 2012 Australian Joint Registry is showing that cementless fixation is close to that of cemented fixation out to 11 years. Older data has consistently shown cementless fixation to not be as good as cemented. In Aaron Hofmann’s paper from 2002 there was 111 month follow-up with no revisions for loosening. In a 2011 paper by Kamath from the Journal of Arthroplasty there were 100 knees with tantalum monoblock; all patients were under 55 and there were no fixation failures.”
“In Leo’s work from 2007 he shows osteointegration, though if you look at most studies about 5-10% don’t osteointegrate. So his seven year results are impressive, but seven does not a lifetime make. He has another thing going for him…as we age we decrease our activity level, so maybe these warranties will last a bit longer. There is data showing that we all decrease our activity over time. I would go with a prosthesis with the best long-term track record. For us, those have been with cement. In 2010 we published a study with 119 knees and a minimum of 20 years of follow-up; we had no revisions and one loosening.”
“You will have reoperations…even with cement. We had three in that group—one for hematogenous infection and two for periprosthetic fractures. Also, if you’re operating on patients who are under age 60 you’ll have a lot of them living out to 20 years…so I’m not sure we should be making those types of claims. I think it is unwise to make such guarantees.”
Moderator Maloney: “Leo, one minute to rebut?”
Dr. Whiteside: “There’s no guarantee that is really a promise. You don’t promise a patient it will last a lifetime. But I think that with the right technology you could guarantee a lifetime with that knee. In a small minority you would have to replace them. When my patients ask, ‘How long is this knee going to last?’ I say, ‘I can’t promise you how long it’s going to last, but you can’t wear this out in 20-30 years—unless you start trying to do athletics.’”
Dr. Callaghan: “There is one statement you made that concerns me. I have confidence that a lot of people are going to take their knee replacements to the grave. But the younger patients need to be followed. I think we sometimes give them a false sense of security when we give them those claims.”
Moderator Maloney: “Leo, you and others have reported excellent results with different designs. Why aren’t we all doing cementless knees?”
Dr. Whiteside: “That’s coming. You look at all of the new developments and they are in cementless technology. Cement is 1970s technology.”
Moderator Maloney: “John, you quoted a lot of good results with cementless knees…why aren’t you doing them?”
Dr. Callaghan: “There’s no question with the hip that we know that osteointegration can’t work forever. I still have confidence that this could happen with the knee too. I used cementless knees when I started my practice in the 1980s. It wasn’t a great design, and as these new designs are coming in people should look at these and try to give those of us who lost confidence with cementless fixation more confidence to return to it in younger patients. One million younger patients will need the operation in 2030 and there aren’t a lot of long-term follow-up studies of cement in patients under age 55.”
Moderator Maloney: “Leo, one of the problems is that you do a cementless total knee, the patient comes in with pain, and you’re worried about osteointegration. You do a cemented one, the patient comes in with pain, and you tell them, ‘Go away, it’s going to get better.’”
Dr. Whiteside: “No, we’d probably have to operate because it’s de-bonded from the cement. Or it’s loose and migrating into the lucent lining.”
Moderator Maloney: “The tendency with a cementless implant is to eliminate that as a potential early failure mechanism.”
Dr. Whiteside: “I don’t think it’s an early failure mechanism…it goes one step too far so you don’t have to take that step later. I don’t think that’s good practice.”
Dr. Callaghan: “That’s why I showed you that slide about satisfaction rates. I’m the first to admit that there are people with cemented knees who are not satisfied. But in this country many people are more willing—with a cementless knee that you see bits of radiolucency around—to go in and re-operate on that patient with cement. Now those people don’t all get better.”
Moderator Maloney: “Leo, perhaps with the bone preparation with cementless designs it’s more important. Irrigation…it looks like you’re constantly irrigating the bone.”
Dr. Whiteside: “You should irrigate and cool and use thinner saw blades…and don’t jam your saw blade and make the bone smoke.”
Moderator Maloney: “John, in a 40-year-old patient should the goal be a cementless total knee replacement? Do you think it’s got a better chance of lasting another 40 years?”
Dr. Callaghan: “We need to take another look at that, especially with the newer polys, the newer surfaces. I think maybe by the time Leo stops operating it might come around.”
Moderator Maloney: “He’ll never stop operating, so we have plenty of time. Thank you both.”
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