Artificial Knee Replacement: An Overview

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Artificial Knee Replacement: An Overview 




Guest:  Dr. Harry Demos – Orthopedic Surgery

Host:  Dr. Linda Austin – Psychiatry


Dr. Linda Austin:  I’m Dr. Linda Austin.  I’m interviewing Dr. Harry Demos who is Assistant Professor of Orthopedics here at the medical university.  Dr. Demos, let’s talk about knee replacement surgery.  Who’s a good candidate for that surgery?


Dr. Harry Demos:  Knee replacement is an operation that is designed for people who are having lifestyle-limiting pain in their knee from arthritis.  So, I don’t put age limitations on that.  But, in general, if you look at the patient population that develops arthritis in their knees, usually it’s in the mid-40s on up.  We do see some younger patients that have rheumatoid arthritis that sometimes need a replacement at a younger age.  But, in general, it’s very commonly seen in the high school football player who tore his ACL playing football and limped on his knee for years and then developed arthritis from having an ACL deficient knee over a 20-year period.  So, we’re seeing them at around 40 years old, for the younger patients.


Now, as patients get older, there are many patients that we don’t see until they get into their 60s or 70s that developed arthritis just over time.  But there are two distinct populations, usually in the 40-50 and then in the 60-70 age population, we see a lot of those patients with arthritis.


Dr. Linda Austin:  Are you ever too old for knee replacement?


Dr. Harry Demos:  It really depends more on physiologic age than chronologic age.  I’ve done knee replacements on 90-year-olds and beyond that have done incredibly well.  A lot of that has to do with what it takes to be 90 years old and still active and still want to have a knee replacement.  Those patients are usually pretty fit, and they’re much healthier than many of the 60-year-olds that end up needing a knee replacement.  So, I don’t think there’s an absolute cut-off for being too old.  It really depends on medical co-morbidities and other problems that people have as to whether or not they’re good candidates for this.


Dr. Linda Austin:  How many of these do you do a year?


Dr. Harry Demos:  About 100-150 a year.


Dr. Linda Austin:  It must be a very familiar procedure for you.


Dr. Harry Demos:  It is.  It’s something that I do a lot of.  I’m fellowship-trained in hip and knee replacement surgery, so it is something that I do frequently.  It’s the vast majority of my practice.


Dr. Linda Austin:  What are some of the most common concerns patients have going into this surgery?  What are the questions you get asked?


Dr. Harry Demos:  With knee replacement, in particular, I always talk to them about the complications and everything else that can potentially happen, but also about the benefits.  Everybody wants to know, what can I do and when can I do it?  And, in general, for knee replacement, I’d want to get people back to doing what they want to do, including recreational activities, playing golf, playing some tennis.  We do have one patient that has won many championships, even at the national level, in her bracket playing tennis.  And that’s part of the reason why we do joint replacement surgery, to get people back to an active lifestyle.


Dr. Linda Austin:  How about really physical things, football, soccer, basketball?  Are contact sports a problem?


Dr. Harry Demos:  I think that contact sports are probably not appropriate.  And most patients who are seeking joint replacement surgery are past the age of doing contact sports.  The things you worry about with contact sports are fractures around the prosthesis.  I don’t think they’re going to damage the prosthesis or pull the prosthesis loose.  But, these are artificial implants and they do see wear-and-tear just like any artificial substance would when it’s put through a tremendous amount of motion, a tremendous amount of stress. 


I often use the analogy that it’s like the tires on your car.  You don’t put a set of new tires on your car to park it in the driveway.  You put a new set of tires on your car so you can drive your car.  And you want to drive your car, and you can drive it down the highway, and you can do what you need to do in your car, but it doesn’t mean that you slam on the brakes every time you come to a stoplight and take every corner at 70 miles an hour.  So, the knee replacement is kind of the same way.  I think you need to be reasonable about what you’re doing.  I don’t impose significant activity limitations on people.  I want them to get back to doing what they want to do, and there are not too many things that are completely out of the question.  I would say contact sports are not the best idea.


Dr. Linda Austin:  How long is the recovery period after surgery?


Dr. Harry Demos:  Knee replacement takes a little bit longer to recover from than hip replacement, and that’s one of the frustrations that we’ve had with knee replacement for many years.  I think we’ve improved that a lot.  And a lot of that came out of the minimally invasive surgery controversies, if you would, that have come around recently.  I think the biggest thing that came out of minimally invasive surgery is an improvement in perioperative pain management and an improvement in physical therapy, not necessarily the length of the incision.  And by improving the level of pain earlier, we’re able to get people back to doing things quicker.


But I tell people that it takes me about two hours to get them in and out of the operating room and get this procedure done, and it’ll take them about two months of doing their job, which is the physical therapy and the work to make this thing as good as it can possibly be.


Dr. Linda Austin:  What are the controversies in knee replacement surgery these days?


Dr. Harry Demos:  There have always been controversies in all types of joint replacement, and knee replacement.  Probably the biggest is minimally invasive surgery.  There was a lot of marketing around minimally invasive surgery a couple of years ago.  The hype has calmed down a little bit as some complications, problems, and things came out.  I think a lot of surgeons not only altered the surgical technique but also altered the implants in order to accommodate for minimally invasive surgery, and that did lead to an increased complication rate in some studies.  So, that’s one controversy.  But I think a lot of that has cooled down a little bit now that there’s not quite as much marketing towards minimally invasive surgery.  I think what’s important is to do the operation through the smallest incision that we can, but still do the operation right, that’s going to last the longest period of time.


Other controversies, there are some controversies about whether we should save the posterior cruciate ligament or sacrifice it.  That’s been an ongoing controversy for 15, 20 years.  And the reason why it hasn’t been resolved is that there’s really not that much of a difference.  There’s a controversy as to whether the platform should rotate or not, whether it should be a fixed platform, cement versus no cement.  There are   many controversies and many things that some people are very set on saying that this is the way that it should be and the only way it should be.  But there’s certainly data to support the other ways of doing things as well.


Dr. Linda Austin:  Dr. Demos, thanks so much for talking with us today.


Dr. Harry Demos:  Thank you very much.


If you have any questions about the services or programs offered at the Medical University of South Carolina or if you would like to schedule an appointment with one of our physicians, please call MUSC Health Connection:  (843) 792-1414

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