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Melanie Cole (Host): Welcome to UAB Med Cast. I'm Melanie Cole. Joining me today to discuss partial knee replacement is Dr. Scott Mabry. He's an orthopedic surgeon at UAB Medicine. Dr. Mabry, welcome back. I'm so glad to have you join us again today as we start talking about partial knee replacement, I'd like you to kind of set the stage for us and the difference between a partial and a total knee replacement.

Dr Scott Mabry: Well, thank you for having me. It's a pleasure to be back again. So just to set the stage, a total knee replacement is where you replace the end of the femur bone, the top of the tibia bone to the entire joint surface. And then there's a plastic piece between, which is essentially the new cushion of the knee. With the partial knee replacement, you're actually just replacing the area of the knee, that just has arthritis. So in comparison, you typically are preserving a lot more of the normal tissue, especially in patients that only have arthritis in one part of the knee, instead of just replacing the entire knee.

Melanie Cole (Host): Are you doing this robotically?

Dr Scott Mabry: So I am doing this with the assistance of navigation. Some people do this robotically and some people do it manually. The studies do show that if you use some sort of assistance, whether it's robotics or navigation, that the component positioning's a little bit more precise and that leads to a little bit better outcomes with partial knee replacement.

Melanie Cole (Host): Expand a little bit on some of the technical considerations when you're discussing navigation. For other providers that are looking at this as an alternative to total knee replacement, and they wanna know what you're doing that's so special, tell them.

Dr Scott Mabry: Sure thing. Well, in the instance of a partial replacement, you really want to preserve the side of the knee that you're not operating on, and then you know, under the kneecap as well. In order to do so, you wanna make sure that you're not putting your. Partial knee replacement in a position that could, cause issues in the rest of the knee over time and make the person develop arthritis sooner than, they would have otherwise. So with navigation and robotics, we're able to take the entire mechanical alignment, just meaning the entire axis of the lower extremity, and we're able to in real time, measure that.

And then when we make our decisions on where we put this partial knee replacement, we're basing it on the patient's own anatomy. And so that we can get the component positioning exactly perfect so that we're not overloading the other side of the joint or putting it in a position that could cause early failure in conversion to a total knee replacement.

Melanie Cole (Host): So as you're using navigation and discussing the technology involved, tell us about the benefits to the patient when we're doing partial versus total knee replacement. And Dr. Mabry, the benefits to the surgeon.

Dr Scott Mabry: Sure thing. I mean, the patient benefits are numerous. First of all, it is a less invasive procedure. , you don't actually have to move the kneecap out of the way to do this or fully move it outta the way I should say. So it is technically less invasive. We typically use a more, tendon sparing approach, when we do this surgery, so it's a little bit quicker recovery from that standpoint. whereas a total knee replacement might take up to three months to recover, most partial needs, are pretty much recovered by six weeks. Most of these, and all of these in my practice are outpatient. So same day surgery.

Whereas most total knees either have the option for outpatient, like we spoke about last time, or some stay a night. so this quicker recovery that way it does feel a little bit more normal to many patients. And I think that can be attributed to the fact that we do leave the ACL, which usually is taken away in the total knee replacement, but also there, the kneecap is the same. The other side of the knee we haven't operated on, so that's the same. So that typically it does feel a little bit more normal to patients than a total knee when you're replacing all those surfaces.

And then there's a little bit slightly lower, incidence of complications after surgery. And I think we can also attribute that to leaving a lot of the knee, without having to replace it essentially. Benefits to the surgeon. It's actually a technically a little bit more challenging, procedures, the fact that it's a smaller incision, so you're working in a little bit smaller. And that you really have to get that component positioning perfect. in order to have the patient have a good outcome. So I think it's a technically a harder surgery, but anytime we can spare the unaffected parts of the knee, I think the surgeon, that can offer this, it feels good about doing that for their patient.

Melanie Cole (Host): What about disadvantages? Dr. Mabry, if you're just taking the arthritic portion of the knee, Is there like something that spreads? Is it likely to come back in other areas, are they more susceptible to tears, such as acl, that sort of thing. Are there any disadvantages from your point of view?

Dr Scott Mabry: Yeah. I think the disadvantage would be in poor patient selection, you really have to make sure that the patients that do get partial knee replacements only have isolated compartment arthritis, meaning it's only on one side of the knee that there's no signs of it In other parts of the knee. You also wanna make sure that they have good, intact ligaments, especially the ACL, and that, they don't have anything like rheumatoid arthritis or another kind of condition that could cause arthritis to progress throughout the knee.

By carefully selecting patients, these last just as long, if not longer than a total knee replacement. But I think that is the key is just making sure that you're doing this on the right person. Otherwise, yes, you can have a partial knee wear out quicker, and end up having to convert to a total knee replacement.

Melanie Cole (Host): We'll then expand on patient selection. When you're looking for patients for whom this would give really great results, what are you looking for?

Dr Scott Mabry: I'm basically looking for patients that have knee pain on one side of the knee, that they really haven't had any prior ACL tear, or surgery on the other parts of their knee. And then I also look to see that the x-rays match up with where their pain is located. But given that that's really the main selection criteria, young, old, everyone kind of does the same with these as long as you're selecting appropriately. Activity level, I think initially they did these and less active people and then we realize doing these in more active people actually keeps their activity level pretty high as well.

So I think it really just has to do with matching the x-rays to the patient's symptoms and then looking for those other things I mentioned that could cause early failure and making sure that we're selecting appropriately.

Melanie Cole (Host): And how have your outcomes been with partial knee replacement? Dr. Mabry, how is activity level after? Speak a little bit about what you've seen.

Dr Scott Mabry: I think in general, the partial knee replacement patients that I have, typically do recover a little bit faster. Most are off assistance at two weeks when I see them back, in clinic. Usually starting to get back into a slightly normal activity about four weeks, and I think by six weeks most of them are doing pretty well, almost fully recovered anyway, and not a ton of pain. You have your outliers here and there, but I think as far as once people hit that six week mark, I feel comfortable letting them get back to normal activity. So I'm pretty happy with the results I've had in my practice so far.

Melanie Cole (Host): That's fantastic, and I'd like you to just summarize for other providers what you'd like them to know about partial knee replacement versus total, and why it's so important to refer to the experts at UAB Medicine?

Dr Scott Mabry: I think, the main thing to know is that this is an option out there. Not every provider, does offer this. I think it is a little bit more technically demanding for the surgeon, and you do really have to be careful with the patient selection. But if you do those two things, I think there is a great benefit in preserving the normal anatomy of a patient's knee instead of just replacing the whole thing. A little bit more normal feel and a little higher activity, it's all said and done. what I would say is the main reason they refer this to a specialist, especially someone that can't offer this, and, not every patient will be a candidate and we're happy to talk through it with the patient and kind of explain if or if not, partially would help them.

Melanie Cole (Host): Well, you certainly are the specialists and experts, and thank you so much Dr. Mabry, for joining us today. And for more information about partial knee replacement or to a referral patient to UAB Medicine, you can call the MIST line at 1-800-UAB-MIST or you can visit our website at UABmedicine.org/physician, That concludes this episode of UAB Med Cast, for updates on the latest medical advancements, breakthroughs, and research, you can always follow us on your social channels. I'm Melanie Cole.