Mathew Pombo, M.D., an orthopedic surgeon at Emory Orthopaedics and Spine Center in Atlanta, Georgia, discusses 3D knee replacement with more precise alignment.
Interview conducted by Ivanhoe Broadcast News in March 2017.
How often is knee replacement done in the United States and are those numbers going up?
Dr. Pombo: In terms of how often I’m not sure. It’s very common in terms of commonalities of surgeries, of any surgery, of any surgical field. I would say it’s in the top five surgeries being performed, certainly more common in orthopedics. It’s probably not as common in arthroscopic meniscus, it’s up there. There was a study a while ago that showed it was in the top four lifestyle enhancing surgeries performed across all specialties. It’s a great surgery to get people their lifestyles back when they get to that point. It’s definitely becoming more and more common I think for several reasons. We’ve always said the baby boomers, we’re seeing that now but we also have a lot of younger people participating in sports and we know that prior injury leads to posttraumatic arthritis. Our generation, our parent’s generations were the first ones that were active throughout their life so we’re really learning more about what a lifetime of muscular skeletal activity does. We’re seeing arthritis at an earlier age not only in the knees but shoulders, really everywhere. It’s becoming an epidemic of sorts. So having alternatives and ways to treat arthritis is important.
What is a 3D knee replacement? When our viewers hear that term they are like that sounds cutting age and space-age, but really, what is it?
Dr. Pombo: It is, it’s a little bit of jargon and every knee replacement is a 3D knee replacement. It evolves through technology, 3D before twenty years ago was an orthopedic surgeon making an incision and going in and looking at bones and saying, look at this 3D piece how are we going to make cuts to take out this arthritis and restore the alignment of the limb. It’s evolved through technology to bring in technology where it’s more AutoCAD programming and engineering to sort of look more precisely through mechanisms that we have and know are more precise then our human eye. I think that’s where the 3D technology comes in. I think some of its marketing to play on that technology pool to individuals. In healthcare’s it’s just been away to 3D conceptualize and see a whole reconstruction in space before you actually make cuts, cement the joint and you’re stuck with it. So it’s been a way sort of see things before you actually do. Sort of a measure twice, cut once philosophy.
If you could explain to our viewers the steps you have to take in a 3D knee replacement as opposed to a standard knee replacement.
Dr. Pombo: Standard knee replacements you make an incision you go in and you look at the bones and you actually make cuts. When you make cuts you put trial components on. You take pieces to space the joint out and sort of rebalance and tension the joint. What we focus on is the mechanical alignment because the mechanical alignment is the key to long-term wear. If you’re off on the mechanical alignment you can get pain and the accelerated wear of the total joint components. So throughout time we focused on the mechanical alignment. And what we sort of evolved through time was realizing that our human eye wasn’t as accurate as we thought it was. So there was navigation during my time of training where we would actually put a raise on bones and be able to look at it on a computer screen so we could see the mechanical axis while we were doing joint replacements. That added a lot of time to the surgery and was a little bit cumbersome but gave us great data that we were more accurate when we had input. So what it involved is patient specific cutting blocks where we did CAT scans or MRIs and we could get blocks made to make the cuts. But we still had to take all those trial components and there could be an assortment of them, ten to fifteen per knee replacement. You try to put which one fits best on the femur and which one fits best on the tibia with a single plastic that fits best to align the joint. Sometimes you have to give and take to find what works best. Historically those knees have done very well but this new technology came out where we were obtaining a CAT scan. We were sitting at a computer with some engineers and AutoCAD designing a complete total knee replacement based on the morphology of bone. So everyone’s bones are a little different, everyone’s design a little different. A lot like our faces and our hair color and our body types as well as our mechanical axis are a little bit different. So by getting this CAT scan from the hip all the way to the foot with people standing we can input components into the computer and actually print off a specific femur and a specific tibia that fits the bone perfectly. A series of three trial components that you can tension and balance the knee because there is still some soft tissue components to the knee that are important. The ligaments around the knee as well as the joint capsules that get contracted or are loose, you have to balance those.
Once you have those scans, the 3D scans, where do you go from there?
Dr. Pombo: We get the 3D scans on a certain protocol and here at Emory we have them. Anyone who does this knee replacement has certain CT locations where they utilize it has a protocol. That protocol is done and we send it to the company. The team of engineers at the company reviews it because sometimes if the patients have too much deformity they’re not a good candidate for the replacement. They will let us know if they are a candidate and then in six to eight weeks timeframe we usually can build that knee replacement for them. That’s one of the negatives, traditional knees I can do within a couple of weeks and they get their medical clearances. This knee takes a little bit of planning because it’s a six to eight week process to actually get it built.
So it’s build your own knee?
Dr. Pombo: It’s definitely cool technology. I grew up in technology that’s what I studied, I’m an engineer by trade and went in to medical school. So these sorts of things are very fascinating to me. I think new technology things like this have so many applications as we go forward in to other areas like hip replacements and shoulder replacements. Things like that I think are going to be fantastic when we can use engineering to be more precise rather than using our own eye. Even though we’re surgeons and we like to think that we are very precise and for the most part we are. When there’s a lot of skin and body tissue and people aren’t skin and bones so it’s sometimes hard when you’re in surgery and people are prepped and draped and you’re looking at a knee to figure out if you’ve got the alignment corrected.
Surgically is it the same surgery then once the knee is personalized?
Dr. Pombo: It is the same approach as we typically use and there are several different approaches. There are minimally invasive approaches to the knee, those came in to vogue and we realized those didn’t provide any long term differences. As surgeons we talk more long term results. Is the wear better, does the knee last longer, what are the acute and long term complications that we see with knee replacements? This is a knee replacement that hasn’t been out thirty years. There are a lot of knees that we’re testing in labs that we’re calling thirty year knees. I get asked that question a lot. My answer is I will tell you in thirty years. But the reality is that same knee isn’t going to wear in a forty year old who is a hundred and twenty pounds as a forty year old who is three hundred pounds. Or the 60 year-old that’s a hundred and twenty versus the forty year old that’s three hundred, it’s a usage pattern. The biggest advancement in knee replacement has actually been in the plastics they’re much lower wear. We’ve got Vitamin E in plastic, we’ve got certain things of the way they are actually molded and heat annealed to reduce the free radicals as they wear because those eat up the cement which we have to do in knees. Mechanical wear leads to those particles and I do believe that these patients’ specific needs have a part in that as we go forward.
Who’s the best candidate and who would not be a good candidate for a 3D knee?
Dr. Pombo: I’m a sport medicine physician so I’m looking for always the latest and greatest for my athletes, my retired athletes, my aging athletes as I like to call myself. A lot of these athletes have had injuries growing up and they’re at risk for early arthritis. So for me the 3D knee reconstruction with a patient’s specific implant that fits perfectly in theory should wear better. It should fit better, it should do better, it should function better. Has that panned out, some of it yes but the long term part we’re still studying but I feel initially it was for my younger patient. It’s a little bit more expensive from a knee replacement but those costs aren’t really transferred to the patient. It’s still an insurance based thing. So initially we were seeing some benefits where certain insurance carriers were carrying it and other weren’t. Now it’s expanded that all insurance carriers are covering it. It’s an outpatient surgery now I do the surgery the same day and patients go home. I don’t have to stick rod and alignment rods up bones, up the femur to basically align the mechanical axis. That’s all done for me on a computer. I have less bleeding, I have less pain. I can tell you from knees I’ve done before where I’ve had to get MRI’s or something else that the bone marrow when you instrument the marrow it isn’t normal anymore. So I don’t have to do that with this particular knee replacement there’s a lot of benefits to it from blood loss. So I’ve actually extrapolated those to my older population, that if there’s less blood loss there’s easier recovery. In those patients that actually have some risk factors it has been better. I think in an older population that’s active I do consider that as well. If it’s a grandma who’s eighty years old I think they could go either way if they’re just looking for pain relief. But somebody who’s looking for a knee that may last longer, that’s patient specific, that we need time and usage out of this I’ve been very happy with the results with this knee replacement.
Talk about Amanda specifically, she’s younger than fifty, when you have a young patient who has tried everything, needs replacement what is the benefit for her? What was the benefit for her specifically with having a 3D knee?
Dr. Pombo: Well specifically for her being young my personal belief and this is obviously a personal opinion that this knee is good for that patient age group. A younger population that the knee fits perfect should wear less. It’s basically like putting a train on perfectly aligned train tracks, it should track better. That’s really the theory of why I’ve really pushed this in the younger population. Don’t get me wrong there’s still more people over sixty five that get knee replacements than under. But that’s becoming more common. In Amanda particularly you know she did well with one and we’re doing her other one six weeks later, we just completed it. She essentially had both her knees replaced within six weeks, has done fantastic and is very happy. She actually took a little while to make the decision on the first one. Really ninety percent of America when you say you need a knee replacement or you are a candidate isn’t ready for it. There’s a big emotional component to becoming ready to have a knee replacement. The thought of putting something artificial in compared to what your momma gave you is tough to swallow. All knee replacements aren’t perfect they’re still mechanical man made bearings so people have to understand that going in. It’s not something that we ever put in and recommend you go snow skiing, because if you have a great result and fracture from a fall you all of a sudden don’t have a great result. I’m a big believer of never telling people they can’t do something if they feel like they can do it. I just want them to understand the risks.
Is there anything I didn’t touch on that you want people to know?
Dr. Pombo: I think 3D knee replacements are sort of the wave of the future. I think we’re still dialing it in. This was the first company that did it and currently the only one that has this technology. I think we’re on a tailspin of sort of technology. It’s an exponential growth, technology breeds more technology so it’s a super exciting time. As surgeons sometime we’re hesitant to jump on board. As I tell my patients, you never want to be the first to try something but you also never want to be the last. I think this knee replacement has really changed my practice. It’s made knee replacement something that younger patients are a little more excited about. I think we relate to technology. It’s not the same knee that grandma gets so that’s easier to easier to understand than when you’re forty eight years old like Amanda. I think it’s the wave of the future I’ve been very happy with it. I certainly am cautious about saying it’s better than other options. I think people have to weigh every option and what’s best for them. This is a newer implant, we’ve been tracking it for ten years or so, has great early term results. Knee replacements are lasting twenty five, thirty years now. We are still are in the early term but our short term results are fantastic and I think from a younger active population that’s very important.
END OF INTERVIEW
This information is intended for additional research purposes only. It is not to be used as a prescription or advice from Ivanhoe Broadcast News, Inc. or any medical professional interviewed. Ivanhoe Broadcast News, Inc. assumes no responsibility for the depth or accuracy of physician statements. Procedures or medicines apply to different people and medical factors; always consult your physician on medical matters.
If you would like more information, please contact:
Alysia Satchel
678-474-8018
Alysia.satchel@emoryhealthcare.org
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