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Speaker: Our first speaker is popular speaker for our meetings, Michael Troiano, DPM, comes to us from Philadelphia where he has extensive training and extensive experience in lower extremity reconstructive procedures and trauma. He provides a great deal of insight to us when talking about various reconstructive procedures. He is active in education program at Temple School of Podiatric Medicine and Temple University Hospital. So let's welcome Michael Troiano to speak on the use of Lapidus for severe bunion deformity. Okay, thank you.
Dr. Michael Troiano: Alright, good morning. I imagine it was this hard for everybody else to get out of bed as it was for myself. So thank you for coming. Lapidus procedure is probably one of my favorite procedures in the lower extremity. The reason why, it's a very complicated procedure, there is many levels to the bunion basically. There is the technicality of performing the procedure but then there is why and the history of course and how. So in order to understand the procedure, we have to understand the history of the said procedure. The procedure dates back to the late 1800, early 1900. It was first described for an atavistic cuneiform. An atavistic cuneiform is when cuneiform articular surface instead of being parallel with the MPJ articular surface in a direct line with the second metatarsal is actually pointing medially, so it kind of cast the first metatarsal off the medial angle. The idea was basically to reshape the cuneiform and fuse the mid tarsal joint including the Lisfranc joint.
So you are looking at first metatarsal, first cuneiform, second metatarsal, second cuneiform. While that was done, initial treatment involved just simple casting, so you can imagine it was a complete failure and then after casting K-wires and again complete failure. So the procedure kind of fell out of vogue and no one really performed it anymore till the early 1900 when screw fixation technology began to become in forefront of foot and ankle surgery and surgery in general. So the procedure was revisited and again same idea, full kind of Lisfranc fusion, first metatarsal, second metatarsal, medial and intermediate cuneiform with Lisfranc screw and the results were much, much more spectacular. So it's something that now is used in every facet. It has all different variations and different ways of doing things. There is screw fixation, there is plate fixation, there is external fixation and we are going to go through some of these. So in order to understand the procedure, we have to take step one back to the development of the bunion. Dr. Schoenhaus yesterday talked about the first ray in the biomechanics and pathomechanics of first ray. Pathomechanics is something that's near and dear to me. I teach the class of Temple University School Podiatric Medicine and dig into root theory and axis of the first metatarsal. And I think when you look at any bunion forming foot, public enemy number one is the Achilles. The Achilles is the strongest plantar flexor in the foot but it's also the strongest supinator in the foot. When that Achilles begins to move laterally in the foot and we get that Helbing's sign, that bowing of the Achilles, we begin to see the strongest plantar flexor and supinator turn into the most formidable pronator, right?
So calcaneus locks into eversion, talus dumps off into plantar flexion and adduction and the distal foot begins to flap into lateral position causing this escape phenomenon of the first metatarsal. Recognize that once that occurs in the axis of the first of the calcaneus, it shifts laterally, now the peroneus longus loses its mechanical advantage, which is the second strongest supinator in the foot, right? So peroneus longus begins to lose its mechanical advantage moving laterally. The subtalar joint widens, so it really loses its mechanical advantage and then it can't stabilize that metatarsal cuneiform joint number one against the underlying terrain. So one develops both hallux limitus, functional hallux limitus when the first metatarsal pops off the ground and one develops a bunion when met primus varus occurs and the first metatarsal moves medially. If we look at the rectus foot type versus hallux valgus foot type, what we see is the first metatarsal here instead of being perfectly straight, begins to get this met primus varus condition to it and then all of the musculature, which should be in line with the first metatarsal actually begins to move into a lateral position. So we begin to see our adductor take over. So after we have Achilles, pronator longus, the adductor begins to take over and it locks the joint capsule right here in the tight position. After that, joint capsule is locked, then the long flexor and long extensor begin to take over and they further take this strain down the track so that the bunion has no ability to be corrected at this point unless it's surgical. So any procedure that one is going to do in the foot and ankle world, you really have to think of etiology of the procedure. In other words, how many tendo-Achilles lengthening are we doing or gastroc lengthening are we doing to fix our bunions. How many subtalar arthroereisis are we doing in conjunction to fix our bunions and I am not saying that every Austin should get Achilles tendon lengthening or what have you but at the least simple things that we do on a daily basis.
We see the patient, they have a bunion, we say, alright, we are going to schedule you for surgery. Are we really fixing the etiology of the condition? Did we cast them for orthotics postoperatively? Did we send them in physical therapy and show them exercises to get the strain off of the Achilles in the hopes that our work will be protected going further. Some questions to ask yourself. Hyper-pronation obviously is the most significant bunion former. This medial eminence is actually not medial eminence. We are going to talk about that in a second more of a hypertrophy of bone. And in the position of the second digit, that second digit we have to be cognizant of because it looks very long to begin with. Once that first metatarsal shifted over, it becomes a whole heck of lot shorter. So we also have to be cognizant about what our second metatarsal is doing. Are we going to develop transfer metatarsalgia or are we going to develop transfer lesion, are they subject to predislocation syndrome? So all of these things going to the bunion and there are so many facets that should be working in your mind when you look at these bunions and procedures for them. Hallux limitus, we want to define as well. Is the person tracking or track bound? In other words, maybe that motion is great but when we correct the PASA, it turns to nothing. There is actually literature that shows the PASA will re-correct itself once the IM angle is reestablished. Is it too much though? Will the person do better with fusion? These are other questions we have to ask ourselves. Thinness of the foot is another question with the Lapidus. Obviously, a lot of our patients -- in a Lapidus fixation taken place, here is a very thin area of the foot. So is this patient comfortable that his or her hardware is going to come out later? I don't care if you screws or plates or what have you, it's my experience about 30% of the hardware that I put in for the Lapidus, patient can't tolerate in a year, so I end up taking it out whether it be screws or plates or what have you.
And the reason is it's such a thin area of the foot and once you kind of move the first metatarsal back laterally, then the most prominent area of the foot becomes the plate or becomes the screws. So is this person comfortable that the hardware is going to come out likely in a second procedure? Biomechanical evaluation, again you have to look at the equinus, the subtalar joint range of motion, metatarsal adductus, first ray hypermobility, and pes planovalgus and what degree of each. Therefore, adjunctive procedures are oftentimes necessary to fix the bunion. And then finally, are you choosing the right procedure? Right? If you look at this person with the severe bunion, is the bunion really the only thing that we need to worry about? Is it worth it to go ahead and correct the flatfoot deformity? Like in this person, they would benefit from obviously an Evans and maybe Koutsogiannis and then the bunion would minimize and then it translates to just an Austin after some time goes on. So don't just focus on the reason why the person is in the office but you have to focus on the whole reason why the bunion developed. Metatarsus primus elevatus is important to identify. I want to spend a second on this slide because as we know first MPJ motion is 65 degrees, necessary in a normal gait. So 35% of that motion comes from just passive range of motion, the weight of the tibia going over the first metatarsal. The normal progression of gait within that other 20 to 25% occurs when the peroneus longus pulls down that first metatarsal cuneiform joint. So when it's incompetent, the first metatarsal lifts and then the joint jams. So it's also important when we do our Lapidus that we plantar flex the first metatarsal or plantar translate the first metatarsal, which out of the two, I prefer the latter, which we will get into in a second as well. So after we have identified this foot, we are ready to go into our surgical intervention endeavor but for our residents in the room and those of us that haven't been doing this for too long, we have to be very comfortable with adjunct procedure.
So adductor transfer, right? So many times where as a resident you learned the procedure text book. We are going to do A, we are going to do B, we are going to do C. But each bunion is very different. There is no set cook book recipe for the bunion. So the adductor results with a malaligned EHL and FHL as the first MPJ longitudinal axis moves medially away from the tendons and then you begin to see that bow stringing. So that adductor influence needs to be cut first and then tagged because sometimes you will transfer it to the medial side of the capsule and then of course the EHL sometimes need to be lengthened and sometimes the EHB needs to be cut or lengthen and then of course you have your adjunctive procedures to the second metatarsal. So make sure this person is consented for all soft tissue and capsular balancing because there is a very good chance you are going to need to do some of those things. Even in some cases, I have tighten up the peroneus longus because it's so bowstrung, you know tightening up to take some of the slack off to make it competent again. Let's look at the sesamoid. Sesamoids are important. It's important to get that first metatarsal under the sesamoids again. If you do not, then you can guarantee that bunion is coming back, I don't care how well you fuse that first metatarsal cuneiform joint. The adductor and the sesamoids are going to continue to pull laterally. Even if release them, they will scar back into position. Even if you take a wedge out, the capsule itself will scar back into position and the person is literally going to rock off of their tibial sesamoid so that the sesamoid gets displaced laterally and the bunion returns. It may not be at the level of the first metatarsal but it may be distally manifested as increased PASA. So sesamoids are absolutely paramount to your operative fixation.
Again, formation of the bunion, we identified this as a hypertrophy. It's actually just bone remodeling. The body amazingly undergoes the -- if you don't use it, you lose the phenomenon. So when there is no articular surface from the first metatarsal to the proximal phalanx, the body basically stops sending resources of cartilage type 1 and type 2 collagen to the area to keep the articular surface and instead it becomes a proliferation occurring because of the lack of cartilage. So basically what I am trying to say is your articular surface will literally snow plough this proliferation off to the medial side and will kind of kick back almost like a tire in mud in a car. It's leaving a gully because of its non-articular area. So the pull is greater than the minimum effective strain of the collateral ligament from the tibial sesamoid causing this hypertrophy or proliferation of the medial eminence. So what that means is that means we shouldnât be tricked by cutting this off first, right? So many times when we do a Lapidus procedure, we just nail off the medial eminence because we are there but in actuality that can save our butt several times because if you cut that medial eminence, it kind of can push the first MPJ into varus. So I think you do your correction first, line up your first metatarsal cuneiform joint and then go back and take off the eminence as needed and you will find that what you need after you have corrected the IM angle is always a whole lot less than what you needed before to correct the IM angle. Formation of bunion, again we have to be cognizant here that osteoclastic activity doesn't cause erosion of the first MPJ to the point of no return. Again, once you realign that PASA, there is evidence to suggest that the cartilage will kind of shift backwards but if it's too far gone, one has to consider fusion may be the best option.
X-rays, weightbearing x-rays and evaluation are must and I say this only because of this guy right here. When we measure our angle, our IM angle, rule of thumb is whatever the PASA is, how much of an angle you have to correct to make it normal, is the wedge that you are going to take from the metatarsal cuneiform joint to correct the bunion. So in another words, if you need to correct 5 degrees, you are going to take out 5 degrees of wedge at the metatarsal cuneiform joint. It's not just eye balling. You can actually measure it, kind of [indecipherable] [00:14:34] and get it. It's more of a science than we think. Obviously, success with any bunion surgery but especially the Lapidus is going to have to do with patient compliance. People love to stand on the podium and say, well, I get my Lapidus or I get bunion weightbearing in four days, terrific. Why? I mean it takes bone physiologically six to eight weeks to fuse. I don't know that to thump your chest a little bit and say I got this patient weightbearing earlier is anything better than developing a nonunion later. So I think first and foremost, let this patient know he or she is going to be in a cast for a month and then a CAM walker for a month and anything that's an improvement from those, you look like a hero and they are very proud of themselves as opposed to saying I am going to have you weightbearing in a week and then that week turns into two months and then they are wondering if something went wrong. I think you always kind of sell a little bit longer in the hopes of anything shorter. Performance of the procedure again, fixation methodology, the art of surgery is very important. How much blood supply are you stripping? Endosteal bone supply accounts for approximately 70% of the blood flow of first metatarsal cuneiform joint. You know that you are getting rid of that because you are cutting it with a saw. So how much trauma are you doing to surrounding soft tissue?
How much trauma are you doing to periosteum, which comprises 25% to 30%, pretty significant. So you have to be cognizant of the fact that you can't be through there and just cut everything. There needs to be surgical dissection with good art of surgery and methodology of surgery. And then of course, for men and women alike what is this person's expectation as far as shoe gear. Are they understanding that they are going to be able to run a marathon? Are they hoping to get back into an old Blahnik shoes or Jimmy shoes. You have to certainly be realistic with what they are going to do especially after the Lapidus. This is a procedure to somewhat correct the flatfoot deformity and prevent the bunion from recurring. It's a long-term procedure but certainly not a cosmetic procedure. Again, if mechanics cause the original problem preoperatively, it will continue subsequently postoperatively and therefore this is the reason why these people all need to have orthotic devices going forward or adjunct procedures. So these are the adjunctive procedures. You should be ready to do. If you don't have them, go back into the cadaver lab, take a course, go back with your residency director or what have you and make sure that you are comfortable with all these procedures because they are just as important as the procedure itself. And kissing the bone together is nice and you get nice and full surface and your screws are biting and you really happy about that, but you certainly have to recognize the adjunctive procedure. So this is my incision for the Lapidus procedure. This is a patient of mine who had a failed procedure by orthopedist. That's their typical incision where they make the medial incision and interspace incision. And obviously, they corrected the bunion but didn't correct the etiology for the bunion, so you can see that this person still has a significant hallux valgus, hallux abductus and overlapping second toe. They are starting to get plantar plate pressure and it's very uncomfortable. I would like to see things, so my incision is pretty long.
Incisions healed side to side not top to bottom. So I think I need to expose this as well as I can see. I need to identify each structure and I worry about the closure after. As long as the closure is done appropriately and with a nice plastic surgical stitch, there will be minimal scarring. So after I make the incision, the first thing I am going to do is I am going to release the first interspace and then tag the adductor here. That adductor, I just hold on to, I just leave it there because I may cut it and I may transfer it and I don't know what I am going to do at this point. So I am just going to be tempted to cut it whereas a lot of us would do that in the first step. It's get out of jail free card. It saved my butt several times. After that, you are going to use your magic shovel, which is your McGlamry elevator and you are going to lift up the sesamoid and displace them from the hypertrophy and articular surface of the plantar first metatarsal. And then we are going to go back and we are going to identify the joint. After we identified the joint here, we are going to look at the x-rays and look at the angle that we have measured and here we can use an intraoperative protractor or we can measure on the base of the cuneiform, the distances preoperatively so we know -- we have a little ruler where we need to be from joint to joint. And then that's the wedge we are going to take out. Now, pearls for taking the wedge out, never, ever, ever take the wedge out of the first metatarsal. Why? Because cancellous bone goes from about here to here and then it's all cortical. So if you take too much of a wedge, you are going to be applying cortical bone to medullary bone or to cancellous bone from a medullary canal and nonunion is going to occur. Second thing is recognize this as a reniform joint. It's a kidney shaped joint and therefore this is concave. This is convex. So if you are going to take your wedge out of the first metatarsal, you have to initially get past the concavity of the joint, past the cartilage, otherwise again you are going to get a nonunion.
So it's always easier to just take a straight shot parallel to the joint with the first metatarsal and then take your wedge out of the cancellous bone and again when I make my cut, my cut doesn't have to take all the cartilage off. I could just take a section here off and then fuse the first metatarsal to the section. Don't get so caught up in leaving cartilage behind on the concave surface because -- excuse me -- on the convex surface because as long as you have your correction, that's all that really matters. So after the two surfaces are cut, lamina spreader get the two pieces out and make sure there is nothing left behind and then temporary fixate the first metatarsal cuneiform joint. I like it, the sesamoids are good. Now, we are going to start the fixation. So this is the claw plate from Wright Medical and I am not a consultant for Wright Medical. It was one of my favorites for a while. Basically, it's a plate that acts like a staple at the same time. You make your two drill holes and then you insert your screws. After you insert your screws, there is an instrument here called an actuator and it pushes the poles of the staple medially and laterally thus bringing the screws together to impart from pressure and it's nice compression. So you can see after the procedure is done, you have the sesamoid back under first metatarsal out aligned with the second. When people say what about the shortening, the other pearl that I would give you is, don't take the wedge for plantar flexion at all, if you can avoid it, because by doing so, it gives you hallux extensus. Instead, just slide or plantar translocate that first metatarsal down and then use your fingers to kind of say is it in line with the second metatarsal. Once it is and they are both bearing their fair share of weight, then you know for sure that you have a good weightbearing surface. Again, this is going to be 50% of the weight bearing, 20% of the weight bearing, 10, 10 and 10, so you want to ensure that the first metatarsal is bearing its fair share of weight. So you can see that before and after in this patient. Otherwise, you can fixate screws. I donât love screws, because in order to put screws in properly, they need to cross in the joint, so a little bit medially, a little bit laterally, you are not imparting equal and even compression and you can actually gap the osteotomy site.
So although screws are the cheaper way, you really have to be talented at putting them in and crossing them perfectly at 90 degrees, which I am not, so I don't use a ton of them. This is the more in vogue way of fixating the bunion with the screw going across the metatarsal either the first into the second or recreating Lisfranc joint. I am fine with this. I just counterintuitively -- I don't think you should put a screw across a non-fused joint. So if you are going to fuse a Lisfranc joint, roughen it up and try to get it diffuse. I don't like to put a screw across the first metatarsal to the second because I think that screw -- if you again think pathomechanically or biomechanically, the first ray and second, third and fourth ray have independent range of motion or axes to the first. So in other words, you are tethering them together and you are locking them as one unit, which they are really not. You can use the staple with screw method. I have used this in the past. It works nicely. Lapidus with interpositional grafting for length, I would tell you, be cognizant that you are not putting screws across autografts. Obviously, it's a live graft. Compression is going to kill the graft but cancellous graft, shag graft, coral graft, totally fine. This is the CP plate from Stryker. It has become one of my favorites. They have actually come out with a new and lower profile set, which I would like to use as well but the idea it uses the plate as the washer. So basically, you mill out a hole on the first metatarsal and then put the plate in the hole. Then you put in the two screws distally here and then kind of put a home run screw across the osteotomy. And what it does is by engaging the home run screw into the plate, it makes this whole unit basically a big washer for the first metatarsal as it impacts the medial cuneiform and I want you to have tight compression, you lock it home with the screws.
So there is pre and post-op, another pre and post-op. This is a young girl with hallux limitus. She has basically no bunion deformity whatsoever, but a hypermobile first ray. So we are going a met cuneiform fusion to impart peroneus longus stability and get range of motion to the first MPJ because whenever she walks, that first metatarsal is displacing dorsally and she is jamming at the joint. Again, this is where the CP plate is used. We are going to take our wedge out in line with the joint, plantar translocated and then milling for the plate and then the home run screw in locking the plate proximally. The other thing is if you've used this plate, I think it's very important to stay medially. Most of these plates you have to stay medially. It's a lot of people will say, gaps or I don't like the plate or what have you. It's probably just the experience that you have. There is a learning curve to some of these and it feels very unnatural to be as medial as you need to be to plate the first met cuneiform. So there is your pre and post op. Complications, when Lapidus goes wrong, it goes wrong pretty badly. Reason being is you usually have a nonunion, so you have to resect farther thus either shortening the first metatarsal or having minimal bone stock. So we have to be cognizant of the procedures as they relate to nonunion, but hardware failure, hallux extensus, elevatus, if someone walks too early, all of these are real conditions and should be addressed immediately. Don't wait for things to go bad. Go back in there and fix what you need to immediately. I will tell you that number one -- I see a lot of Lapidus nonunion and revisions. I think the number one cause for that is not taking enough cartilage. People kind of curette off the cartilage and they say okay thatâs enough but in actuality that bleeding Paprika sign is underneath the subchondral bone, which is few millimeters away from the cartilage.
Obviously, make sure that you have appropriate candidates. You don't want to do a Lapidus in somebody with IM angle that doesn't necessitate it and no hypermobility. Obviously, make sure your screws are compressed in the joint and cross directly in the middle of the joint and hopefully you will have some good luck and some good results. So thank you for your time. Appreciate it.
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