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Foot & Ankle International
FAI February 2025 Podcast: Correction Target of Supramalleolar Osteotomy for Early Varus Ankle Arthritis: Is Overcorrection Necessary?
00:24:14
The aim of this study was to investigate the clinical and radiologic outcomes following supramalleolar osteotomy for early varus ankle arthritis with the medial translation of the talus, wherein the lateral translation of the talus center to the...
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- [00:05]
A
This is Mark Easley and I have the distinct honor of talking to Dr. Wu Chun Li, the senior author of February's lead paper in Foot and Ankle International. The paper is titled Correction Target of Supramolar Osteotomy for Early Varus Ankle Arthritis is overcorrection necessary? Dr. Lee is a world renowned foot and ankle specialist from Korea. He is an MD and PhD and works in the Seoul Foot and Ankle center at the Dubalo Orthopedic Clinic in the Gangnam Gu District of Seoul. While Dr. Lee has many areas of foot and ankle expertise, he is particularly skilled in joint sparing surgical management of ankle arthritis, especially supramolar osteotomy. Dr. Saltzman and I selected this article so that Dr. Lee May May share with us his extensive experience and decision making with supramolar realignment of early varus ankle arthritis. Welcome to the program, Dr. Li.
- [01:07]
B
Yes, thank you for having me and for this opportunity.
- [01:12]
A
Wu Chun, thank you for recently visiting us at Duke University. Our foot and ankle team learned a lot from you and still talks about the wonderful exchange of ideas. Now, as senior author for this investigation and paper, would you please provide the listeners with a brief summary of your paper and its major findings?
- [01:36]
B
This article is about Target of Correction in Supramolar Osteotomy. Before I dive into the summary, I would like to emphasize that this is not an article about various different types of joint preservation surgeries. This paper reports the results of medial open ratio osteotomy in very limited patients groups. Results of this study begins with a sentence which is radiographic and clinical results improved in all patients and these results may mislead the readers that the SMO is effective for all various arthritis. Therefore, I am reiterating that this article only deals with early varus arthritis with small Taylor tilt which was less than 8 degrees. The borderline of 8 degrees talar tilt was chosen because my previous study on indication of supramalleolar osteotomy showed that the indication for supramalleolar osteotomy is varicose arthritis with less than 3.73 degrees of tility. The study was published in JBJS in 2011 after so many experiences with medial open wage supramolar osteotomy. After publication of that study, I still believe that the tilt larger than 7 to 8 degrees is not a proper indication for isolated supramalleolar osteotomy. Now let's get back to the summary. The aim of this study was to investigate the clinical and radiological results after supramole osteotomy and I have translated the Taylor's center letter to the tibial axis in an arthritis with immediate translation of the talus preoperatively. Another aim was to compare the results in different degrees of postoperative tibia platformed Vegas. So the anchors were categorized as neutral group and overcorrected group according to the postoperative alignment of the tibia platform. Neutral group means post operative medial distal tibial angle or TAS was less than 94 degrees. 94 degrees was mean plus 2 standard deviation in Korean or Japanese papers. Overcorrected group includes the anchor with 94 degrees or larger MDTA. We could not find any difference in clinical and radiological results between the neutral group and overcorrected group. Therefore, the conclusion of this study wrote that later translation of the telos can be used as a correction target target for medial open with supramal osteotomy and overcorrection of the tibia platform seems not necessary.
- [04:25]
A
Wonderful. That's great. Yeah, it's terrific work. And thank you also for your clarification on the indications for this particular procedure in osteotomy. We Would you please do one favor for me and the listeners? Many of the listeners may not be as familiar with the Takakura staging system for various ankle arthritis and you also mentioned the Knoop in one of your references to the Knoop and Hinterman classification. But would you please Describe in detail Stage 2 and 3A the two stages that you studied in this investigation?
- [05:01]
B
Yes. Stage 2 shows medial joint space narrowing at either the medial gutter or both of the medial gutter or tibia platformed telodome joint space. So there is no obliteration, but there can be a joint space narrowing either the superior or medial gutter, superior or medial joint space. Stage 3ameans medial gutter obliteration. But some of the stage 3a arthritis show parallel joint line with normal joint space at the tibia platformed telar dome joint space only obliteration of the medial cataract.
- [05:40]
A
Thank you. Yeah, I think that speaks to your idea of a medial translation that you're correcting with a lateral translation. So that's very important to understand. Thank you for the clarification. Wu Chun, in your retrospective analysis of a three to four year period, you and your colleagues identified 526 patients with either stage 2 or 3 a varus ankle arthritis who had undergone a supramalar osteotomy. In your article in your publication, figure 2. The plain radiograph of your case example with congruent varus ankle alignment suggests minimal arthritis. What is the natural history of an ankle such as the one you showed in this case example in Figure 2? Will this invariably lead to advanced ankle arthritis without supramolar osteotomy or do you think there's some patients that have physiologic varus alignment that does not progress to advanced ankle arthritis?
- [06:40]
B
It is correct that SMO alone or supramal osteotomy in combination with other surgeries was done in 526 patients during the study period. However it does not mean all those patients had stage 2 or 3A arthritis. Large proportion of these patients had more advanced arthritis, therefore other surgeries for realignment were combined. All dome types of primaryolar osteotomy was done instead of medial open edge supramalleolar osteotomy. In this study only those patients who underwent isolated supramalar osteotomy was included and inclusion criteria was anchors with The Takocura Stage 2 or 3a and medial translation of the talus relative to the tibial axis. Regarding your question about figure two, this ankle is congruent as you indicated but the telos is medially translated to the tibial axis and the medial gutter is definitely narrow which is Takahura stage 2 medial translation is caused by medially directed shear force. Therefore it would deteriorate to stage 3A with complete disappearance of the medial gutter. The patient usually come to clinic for medial sided ankle pain when you take a weight bearing ct. Usually at least anterior part of the medial gata is completely obliterated at this stage and it causes pain from direct bony impingement. Medial cutter narrowing or obliteration may or may not further deteriorate into stage 3B which is obliteration of tibial platform telodome joint space. However, I correct the alignment at this stage because the patient has already long standing debilitating pain in the ankle. I think this type of arthritis may not be common in western countries because the low limb alignment is different from oriental people like Japan, China or Korea. And then maybe the reason why more supromol osteotomy is done in oriental countries.
- [08:50]
A
Great, that's a wonderful explanation and it's terrific work and I've already learned a lot. But we have more to learn so we'll keep asking you some questions regarding your article. So Wuxian, all 93 of your supramolar osteotomies healed you and your co surgeons emphasize that you performed both osteotomies and just proximal to the syndesmosis, thereby maintaining syndesmotic stability and avoiding violation of a lateral tibial cortex and thereby maintaining a lateral hinge effect. You did not bone graft any of these tibial osteotomies and you used plate fixation. Would you please provide the readers with more surgical details so that they may achieve for their patients similar outcomes to yours? Specifically, how do you open the osteotomy without cracking or breaking the lateral cortex? And if you were to violate the lateral cortex, if it were to break, what do you do? And then do you typically use locking plates or non locking plates for fixation of the osteotomies?
- [09:56]
B
I cut the bone almost 3,4 of the circumference so the lateral cortex is preserved. And when you push the distal segment laterally, I think there occurs some cracking without causing complete discontinuity of the cortex. It may be easier to understand if the lateral cortex is infected like torus fracture in children. One of the key points to obtain correction without complete osteotomy is the pre bending of the tibial plate. It is slightly underbend than curvature of the medial surface of the tibia. Then after making so cut medial anterior and posterior part of the tibia, then the plate is applied without completing the osteotomy. Proximal screws are inserted. Usually I use seven hole plate and four holes proximal to the osteotomy and three holes below the osteotomy. The first screw inserted is just above the osteotomy. Then all remaining proximal screws are inserted. As the proximal screws are tightened, the distal part of the plate pushes the distal segment laterally. Then small gap starts to open at the osteotomy site because the plate is slightly underbent than the tibial surface. If the medial surface does not open, then thin osteotomy is placed at the osteotomy side and gently tapped with the mallet. Then it opens. You don't need to open it widely, just a small gap like 2 to 3 millimeters. Then further tighten the proximal screws. Further opening of 1 to 2 millimeters can be done by inserting thin osteotomes. Enter and posture to the plate if necessary. I use non locking plate. Then you can adjust minimal amount of opening as you want. And I think there is no problem with complete lateral osteotomy and instability of the whole construct.
- [11:50]
A
Wow, those are great hints. And I know your your focus is on neutral or over correction if overcorrection is necessary. But I think it's very important that the readers understand these details. So that was wonderful for you to explain the detail of how you do the osteotomy.
- [12:07]
B
Thank you.
- [12:08]
A
Wu Chun, you and your co authors conclude that the traditionally taught overcorrection of supramalar osteotomies and treating varus ankle arthritis is not necessary. Would you please clarify for the readers when isolated tibial and fibular osteotomies are sufficient and when associated procedures such as calcaneal osteotomy, tendon transfer and ligament balancing are indicated? You had mentioned that you do that and you have done for many others and that you've limited this to 2 and stage 2 and 3A for the Takakura staging system. But just give the readers a little more idea when you have to do more than what you described here.
- [12:48]
B
Lateral closing osteotomy Calcaneal osteotomy has less ability to correct the coronal plane alignment then supramalleolo osteotomy. So at present I do not use it for correction of telo tilt or medial translation and medial displacement. Calcaneal osteotomy, rather than the wire type osteotomy is often used in an ankle with definite hindfoot vagus to prevent postoperative lateral impingement after supramal osteotomy, but those cases are excluded from this series. Regarding tendon transfer, I have reported the results of PTT transfer for more advanced varus arthritis, but I have experienced some patients with failure after tendon transfer, so it is only used for arthritis with definite paralytic origin. Regarding the ligament balancing, I do lateral ligament repair after removing lateral impingement, preventing the lateral impingement, preventing congruent reduction of the talus into the ankle mortise. But I do not trust ligaments can maintain the correction obtained at an operative field.
- [14:03]
A
Great. So I'll continue with that a little bit more. Your colleagues and you emphasize that for the talus to translate laterally, the medial opening wedge tibial osteotomy must be accompanied by a fibular osteotomy or with or without lateral gutter debridement. In all of the cases you have to do something laterally as well. And then in the discussion of the paper you mentioned that lateral the Taylor tilt does not correct and you showed in Figure 4 that it might be that the tight medial soft tissue structures could account for this lack of talar tilt correcting. And you also cautioned us earlier. There are certain degrees 7, 8 degrees of talar tilt that are difficult to correct. But my Question is, you mentioned the lateral tightening the lateral gutter debridement and your goal is to translate the talus laterally. Are there any cases where a medial deltoid ligament release is necessary? And if so, do you find that a medial release could correct Taylor tilt and also produce greater lateral talar translation?
- [15:11]
B
Or.
- [15:11]
A
Or is it too risky to perform a media release as it caused more problems?
- [15:18]
B
I have learned a lot as my experience has accumulated and I think I'm still learning. Basically, I do not trust the validity of soft tissue procedures like tendon transfer or ligament balancing. Even though you may achieve better looking or parallel joint lines with soft tissue procedures including deltoid release. But I do not think it can be maintained or it would be helpful to obtain better results in the long run.
- [15:50]
A
In my practice and at our institution, we maybe do that more. But I also do as you do too. Ankle replacement surgery. So I do it. You have the extra stability of the ankle implant, but I was just curious if you do. If you address the tethering with the deltoid release. So that's very helpful. Okay. Now we'll talk about something that's not medical. Okay. So, Woocheon, your hospital is in the Gangnam district of Seoul. What does Gangnam mean and what is the most popular or your favorite attraction in the Gangnam district?
- [16:23]
B
Gangnam means the south of the Han River. The river flows through the center of Seoul, dividing it into south and north. And originally Seoul was mostly north to the river. Then Gangnam has been developed more recently since 1970s. So everything's new and road is wider than northern part of the Seoul. And usually the shopping and entertainment areas are popular attractions.
- [16:51]
A
Great. So you're in a good spot. I remember when I came to Seoul for the international meeting recently. It's in the same area. It's really impressive. Very nice. So you're very lucky and fortunate to be practicing there. All right, back to the article. Wu Chun, you and your colleagues did a lot of detailed work in the radiographic measurements of the medial distal tibial angle, the talus center migration and the tibial axis talus ratio with excellent intra and inter observer agreement. I can imagine that the subtle changes preoperatively and at follow up were difficult to interpret on on those plain two dimensional radiographs alone just in April of 2024. Correct me if I'm wrong, but I think that you and your colleagues published on the effects of supramolar osteotomy on osteochondral lesions of the talus. And that investigation included a CT scan, a computer tomography analysis. Is your team considering a prospective weight bearing CT study of SMOs for early varus ankle arthritis patients evaluating the same parameters but with more detail that is afforded by 3D analysis with weight bearing CT scan?
- [18:12]
B
Yes, we are always thinking about 3D analysis and I became more and more confident that there exists larger three dimensional distortion of the telos in the ankle mortise in more advanced arthritis. Therefore, I try to correct the deformity 3 dimensionally in more advanced arthritis than just media open meshis from Malayalar osteotomy. Axial plane rotation is particularly difficult to understand and difficult to correct with conventional coronal plane correction method like SMO or soft tissue procedure. And we have found that soft halo arthrodesis or dome type supramalleolar osteotomy is useful for more advanced barato arthritis which has a definitely more axial rotation.
- [18:58]
A
Great. Well, thank you. Yeah, obviously my institution with Cesar to Cesar Neto spearheading our efforts with weight bearing ct. We talk about it a lot and so I was curious about you. You'd mentioned it earlier too, so great to hear that you're going to even provide us more information in three dimensions and I'm sure that won't be very long from now. Wu Chun, for this investigation you identified 90 patients who underwent medial opening wedge tibial osteotomy in combination with a fibular osteotomy. Your figure 1 flow chart mentions that in the same study period you had 28 patients who underwent supramolar dome osteotomies. And you just mentioned that that you can do greater correction. Could you give us a little more detail that for early ankle varus arthritis, when do you favor a dome osteotomy over the technique you described in this investigation? And does a dome osteotomy allow for the MCS to open and the talus to translate laterally?
- [20:01]
B
Actually, I'm doing dome type supramalleoloftomy as frequently as medial open wages supramalleolo osteotomy recently because I have found that telosis internally rotated in axial plane as the arthritis deteriorates and the talar tilt increases. With dome types of primaryolar osteotomy, the telous is externally rotated in axial plane because preoperatively it is internally rotated in axial plane, but after dermosteotomy it is externally rotated. It means disappearance of impingement between medial malleolus and the talus which occurs together with the decrease of the teletil. And we are working on the study to investigate the results. Of dome supromolectomy in more advanced arthritis with large tallow tilt.
- [20:53]
A
Terrific. Yeah, I want to see that. I use a dome osteotomy, so please teach me more. That's great to hear. One more non medical question, Wu Chun. I think that most of us know the musician Tsai and I probably am saying his name wrong, but I sure know who he is. He's the one who popularized the song and the video Gangnam Style. So are Koreans still doing the Gangnam Style horse dance? And if so, next time I see you, will you be able to teach me the dance?
- [21:24]
B
Thanks for your jokes. It is long time since the horse dance was popular and it used to be fun to enjoy the horse dance, but it is not common to see it even in Korea.
- [21:37]
A
So I've missed it. Huh? So now I have to be K pop K pop fan, huh? Yeah. All right. Well Wu Chong, this is excellent work. As our podcast comes to its conclusion, is there anything else you would like to share with the listeners?
- [21:53]
B
I would like to emphasize that supramoleal osteotomy is basically different from high tibial osteotomy. So we should not plan the supromol osteotomy by extrapolating the results of hto. HTO has been used for joint preservation of various knee arthritis for a long time for so many patients to correct a similar looking virus deformity. So we tend to think the mechanism of improvement after SMO is similar to that of the hto. However, I believe HTOO and SMO are basically different. Surgery HTO was developed to unload the medial compartment of the knee and it is much more useful to achieve that purpose than supramalleolo osteotomy because there is a long bony segment below the osteotomy which is about 25 to 30 centimeters. In contrast, the bony segment distal to the SAMO is only about 3 cm. And there are two mobile joints distal to the osteotomy which are the ankle and subtalar joints. So valgus angulation at the SAMO does not guarantee the valgus of the talus and hindfoot. Valve circulation of the SMO may cause valves of the heel or the talus. In addition, ankle arthritis is not just a coronal plane deformity. As we just mentioned, the axial plane rotational component increases as the teloar tilt increases. Therefore, SMO is different from HTO and the result of this study support that overcorrection of the tibial platform into Ferguson does not lead to more correction of the telotit or radiological staging.
- [23:36]
A
Wow Wu Chen, I wish we had more time. I learned so much in these last 20 to 25 minutes. It's just extraordinary. I really appreciate you sharing all your wisdom. That really brings us to the end of the podcast. And so I'd like to thank Dr. Lee for enlightening us with his insights on his and his co authors Foot and Ankle International Publication Correction target of Tupor Mallelar osteotomy for early varus ankle arthritis Is overcorrection necessary? And I would like to thank everyone for participating in this month's FAI podcast.