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Foot and Ankle Anatomy: Specific Ligaments

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Now let's begin our, uh, story of anatomy.

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Looking at some of these ligament disc complexes,

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of which there are three, we're gonna start

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with a lateral ligament disc complex.

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Some call this the low lateral ligament disc complex.

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They're separated from the syndesmotic complex.

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There are three ligaments here,

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the anterior talo fibrile ligament,

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the posterior ta fibrile ligament,

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and the calcan fibrile ligament.

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And there are some differences with regard

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to their general anatomy.

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The anterior and posterior talo fibrile ligaments are short

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ligaments as opposed to the calcan fibrile ligament,

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which is a long ligament.

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These ligaments are capsular ligaments

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that will become important a little bit later.

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The calcan fibrile ligament is an extra capsular ligament,

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much like the fibular collateral ligament of the knee.

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In addition, and perhaps very important for you

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to know is these two ligaments,

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the capsule ligaments are related only to a single joint.

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And that joint is the ankle joint.

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The calcan fibrile ligament relates to two joints,

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the ankle, and then also the posterior subular joint.

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This will become important later on when we deal

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with examples of isolated tearing

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of the calcaneal fibrile ligament.

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Alright, I'm adding to this diagram now two of the

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syndesmotic ligaments, the anterior tibial fibrile ligament

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and the posterior tibial fibrile ligament.

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We're gonna talk more about those in a moment,

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but let's do something now.

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The experiment of dividing this particular lateral region

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into those ligaments that are low lateral ligaments

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and those ligaments that are high lateral ligaments.

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And the reason I do that is

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because of the entity known as a high ankle sprain.

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High ankle sprains generally relate to abnormalities

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of the syndesmotic ligaments.

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Okay? Of which there are four,

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I'm just showing you two at this moment.

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The difficulty with that particular term, high ankle sprain,

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it may occur as an isolated phenomenon,

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but it also may be associated with a low medial problem

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with the deltoid ligament.

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So keep in mind,

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although we may call this a high ankle sprain,

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and there may be problems low down on the medial side

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to give you an idea of the complexity of these ligaments.

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Okay. I wanted to show you a view as if you were the back

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of a shoe looking forward.

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And as we look forward, we see portions

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of the ankle joint here and the posterior subular joint.

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Here we can recognize the lateral ligament, the

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Posterior talo fibrile ligament here,

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and we can see portions of the calcan fibrile ligament.

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Here is another ligament, a tibial slip intimate

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with a posterior talo fibrile ligament.

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And then we can see two of the

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syndesmotic ligaments, the inferior transverse ligament,

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the lowest of the syndesmotic ligaments,

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and above it, the posterior tibial fibular ligament.

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Now let's look at these lateral ligaments in more detail.

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The posterior talo fib ligament is shown here

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with its attachment on the fibula with the white arrows,

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and its coarse with the uh, arrows.

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It is typically striated, it may have areas

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of fat within it.

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It attaches the lateral tubercle, uh, uh,

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or attaches the lateral tubercle, trium trigonal process

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or trigonum of the Alis with the fibula.

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So that is the course of it. It is a capsular ligament.

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It is almost horizontal

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or horizontal oblique, so you may see it, uh,

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almost in a single image

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or certainly in two consecutive axial images.

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The anterior talo fbri ligament is also a short capsule

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ligament running from the fibula to the adjacent, uh,

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ALIS as shown here.

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Alright, this is an important ligament

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and one that is often torn.

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And I wanted to show you what it looks like.

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And I wanna indicate an important thing about the shape

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of the fibula.

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When you are dealing with low lateral ligaments, such

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as the anterior talo fibula

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and the posterior talo fibula, this is the shape

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of the fibula that you will see in your axial images.

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That tells you with this concavity on the medial aspect

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of it, that you are dealing

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with the low lateral ligaments.

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Now, another point I wanna make about the anterior pallo

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fibrile ligament, I like to see it on two consecutive axial

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or transverse images.

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And the reason you should see it on two, not one

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is often it has more than one bundle.

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You can identify a larger and thicker superior bundle.

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I'm showing you that here with the orange arrows. Okay?

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All right. So this is, uh, a, a one band

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or bundle of the ligament,

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and then there is an inferior band

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or a bundle, which tends to be smaller, that is intimate

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with the calcan fibrile ligament.

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So that is why typically in most normal persons,

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you will see this particular ligament on two consecutive

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transverse images.

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We turn to the third lateral ligament,

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which is the long extracapsular

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Ligament known as the calcan fibula ligament.

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It extends obliquely backward, okay?

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From the fibula to the calcaneus corresponding

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to this particular picture,

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and it attaches to one

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of those three bumps on the lateral surface of the,

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uh, calcaneus.

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Okay? And that is a very helpful clue to, to

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the attachment side of this ligament.

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And in fact, I use that often to identify

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the lower part of this ligament

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and then follow it as I move upward of my axial images

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to reach the fibula.

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All right? Remember again, this is a stabilizer, not just

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of the ankle joint, but the posterior sub joint.

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This is in a cadaver, the MR image.

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Not beautiful, but it's a nice demonstration of two

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of the low lateral ligaments.

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This is the posterior talo fbri ligament.

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There's the concavity

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that I mentioned on the medial aspect of the fibula.

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This is what it looks like

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extending horizontally across from fibula to TAUs.

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And here is the calcaneal fibrile ligament attaching

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to a bump on the lateral aspect of the calcaneus.

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You can see it here,

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and I wanna point out that nearby are the perineal tendons,

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the brevis above the longest below.

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In the old days, we used to do a lot

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of ankle arthrography when I was a resident, in fact,

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in New York, to look for acute tears of these ligaments.

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And when we filled the ankle with contrast material,

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even though the calcan fibrile ligament was extra capsular,

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often the capsule was ruptured.

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And we would recognize it

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because we would get contrast material

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around the perineal tendons.

Report

Faculty

Donald Resnick, MD

Professor Emeritus, Department of Radiology

University of California, San Diego

Christine B. Chung, MD

Professor of Radiology, Executive Vice Chair, and Director of UCSD MSK Imaging Research Lab

UC San Diego

Karen Y. Cheng, MD

Assistant Professor of Clinical Radiology

University of California, San Diego

Tags

Musculoskeletal (MSK)

MRI

Foot & Ankle