Board Review Foot Conditions

Panel on Posterior Tibial Dysfunction

Harold Schoenhaus, DPM

Harold Schoenhaus, DPM, FACFAS and Guido LaPorta, DPM, FACFAS, MS define and discuss posterior tibial tendon dysfunction (PTTD), its symptoms, treatment and clinical signs. Dr Schoenhaus outlines indications for surgery and diagnostic techniques. Dr LaPorta presents imaging studies and discusses case studies.

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Goals and Objectives
  1. Recognize the clinical signs and develop a treatment plan for PTTD.
  2. Describe the underlying etiology, surgical techniques and current treatment options for PTTD.
  3. Evaluate the dysfunction a etind deformity, and formulate surgical interventions via imaging studies.
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  • CPME (Credits: 0.5)

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    Release Date: 03/16/2018 Expiration Date: 12/31/2018

  • Author
  • Harold Schoenhaus, DPM

    Surgical Editor for PRESENT e-Learning
    Penn-Presbyterian Medical Center
    Philadelphia, PA

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  • Lecture Transcript
  • Male Speaker: Next area is going to be associated with posterior tibial dysfunction and Dr. LaPorta and myself will be sharing some thoughts with you, and I will probably be a lot more wordy than he is. He is right to the point; I am too verbose, I guess. So if we could drop those lights down. Talk about posterior tibial dysfunction and I am going to concentrate somewhat on stage 2 . We’re going to talk about partial tears of the tendons without definitive evidence of bony or cartilaginous adaptation or evidence of degenerative joint disease. Once we have associated joint disease, we advance into another level, stage 3 or 4, which is going to require other types of intervention. This foot still demonstrates flexibility with the ability to reposition the associated subluxations. Recognize, we usually develop peritalar subluxations with posterior tibial dysfunction. Complete rupture of the tendon may be seen, and when it is seen in early stages you will not get the associated degenerative changes. Obviously, it does not take a rocket science to realize that when there is a defect between the tuberosity of navicular and the medial malleolus that you could put your thumb in, that you have in all likelihood a tear, and this can be of an acute type posttraumatic type of injury. It’s interesting once the posterior tibial tendon loses its stabilizing capability in the transverse plane as a supinator, the dominant peroneus brevis which is antagonist abducts the forefoot on the rearfoot and we see the typical peritalar subluxation in the transverse plane. You can also get sagittal plane involvement as well. We talk about this test. It’s is an important one. The patient that cannot get up on the toes and observe supination or an inversion of the rear foot demonstrates pathology of the posterior tibial tendon unit. Diagnostic tests; let me go back to that a minute. I think the most important one in my head is the MRI. Certainly going to look at x-ray to see the changes around the joints, but certainly MRI is going to identify where the defect might lie and the extent of abnormality or tear, so that we will be prepared to identify for the patient how long an incision might have to be or what we might have to repair. And here is an example of a nice defect right within the tendon sheath, fluid, and abnormality of the tendon. Earlyon conservative management - strapping, padding, NSAIDs, PT, casting, orthoses and ultimately surgery. More times than not by the time they get to our offices, they have already gone through some regimen of conservative management. Indications for surgery - Painful flatfoot, medial arch, and ankle pain, knee pain. Interesting; you see these patients develop genu valgum and pain up into the medial knee. Minimal response to conservative management. These patients usually come in with the contraptions they have been wearing and say, “Do something.” The typical intraoperative findings - Rupture of the tendon may be present, degeneration, partial tear, proliferative synovitis and something I coined , posterior malleolar chondromalacia. And here is an example of the incisional approach. Recognizing that you are looking at the first compartment of laciniate ligament sitting behind the medial malleolus. Be careful on your dissection. You can interfere and compromise the neurovascular bundle sitting in the third compartment. So, I try to preserve as much soft tissue as possible to close. Here, we are looking at partial tears, longitudinal in nature. Be sure you rotate the tendon, take it out of the groove and look inferiorly all the way down to the insertion to the tuberosity navicular to determine the extent of pathology. Now there is the typical synovitis of the tendon sheath. It is angry. You often see a defect. You do have hyaline cartilage behind the medial malleolus. That is how the tendon can glide very nicely. That is chondromalacia and that is an irritant and will continue to irritate the tendon. There is an additional scarring down of the tendon that must be completely freed. There is your neurovascular bundle. If you don’t maintain the tendon sheath, you can use substitute materials such as acellular dermis to substitute for a new tendon sheath after the repair is complete.


    So, we free up the tendon, identify extent of pathology. If the disease is too involved, I will resect portion of the tendon, consider what I call the length tension ratio of the tendon. It has to function again under tension. If I'm using an allograft, here we are taking an end-to-end suturing technique,. I usually suture it over the medial malleolus and then pop it back into the groove, so it’s under tension. Curetting out the tendon, tubularizing it is important. And I often use GRAFTJACKET rolled up into the tendon to help in the repair process. I am pretty aggressive on this. And then you can even create a little burrito. if you will, wrap GRAFTJACKET around the tendon,so that it is completely protected following your repair. Arthroereisis in stage 2 PTTD - I use a fair amount of lateral arthroereisis. The peritalar subluxation that had existed will continue even after you’ve repaired the tendon. So what I want to do is realign the subluxation, allow the tendon and the soft tissues to heal in a more appropriate position, and it will also prevent the talus from drifting down and in against the soft tissues. Not used in advanced cases, and you are just taking a flatfoot and obviously realigning the subtalar joint through the blocking motion of a sinus tarsi plug. And that’s pretty much what it looks like. I don’t care what material you used. Once again, I've gone through the evolutionary process of everything from horseshit and splinters to polypropylene, silastic, titanium. I don’t care what you stick in the sinus tarsi. GRAFTJACKET rolled up; it is an excellent block of motion. And I won’t bore you with all this junk, but the technique is adjunctive. It just places the foot in a better realigned position and allows for the soft tissues to now readapt and go for further advancement of what you’ve just accomplished with PTTD. So, I am going to stop at this point and I am going to ask [Indecipherable] [07:33] to come up and share with us his comments on it,and then we will open this up for any questions, discussions before we enter the next talk depending on time.

    Male Speaker: Thanks Harold. I noticed you did not mention it. Initially, you used to use a penile implant for the arthroereisis which I think says a lot. That was free information by the way. So, I am not going to talk to you about surgery much. I think Harold pretty much covered the types of procedures that you can use to address this, but I want to come at this from a different angle. I want to show you what can get you into trouble because you don’t fully understand the deformity, and I will begin with imaging studies. In the imaging studies that I normally think most of us would do to evaluate this deformity is AP lateral of foot and AP of the ankle, but to that I want to add hindfoot alignment views, which will give you a full length shot of the tibia. And in very difficult cases where you're really confused clinically I think it’s important to get what I’ll refer to as orthogonal mechanical axis views of the lower extremity, which means one shot, three different films spliced together of hip-to-ankle. And I’ll throw this up because this is the normal view you get of the ankle. And this is very interesting because if your x-ray tech is like mine, trying to do me a favor, she will line up the tibia perfectly within the x-ray view and take a straight-on AP and you will look at that and say, “Hmm, vertical tibia with a little bit of a valgus ankle.” So, I have a valgus ankle that’s contributing to this advanced flatfoot deformity. But if I take the same patient and I do orthogonal views of the lower extremity, I see something entirely different. And what I see here, if I draw what is referred to as the mechanical axis of the lower extremity, is that on the right side, it’s perfectly normal.


    If I draw a line from the center of the femoral head to the center of the ankle, it goes right through the center of the knee, it should do that. However, on the left side, the pathologic side, I notice that that same line is now lateral to the center of the knee. So, now, we have an asymmetrical situation here and typically what I hear is, well obviously, this foot deformity is causing knee pathology. Well, the only problem with that is that when you have deformity at the ankle or foot or deformity proximal in the femur, it has no effect on mechanical axis. So, when the mechanical axis is off like this, it is because there is knee pathology. So, you ask yourself, now is this primary knee problem, is it a primary foot problem, is there a leg-length discrepancy, and obviously this is a primary knee problem and I think you need to know that because if in fact you are going to do a fusion technique of the foot, you are actually going to exacerbate the knee problem. Now you may elect not to do anything about the knee because it is close enough that you are going to work with it, but in many cases that can get you into trouble because you have a foot that appears to look now straight and you are happy with your correction, but what you have caused is a valgus movement on the knee increasing the medial thrust. Here is the hind foot alignment view, also very important for this deformity. This is taken like you would take a Harris and Beath view and if you look at this; we all know this is a fairly severe flatfoot. You can see the abduction of the forefoot and we know that the heel is not directly underneath the tibia and in fact the evaluation of the heel should be that it is parallel to the bisection of the tibia, but it is about a centimeter lateral and in this particular case, it is 2 cm, and I see this more often than not. So, why do I always hear that the heel is in valgus because in this particular case, it obviously is not in valgus? It is vertical, but it is laterally translated. Well, what happens here is that if you look at the outline of the soft tissue and bisect the soft tissue which is what you and I see clinically, that is what is in valgus, not the bone. The soft tissue is in valgus. So, it would be inappropriate to approach this by causing a varization osteotomy of the heel in the frontal plane. You do not want to do that. So, in this particular case, how would you approach it? Well, if I were going to do an Evans procedure for the lateral column shortening if you will or abduction of the forefoot, I would do that first because that is going to have a secondary effect on the heel and in fact you repeat this view on the x-ray table non-weight-bearing at a 45-degree angle heel view and you see what effect it had on the heel. After doing your Evans, your heel may actually medially translate. If it does not, then you can elect to go back and do a medial translation of the heel bone and you can see various permutations that you get with this depending on how much lateral translation of the heel. Now, you look at this in clinically, this foot is a train wreck, severe valgus deformity of the heel. Not really. It is only in about 5 degrees of valgus. It is laterally translated. So you do not correct this by varization, you correct this by medial translation. So, here are the normal numbers and I know people go nuts when I do this, but in fact what are you correcting if you do not know what the normal looks like and when I look at a lateral view, here is what I look at. The 80 degrees is in fact the slope, the anterior slope of the distal tibia. It is not at right angles. It is at 80 degrees. As it approaches 90, you get an osseous equinus, very important to know and I will show you an example why. How about the talus? Well, if you bisect the head and neck of the talus and compare it to the bisection of the tibia, it is normally 118 degrees of plantarflexion of the talus and it is a very tight fit. It is about 4 degrees either side. So, that is important to know also. You also noticed that the bisection of the tibia passes through the lateral process of the talus, very important relationship. That is where you want your talus to end up when you are done.


    Now, if you look at the calcaneal bisection line, you will notice that I use the body of the calcaneus. Why do I do that? The reason I do that is that there is only two ways to evaluate deformities, anatomic axis which is bisection of a bone or mechanical axis which is the center of joint. So, if you draw the typical calcaneal inclination angle using the bottom of the heel and compare it with a bisection of the first met or bisection of the talus, you are mixing apples and oranges. One is a mechanical axis and the other one is not. So, consequently you have got to do the same kind of planning. You will notice on this lateral view that I have a 28-degree inclination of the heel; that is normal and you will also notice that the bisection of the talus is 24 degrees; that is normal. These are all plus or minus 2. So they are very close. That means that my top of the triangle is 130 degrees. This is a perfectly normal arch structure and it is what I would try to recreate if I am doing any kind of surgical procedure. A bisection of the first metatarsal is not the same line as the talus; it is off about 2 degrees either side. So, remember that because when you are extending the bisection of the first met proximally, it usually is not the same line as the bisection of the talus. The green line is very interesting because in all of these cases whether you have a cavus foot or a flatfoot, you have deformity on the lateral side. On the lateral side in a flatfoot, it is short. On the lateral side in a cavus deformity, it is usually long and/or plantarflexed. So, if I bisect the fifth met and extend it back, look where it crosses, it crosses the calcaneal line in and around the area where I would normally do a calcaneal osteotomy. Consequently, most of the time you can correct lateral column deformity with your calcaneal osteotomy, you should not do the separate one in the cuboid or in the tarsus in order to achieve the same effect. In a flatfoot, if you look at this, the horizontal plane is a line parallel to the floor, you see here, my CIA is 20, my talar declination angle is 40 and my metatarsal declination angle is 22. So, when somebody says to me, well you know I do cotton here to recreate the arch; my response is why would you do that? Twenty two is normal. Why would you want to over-plantarflex the first met to create an arch? It is nowhere near where the deformity is. All the deformity is in the rear foot in this particular case. So one way I like to look at this is that here is the triangle and here is the second triangle. The only problem with this is that in the normal foot there is only one triangle. So, what you are trying to do in a flatfoot is get both of those lateral triangles in the deformed foot to equal one triangle. You do that by picking the right place to do your procedure. Another very important angle is the lateral talocalcaneal angle. Normally, it measures 54 degrees plus or minus 4. Why is this important? Because if you have that, this is not a foot you would do an arthroereisis in, you would overcorrect the talus and the ankle mortise producing an equines, an osseous equinus. If this angle dips below 50 degrees, usually in the high-to-mid 40s, perfect case for an arthroereisis. So I look at that and think that that is a very important angle that you should be aware of and here is that anterior distal tibial angle. Okay, if you look at the top view, you will notice that a bisection of the tibia and a line representing the ankle measures in the neighborhood of 80 degrees. The range is 78-82. This means that when the patient is in midstance in single leg support, their knee is flexed 10 degrees and their ankle is dorsiflexed 10 degrees. You need this slope in order to have that arrangement because the body is set up that when that is occurring and the knee is flexed 10 and the ankle is dorsiflexed 10, the joint is horizontal.


    It is parallel to the ground. It is stability under stress. In the example, on the bottom, you look at that, you see the bisection of the tibia and a line representing the ankle measures 90. This is called tibial procurvatum. The result of this is that it is an osseous equinus. So I do not care how many time you lengthen the posterior muscle group and the table because the extremity is not loaded, you will get dorsiflexion. In gait, when the extremity is loaded and your distal angle measures 90 degrees, you have an osseous equinus. It is not going to get more dorsiflexion than it already has and you need to know that preop and I am sure you have seen it, if you have done gastroc recessions or tendo-Achilles lengthenings, and postoperatively, the patient does not have nearly the amount of dorsiflexion you expect them to. The reason is not your technique; the reason is that we did not recognize that this patient really does not have the architecture to allow normal dorsiflexion. Additionally, the knee is angled back 81 degrees. So, you can see that when each joint is dorsiflexed 10 degrees or flexed 10 degrees that those articular surfaces become parallel to the ground. So, here is a case. Alright, this case is referred because the left foot is flat. So, do I correct the foot or I do not know? Does it need foot surgery? Does it need leg surgery or does it need both? I mean this patient has a distal tibial varus of 10 degrees. So whatever flatfoot they have is in compensation for this distal tibial varus. Here is a valgus ankle after an ankle fusion and you can look at this and say, well the tibia is straight and definitely in valgus, is it the heel, do I want to correct the heel, I do not know about that? So I am going to create a deformity to correct the deformity. That does not make much sense. So you need to localize where your deformity is and pick the procedure. If you look at this particular patient, this patient comes in with a flatfoot. So, do I just look at the foot? Well, you might be tempted to do that if your x-ray stops about 2 inches above the ankle, but if you go up a little bit higher, you will notice that this patient has an oblique plane deformity. There is a valgus of the distal third of the tibia and there is a recurvatum of the distal third of the tibia. I would venture to guess that if you corrected that, the flatfoot will go away because there is no reason to compensate. So, based on that, I would just like to say that you should pay attention to the concept of CORA, you need to get above the ankle. You need to look at that extremity because in many cases, the foot is compensating for a deformity that is higher up and although it may not be severe enough for you to attack it primarily, you need to know it is there because the last thing in the world you would want to do is correct the foot and increase symptoms. Thank you.

    Male Speaker: Certainly, what you learn from a combination of approach is that lower extremity is one of the most difficult areas of the body to operate on because of the mechanics, the functional adaptation, the reactive forces of gravity, gait analysis, normal gait, all of the things that happen that we as surgeons have to take into account when we try to identify the etiology of deformity and how to correct it. It is interesting I have always felt that a calcaneus abducts and does not go into eversion, and some of that came from Root’s [phonetic] original talk about compensative forefoot varus that requires the calcaneus to evert to compensate to get the medial side down and yet when you look at x-ray after x-ray, it is a transposition which certainly alters or modifies what type of osteotomy