Hi Dr. Amanatullah! How are you?

Dr. Derek Amanatullah:

I’m amazing thanks again for having me.


Absolutely pleasure to have you always. Let’s start talking about revision surgery. Just at a high level what is revision surgery?

Dr. Derek Amanatullah:

The revision surgery is basically a redo of a first time hip or knee replacement. It can happen for lots of different reasons, different reasons in the knee and the hip. But really, a revision basically is exactly as it stated: it’s a second go or even more than a second go at getting the joint replacement to work correctly.



We’ll start with hip replacement revision surgery. Just talk a little bit about what would cause someone to need of revision surgery done to a hip piece and what you do when you go in there to revise it.


Dr. Derek Amanatullah:

So there’s lots of ways that a hip replacement could fail. The good part is most of them don’t fail. So kind of the aggregate data would say after a prime well done primary or first time hip replacement, ninety to ninety five percent of them are in place or haven’t been revised by about twenty years so they do really really well. What we’re talking about now that ten percent or five percent. In that percentage, the things that can cause hip replacements to fail are infection, dislocation, that the implants loosen up, or that wear debris or wear particles can cause the implants slowly loosen up through inflammation. Additionally other things might be a fracture or something that compromises the bone.


Of those things they’re all really get handled almost in the same way except infection.

So the reason infectious revisions are treated differently is because I have to get rid of the infection first before the hip can really be revised. If it’s an infection, the infection basically dominates the treatment of that patient so what we would do in that case is likely remove the implants or we might do something called a irrigation debrisment, change that hit the kind of the modular parts the head in the liner. I know that all sounded really complicated but the first thing to do is to get rid of the infection no matter what.


After the infection is gone, the infection surgery gets treated the same as the rest. What we wanna do at the end of the day is get stable implants so the implants are not stable because a fracture or the implants are not stable because wear debris or the implants are not stable because of loosening, we remove the implant that’s not stable and make it more stable.


If the implants are fixed in place, meaning there could be at this location but the implants are fixed in the bone, we may need to remove those implants from the bone. To do that I might you’ve actually even need to make a fracture, break the bone to remove the implant safely that sounds like a difficult thing it’s actually easier and more soft tissue friendly for the patient to break the bone than it is to compromise the tissues around the head.


So lots of things might happen in order to revise the hip but what we want is stable implants it’ll grow into the bone with a hip that doesn’t dislocate and doesn’t have an infection. That type of hip puts us in the best place to reduce pain and give people a functional leg after hip replacement surgery.



Let’s move on to knee replacement surgeries because I imagine they’re a little bit different when you have to go in and revise a knee. Talk first a little bit about how they’re different structurally, and then talk about what you do differently, the different issues that can occur in that particular joint.


Dr. Derek Amanatullah:

Yes so knees are definitely different.


What I would say about the differences that you can imagine a hip joint is actually a little bit simpler. It’s basically a ball and socket. So the goals in that surgery are simpler. I need to have implants fixed in the bone and the need to have the hit that ball and socket to stay in place when you move through the hip range of motion.


The knee is a little bit different. The knee is a complex joint. Tt’s actually three joints: one joint on the inside of any one joint on the outside of any one joint on the top of the where the kneecap runs over. And so I have to balance three joints to get that knee to work correctly and so there’s different ways that knee replacements fail.


They also fail by infection, but in general they don’t dislocate like hips. They can be unstable were positioned incorrectly. They can also be subject to fracture or wear debris just like hip replacements. So there are subtle nuances to getting this to work correctly. But it really gets into how you balance and how you get those three joints to work correctly.


Additionally, how you get the implants out. So In infection you treated the same way.

Basically you have to treat the infection first. That could mean taking the implants out or changing the modular parts but once those things have been handled, we treat all the knee revisions basically the same way. We remove the components that are positioned or loose and we need to get him fixed in the bone.


But there’s no special fractures that we make around the knee. The knee can be subject to a lot of bone loss when the implants come out because most knee replacements are cemented into position and sometimes that cement can be even stronger than the bones so the bone comes out instead of the cement.


The good part is is getting knees  fixed into position isn’t that complicated and there’s lots of new things that help us get the knee replacements is fixed. We have things called cones we have things called augment what does do is they replace the bone with metal.

And Let us put the new knee in that in the perfect position so that we can revise that knee to get those three joints balanced correctly.


There’s big differences between needs and have ultimately. But really, most of that’s on the surgeons and have lots of patients to come back to me after a revised knee they’ll say it’s better than when they originally got it because it’s really about getting it in the right position for that patient to have a stable balanced knee meaning that all those three joints are in the right spot making the right compromises to get the good function out of that knee.



Absolutely explained as always Dr. Amanatullah thank you so much!


Dr. Derek Amanatullah:

No worries thanks for having me again.