Jason R Miller, DPM, FACFAS reviews the principles behind 1st ray instability and discusses surgical techniques for proper correction. Dr Miller begins by defining hypermobiity and how much motion occurs in the 1st TMTJ. Next, he describes Lapidus Arthrodesis in detail. His lecture contains a step-by-step pictorial of the procedure as Dr Miller narrates his preferred surgical technique through multiple case studies.
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Jason Miller, DPM
Podiatric Residency Director
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Interviewer: Continuing the program we are very happy to have Dr. Jason Miller from Pennsylvania, who I have known for a good number of years certainly at the Temple University School of Podiatric Medicine. He has an excellent ability to disseminate information from the platform. And I have asked him to talk on first tarsometatarsal phalangeal or first tarsometatarsal fusion. So please welcome Dr. Jason Miller.
Dr. Jason Miller: Good afternoon everybody. I wanted to go over some things today that we are going to talk about regarding the Lapidus procedure of the first TMTJ fusion. I do things maybe a little bit different than some people would, its not rocket science, but I think it�s a different sort of technique to sort of overview when looking at doing first tarsometatarsal fusion. So we want to understand the rationale for why we do this procedure and you know unfortunately reviewing cases, seeing things out in legal realm, today where we see people using inappropriate procedure selection where this a Lapidus should have been performed. It for some reason it seems that throughout the country people are scared of doing a Lapidus and I am not really sure why but there is plenty of good indication for it. We will look at some newer fusion techniques, some newer fixations and newer hardware that we can utilize to help enhance at least our weightbearing, maybe our fusion rates as well. And hopefully future studies will show us whether or not we are getting better fusion rates with that.
So when we talk about instability or hypermobility we need to sort of define you know kind of what that is, does it really exist you know how do we measure it, what are the tools that we use to determine whether or not somebody is truly what we call hypermobile. And what is the significance of hypermobility to our procedure selection. So when we first look at where did instability or First Ray hypermobility came from. It really wasn�t talked about until the 50s, the first was really with hex with the windlass mechanism discussions in that early 50s and then Lapidus in 56 talked about idealistic trades of the first tarsometatarsal area and then also ligamentous support in the 80s so not a whole lot was going on there. So how much motion usually does occur at the first TMTJ, there were multiple studies in the late 80s, this was a really hot topic, right around that time. And really what we know is that -- the tarsometatarsal joint has usually less than 2 degrees of motion if we look at across the board and really only minor amounts of motion, and when we look at different axis�s vertical and transverse axis in motion. So the conclusion is, is that motion at the normal its first tarsometatarsal joint, if we take a compendium of all the literature is really minimal with an average of only about 3 degrees that dog is awesome, isn�t it, you can�t tell if it has to go to the bathroom of it�s hungry or neither one of the two.
So with the issue of hypermobility what a clinical correlation that were made way back you know if we look back some of the original literature by Morton in the 1930s with short first metatarsal up through Root Biomechanics, you know which have always, lately been held in contest, we go through and look at all the studies that have been have been performed, we realize that patients that have moderate to severe HAV, nearly 50% of the First Ray motion was at the first metatarsal-cuneiform joint. So as the deformity increases the access in motion changes with more motion occurring at that joint. And that was looked at by Hofbauer in 1996.
So if we look at quantitative assessment at first TMTJ, in the Klaus Study in �94 used clinical measuring device and looked at what he referred to as tarsometatarsal reorientation arthrodesis and looked at sagittal plane relationships or looked at met primus elevatus or supernatus of the First Ray. Certainly we know the effects of the peroneus longus tendon on a First Ray mechanics and it was really well described in the journal of Foot and Ankle Surgery by Johnson and Christensen in �99. And what really what they showed and demonstrated from that study was that the peroneus longus creates an E-version locking effect that the First Ray and therefore has a very strong stabilizing components of the medial column. And that arthrodesis of that joint then functionally mimics that PL activity. This is one of the reasons why a Lapidus fusion in a patient that has already has a hypermobile flat foot or has a flat foot deformity, does have a powerful impact on what the rest of the foot is going to do following a Lapidus procedure.
So what are the consequences in the Lapidus on PL function? And this was idea and Acta is meeting back in 2000 down in Florida, looked at the effects before and after arthrodesis on the PL and they found that arthrodesis did indeed increase the efficiency of the PL in stabilizing that medial column, sort of again sort of resounding that 99 study by Christensen. So the issue of hypermobility if we look at radiographs there was a lot of literature done by radiograph Jordan Grossman and Hofbauer looked at hypertrophy and the met shafts, you know Mann, Hirsch, Brogue and Tanaka, all good studies that looked at Coleman Block Test, shapes, angles is all things that you were taught either in residency or when you were in school, what to look for when you are determining whether or not at first tarsometatarsal joint might be hypermobile just by the look at the x-ray without even physically being able to examine the patient.
So the indications then are severe met primus adductus or were significant intermetatarsal angles. So moderate metatarsal angles should be looked at with hypermobility so even somebody that you normally say well gee, I could do a callus or offset B here, I might be able to even do a chevron on this but if there is hypermobility then you don�t want to do that. Particularly in a younger patient because that patient will be back in your office and will not be happy, the timeframe is hard to say but you know few years you know but inside a 10 year is a guaranteed that bunion deformity will be back, if the hypermobility was not addressed. So adolescents that have hypermobility or generalized ligamentous laxity a Lapidus is absolutely standard care for these patients. So one can either do this while the patient�s growth plates are still opened using either mini rails or stamens or my preferred method is to try to encourage a patients to wait for surgery until the growth plates are fused and then get the kid to the OR. And obviously if there is arthrosis at the TMTJ or if we are talking about revisional surgery the patients already had had a procedure and the last thing we want to do is get back and cut on the head again.
So I put this picture and since it�s the 100th anniversary of the Titanic sinking, I thought that was pretty funny that the Van says Titanic service is on the side and it went into the dry dock area there, but contraindications would be an absence of First Ray hypermobility in an IM angle that�s not very high or if the patient already has a significantly short ray, unless you can account for this by performing graphing or callus distraction technique at the same time. So clinical assessment often times what we will see is we will see IPKs are diffused keratotic lesions under second met head, usually the second MTPJ and long-standing hypermobility will actually be subluxated or have hammertoe deformity or the patient may have been treated for capsulitis may have been injected in the second toe, we can even see neuroma formation between the second and third metatarsals, in these patients. We will notice excessive First Ray motion or hypermobility on examination. We will sometimes see even a splayfoot deformity, we will see that 1/5 configuration where we have widening of the foot. And basic physical evidence of generalized ligamentous laxity.
So this is just looking at some objective assessments of First Ray motion. And this is an overview of the study that we looked at radiographic and statistical analysis of a 100-feet and basically looked at normal First Ray sagittal realm of 4.37 degrees and also looked at correlating that with the thumb and with First Ray a hypermobility and found that there was no correlation between First Ray motion, sex, age, IM angle, near elbow or shape of the cuneiform and the study. So we are often taught that shape of cuneiform makes a difference, the study is saying, no, but they found that the hyperflexibility of the thumb was an issue. Radiographic assessment, again we talked about high IM angles, we talked about hypertrophy of the second metatarsal cortices that you see frequently in this hypermobile feet. Again one way that you can make a determination if you are given an exam or an x-ray with thick cortices on the second met, even if you can�t physically tell by examining the patient you can often theorize if a patient does have some sort of high IM angle or bunion deformity that there is probably something going on with hypermobility at the first tarsometatarsal. So subluxation or dislocation of MTP, thinner plate tears associated with this or sagittal plane subluxation or elevation. So the influence of x-ray orientation at the first TMTJ angle that was looked at in �94 by Brogue and significant differences in the first TMTJ angle were noted with respect to the x-ray being positioned. And its really not a good measurement to use as an indication for arthrodesis based on the results of that study.
So, operative technique there is lots of different ways that you can approach the Lapidus, the incisional approach is very variable, some surgeons like to go more medial others prefer to go more dorsal, some even like to go into the dorsolateral components so they can really see that lateral condyle. You know I tend to stay sort of right on the midline for this. Joint mobilization is important to intersection and preparation, joint realignment and provisional fixation and osteosynthesis. We are going to cover little bit of all that and go flyers.
The technique, the alignment in the sagittal and transverse planes are obviously critical and I don�t know how many times you guys have seen x-rays that are subpart results for a Lapidus procedure so they did a great job fusing it, but there is still a 17 degree intermetatarsal angle and the patient starts at bunion and they try to correct them by staking the first met head and taking off a whole bunch of bone off the head which is really a bad technique to see have happen. One of the things I found to be useful is either the pinning their first met to the second or using a toe clamp or bone clamp subject to meta�s position and actually grab on to the second met. So we definitely don�t want to cut into the second met and I have seen cases I have reviewed a case where you know either a surgeon or a resident actually cut through the second metatarsal while they were plaiting the first metatarsal and its very easy to do because that first metatarsal is not as wide as you would like to think it is and that sock and very easily pass through and create a full fracture right through the second metatarsal base since its right there.
Typically I almost like to remove in every case the lateral condyle the first met, one can use around jure or saw to do this. I prefer using lumber in osteotomes terms a small curve, the half-inch osteotome, I can strip on this entire cartilage off in one pass on each side of the cuneiform of the first metatarsal with that thing right down the subchondral bone. So you know prepping the joint well that doesn�t take long it�s the positioning that that takes the most. So we then typically will translate the met on the cuneiform where is typical plane as needed again avoiding that second metatarsal and use a laterally based wedge from the cuneiform if necessary. You should always take bone from the cuneiform not from the first metatarsal, something to remember if ever asked that question in any sort of testing environment.
So the met can be translated dorsally or plantarly on the cuneiform, the retrosection and maybe required but you have to remember you are going to have short name, so you need to have your pre-op x-rays there and know how short or long that metatarsal is from the get-go. So if its really short already and it was bordering on being a problem then you may want to look for a wedge graft to actually place into their do, like an opening wedge sort of Lapidus and fuse that together. I typically like to finish straight to fusion side with either [indiscernible] [12:48] K-wire or small drill bit and using any sort of graft to fill in if there is cystic change is there, if it was very arthritic. Standard fixation over the years have been 3/5, 4/0 or even 4/5 screws cumulated to solids. Most common error when using regular screw fixation is putting the screws too close to starting too close to the joint itself.
You got to really start far back from the joint or to get good purges. And if screws go into other cuneiforms, studies have shown that this really doesn�t cause a problem. If the screw actually enters into the intermediate cuneiform, really not too much of an issue, callus sinking is more important than that. So here�s an example of drawing resection with planning going in using the saw and planning there, and actually taking out wedges of joint.
Now this is an example of that I prefer to use and this is showing the Vilex Lapidus plate and has a disclosure I am a consultant for Vilex so you can take that into consideration. I use a lot of different plates I have been using plates for the Lapidus essentially since they were first came out way back with Darco when it first came into the U.S. and I was I have been looking for something better, always trying to find something better for Lapidus. So this is the way I perform the Lapidus procedure. I will typically get my planting done as you are seeing earlier. I will get this in the position and then using this instrument that�s actually on the Vilex set, it even has little degree measurements on it, I will dial in the amount of correction at the first and second metatarsals. And that can be done percutaneously or if you have your incision open up far enough you can put it through your incision. So once I have that in place I will typically throw my leg screw from the first metatarsal into the medial cuneiform and I usually like to get it down into that BP portion down in the plantar medial aspect of medial cuneiform. So its nice place to have a screw there is a lot of real estate they have to get a screw into. And at this point I will place my plate on before placing the screw in. So I will provisionally fixate this, make sure that all my things are good, look at, get to see arm, look at it. And once I am doing good, now I am actually going to put some screws into plate. And I might seem a little backwards because most people will typically throw their interfrag or their compression screw first before they actually fixate the plate, I don�t do that and I will show you why in a second. So I will get, I will drill this in the event that I want to switch out to you a locking screw later, using the towers and then on this screw which is somewhat oblong I will actually drill this to dynamize compress the fusion side. So I will drill the screw so that I can get some compression now this is oblong I can get a couple millimeters of movement on the screw once I compress. I will measure that, get that screw in and notice that I don�t tighten the screw all the way down. So at this point oops, I will drill for my cannulated screw that�s going to give me interfrag compression and then place that cannulated screw in which is a headless screw kind of sinks really nicely right into the bone. And now at this point I will tighten that last screw and take an x-ray and at this point usually what you will see is that everything is nice and corrected. I will remove my clamp actively under fluoroscopy to make sure that first metatarsal doesn�t translate or move, now that the clamp is not there anymore. And typically it will not but occasionally if you are cheating yourself and you didn�t really get good position on the plate or your other screws you may see it want to kind of wag back again and you may have to go back and start over and do some planning. And at this point I will finish my construct, typically I will do a locking screw here and here, not always if the bone is solid I won�t replace that screw with the locking screw I will just get a good bicortical bite on that and just do a locking screw in the cuneiform since the cuneiform tends to be able to softer thinner cortical shell bone and your end result looks as such.
These are the different options, you guys you can go and check this out at the Vilex stand some different platting options for TMTJ fusions whether it�s the first 1 through 2, 1, 2 and 3. And your standard fixation options, personal wire stamen pins. Here is the old Darco system that I was using back in the day that was step platted and you know gradiated you know in 1, 2 millimeter, 4 millimeter however you want to shift it. And here is a case study with using another platting system, on this case you want to know this patient has met primus elevatus so that�s got to be corrected. That�s a problem and if its not corrected we will talk about what that�s going to do so that red line is where we want to be, right here when we finish our correction.
So using the Anchorage Plate here which is obviously another new modern plate, these allows to stay incorporate the interfrags screw right into the plate itself. So it looks good here, get good IM correction but did we correct the MPE, what happened to that slide, its gone, alright. Like they always say, I can guarantee you its corrected but I don�t know what happens when that picture its gone. I guess my two and half hour wait on the Philadelphia Tarmac made me stir crazy and I must have deleted by accident because that was one of the things I wanted to show you. Well here is another one with the significant metatarsal adductus angle. And with these you don�t want to run into the trap of trying to squeeze this tide up against the second metatarsal head. What we wanted to be is about parallel and we want it to be stable and diffuse it in place. And here you can see one there you go, we are parallel to the other mets we are not excessively plantarflexible, we are excessively dorsiflex, that�s where you want to be, you want to follow the rest of the forefoot on corrections with these so.
Complication wise if we excessively plantarflexed that first metatarsal head it can lead to sesomoiditis and I have seen patients come into the office with this already and its not much plantarflexion that can do that. You know maybe 1 to 2 millimeters under the second met is all it takes in some patients to get retracted, irretraceable sesomoiditis. So if we dorsiflex it we increase our pronation component and that�s a very tough thing to accommodate even with an arthodesis afterward. Excessive shortening typically you get the cock up hallux and lesser metatarsalgia in those patients. You got to be very careful with dissection in this and that could be a whole lecture in itself just talking about dissection of the Lapidus, if you can try to map out continuous nerves ahead of time with the patients then scan I will typically try to strum things to see if there is any sort of variation from your typical sarrafian anatomy, sometimes you will get a crossing branch that goes right where you want to put your plate and it may change your fixation, it may change what you want to do because you know you are going to have to sacrifice the nerve if you are going to get a plate in or cross screws.
So also looking at the 10% nonunion rate usually this nonunions are asymptomatic, I would say maybe 1% or 2% over the years of the 10% if you actually see that tend to be actually symptomatic if they do develop a nonunion. So contraindications some people say osteoporosis is a contraindication, I would say it�s a relative one. And I think that using locking plates and this fixation is much better, you don�t want to use cannulated screws in somebody who has got significant osteoporosis because I think you are asking for trouble. And I would definitely use locking plate fixation on a patient that has osteoporosis.
So in these cases you have to consider whether or not you even want to do a Lapidus if that�s that bad if your osteoporosis is that significant you know maybe go with something more joint to salvaging like a callur or something. So some says its contraindicated in the absence of a short met, in those cases I think that you can do distraction Lapidus procedures in using a graph and opening what graph in those cases and not an absolute contraindication we talked about before about adolescents, try to postpone it so they are mature. So time will tell whether or not these newer plates have reduced our nonunion rates, we don�t know yet, they haven�t been out long enough to know that, my gut feeling is that they will probably stay about the same maybe slightly last because I think preparation is really the key. One thing I do know is that it allows for early weighbearing, I am not quite as cavalier as some guys, I know Larry is pretty cavalier, he weightbears them early, I know you know a few my other colleagues are, they will weightbear these patients immediately after surgery or within one week or two. I usually wait till three weeks on Lapidus and have a full weightbearing. So the straightforward, easy to do and don�t forget tomorrow�s cinco de mayo so remind yourself tonight after your first or second drink. So thank you guys for your attention, does anybody have any questions.