More Pearls on Peroneal Dysfunction

© 2024 HMP Global. All Rights Reserved.
Any views and opinions expressed are those of the author(s) and/or participants and do not necessarily reflect the views, policy, or position of Podiatry Today or HMP Global, their employees, and affiliates.

Transcript

Jennifer Spector, DPM, FACFAS: Welcome back to another episode of Podiatry Today Podcasts, where we bring you the latest in foot and ankle medicine and surgery from leaders in the field. We welcome back Dr. John Visser with us today, talking even more about peroneal tendon dysfunction and a very comprehensive way of evaluating and treating these conditions. He was talking about one-cable and two-cable scenarios, and today we're going to get into zero-cable scenarios and even other details on this topic. We welcome him back and hope you saw us for our first episode but Dr. Visser let's get into this zero-cable scenario. What can you tell us about that?

John Visser, DPM, FACFAS:This is the most severe of the lot and these are ones that you don't see very often. When you do, you really have to evaluate the patient very, very carefully in this situation. Before I go into that, though, I'll talk a little bit about that C pulley for the peroneus longus, where I'm down to potentially a one-cable situation with repair or consider a transfer here. In that case, the os peroneum is obviously involved. It is a source of pain. It may be in its proper position indicating that the longus has not been ruptured at this point, but an MRI is really important here to see if there is a tear in the tendon and the source of pain. Sometimes on an X-ray, the DP view will show a proximal retraction of the os peroneum into the lateral wall of the calcaneus, which would indicate to you that you have a fully ruptured peroneus longest tendon. So, in the C instance, where you're obviously dealing with a one-cable situation, just because of the anatomy here, you get into it and you might be able to go and initially just shell out the os peroneum. The tendon is not in bad shape, you're able to tubularize the tendon or repair that deficit and you restore your one-cable situation. There are instances however, where the os peroneum has damaged the tendon considerably and when you excise it you've really lost the contents of the tendon. Obviously, the tendon distally that goes to the first ray cannot really necessarily be retrieved sometimes, but sometimes it can. And if you can retrieve it, it's good to do so as well as the proximal portion. And that can be transferred into the brevis. The brevis is close. It's at the fifth metatarsal base just above the cuboid notch, and you can go ahead and make your transfer there. And again, in this situation, the brevis has a pretty good pull and strength so it carries a little bit more strength than it normally would in the area of the A pulley. So there's a good example where you might have a zero-cable then and then have to do a transfer in that particular situation. Allografts are not helpful here at all in this situation.

Then you have the so-called zero cables that I mentioned, and this is a situation where both the peroneus brevis and the longus are badly damaged. When might you see something like this occur? There can be really three situations that you'll encounter. The first situation may be a case where the patient may have had a systemic problem or they had an injury and the surgeon had went in and did a surgical repair, a tubularization process, but it didn't work. And they went in and did it again and it didn't work. So what ends up happening after two, maybe three operations, the patient has advanced tendinosis. The tendons are not able to move into the groove in any particular way. They've lost all their gliding function and they actually lose their ability to function in general. Over time, what you'll begin to see is a developmental adducto-cavovarus foot deformity. The subtalar joint will begin to tilt into a varus situation because the tibialis posterior tendon, the flexor digitorum longus, and to some extent the FHL will have a mechanical advantage to cause closed kinetic chain supination of the subtalar joint and you have no peroneal function to resist that. And so you will see the subtalar joint begin to go into a supinated, adducted position. The midfoot also moves with the subtalar joint as we know.

Whatever the subtalar joint does, the calcaneal cuboid joint does, so if the subtalar joint is supinating, the calcaneal cuboid joint is supinating, and it begins to go into an elevated adducted position. The longitudinal metatarsal joint axis, which is at the talonavicular joint, obviously moves opposite from the subtalar joint, so instead of it basically supinating, it's pronating because it's trying to keep the forefoot on the ground and we don't have the peroneus longest there anymore to hold the first ray down. So, depending how far this progresses, the forefoot can actually come off the ground because we also have a situation where the tibialis anterior tendon is able to fully pull on the first ray. It has no mechanical antagonist, the peroneus longus. Again, the flexibility of the foot, the relative rigidity of the foot will determine how fast these things manifest themselves. So when you get into a situation here where you're gonna have to do a repair, you may have to address some of these things in conjunction.

Dr. Spector: Can you run us through a clinical example?

Dr. Visser: So let's take this particular case. We've got this adductovarus foot. These usually we will only kind of manifest themselves more in the subtalar joint with a little bit of a varus positioning. That being because even though the tendons aren't functioning, they're still there. They're still holding things. And so the foot can be stabilized to some extent. The problem is, what can you do with this? Can you go in and remove it? Repair it again? No, you can't. The tendons are badly damaged. So you have to establish gliding function again. And how are you going to go about doing this? How are you going to get gliding function in this area where you basically have the tendons stuck in cement. Well, the way we do it is a two-stage operation. We start out with a silicone rod, a six millimeter silicone rod. As you know, silicone rods are still used in hand surgery for reestablishing a tendon function there. And you can get these six-millimeter rods. And what you do is you go in, you excise the tendons. The tendons are they're just shot and they're gone. They're not functioning. You got to get rid of them. You go ahead and you anastomose. You ride approximately at the peroneal brevis or longus or both depending. The brevis usually is the one that's there easy to get and you run it in the peroneal tunnel right behind the retrofibular groove and take it down to the fifth metatarsal base and then go ahead and anastomose the rod at the fifth metatarsal base. When you do that the attachment of an anchor at the fifth metatarsal base is what you do first and then how you tension this is you tension it from distal or from proximal to distal. You go ahead and do the silicone rod, run it through the peroneal tendon, tension it, in dorsiflexion and abduction, and then go ahead and close your wound. You can do adjunctive procedures at this point.

I don't normally because what I'm going to want to do is in the second procedure, I kind of see what I have as foot deformity, and then if I need to do adjunctive procedures then, which I most always will, I will do them at that time. Between six to eight weeks later, then what has happened is you have developed basically a nice tunnel, because remember your soft tissue will not bind to the silicone, and the silicone will glide freely in that tunnel. So you maintain gliding function of the tunnel, you maintain stability of the retrofibular groove, and you also have stabilization of the superior peroneal retinaculum.

So, then you take an allograft in your second stage and you go ahead and at the proximal portion you cut the allograft to about the size of the actual silicone rod, a little bit bigger instead of being six millimeter, go about eight millimeters. You go ahead and you anastomose the tendon, your cadaver or your allograft tendon, into the silicone rod, and then you go ahead and open the very distal portion of your incision, which is at the base of the fifth metatarsal.

You then find that silicone rod there and you then take the silicone rod and you pull the allograft through the newly developed tunnel. You go ahead and then you go ahead and attach your allograft to the fifth metatarsal base and then you do as what you did initially and you go ahead and use a Pulvertaft technique with the foot in maximum abduction. You cannot over-tension these. If you do them at 90, they will be functionally weak. You sit there with that foot in a splint, dorsiflexed maximally and the residents are like, "Holy cow, you know, is that guy going to be able to walk again?" And he comes in at two weeks later and it pops back down into a neutral position that I can tell you. So don't worry too much about that. At that point, then you can do your adjunctive procedures.

Anything in the midfoot, usually not once you restore function and tension to the peroneals, you'll see then that the midfoot will come back into a more normal position, but in these cases you usually don't see many midfoot changes at all So if you're gonna do anything here, it's usually a Dwyer osteotomy.

Dr. Spector: What other procedures might you add in at this point?

Dr. Visser: Now what I also do for the midfoot even though I'm not seeing a whole lot of deformity I know that side of my foot laterally is not as good as what on the medial side. And that tibialis posterior muscle tendon, it's a strong one, we know that. So I'm going to go in, I'm going to weaken it, I'm going to go in and I'm going to do a Z-plasty of the tendon and weaken that thing. I'll do the FDL also. I usually don't address the FHL. It's too far posterior that I think it has that much of force on the subtalar joint. So I will usually leave that alone. And whether I need to do the FDL, I'm not sure, but it's right there. So I go ahead and do it. That's very critical, because if you don't address that, that particular muscle tendon will overpower what you've done. You know, that transfer restores function, but it basically only brings the peroneals into about maybe a 3 /5 functional work that will function at that level. So, you've got to do something to offset that.

So that's the first type that you might run into. The second type of a zero-cable is a situation where, again, here you have ruptures of both of the peroneal tendons. They're both been ruptured by tendinosis. There's been no surgery on them. They've had no surgery whatsoever. Okay. And what you will see is they will obviously have various forms of deformity of an adducto-cavovarus foot, a so-called non-neurologic cavus foot, which can occur here. MRIs are done, shows bad damage. Usually where is the damage at the A pulley for the brevis and usually the longest is at the C pulley in the vast majority of cases but certainly you can see situations where the B pulley is affected in both areas and you have this situation. Now the important part here is what are you going to be able to do here now, okay? And that all depends on how functional the peroneal musculature is. So how do you determine that? How do you make that call? Well, one of the ways is you can have your radiologist get an MRI and make sure he looks at the peroneal musculature to see if there's any signs of fibrosis, fatty infiltration. This would indicate that that the peroneal muscles have not been working for a while and they're not very strong anymore. So if that were the case, and you found that out, you would be in a situation where you would have to not consider basically utilizing an allograft here because if you put the allograft in, the muscle's not functioning very well, you're not gonna give good function of your peroneals there. So now what you gotta do is consider I gotta get a motor unit over to that side of my foot.

Now, what am I going to do to get a motor unit over there in that situation? Other things that you can do clinically to see if that's an issue, look at the girth of the peroneals on both sides, see if there's atrophy present. And you can't tell that as long as you isolate off the medial side, usually you block it, and you can kind of definitely tell whether the peroneals have been affected. If that's true, then usually you have two options. You can transfer the FHL tendon over to the fifth met base, or you can transfer the FDL tendon to the fifth base. Most of the time I use the FDL, although it's a smaller tendon, it's a longer tendon that I can work with usually. And basically it's a location because I want to go back of the tibia. I don't have to fight the soft tissues and back of the ankle. So what I'll do, I'll go in at the navicular tuberosity, make an incision there and then find the FDL tendon near the Master Knot. I'll cut it and then I will measure the distance from the ankle joint up to the tibia, which is usually somewhere around 6 to 7 centimeters, and I'll make an incision over that medial tibia. The first muscle tendon I run into is going to be the FDL tendon. Now, as a little tip here, if you're doing tibialis posterior transfers for any particular reason, I'm not talking about this case. Remember, it's underneath the FDL. So if you're going to want to pursue that, make sure you get the FDL pushed away and it's underneath that. So then again, I retrieve the FDL tendon in the proximal incision. I will then take because my peroneal tunnel is completely opened up because what I've done is I've made a long incision I've excised the peroneals both of them they're all cut out there they're worthless you can't do anything with them so then what you do is you take like an over uterine retractor or a bigger Kelly and you go and you got to hug the posterior tibia at the ankle level and you go into your medial incision, take your tendon and obviously you have whip stitched that prior, bring the whip stitched portion through the back of the tibia into the peroneal tunnel and you will find that you will usually have plenty of tendon in that particular situation, okay?

So what happens if you don't have enough tendon? You can do a turn down. You can go ahead and cut the tendon in two pieces, starting in a proximal cut and a little longitude, a transverse cut. Pull that tendon down to about a third of the way, reinforce that area, and you're going to have almost two to three times the length of the tendon that you originally had. So that's a little tip for you if you get in short on these. And again, so then I'm going to run the tendon right into the peroneal tunnel, right behind the retrofibular groove. When I do excise the peroneals, I'll leave a section. And this is important too about length factors. You can release some length to the brevis tendon at the fifth metatarsal base. So you have plenty of area there to do your Pulvertaft technique in that case. In this situation, I will usually go opposite, I will anastomose into the brevis tendon at that level. It's coming around the tibia and I'm going to go ahead, I'm going to dorsiflex and abduct the foot maximally and intention that to get the correction that I need in that particular situation. And obviously then you close your wounds and I'm going to do the same thing. I'm going to weaken that TP tendon, I just don't trust it. It's a transfer but it is a phasic transfer but it's still going to end up with three over five strength and I'm not going to trust it so I'm going to do something to weaken it. If I do have a varus state to the heel, I will address it.

And I'm going to talk about the other structural parts of the foot after I do this last part on the zero tendon. And that would be simply that when you did your MRIs and you did your evaluations, you find that the peroneal muscles were good. They're fine. No problem. Their strength's good. You can go in intraoperatively and test them and see if they retract when you take like a Kelly clamp and pull down on them and they retract back into that particular situation and you can even use a little Bovie to stimulate those. The problem with a Bovie in cases where you have intramuscular fibrosis, If it's not an overly fibrotic spot, then it'll still contract. So you can't depend on that in that particular situation. So in this case, I've got a good tunnel. The tendinous damage is gone. I remove it, but here I can use an allograft because the muscle is still very functional. Again, here though, I will attach distally at the fifth met base and then Pulvertaft approximately half the peroneus brevis to get as much tension as I can. You can do a double allograft if you like and do both the longus and the brevis. Personally, I think it's a little bit too bulky to do that. It's a lot of extra work for probably not helping you a whole lot, but you could make the case for it and you just debulk the tendons enough so that your retrofibular groove is not damaged in any particular way.

Okay. So where do we go from here? So now I've got my repair done. I got to look at the foot. This so-called progressive elevating foot deformity where the foot is in a cavovarus situation. Again, it depends on the flexibility of the foot. The foot is very flexible. You get a lot of deformity. A lot of deformity. If it's kind of a neutral foot that has normal range of motion, you will get a heel varus situation. The subtalar joint will be in a varus situation. The heel will have to be addressed usually with a Dwyer osteotomy. You've balanced your tendons basically at the peroneal level and at the tibialis posterior and flexor digitorum, longus level, if by chance there's a lot of a situation where your foot is in varus, where for example the forefoot is sitting off the ground because the peroneus longus was not working and the TA is pulling up on the forefoot bringing it off the ground, then you're going to have to consider a tibialis anterior transfer or a split transfer to basically allow the forefoot to come to the ground. It can be very flexible and that transfer alone can fix the problem and bring the forefoot on the ground or it may be still in a fixed position and it may require an osteotomy.

Dr. Spector: Are there any particular case examples that stand out to you?

Dr. Visser: Oh, maybe four or five years ago. I had a patient that had surgery at another institution. The patient had had double tears, interruption of the peroneal tendons, okay? The surgeon recognized this by the MRI, okay? So without being able to kind of think out what he would need to do in the situation. He decided, well, I'll go ahead and do a triple arthrodesis. So you do a triple that will stabilize the TP tendon against your subtalar joint. You can bring your subtalar joint into a vertical position. Your TN joint’s rotated down into position. And so yeah, it kind of makes sense. No problem there. But then what happened is the patient is in the early recovery stage, the forefoot pops off the ground. And the patient is sitting there with the heel corrected in corrected position. The forefoot abductions corrected. Yeah, the forefoot's in a varus situation. The surgeon looked at it and thought, well, you know, the TN had fused and thought, Well, maybe I’ve got a malunion here. So he went in and did a derotational osteotomy of the talonavicular joint, thinking he had a malunion. So he goes ahead and does the malunion and boom, it pops back up, okay? So the patient comes in, she's very distraught by all these operations she's had and why should this foot so, it's unstable when you have a situation of a rigid foot with the forefoot sitting off the ground. It's really problematic to try to get around. So I took a X-ray and I looked at it and I said, you know what? Where is this thing elevating at? It's not at the TN joint. It's at the NC joint. Ooh, the tail, the tibialis anterior tendon. Guess what? That's the antagonist to the peroneus longus, which is ruptured and gone. So I transferred the TA tendon to the cuboid and fixed the problem.

Dr. Spector: And thank you, Dr. Visser. We invite you to view this and other podcast episodes on Podiatry Today Podcasts, SoundCloud, Podiatry Today, or your favorite podcast platforms.