Thank you for the opportunity to present. Today, I'm going to be talking about ankle fractures and specifically the syndesmosis. My name is Daniel Gus. I'm one of the orthopedic surgeons from Mass General. And so these are my disclosures. They're all in the disclosure program. None are related to this talk specifically. And so there's a few goals for this presentation. First of all is how to diagnose syndesmotic instability. The second is the implications of associated malleolar fractures. Also some technical tips about reducing the syndesmosis, a note about hardware choices, as well as the idea of collateral damage, the surrounding ligaments around the syndesmosis and ankle. And so here's the first key point. When you're talking about this ankle syndesmosis, making the diagnosis far outweighs the incremental clinical implications of fixation strategies. And so this is an example. This is a 28-year-old female who sustained a fall on uneven ground. She was treated elsewhere and came to establish post-operative follow-up. And these are the two-week radiographs. Three months. And this was before she came to see me. And she ultimately, as you can see, developed syndesmotic widening. And after about three months, underwent a revision fixation. But as you can see already on this radiograph, there's already some lateral plafond erosion. And sure enough, at one year, this is what we found. And at this point, she was referred to our clinic. And so when we talk about the critical importance of the syndesmosis, this is the image that should be emblazoned in your mind. Because now what? She's 28 years old, and how do you salvage her ankle? This is another example. This is a 23-year-old male who was playing football, sustained an ankle fracture, and underwent surgical fixation elsewhere, and then came back, was referred to our clinic about one year after the initial procedure with persistent pain. And when you look at a weight-bearing CT scan, you can see the widening at the distal tibiofibular joint compared to the contralateral normal side. And so again, this is another salvage situation. And in his case, we performed bimalleolar osteotomies, lengthened the fibula, and fixed the syndesmosis. And so this is another example of the critical importance of diagnosing and treating a syndesmotic instability. This is another example. This is a 27-year-old who fell downstairs, initially self-treated as a sprain. You can see that at the initial radiographs, this is before he came to see me, but you can already start seeing some calcifications within the syndesmotic ligaments. Radiographs at the time, to the credit of the treating provider, did not show a proximal fibular fracture. But when he came to my clinic four months later, you can start seeing significant heterotopic ossification forming at the distal syndesmosis. And weight-bearing CT scan shows widening at the distal tibiofibular articulation. And you can see the heterotopic bone forming within the syndesmotic ligaments. And so he underwent a fixation and did well. But the key to think about the anatomy of the syndesmosis is that the syndesmosis has very little bony stability. In about three-quarters of people, you do have a little bit of a concave region within the incisora for the fibula to sit in. But in 25%, it's either flat or even convex. And so it's very dependent on the ligamentous structures. And by that, we mean the AITFL, the IOL, and the PITFL. And in order to destabilize the syndesmosis, our arthroscopic research has shown that all three syndesmotic ligaments must be injured, or a partial injury to the syndesmosis can be rendered unstable if the deltoid is also involved. Interestingly enough, also the lateral ligaments can contribute to syndesmotic stability. And the reason that is is because the collateral ligaments do connect the fibula to the tibia. But they do it through the talus. And so when you have an injury to the collateral ligaments, that tethering effect is lost. And that's how it can render partial syndesmotic injuries unstable. And so how do you make the diagnosis? Because as we've started, that's the most critical aspect. And so physical exam is invariably the start. Patients may have pain with proximal squeeze. They may have some instability with sagittal fibular shock, or even pain with an external rotation. Radiographs have low sensitivity. And the key thing that you want in any imaging modality is three things. You want to be able to examine the ankle under physiologic load. You want to afford a contralateral comparison. And in a perfect world, you want to be able to see it in 3D. And that's where we've moved more and more to weight-bearing CT, where volumetric analysis can help identify syndesmotic instability with a very high sensitivity. In the future, some of our work has also utilized ultrasound, given that it allows one to make the diagnosis at the point of care at the bedside. And so how do you diagnose syndesmotic instability in the OR? The threshold values are difficult to specifically identify. But what we found is that in the coronal plane, which is the classic way in which we do it, the cotton test, you have to apply about 100 newtons, 5 centimeters from the fibular tip. That's actually a good amount of force. That's about 22.5 pounds. And the threshold is about 3 millimeters of diastasis. Sagittal plane instability actually may be more sensitive. And more and more, I find myself actually looking at sagittal plane. It's a similar amount of force, but what you're looking for is a total of 2 millimeters of motion in the A to P and P to A plane. And so my approach is to fix the fibula and then move the fibula in a sagittal plane to see if there's excessive motion. The key point number two is that syndesmotic fixation, no matter how robust, cannot overcome malreductions of the associated malleolar fractures. This is an example of a 20-year-old female. She jumped out of a second story window onto a snowbag. This was a few years ago in Boston when we had enormous snowstorms with giant pileups. And she was fixed by a local provider with this construct. As you can see, the fibula is short. The distance between the fibula and the talus is elevated. The talocrural angle is near neutral. And so she presented in my clinic with these radiographs. And again, this has now become a salvage situation. And so we performed the fibular osteotomy and lengthening because nothing can overcome a shortened fibula and then repair the syndesmosis. And because of that fact, I'll chase the fibula high. And what I mean by that is it is incredibly hard to anatomically reduce the syndesmosis and get the fibula out to length without fixing the fibula fracture. And so that's why even when a fibula fracture is quite high, I will chase it and get anatomic reduction of the fibula and use that to then anatomically reduce the syndesmosis. Point number three is remember the ligamentous attachment points. And the syndesmosis is stabilized by ligamentous attachments. And so when you're repairing these bony attachment points, you're functionally repairing the ligaments. And what I mean by that is in this example, you can see a bimalleolar ankle fracture is when you have widening between the fibula and the tibia, that represents some degree of injury to the interosseous ligament. When you have a deltoid, excuse me, when you have a medial malleolar fracture, that's the attachment point of the deltoid. When you have an avulsion fracture off the anterior aspect of the insusure, that represents an avulsion of the AITFL. And when you have a fracture in the back of the ankle and the posterior malleolus, that's functionally a discontinuity of the PITFL. And when you think about stabilizing the syndesmosis by recreating a ligamentous attachment point, that's what you're doing by repairing these bony attachment points. And so this is an example of a fixation strategy. And so it begs the question, when does one repair the posterior malleolus? And so the reasons to fix the posterior malleolus can often distill into one of two reasons. One is to stabilize the tibiofibular joint, the syndesmosis, because of the attachment point of the PITFL. And the other is to stabilize the tibiotalar joint. And both have been supported in the literature. There's some literature about fixing the posterior malleolus in order to stabilize the syndesmosis. I find that I'm frequently also doing it not based on the size of the fragment. These dogmatic percentage points, like 25% of the plafond should be fixed, probably should be replaced by thinking about instability, either syndesmotic or tibiotalar. And in this example, you can see that the posterior malleolar fracture is causing a posterior subluxation of the tibiotalar joint. And so here we fixed the posterior malleolus. And what you find with a cotton maneuver is that the syndesmosis has been rendered stable. And that's because by fixing that fragment, we also fixed the PITFL. And these are radiographs after she's healed that show excellent maintained distal syndesmotic stability. The other key point number four is that it's open reduction internal fixation, not open internal fixation. Reduction of the syndesmosis is a reduction maneuver. And so there's a few strategies to do this. There's a lot of literature about the fact that the syndesmosis can be malreduced. One is visualizing the anterior insessura, actually elevating the soft tissue so that you can see the relationship between the anterior fibula and the anterior insessura. And some studies have suggested that that lowers malreduction from 44 to 15%. Often if it's going to be a difficult reduction, one can also get a perfect lateral of the contralateral side before draping using the C-arm. And then by measuring the distance between the posterior fibula and the posterior tibia, one can use that as a surrogate for syndesmotic reduction on the operative side. The other critical component, like when we reduced fractures, is where you put the tine. In this case, especially the medial tine. There's studies that suggest that it should be placed into the anterior third of the medial tibia. And if I have a masoneuve fracture with significant fibular displacement that I know I'm really going to have a reduction maneuver, I find that I'm actually getting a contralateral CT to guide me where I need to put it. And more and more I'm using a lag screw technique because while a clamp is a very powerful technique, it also risks malreduction. And so I put my screws under lag technique across the syndesmosis, avoiding over-tightening. And then there's some caveats when you think about malreduction. One is that most articles are evaluating malreduction using CT scan and then having thresholds of 1 to 2 millimeters of displacement. Arguably we would see malreduction in a lot of orthopedic procedures if we started evaluating them more rigorously with 3D imaging, like we've started to the distal tibiofibular joint. The rate of malreduction may normalize if the hardware loosens, breaks, or is removed. There's some studies that suggest only a 4% malreduction if the screw is removed. And then it's actually harder than one would think to prove clinical outcomes with malreduction. Certainly much harder than proving the poor clinical outcomes if one fails to diagnose. There are some studies that do show poor outcomes, but these are generally a non-validated outcome scales. But there's other studies that show no difference with the syndesmotic malreduction. Key point number five, rigid versus flexible fixation is probably outweighed by the decision to fix. And so by deciding to fix rather than whether you're going to use a screw or a suture button is probably already winning the war. First and foremost, both screw and suture buttons have excellent clinical outcomes. There are some studies that suggest a little bit of a poor outcome with screws, but these tend to be a non-validated outcome scales. And again, others show no difference. There are studies that show improved outcomes with suture buttons, but the benefits can be very incremental. There are studies that show that screws maintain better sagittal plane control. Because the suture button works as a compression vector, it's great when it's parallel to the suture button, but orthogonal forces are poorly resisted. And again, the insessura often affords very little bony stability. And again, nothing overcomes malleolar or articular malreduction. Key point number six, it is better to over-fix than to under-fix. This is an example of a U.S. Marine that walked into my clinic about six to eight weeks after having sustained an ankle fracture, and you can see the medial clear space widening. We took him to the OR and did a fixation, narrowing the medial clear space. And then two weeks post-op, he walks into my office without his operative splint, and you can see that he's again displaced somewhat at the tibio-talo joint. So in this case, we had a long conversation. We took him back to the OR, used a rigid locking plate, multiple screws, and in this case, we even placed a circular frame to prevent weight-bearing across the ankle joint. And then lastly, the deltoid complex contributes to syndesmotic stability. We brought that up earlier when some of the arthroscopic data that shows that a partial injury to the syndesmosis can be rendered unstable with the deltoid injury. And in my own practice, what I found is that when I do have a syndesmotic instability, I'll fix the fibula and then the syndesmosis, and then I'll do an external rotation stress test. And as you can see in this scenario, if the patient is still gapping at the medial tibio-talo joint, then I will repair the deltoid. And so in summary, making the diagnosis is by far the most critical aspect. Nothing can overcome malleolar or articular malreduction no matter how you fix the syndesmosis. And the most common mistake I see is the failure to maintain fibular length. And that can be challenging, especially in common unit shortened fractures. But it also means that I'll chase a fracture high in order to make sure I'm getting sufficient length. Fixing the ligamentous attachment points equals fixing the ligaments. And so when I think about posterior malleolar fractures, I think about why I'm fixing it, either to maintain stability of the tibio-talo joint or the tibio-fibular joint. Then consider the reduction techniques for the syndesmosis. It is a reduction maneuver, especially if you're using a clamp. And I expose the anterior insessura. Think about the medial tyne position. And especially with significant fibular displacement, consider a perfect lateral or the contralateral side. There are some studies with benefits of flexible fixation, but they tend to be incremental. Remember, it's not the screw that malreduces the distal tibio-fibular joint. It's the clamping that the screw can't then undo. But when using suture buttons, remember, it may be beneficial to use multiple buttons and to diverge them to maintain better sagittal control. It's better to overfix than underfix. And then consider the deltoid complex. What we tend to do is an external rotation stress test after syndesmotic fixation, and then based on that, decide whether to fix the deltoid itself. And so thank you for your time. And I appreciate, again, the opportunity to speak.

ankle fractures

syndesmosis instability

diagnosis

treatment

malleolar fractures