Section: CME Category: Biomechanics

Frontal Plane Correction of Hallux Abducto Valgus - Fact or Fantasy?

Douglas Richie, Jr,, DPM

Douglas Richie, DPM discusses past and current literature involving the pathomechanics of frontal plane deformities in hallux abductovalgus and proposes a preferred method of utilizing the Lapidus procedure for fixation.

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Goals and Objectives
  1. Understand and describe the pathomechanics and development of frontal plane deformities in hallux abductovalgus
  2. Describe the past and current literature discussing the issue of frontal plane deformities in hallux abductovalgus.
  3. Describe the function of the first ray when the axis is inverted, neutral, and everted.
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  • Author
  • Douglas Richie, Jr,, DPM

    Clinical Associate Professor, Department of Biomechanics
    California School of Podiatric Medicine
    Clinical Associate Professor of Podiatric Medicine and Surgery
    Western University of Health Sciences
    Past President, American Academy of Podiatric Sports Medicine

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  • Lecture Transcript
  • TAPE STARTS – [00:00]

    Speaker: I decided this year to have a Bill Orien Memorial lecture. For those of you who might have been familiar with Bill Orien, first of all, he is a dear friend of mine for many years because of our affinity to biomechanics. He was the engine behind Root, Weed and Orien. He was the guy, the driving force who forced these two geniuses to get together almost every weekend in California and write a book called "Biomechanics Of Lower Extremity." He was a pioneer. He was a surgeon. He was a well-respected member of our community in biomechanics. I invited him to the school in Pennsylvania one time to lecture. It was a cold, rainy day. He drove from the airport. I met him at the hotel. He opened up the trunk to get his suitcase out. He closed the trunk down and smashed his nose. His nose was bleeding and I said, Bill, are you going to be okay? Don't worry about it. I'm fine. He went ahead and gave me two days at the college in biomechanics. He spent so much time trying to educate this professor and have us understand the importance of biomechanics. And I feel remiss at times that our profession has divorced itself from that type of thinking. Unfortunately, Bill passed away this last year in December and his contributions will live forever. And I was proud to be able to say that he was my friend.


    At this point, I decided to have Dr. Doug Richie come in and represent a talk based upon some of the biomechanics that I've already shared with you and talk about controversies in frontal plane Lapidus procedure. So please welcome Dr. Doug Richie.

    Doug Richie: Well, thank you. Yes, I got that picture from Cheron Orien [phonetic] and she sends her regards to you, Al. That was very eloquent and very accurate in his description of Dr. Bill Orien, who among many things was a mentor of mine and it's a privilege to be up here to dedicate this lecture to him and share with you how he contributed to this topic that is actually very controversial and appropriate topic today in podiatric foot surgery. This book, "Normal and Abnormal Function of Foot" authored by Root, Weed and Orien and published in 1978 has been cited more in the medical literature than any other podiatric work. Google scholar shows that this book has been cited over 1000 times in other scientific articles, mainly outside of the podiatric literature and in the physical therapy and surgical literature. Prior to that publication, this book was published about five years earlier on the examination of the foot and ankle and finally, the neutral suspension cast technique which ultimately produced the Root Functional Foot Orthosis was the predecessor to those three sentinel works which today are really the foundation of what we still do and still works in our hands. This lecture is focusing on a topic and a trend that is rapidly engulfing podiatric surgical symposia around the country.


    And I want to step back and show just what Al said about the importance of biomechanics and understanding the true nature of why we do surgical procedures and whether it's really biomechanically sound. That's a picture of Merton Root and this is the article, a paper that I was part of a group of researchers, my senior year at CCPM and it was the last paper that Root ever published and it was really an honor and a thrill to be part of this team which also did include Bill Orien and I was just reflecting also on Howard Marshall who ran the campus at the southern school of podiatric medicine and his son Scott Marshall is here today which is kind of fitting. This is what it's all about. This is the axis of the first ray originally described by Hicks. It is not pronatory-supinatory axis. It's a unique axis that allows dorsiflexion with inversion, plantar flexion with eversion contrary to the pronatory-supinatory motions we see elsewhere in the foot. But it's that unique axis that allows the progression of hallux abductovalgus because as the first ray dorsiflexes, it inverts and it adducts away from the rest of the foot about that axis. It has been shown that patients with hallux abductovalgus have hypermobility of the first ray. But what's interesting is we have now learned that it's the hypermobility that doesn't preceded hallux abductovalgus. It's the result of hallux abductovalgus. That as those sesamoids deviate laterally but really the first ray deviates medially off the sesamoids, it becomes destabilized.


    The first ray becomes hypermobile. So we have learned to recognize that the hallux moves one way and the first metatarsal moves the other way. In the transverse plane, the hallux abducts, the first met adducts. As the first metatarsal inverts about the Hicks axis, the hallux everts. And the frontal plane deformity of pronation is actually in the hallux. The hallux pronates and the first met inverts. This is seen when we look at the patient standing upright in gait. Three years ago, members of our profession challenged that notion. And they said that the first metatarsal is not inverted, it is everted in the hallux abductovalgus deformity. And not only that this frontal plane deformity must be corrected. Basically, before I get into this, this is [indecipherable] [07:14] that I'm going to drive home and the rest of the lecture is that we know that patients with hallux abductovalgus have unstable hindfeet and the majority of them stand and walk in a pronated position. And this pronation of subtalar joint carries the first ray into pronation with it. The first metatarsal though is independently dorsiflexed and inverted relative to the rest of the foot and it's that unique relationship with the first metatarsal that is critical to our surgical correction. When we do a surgical correction for hallux abductovalgus, we realign the first metatarsal relative to the rest of the foot. We do not realign it relative to the ground.


    When we close down that IM angle, it is relative to the second metatarsal. It has nothing to do with its relationship to the ground or the supportive surface. If pronation of the entire foot positions the first ray "pronated" on the ground, correcting first ray pronation with this new Lapidus procedure will not change the pronated position of the entire foot. If your goal is to correct pronation of the first ray, you must de-pronate the foot. Now, where did this all begin? It actually started back in 1980 from an eminent podiatric researcher named Daniel McCarthy who published a series of beautiful, elegant anatomic studies of different pathologies in the foot. And he discovered that the first metatarsal look pronated or everted in hallux abductovalgus. Later, Scranton also showed this same pronated position of the first metatarsal in his radiographic study. It's interesting that nobody really noticed those papers because after 1980 when they were published, nothing happened until 27 years later as series of papers shown here beginning in Japan published in orthopedic journals and finally with Larry D. DiDomenico in our profession began observing mainly if not only through radiographic measures that the first metatarsal appears everted in hallux abductovalgus and speculation began to develop that you needed to correct that to get a better surgical result with HAV surgery. But the real thrust of this movement came from this series of papers published by Paul Dayton, all published in the same journal, The Journal Of Foot And Ankle Surgery building a case for de-rotating the first metatarsal in hallux abductovalgus in the direction of inversion and doing it with a Lapidus procedure.


    The question is, is this valid based on biomechanical studies? We need to understand when we look at the position of first metatarsal in hallux abductovalgus, we have to understand motion versus position, position on the ground versus position relative to the rest of the foot and whether we are actually correcting that with a Lapidus procedure relative to the foot or relative to the ground. If you are going to propose a new paradigm about how the first ray moves, you really should conduct a kinematic study in high level gait lab as what is done in the biomechanics community today. That wasn't done and hasn't yet been done by advocates of the frontal plane HAV correction. So if we look at these studies that I showed you up here and there is about 10 of them, the first question is did they evaluate frontal plane position of the first metatarsal relative to the second metatarsal? The answer is no. Did they evaluate the position of the entire foot when they did this evaluation of pronation? No. Did any of these studies evaluate the position of the foot on the ground? No. So let's step back and look at the flaws of some of this research and how that can be misleading. Now, before I do that, all of you out there have evaluated patients with stage 3 adult-acquired flatfoot, severe collapse flatfoot. And I remember years ago Don Green gave a lecture on adult-acquired flatfoot and he said, you know every time you take an AP x-rays of those feet and you put it up on the screen, you think your assistant made a mistake because the AP x-ray looks like a medial oblique.


    And you know something, he is right. And so if we look here at this stage 2 adult-acquired flatfoot and I'm going to take an AP x-ray, the first thing is her hallux is severely everted, but she doesn't have a true bunion. And look at her AP x-ray that looks like a medial oblique view because her entire foot has carried the forefoot in the eversion just like you position them on an orthoposer for a medial oblique view. And it has carried the first metatarsal in this severe pronation. But the first ray on this patient is actually dorsiflexed and inverted relative to the remainder of the foot. The sesamoids are deviated laterally but there is no bunion deformity. This is all an illusion, is it not, based on position of the foot on the orthoposer. Let’s go back to Daniel McCarthy's study published in JAPMA way back in the early '80s. And he not only didn't look at the position of the foot, he took the foot away. He chopped off the first ray, he froze it and then did frozen section through the foot to look at the anatomy of a bunion but the foot has now been detached. And when he looked at the cross-section, he said, my god, that first metatarsal is everted relative to the second metatarsal. That's the second metatarsal. Here is the first and my gosh, it does look everted. But guess what, it's also plantarflexed. When he chopped off the foot and froze it, the first ray was left in the plantarflexed position and just as Hicks taught us, when the first ray plantarflex, it everts, when it's in the plantarflex position.


    This is the pivotal study quoted by the Lapiplasty advocates where they say 89% of patients with hallux valgus have a pronated first ray. This is a well-quoted study from Foot And Ankle International and it's interesting the lead author is in this original paper De Geer and later when you download the reprints of this paper, the name has been changed to Kim. Not sure why? So the lead author now is Kim not De Geer. And they did a CT scan through the foot of a patient with hallux valgus but the first error is -- here read the methodology, they plantarflexed the ankle 45 degrees and they placed the first ray plantargrade onto the orthoposer plate that would automatically dorsiflex the hallux 45 degrees. It would plantarflex the first met. So lo and behold, this cross-sectional images show a plantarflexed first met relative to the second and it's everted but it's all due to the position and they conclude that this pronation deformity dominates hallux abductovalgus and it needs to be corrected. Well, it's not in a full weightbearing position. It's a plantarflexed first ray. When we shoot a plantar axial sesamoid view, it automatically dorsiflexes the hallux and it plantarflexes the first ray giving you a pronated appearance of the first ray but it's simply following the Hicks axis. Now, these tangential sesamoid views were used for most of the papers published in Journal Of Foot And Ankle Surgery where they took tangential views and lo and behold, they saw a pronated position of the first metatarsal. I took this picture out of one of those articles and I said, boy, that whole foot looks awfully pronated to me. [Indecipherable] [16:04] that the first met look pronated as well.


    Look at this picture from Dayton's paper. On the right hand picture, he shows pronation of the first ray and the entire forefoot of course looks everted or pronated. And then in this picture, there was supination of the first metatarsal and in this case, the entire forefoot is supinated. We are looking at a supinated forefoot deformity not a supinated first ray. So here is one of Dayton's papers and he is showing these axial projections of the first met in this so-called pronated position, etc, but as I've tried to show you there is lots of errors there. And out of frustration as I was trying to teach this to other people, I said you know something every time we do a bunion surgery, we can very easily look at that first metatarsal and tell if it's everted or inverted, can we not? Here is the picture I took in the operating room and there is a left foot and we disarticulate the hallux and just look at the sagittal groove and look at the head of the first metatarsal and you decide. Is that inverted or everted? Why would you ever take that first met and invert it even more with this new Lapiplasty technique, it makes no sense. There is no mystery here. In every case that I do a bunion and I look at it, that sagittal groove and the articular head of the first metatarsal always looks dorsiflexed and inverted exactly what Hick said almost 80 years ago. So Dayton challenged Hicks and in so doing challenge my study with Merton Root and Bill Orien and that's why I'm up here today lecturing on this because I spent years studying this and our methodology was sound and our conclusion were sound and it's a little frustrating when we see people get up and say there is little proof of how the first ray moves.


    And that the findings regarding first ray and range of motion have been conflicting. There is no conflict here. No conflict whatsoever is I'm about to show you. Our paper basically was done in 1981 and it was using more crude methodology but we basically did the right thing. We positioned the foot in subtalar neutral and we froze all the joints of the foot except the first ray and we moved the first ray up and down so we could see pure first ray motion and not foot motion. And in every case out of 16 cadaveric specimens, we found the first ray always dorsiflexed and inverted and always plantarflexed and everted, always, just as Hicks said. There was no conflict. There was no controversy. The evolution of the first ray follows that Hicks axis because the first ray went from a grasping organ in upright primates to the human being where the first ray became a stable pillar for stabilizing the longitudinal arch. But as a grasping organ, the first ray must plantarflex and evert -- must plantarflex and evert as a grasping organ. That is the first ray in its primal state as it developed and progressed to the human state. To say it doesn't do that is basically taking task with Charles Darwin and I don't think too many people are ready to do that. Our study was followed by Cherie Johnson and Jeff Christensen who also validated the Hicks axis. I'm going to go quickly here. But this is a really key paper that I think many people overlook and Al kind of touched on this and that's the locking mechanism of the first ray. Hugo Perez and coworkers with Jeff Christensen up in Seattle in a great cadaveric study showed that as the first metatarsal is brought into eversion, it becomes more stable.


    It becomes locked. It resists dorsiflexion. And they showed this cross-sectional view of the first metatarsal base and intermediate cuneiform and they showed how the joint surface locks as they evert the first metatarsal. It is favorable to not only plantarflex the first ray but to evert it when you do a Lapidus procedure because it enhances the natural locking mechanism. Here is the sagittal plane motion when the first ray is everted. Here is the markedly increased motion when it is inverted. Other papers that validated the Hicks axis, I just showed there but I want to show you the illusion of the pronated first metatarsal. Now, these frontal plane Lapidus guys say well, if you ever look at the first met in the bunion, it always has the lateral round sign, the lateral round sign and that's because it's "pronated." And when we go in and do our Lapidus procedure and correct it, the round sign becomes more of a squared off metatarsal head and until you invert the first metatarsal in a bunion surgery, you haven't corrected the bunion properly. So you want to get rid of your lateral round sign and the only way to do it is to do an inversion Lapidus procedure and here is the paper, right here. So here they are drawn, the angles and what's really interesting is this is a pre-Lapidus x-ray and the post-Lapidus. I question would anybody in this room do a Lapidus on this patient? Kind of wonder.


    But here, I'm going to show you another way to correct the lateral round sign. Here is the patient with mild bunion and I took AP x-ray and sure enough her lateral head is rounded. But instead of doing a Lapidus and instead of inverting her first met, I did this. I moved her into subtalar neutral and now the first met has that perfect squared off appearance that these Lapiplasty people say you want to achieve when you do a bunion. So I say, you know something, I corrected that by really going to where the big problem is. The problem is the rear foot. It's a pronated rear foot that pronates the first ray. And so here is the pre, here is the post with no surgery. Just correcting hindfoot alignment. Now, just concluding here, the only way to really tell if the first metatarsal is inverted or everted on the bunion deformity is to do a weightbearing CT and we are going to be getting a lot of biomechanical insight into all of the motions within the foot during gait and stance with three dimensional CD. We are getting great insight now in to the adult acquired flatfoot. These guys looked at patients with a bunion and they did a weightbearing CT. This is how it's done, not like the Kim study where they had the ankle plantarflexed and these are their pictures and lo and behold, you know what they found? The first metatarsal does not rotate in hallux abductovalgus in the direction of pronation. The more noticeable finding was that the hallux rotates into an everted position, the hallux. It's the hallux rotating in the eversion, the first metatarsal rotating in the inversion.


    So I'm going to finish up with another ultimate question and that is if you have a new surgical procedure that you are going to teach to the surgeons all over the country, should you go out and do some preliminary prospective studies and measure that procedure compared to traditional procedure and after at least a two-year followup say this procedure works as good or better than everything else you guys were doing. Hasn't been done yet with the Lapiplasty. There is no head-to-head comparison. But guess what, there is a frontal plane Lapidus paper. There is actually three papers on the frontal plane Lapidus from Scandinavia, from Klemola et al. Paper one, paper two, paper three published in the Scandinavian Journal Of Surgery, Foot And Ankle International and the first paper in our journal, The Journal Of Foot And Ankle Surgery. What's most interesting about Klemola's studies are he didn't invert the first ray like the Lapiplasty people said. He did the opposite. He everts the first metatarsal like Perez et. al. say to move it into a more stable position and you know what, he gets really good results. So here is his first paper and this was more of a brief retrospective review of about 84 feet and he looked at the radiographic measure and he really went into discussion about why we have all these controversies about range of motion of the first ray. And he quotes Jeff Christensen's work and he says, you know the first metatarsal always dorsiflex and inverts just like Hick said and if it looks pronated, it's because of the rest of the foot is pronated on the floor. His next paper looked at dynamic stability after he did this Lapidus procedure and he found significant improvement of stiffness of the first metatarsal and improvement of weightbearing when he everted the first metatarsal with the Lapidus procedure.

    And finally, most impressive was his 8-year followup study on the eversion Lapidus procedure, 8-year followup, 70 patients, 88 feet. Here is a picture of him rotating it into eversion not inversion and with functional scoring AOFAS clinical outcome scores good to excellent results as good or better than most other bunionectomy procedures doing the opposite as what the Lapiplasty says to do. So in summary, this is what we know. A portion of patients with hallux abductovalgus do have a pronated position of the first met relative to the ground but not to the second metatarsal. This everted or pronated position cannot occur from independent rotation of the first ray. It can only occur from pronation of the entire foot. Failure to correct the pronator position of the first met may in fact lead to failure of HAV surgery but it's really because you did nothing to correct overall foot alignment or improve foot function with something like custom functional foot orthotic therapy as a followup. Traditional surgical procedures which provide transverse plane realignment of the first metatarsal can correct the illusion of the pronator position of the first metatarsal in HAV deformity but they are really not correcting the underlying cause of the problem. Keep in mind that no prospective or even retrospective clinical studies have been conducted to show that frontal plane inversion with the Lapidus procedure does provide a better outcome than other standard procedures. I think we still have a lot more work to go but my purpose here today is to have everybody step back and realize that there is sound biomechanics and sound research out there about the function of the first ray that cannot be ignored if we are to embark on new surgical procedures. Thank you very much.


    TAPE ENDS - [28:18]