Deformity Planning in Total Ankle Replacement

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* Editor's note: At 12:48 in the recording, our podcast guest wishes to clarify; "In severe deformity if you find the fibula to be posteriorly translated secondary to malunion or a tibial recurvatum that has caused anterior translation of the talus, cutting the fibula above the syndesmosis can be helpful."

Jennifer Spector, DPM: Welcome back to Podiatry Today podcasts, where we bring you the latest in foot and ankle medicine and surgery from leaders in the field. Today, we're excited to have with us. Dr. Kelsey Millonig to talk to us about deformity planning implications in total ankle replacement Dr. Millonig is a fellowship trained foot and ankle surgeon with degrees including her doctor of podiatric medicine and her master's in public health. She's a fellow of the American College of Foot and Ankle Surgeons and as a medical student she was selected to intern at the World Health Organization headquarters in Geneva, Switzerland. Her reconstructive fellowship was at the Rubin Institute of Advanced Orthopedics International Center for Limb Lengthening in Baltimore, Maryland. She also holds multiple leadership positions in numerous national podiums, podiatric, and public health committees, including the American College of Foot and Ankle Surgery, American Public Health Association, and the American Podiatric Medical Association. Welcome, Dr. Millonig, we're so excited to have you with us today.
 
Kelsey Millonig, DPM: Thanks for having me today.
 
Jennifer Spector, DPM: Well, let's get started. When we're thinking about total ankle replacement, there's a lot of planning that goes into this. So what types of deformities in particular,do you feel that surgeons should keep in mind when patients might be undertaking this procedure?
 
Kelsey Millonig, DPM: Yeah, as you mentioned, there's so many things to consider when you're talking with a patient about a total ankle replacement. And I think that in general as foot and ankle surgeons, we do a pretty good job of evaluating a deformity if it's within the ankle joint, meaning it's within the tibiotalar angle, if there's any type of talar tilt, if there's potentially a pes planus deformity that needs to be addressed or a cavus deformity within the foot that needs to be addressed.
 
But something that I specifically like to draw attention to when I talk with those in training about total ankle replacements or those that are really looking at doing this more in practice is, in addition to specific foot and ankle deformity, we also need to be evaluating proximally and evaluating the entire limb for any type of deformity and doing deformity planning associated with that.
 
By that, I mean really looking at, does the patient have some type of genu varum or valgum? Is there a tibial deformity that's present and that is what has caused the ankle arthritis because there's an actual variation within the tibial anatomy that has caused that, potentially post-traumatic, we don't know. But if you, particularly this is true, if you have a patient that comes into you with non-post-traumatic ankle arthritis, I really find that those patients, I want to take a step back and look at that and say, okay, what is the reason that they've developed ankle arthritis in this specific limb compared to the other limb if it's not bilateral? And it's typically because there's some type of deformity that is driving the arthritic change.
 
Jennifer Spector, DPM: So how might deformities like this impact the preoperative planning or the preoperative evaluation? Are there any particular steps that you like to take for evaluation of these deformities?
 
Kelsey Millonig, DPM: I think with any evaluation of a patient things that we've done in the past. all starts with our clinical exam and everything is dependent on the clinical exam. But I do think it's easy for us as foot and ankle surgeons to sometimes really hone in on just the foot and ankle instead of taking a larger step back. And so, of course, evaluating all foot and ankle mobility is incredibly important. If they have a pes planus deformity, is it reducible? Or is it reducible? Is it not? How is that contributing to any type of ankle deformity or to be a talar angle changes?
 
But beyond that, when I'm doing a clinical exam, I always have my patients stand, I have them roll their pant legs up above their knees. So I can really look at their patellas. And I look at how they're standing. And I evaluate, what is their limb length, how are their biomechanics working? And is there some type of more proximal limb deformity that is present?
 
And clinically, if I have any type of suspicion whatsoever, and in the majority of my patients, I do send them for limb length films so that I can do a full preoperative deformity planning workup for my total ankle replacements. And what that looks like in my hands is I take those limb length films and then I follow through with doing a full deformity planning and work up with them on Bone Ninja, which is an app that you can utilize that is derived from where I did my fellowship with the Rubin Institute out in Baltimore. And you can actually go through and do all of your limb planning to look at the mechanical access, see if there's any mechanical access deviation within the limb, see if there's any alterations and changes within the LDTA, which is the lateral distal tibial angle, or the ADTA, which is the anterior distal tibial angle, see if there's any type of deformity within the tibia itself.
 
Jennifer Spector, DPM: That's great. And these plans that you're able to make and this mapping that you're able to do of the lower extremity, does this then inform any adjunctive procedures that you might choose as part of a total ankle replacement. undertaking?
 
Kelsey Millonig, DPM: Yeah, I think that's a great question. If something is found—so for example, I've had several patients that came to see me specifically because they're looking for a total ankle replacement and they'll come into my office and I'll say, "How long have you been bowlegged?" And they kind of laugh and joke, and they're like, "Oh, my whole life."
 
And I say, "Well, you have a true genu varum deformity that really needs to be addressed before I can address your total ankle replacement, because if we address the total ankle replacement, it's going to fail because you have an abnormal mechanical axis deviation, and so the replacement will not uphold moving forward."
 
And so I do think that it is important. So I've had patients that I refer to my orthopedic colleagues for more proximal deformity correction. And I've had patients that come in and they have a unilateral ankle arthritis, no post-traumatic history. And they're just like, “Yeah, I don't know. I just developed arthritis in this ankle.” And then I dive in and I start doing their deformity planning and I find that they actually have a 10 degree distal tibial varum deformity that's a little bit more proximal than can be addressed within the replacement itself that needs to be realigned prior to a total ankle replacement so that the patient can ensure that we have a successful replacement for many years down the road.
 
And I think that this is true of many procedures that we do in the foot and ankle and a reason that I'm a huge proponent of deformity planning in and making sure that we have kind of a keen eye to look for any of those small intricacies that might be contributing to the reason that a patient has developed ankle arthritis.
 
Jennifer Spector, DPM: So assuming that things are in more of a rectus alignment from the proximal standpoint and focusing back in on that arthritic ankle, are there any additional risks or concerns that you might want to consider if there are tibiotalar deformities that have still not been addressed?
 
Kelsey Millonig, DPM: So once we've realigned the mechanical access of the limb, and we've ensured that the proximal limb has appropriate alignment to uphold the ankle, and we've ensured that the foot has appropriate alignment as well, or at least a minimum has mobility that it will not cause additional stresses through the ankle replacement if the foot needs to be realigned at all.
 
We do need to look at the tibiotalar alignment. Is there significant varus or valgus malalignment? You know, in the varus deformity, we typically talk about 10 degrees, and in valgus we typically talk about 20 degrees as being thresholds. But if we really look at that, are those thresholds present because we need to consider ancillary procedures such as foot realignment procedures, if that means fusions versus extraarticular procedures to help with realignment, does that mean that we need to do more? If you realignment typically in those tibiotalar deformities, there is a need for either a deltoid reconstruction or a lateral angle reconstruction. That will definitely affect the longevity of the total ankle replacement.
 
I also think in the significant deformity cases, we have to ask ourselves, do we want to do a stemmed implant or not? If there's significant deformity, I do tend to lean towards a stemmed implant for the reason that it provides additional stability without having to rely on the reconstructed soft tissue surrounding the ankle joint.
 
Jennifer Spector, DPM: So are there any particular interoperative maneuvers or steps that you find are most crucial when you're successfully addressing these deformities intraoperatively?
 
Kelsey Millonig, DPM: So yes there are a number of things that we can do intraoperatively to help us and I think as we talked about one of those important things is the preoperative planning that goes into this and it needs to be very detailed and purposeful, but one of the things that I will do is I do typically utilize patient specific instrumentation and I find that this is incredibly helpful for a number of reasons.
 
One, the preoperative planning that it allows you to do is second to none because it does analyze and look at the mechanical axis that helps you analyze and look at how cysts might impact if your implant is able to embed appropriately. And it does talk about any type of tibiotalar deformities, particularly if you're able to utilize a weight-bearing CT, which I think is definitely the ideal scenario if you have availability. Unfortunately, in Iowa, those are few and far tween right now.
 
However, with using PSI and understanding how to use other instrumentation to address the tibiotalar deformity, you can utilize peel techniques, meaning if they're soft tissue contractures or capsular contractures, you can do a capsule release. Sometimes that's very, very helpful. You can do a peel or a deltoid peel, meaning that you can release the soft tissue from within the ankle joint if you're contracted into a varus alignment.  
 
And oftentimes what I will do is I will do my procedure, make sure that I have my appropriate alignment with all of my cut guides under intraoperative x-ray, but I stress my ankle in every fashion after a total ankle, meaning that I stress the lateral ankle ligaments, I stress the medial ankle ligaments, I stress the syndesmotic ligament, and I do that for every single total ankle procedure that I do because I want to make sure that if there is an ancillary procedure that I need to consider, that I've addressed that intraoperatively following my implant, because your implant will bring stability depending on, again, how thick your poly is and what other ancillary procedures you have done.
 
Something that I think is worth considering is if you are in private practice or a new practitioner who is operating on your own, that it is helpful to stage these procedures and do the foot procedures if they needed to be done for any type of realignment or proximal procedures that maybe need to be done a tibular osteotomy to realign your mechanical access and then come in and do your total ankle replacement and your ancillary soft tissue procedures as needed.
 
Something else that I should note too that is kind of an interesting thing to consider is that if you do have to do some significant realignment following a severe deformity with a total ankle replacement, you may actually find that at times you may need to cut the fibula to help the fibula kind of realign, particularly if that fibula is posteriorly translated. That can be secondary to residual post-traumatic deformity or something that is inherent within the patient's anatomy.
 
And if you do need to do that to make sure that you maintain appropriate fibular stability for function of the total ankle replacement, you just need to make sure that you do that proximal to the syndesmotic ligament. And as long as you do that, that'll still uphold appropriate fixation and allow your ankle to function a little bit more appropriately with appropriate alignment as well. *
 
Jennifer Spector, DPM: So once you have your appropriate preoperative planning, your thoughtful intraoperative approach, what postop considerations do you feel certain should keep in mind when they're dealing with patients that started out with higher levels? level of deformities than say the average?
 
Kelsey Millonig, DPM: Yes, one of the things, particularly postoperatively that I do consider with these patients because I am often staging these procedures is that I do try to overlap their postoperative recovery, meaning that typically with my total ankle replacements, depending on any additional soft tissue reconstruction I've had to do, I will allow them. them to weight bear somewhere between four to six weeks after their incision is healed and get them actively rehabbing.
 
However, if they had to undergo a tibial osteotomy and that means that I need them to be non-weight-bearing for closer to six to eight weeks I will do that procedure and then I will plan for the total ankle replacement in a staged fashion to try and overlap their postoperative protocols that they can have kind of an overlap with our non-weight-bearing procedures if possible. Sometimes that's not possible because a CT scan needs to be done to ensure that the osteotomy is fully healed before we can move forward with a total ankle replacement.
 
Similarly, if I need to do a medial calcaneal slide to help realign a flat foot that's flexible underneath the total ankle, that can be done with an overlap as well, meaning that can be done four weeks prior to the total ankle replacement so that there's some overlap in their recovery. So that is something to think about if you're considering multiple procedures or stage procedures for these more complicated total ankle replacements.
 
Additionally with that, if I do soft tissue procedures or soft tissue reconstructions, I will keep my patients non-weight-bearing for a longer period of time. So I typically will keep them non-weight-bearing for six to eight weeks. However, I'm very aggressive with their range of motion. So as soon as we are two weeks out, I typically do not take patients’ total ankle stitches out until three weeks because I'd like to ensure that that anterior incision has a lot of appropriate time to heal. But I will have them start doing aggressive range of motion at two weeks, even with their stitches still in. And then as soon as their stitches come out, even if I don't have them weight-bearing, I do have them doing significant range of motion exercises to really get that ankle replacement moving, because you have to think that many of these patients have not moved an ankle normally in several, years. And so beyond the weight-bearing protocol, I think that the range of motion protocol is very important.
 
Jennifer Spector, DPM: Is there anything else that you'd like to share with the audience about deformity planning when it comes to TAR?
 
Kelsey Millonig, DPM: This is an inherent bias that I have across the board, but my biggest comments regarding any type of ankle procedure, particularly ankle fusions or ankle replacements is that just to ensure that you really understand appropriate mechanical access, planning for your entire limb, and really look proximally to ensure that there is not something that is causing the ankle arthritis that has not been attributed to. I particularly mentioned this because I've seen several patients that come to see me for second or third opinions because of my deformity background that may have had an ankle replacement in place which did fix the ankle arthritis.nHowever, it did not address the more proximal deformity and the ankle replacement can then have an earlier failure rate, which is something that we all talk about with total ankle replacements.
 
And so if you have any interest in deformity or deformity planning please reach out. I think there are so many great resources out there the Baltimore limb deformity course is of course one of those things but there are a lot of great resources available for that just to familiarize yourself and make sure that you can evaluate that appropriately.
 
Jennifer Spector, DPM: Well thank you so much for joining us today Dr. Millonig again for sharing your insights on this important but sometimes complex topic. We hope that you'll join us next time on Podiatry Today Podcasts, that you can find us on your favorite podcast platforms, including podiatrytoday.com, SoundCloud, Apple Podcasts, Spotify, and more.
 
Kelsey Millonig, DPM: Thanks so much for having me.