Ankle Fractures: Points on Intraoperative Decision-Making

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My name is Larry Fallat. I'm program director of Corwell Podiatry Program Foot and Ankle Surgery, and I practice in Wayne, Michigan.
 
Considering operative intervention for ankle fractures, how should surgeons approach decision-making regarding the syndesmosis?
 
Evaluating the syndesmosis usually starts with standard X-rays, the AP view, and we look at the amount of overlap between the fibula and the tibia as a guide to determining how much of the syndesmosis is torn.
 
When these two bones are separated, that's usually a good indication that syndesmosis is damaged. Now, we usually see this with the Weber C fibular fractures, but there are criteria that we can use to evaluate the extent of damage to the syndesmosis. So that decision probably should be made prior to the patient getting on the operating room table. And many times with standard X -rays, you can determine if the syndesmosis is torn by looking at the amount of separation between the fibula and the tibia. However, if you're not sure if the results of the X-ray examination are variable, we can always get a CT scan for further evaluation.
 
Intraoperatively, we can use a test, an old test called the hook test, where you can put a hemostat, a bone clamp, a bone hook, anything on the fibula and separate the fibula from the tibia. If there's excessive motion, especially in the external rotation plane, then you know that the syndesmosis is torn and needs to be addressed. And again, this usually happens with a Weber C fibular fracture.
 
What is your approach to fixation choice? For instance, how might surgeons assess if rigid or flexible fixation is best?
 
Well, that's a good question. And traditionally, rigid fixation had been used, either one screw or two screws and for years there was a debate over whether you fixated using three cortices, four cortices, one or two screws or even more. As a rule of thumb, if we're operating on somebody who has diabetic neuropathy or osteoporosis, even osteopenia, or somebody that you may suspect is going to be non-compliant, I would recommend using rigid fixation, using bone screws, and again, whether you use one or two screws or three screws is the surgeon's choice.
 
Now, flexible fixation is an excellent modality, and we use that on occasion. I use this more on patients that I feel are going to be compliant, maybe athletes who are going to let the area heal. So the disadvantage of flexible fixation is sometimes the fixation will fail and the fibula will separate from the tibia.
 
Also, the fibula has got a normal range of motion and I like flexible fixation for that. It will allow some external rotation of the fibula, especially when the talus is put into dorsiflexion. The wider anterior part of the talus will cause some physiologic separation between the fibula and the tibia. Flexible fixation allows this.
 
Rigid fixation doesn't and if the surgeon uses screw fixation and he doesn't have the fibula reduced into the incisura, that's rigid, that's not going to change at least until the screw breaks with maximum dorsiflexion.
 
From your point of view, how should surgeons evaluate the best pathway for a posterior malleolar fragment?
 
So again, standard X -rays will usually give you the information you need, but a CT scan will give even more information. For decades, the criteria was if 25% of the articular surface was involved, it was mandatory that we reduce it and stabilize it. However, recent literature is now saying that even with 10% of the articular surface posteriorly involved, the surgeons should do surgery or if there's at least 1 mm of step off, surgery should be considered. And the surgery should be a reduction, either closed or open, with fixation. And if we look at the fixation, we can use either the indirect method, screws going from anterior tibia to the posterior tibia, or we can make a posterior lateral incision and reduce the fraction, apply plates or multiple bone screws. So that's a procedure that's gaining a lot of acceptance, especially in the orthopedic community.
 
And the incision is made between the fibula and the tibia. Now, there's a lot of anatomy there, so you have to be careful. And under no circumstances, should you cut or section the posterior inferior tibial fibular ligament, that stabilizes the posterior fracture. So that has to be intact.
 
Exposure sometimes can be a little tricky with this approach. Also, if there's a bimalleolar fracture, if the fibula is fractured, you should be prepared to fixate the fibula from this incision, and essentially you're going to apply an anti-glide plate or a posterior plate to the fibula.
 
When might fixation come into play for the medial malleolus in these injuries?
 
So, if it's displaced, then it has to be fixated. Now, some of the literature has implied that that should be fixated first, but traditionally we’ll fixate the fibula first, then the medial malleolus, and then the posterior malleolus. But the medial malleolus has got to be reduced and fixated.
 
And the same goes for the deltoid ligament. If the deltoid is completely sectioned, but the medial malleolus is intact, the deltoid should be repaired. And again, 10 years ago, ago, nobody was repairing the deltoid ligament. But if it's significantly, I should say if the talus is significantly displaced, the deltoid ligament should be surgically repaired.
 
What else do you feel surgeons should consider?
 
So I have our residents take a look at the incisura on the CT scan. So studies have shown that with a deep incisura, traditionally there is the likelihood of displacing the fibula posterior and with a shallow one displacing it anterior. So the surgeon has got to be aware and make sure that he reduces the fibula into the incisura regardless of the characteristics of the incisura. So you can't ignore that. You have to be aware of the shape of the incisor because it could be a fracture in your reduction in alignment.