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Foot & Ankle International
FAI May 2024 Podcast: Discrepancies Between Intraoperative and Postoperative Ankle Motion Measured for Anterior-Approach Total Ankle Arthroplasty
00:19:18
Although intraoperative ankle motion serves as a foundational reference for anticipated motion after surgery and guides the addition of procedures to enhance ankle motion in total ankle arthroplasty (TAA), the relationship between intraoperative and...
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Foreign.
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This is Charlie Saltzman, editor of Foot and Ankle International. Today I have the distinct honor of talking with Dr. Constantine Dimitrikopoulos, who is the senior author of MAID's lead paper in Foot and Ankle International. The paper is titled Discrepancies Between Intraoperative and Postoperative Ankle Motion Measured for Anterior Approach Total Ankle Arthroplasty. I selected this study to discuss because I found its findings both eye opening and perhaps even a little discouraging. I wanted a chance to learn more and to think about how the implications of the findings might affect my practice and yours. Dr. Konstantin Dimitra Koppelis is an associate professor of orthopedic surgery at the Hospital for Special Surgery in New York City, which is part of the Cornell University Medical System. Dr. Demetra Kopolis serves as a member of the AOFES Research Committee. Welcome to the program, Konstantin. I'd like to start by asking you to give a brief summary of your paper and its major findings.
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Charlie, thank you for having me on the podcast and I'm happy to talk about this paper and share with you our work. This was the first thing I'll say is that this was the idea of Rogerio Bitar, who is an orthopedic surgeon in Brazil and was one of our international research fellows in ankle arthritis and ankle replacement and and joined our hospital for a year. He would watch us operate and do ankle replacements and also did research with us, both clinical research and in the laboratory. And he would see that during surgery we would get to the point at the end of the case when we would have our implants in and we would trial our polyethylene inserts and we were deciding between the size of poly to use and assessing range of motion and are we getting more stability? Are we losing dorsiflexion? Do we need to do a gastroc recession or do we need to do an Achilles lengthening? We weren't really sure how to make these decisions. The biggest question we had at that time was, well, if I know that the patient will have this motion once it's all said and done, then maybe I don't need to do an Achilles lengthening, or maybe I don't need to do a gastroc recession. But what if they lose some of this motion? Do I need to do one to get them more motion with the expectation that they will lose some motion in the postoperative recovery? That negative tilt comes with the knowledge that we're not very good at improving range of motion after ankle replacement. You know, we're good at alleviating pain, we can improve function. Patients are happy in that respect. But most, and I would say almost all studies, show a very modest, if any, improvement in the range of motion in the ankle and in the foot when you look at the tibia relative to the entire foot. And so with that knowledge and with that framework and watching us sort of try to make this decision, he said, well, why don't you just measure how much motion you have during surgery and then measure how much motion you end up with after surgery, and then you'll know how much of it you keep and how much of it you lose. And that's really how the study began. And so our fundamental question was what percentage of intraoperative motion achieved during an ankle replacement is maintained at final follow up? And in this case, we defined follow up as when range of motion is maximized. And Mark Myerson's early work suggests that that's around six months. So we said, okay, we'll look at patients at six months, maybe up to a year, to see that initial, initial, final range of motion. How much of the intraoperative motion is retained at the end? And so we had a group of about 67 patients. And all these patients had preoperative weight bearing, maximum flexion and extension X rays, which I think is probably the best way to really separate out tibiotalar motion from tibiopedal motion. And these patients had intraoperative neutral X rays judged by the surgeon placing the foot in a neutral position relative to the leg, and then maximum dorsiflexion and maximum plantar flexion, passive motion intraoperatively. And then at that final follow up, Mark, which was a minimum of six months, but average, it was about a year. Again, similarly, weight bearing X rays, maximum dorsiflexion, maximum plantar flexion, what we found was that, and this was very interesting truthfully, because I would have assumed that we lose dorsiflexion and we lose plantar flexion, and maybe we keep two thirds of it, maybe we keep half of it. But what we really found was that we actually maintain the dorsiflexion motion that we achieved during surgery. So that the vast majority of our patients, over 90% of patients, if you achieve 10 or 12 or 15 degrees of dorsiflexion intraoperatively, you can expect that your patients can maintain that motion at an average of a year after surgery. But plantar flexion, we actually found that you lose some of that motion, more than half of it. I would Say, that's probably because of the way we really made that comparison and assessed it, because it's probably not a fair comparison to compare supine passive plantar flexion intraoperatively with post operative weight bearing plantar flexion. Those two things are probably not the same. And when we compared preoperative to postoperative plantar flexion, we really didn't see any difference. And so what we really saw overall was again, very modest improvement in range of motion. We had an improvement of about two and a half degrees of total arc of motion at the tibiotaylor joint from pre to post. When you looked at a dorsiflexion and plantar flexion separated out, there was no difference. When you look at global motion or tibiopedal motion, tibia to foot, we did see an improvement in dorsiflexion and in total arc of motion before and after the operation.
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Constantine, did it surprise you that you found no clinically important increase in motion on average between pre op and a year post op?
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Well, it didn't because it's been published and others have found that to be the case for the most part that any improvement in dorsiflexion is modest. I counsel patients as such. I tell them the reason to do this is to alleviate pain. To preserve the motion you have, maybe we can get some more range of motion. And we found that in our study in the sense that patients who had less motion before surgery were more likely to gain motion after surgery. So those that are more stiff have more opportunity to make improvements. And so though it's not surprising, I don't want to say it's discouraging, but it's certainly motivating for us to try to better this situation and for us to really try to find a way to get more motion for our patients after an ankle replacement.
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And in particular, just so the audience that's listening reflects on this a bit, you found a decrease in plantar flexion passive motion arc between intraop and post op. I guess it begs a question, why does this happen? And do you think all ankle replacement designs could have this problem? Do you think it's design related? Do you think it's soft tissue related? Do you think there's certain incisions that might make it better? Maybe you could talk to us about how you've thought through that.
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I think that's a great point and a great question to think about. We spend so much time thinking about dorsiflexion, but patients who lose plantar flexion are also equally bothered by that. And there are some issues when you lose platoflexion in terms of activities of daily living, going downstairs. It's difficult to engage your calf if you don't have the range of motion to do so, and so you have some weakness there as well. But I think that when you're in the operating room, the ankle is wide open, patient's asleep, they're under spinal anesthesia, and you maximally plantar flex their foot. Then you check it again six months later. Now the incisions close, the capsules closed, the retinaculum is closed, the skin is closed. They're taking this weight bearing plantar flexion X ray where they're instructed to keep their foot on the ground so they can't lift their foot off the ground. Again, it's not a true fair comparison, but certainly the soft tissue component matters. The healing of the anterior capsule, the healing of the skin and the soft tissues anteriorly will restrict some of that plantar flexion. The question of well, is the same true for a lateral approach ankle? That's a great question and I certainly don't know the answer to that. I think there's a lot of benefits to an anterior approach ankle and there's some negatives certainly. And the same is true for a lateral approach. We see this in total hip replacement, that there's different approaches. They have positives and they have negatives. There's also a modified anterior incision that has been published and Tim Daniels has published on this modified anterior approach in terms of decreasing wound complications. And I certainly think an incision like that, a curvilinear anterior incision, probably doesn't in my mind change scarring. That may happen at the capsule, but it may actually allow earlier range of motion, immediate post operative range of motion, if you will, in a safer way. Because again, at least for, in our case, for our patients, we immobilize them for two weeks. We want the skin to heal. So our patients are in a splint. But when patients have a knee replacement, they're not in a splint. They move their knee right away. What holds us back, or what holds me back from immediate ankle motion after surgery is I'm worried about the wound healing. Maybe a curvilinear incision would allow earlier range of motion at the ankle and that would make a significant difference. This is something that we've thought to look at and to do and hope to do is a pilot study and then go from there. I think that's where maybe Incisions matter, but a lateral incision is something completely different. And I think it would be worthwhile to look into and see what that data would show.
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Has this study affected your practice yet or is it about to change how you look at it? In my mind, I think, okay, if you see a patient who has a lot of plantar flexion pre op, maybe you'd like to use the Daniel's approach. If they're young, they got good skin, no other incisions, not diabetic, not a smoker anyways, they fit this criteria. Maybe it's a narrow criteria that you would might try an approach that'll have less chance of maybe scarring in. I don't know. Have you thought through how this might affect you? I'm just suggesting stuff that I have never done.
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So I'm asking. Yeah, I think the biggest thing, the biggest change that I have made from this study has been to really think about why do we lengthen the heel cord and when is it truly necessary? And I think of healed cord lengthening. And I, and I use that term broadly to include a tendo Achilles as well as a gastrocnemius recession. I tend to do a gastrocnemius recession, but you could also say for a gastroc soleus recession. But when do we really need to do some type of release posteriorly or heel cord lengthening, when is it truly necessary? And I think of it in, in two broad buckets. One is to achieve better motion. And we don't really know how much of that is true now because one thing that would be interesting would be to. It would be very difficult to do, but you would have to have a very large sample size and randomize patients to lengthening and not lengthening. Because ultimately we're all looking to achieve a certain amount of dorsiflexion during surgery. Those who had a heel cord lengthening achieved that preset predetermined amount, which in our clinical judgment is about 10 degrees. And then they maintained it. But the question is, who really needs one for motion and then who really needs one for deformity correction? And as we all appreciate and know, when you're correcting a valgus ankle with a, with the valgus hind foot and those patients, when you correct them, everything is much tighter. When you have significant anterior translation of the talus and you want to translate the talus posteriorly, particularly with an anterior approach ankle, it helps to have an Achilles lengthening or a gastrocnemius recession to give you some, to allow the Talus to shift back into the ankle mortise, particularly also when you have big varus deformities. It's much easier to get the talus out of varus if you can weaken the soft tissues a little bit posteriorly. So sometimes we do it for motion, sometimes we do it for deformity correction. But when is it truly necessary? And I think a lot of times, at least in my young practice of about 10 years, I've really tried to minimize bone resection. And maybe I've done that in some cases. Maybe I've gone too far in that sense. And we minimize bone resection so that we can retention the soft tissues. We minimize bone resection so we can preserve bone for later revision. Sometimes we minimize bone resection to lower the joint line and try to restore the physiologic joint line because typically the talus tends to erode into the distal tibia. But maybe in some cases I've resected too little bone and made the ankle too tight. And maybe I've had to resort to heel cord lengthenings more frequently than I should. And so I really have tried to think about this concept of bone resection. How much bone should we be removing, how much bone per individual patient, when to really do a heel cord lengthening, when to do a gastrocnemius recession. And aside from thinking about all this, I will say that in practice, I've been doing fewer heel cord lengthenings since we've published this study.
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Great summary of the complexities and the thinking that is involved with trying to optimize outcomes. Anything else you might like to add for the audience who's listening?
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Well, what I would say is I think, I think this, the issue of motion is important for patients. We know that it correlates to their satisfaction after ankle replacement. And we tried to temper their expectations before the surgery because we know that that is going to ultimately be a key to their success. If we can convince patients that the real goal of the operation is to alleviate pain and preserve their motion, because that's what we know is a reasonable expectation, then we're more likely to be successful. But I think ultimately we want to restore motion. And so for those listening, and if you're still listening at this point, I would say that please do your own research and please do your own studies and please contribute to this question of what are the techniques, what are the surgical techniques? What are the post operative protocols, the rehab protocols? I mean, we don't, we don't have a standardized rehab protocol for ankle replacement. Many of us do different things. How long do we immobilize? When do we begin motion? When do we begin weight bearing? But I truly believe that we need to do more work in this area, and I hope to see more of these studies from my colleagues. And we hope to do more from our end as well.
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Well, thank you, Dr. Demetrakopoulos. I am Charlie Saltzman, editor of Foot and Ankle International, and today I've had the distinct pleasure of talking with Dr. Dimitrikopoulos from the of Special Surgery in New York City, who is the senior author of this month's lead paper in Foot and Ankle International titled Discrepancies Between Intraoperative and Postoperative Ankle Motion Measured for the Anterior Approach Total Ankle Arthroplasty. Really appreciate your taking the time to be on the program today.