I typically start with the patient sitting on the table and either their knee bent like this with the foot flat on the table or they're going to be lying supine with their heel on the table or on a bolster so that they can easily rotate into a lateral decubitus position when I move to a more like posterior lateral or if I need to perform an interventional procedure and I always have a rolled up towel handy because it can support the ankle to help minimize anisotropy and you can wipe your fingers on it. All right, so this is my scanning protocol, a lot of plus minuses with dynamic scanning if people can tolerate it and then but ATFL, joint recess, AITFL, CFL, peroneus longus and brevis with dynamic scanning, the superior and inferior peroneal retinaculi, superficial peroneal nerve plus branches and sural nerve, same thing. And then if the sinus tarsi is a question, then I'll look at that and some of these ligaments but these are really tough to find and I think a lot of times are not applicable to the case so I don't do it every time and same thing with peroneus tertius. You guys know the anatomy, I'm going to skip through this part but make sure you know the anatomy. Techniques, so this is a great little slide just to show you kind of to think about a clock face when you're looking at these lateral ligaments. This is a right ankle so the AITFL is going to be at the two o'clock position, the ATFL at the four o'clock and the CFL at the seven o'clock position. So just a good way to remember it. With the ATFL, it's appreciated as a fibular structure that connects obviously the fibula to the talus with this joint recess below so you can kind of appreciate it here on this normal exam. And then during plantar flexion, the superior bundle fibers tense and the inferior bundle fibers relax and then the opposite happens with dorsiflexion. Obviously this is a pretty weak ligament. This is a dissection that Doug and I did last year just showing the ATFL in all its working glory and this is just a stress attempt for a normal ATFL. You see maybe a little fluid under here but otherwise the ligament obviously looks intact. So if your patient can tolerate it, you're basically just doing an anterior drawer with one hand if you can, otherwise an inversion stress maneuver if their feet are too big. Let's see here. There we go. When you're doing a stress view, this is a comparison case. This is actually my fellow's ankle. So at rest, she was about 7.8 millimeters and then with a stress, she was at 8.8 millimeters. So normal is about 6 to 10 millimeters long. So as long as you're measuring in the same spots, I'm usually pretty happy about that but I usually sit on the bottom end of the ATFL or the deepest portion of it to try to measure and it's usually about 2 millimeters thick. Just a random aside, there are multiple bundles of the ATFL potentially. So a lot of people have single flat bands but some people have two or even three bands. So just be aware of that that there might be some variability there. So now when I move to the AITFL, this is kind of the positioning I go in. So I go from that four o'clock position and rotate up to the two o'clock position. This is just the ultrasound version of me doing that. So you saw the ATFL before. Now we're going to lose the talus here and then the tibia is going to come into place and then we're going to see the ligament right there. This is what it looks like as a still image with a stress view. And then this video is actually courtesy of Doug showing a stress testing and some gapping consistent with a partial thickness tear. So now if we go on to the CFL, so this is our hammock ligament. And so this is again another dissection showing that calcaneofibular ligament with the peronei sitting on top of it. And so you can understand how it kind of acts as a hammock between neutral and dorsiflexion. And it crosses both the ankle and the subtalar joints. I typically have the patient rotate the ankle medially to be able to scan it and then have them go into that dorsiflex to neutral position. I very rarely look at ligaments in short axis view because I don't really think it gives me all that much extra information. So in terms of our case, here's some of the ligaments. So the ATFL, okay, so this was right after his injury. And so there is obviously sharp fluid demarcation in the talofibular recess with significant hyperemia, which we see here. But even though it looks like there's maybe some ligamentous hypertrophy, it does seem to stay intact when we try to distract it. So I said that this is evidence of a joint diffusion causing distension of the joint recess deep to the ATFL with cortical irregularity, which we see here on that distal fibula, which correlates with the x-ray we saw. And then the ATFL itself appears thickened with abnormal hypoechogenicity and hyperemia, but the ligament itself appears intact with dynamic scanning. Then we rotated up to that AITFL and the CFL, and these all looked pretty good. So here's a stress test between the tib-fib of the AITFL and then his calcaneofibular ligament looks kind of like this cord-like fibular band and becomes kind of artifactually hypoechoic because of anisotropy as it approaches the lateral malleolus. So then just when we try to do that stress testing with him going from dorsiflexion into neutral, we can see that hammock show up pretty nicely in the image. So no gapping there, looks pretty normal. So then I move on to the peroneae. Madera taught me a long time ago, don't get excited about the thing that you think it is because you'll miss a bunch of other stuff. So I try to stay with this same flow of how I scan just because of that so that I don't miss things. But this is what we were kind of suspicious on with this patient. These are best visualized in the transverse plane superior to the lateral malleolus and in the retromalleolar groove. And then the peroneus longus lies posterior to the peroneus brevis, obviously. When we scan distally to distal tip of the fibula, you might see a low-lying muscle belly if they have a low-lying peroneus brevis, which is a normal variant. These healthy peroneal tendons should look fibular because of this collagen bundles that are embedded in it. And then it's really rare to see calcific tendonitis in the peroneal tendons, but you want to evaluate for that, obviously, too. And then you're just going to follow the tendons down to a point where they diverge. And you can follow each one down to their insertion, peroneus brevis to the base of the fifth. And then the longest, I don't actually follow all the way under the foot unless there's something irregular about it. It's pretty rare to see a tear of the peroneus longus underneath the foot, but you might see it kind of a little more distally at the cuboid notch or the os peroneum. Tendinosis itself can appear as this hypoechoic enlargement of the involved tendon without tendon fiber disruption. So you want to make sure to evaluate that in short axis and long axis. So I always do a once-over dynamic scan of the peroneal tendons just to get a lay of the land. Sorry, these sine loops look really crappy on this computer for some reason. But you can really appreciate that you're looking for any irregularities, fluid, and possible fadules. Possible fatty infiltration. And here, as we pass the retromalleolar groove, there's some edema it looks like there. The SPR looked a little thickened and the peronei themselves look a little irregular. So we're going to take a little deeper dive into those guys. So with these, it did look like there might be a longitudinal split tear of his peroneus brevis. So that is defined as an irregular hypoechoic defect at the periphery of the tendon, causing the tendon to be focally attenuated. And the PL might insert itself into the defect, which looks like that's what's happening here. So here I see peroneus brevis. Here I see peroneus brevis. Here I see peroneus longus. And then he has a low-lying peroneus brevis muscle. And sorry, I still use the term peroneus. I know it's fibularis. I like peroneus better. Deal with it. I'm from Canada. I don't know. And so on this, I said there's some abnormal anechoic fluid surrounding the peroneal tendons at the level of the distal fibula. Peroneus brevis itself, there's an anechoic cleft that extends to the tendon surface, which is suspicious for a longitudinal split tear. And then this low-lying peroneus muscle belly. You can also see tenosynovitis. So this is an image from Maderek that he gave me a long time ago. And then here's our case. Now, this is a flipped image. So this is a left. That was a right ankle. So this is our fibula. But you can see there's just a lot of hyperemia appreciated here on color doppler within the sheath. And it can appear either anechoic from simple fluid or more hypoechoic or even hyperechoic from complex fluid or synovial hypertrophy. And it hurts. This hurts with sonopalpation. So having a little bit of fluid in the sheath is not unheard of here. So just be careful calling it abnormal if everything else looks stone-cold normal. But this obviously does not look stone-cold normal. So we said there's increased hyperemia with abnormal fluid surrounding the peroneal tendons at the level of the distal fibula. And there's distension of the tendon sheath. And it's painful with sonopalpation of the area. So another little aside. This is a very busy slide. And I'm sorry. But it was a fun find. So there are some accessory muscles that have been described in the retromalleolar groove, peroneus cortis, and peroneus clincus. Oh, somebody's not muted. And it could be implicated as a cause of pain in the lateral ankle. So this is from a cadaveric study by Singh that found that this peroneus cortis actually exists in about 21% of limbs. And it originates from either the lower part of the fibula or the peroneus brevis itself or the intramuscular septum. And it's separated by a fat plane and usually has a thin tendon. So this is it in long axis view separated from the others. So you can kind of see the tendon here. This is an image from a cadaveric that shows it in short axis view. And then this is just a scan. This is a correlative case. This is not our current case study. But this is indeed my fellow. And she has this little blip that comes off the side here. So we'll do this. We'll scan proximally again. So retromalleal groove, peroneus longus, peroneus brevis. And then over here, this little extra piece is going to come off right here. And it gets its own little muscle belly here. So then we said, oh, maybe that's a thing. Let's follow that distally. So then following a distally kind of lost the fibula there. But then we see peroneus brevis here, peroneus longus here. And then this little thing is coming off of it. Let's do this again. Sorry. So peroneus longus is right here. And then here's this little piece. And it just inserted right there. And then if I follow peroneus longus further, it comes all the way down to the tubercle here. So here's peroneus longus. Here's peroneus brevis. And that other little muscle that was kind of popping off the bottom of the peroneus longus right here, attached right here. And that's attaching, it looks like, at the retrotrochlear eminence of the calcaneus, which is a typical place for peroneus cortis to attach. So that's kind of what you might see on that scan if it is in existence. In terms of the superior peroneal retinaculum, it's this apnerotic-like band. So again, here's this dissection that Doug and I did. But so you see this little triangular fibrocartilage ridge that kind of holds the tendons in place and adds to the thickening or adds to the depth of the retromalleolar groove. On ultrasound, it normally appears as this thin hypo-echoic band with this hypo-echoic thickening where the triangular fibrocartilage is. And then because it's so superficial, I always use kind of a really high-frequency linear transducer. So I think a hockey stick's a really good option here. And it can also be absent in some cases. Injury can occur because of sudden dorsiflexion. And you get stripping of the SPR from the distal fibular attachment. So here's a normal-looking SPR right here, this black kind of hypo-echoic structure. Here's peroneus longus, peroneus brevis. Here's the malleolus. And then if you can't really visualize that compared to that, let's see if I can. There we go. So we took this. I flipped it over. So there's the malleolus. Here's this little ridge, this little triangular cartilage, and then the retinaculum itself. So in our case, it looks pretty thickened and quite irregular here. And then on dynamic video, you have to be careful you're not putting too much pressure here because you will stop it from subluxing. I always do a dynamic scan to look for any peroneal sheath instability. And so I have them turn their foot inwards to stretch the retinaculum first. And then I have them evert against resistance and then kind of circumduct a little bit. So dorsiflex, evert, and kind of circumduct. And so you can see that he kind of hops on top of the ridge but doesn't actually come all the way over. So this looks like it's subluxing, but it's not like a full type one where you get tearing of the superior retinaculum off the periosteal attachment to allow for dislocation. So I said this retinaculum is thickened because you can actually see it quite easily. Hypoecobic and hyperemic and appears partially torn at the lateral malleolus. There's peroneal tendon subluxation occurring with dynamic evaluation in ankle dorsiflexion and eversion. This is just another image that shows from a derrick. This shows it actually dislocating all the way. So this shows a full disruption with our peeling off of the fibula. And so this peroneus brevis is now subluxing and dislocating all the way over to the anterior portion of the malleolus. So again, back with our case, this is actually four weeks later. So the hypoecoic distention that we had seen in the tendon sheath has kind of improved it looks like. But the retinaculum does still appear to be holding steady. So the tendon still can't fully dislocate anteriorly. They just kind of do this acute little peroneal dance for me, I guess. So I'm standing by my statement from before. OK, and then the inferior peroneal retinaculum is the other thing we want to look at. So this is distal to the fibula. So the tendons kind of lie on the CFL and then they're stabilized by the inferior peroneal retinaculum. They do share a common sheath before they divide. And then the peroneus brevis goes on above the tubercle. So I just took it off. Peroneus brevis is sitting on top of the tubercle. Peroneus longus is sitting below the tubercle or closer to the ground. Mean thickness of this sheath is like less than a millimeter. So you can't really see it super well, but it just is this little structure right here. And you can get thickening of the IPR, which can lead to local reduced gliding of the peroneal tendons and subsequent tendinopathy and stenosing tenosynovitis. Bony avulsions of the tubercle are quite rare, but they can happen. So obviously, you're going to evaluate for that. So I call this a normal looking IPR. All right, so then I switch over to evaluate the neurovascular structures. So you have this superficial peroneal or fibular nerve, which obviously innervates our peronei muscles. And then there's terminal branches that send sensory supply down to the lower two-thirds of the anterior lateral leg and the dorsum of the foot, except for the first web space. This tends to come kind of superficial out of the fascia about five centimeters above the ankle joint and becomes subcutaneous here. And then it divides into two terminal sensory branches, which are the intermediate and medial dorsal cutaneous nerve. There is some variability here because you can see an accessory peroneal nerve that comes down. It'll arise off the SPN and then course under the fibular brevis muscle and then travel distally to the foot posterior to the lateral malleolus. So it kind of sweeps around down here. So you might even mistake it maybe for a sore nerve. So follow your nerves. Make sure you know where they're going. In terms of the sural nerve, Blake, I think, did a scan of it pretty nicely in his posterior knee lecture. So you can go back and look at that. But I do incorporate the distal portion of the sural nerve in my lateral ankle scan. So obviously, this nerve is made by the medial sural cutaneous nerve and lateral sural cutaneous nerve meeting to form the sural nerve. And it's accompanied by this lesser saphenous vein and is contained within the same little sheath. It passes along the lateral side of the foot and then gives off branches to the intermediate dorsal cutaneous nerve. On ultrasound, you can appreciate it. It obviously has this honeycomb appearance like all nerves tend to do. And it's pretty hyperechoic. It's pretty bright. When you're scanning, you can use the lesser saphenous vein to assist with localization. And at the distal leg, it will lie just kind of lateral to the Achilles tendon. So you need to make sure you have enough gel and you're only using light pressure to avoid compressing the vein and kind of losing this picture. So you can see it right here. And this is just a case of a transection that does show that this nerve can get injured in a lot of surgeries, especially on the Achilles, because of how it wraps over the Achilles here. And so if anybody's ever complaining of nerve pain, burning, tingling, if they're post-surgical, you have to look at the nerve in long axis and short axis view. You can find them much better in short axis and then rotate on it. And then you can see there's a transection with two neuromas here just kind of sliced in half. So this is all no nerve anymore. OK. So with our cases, the sural nerve is up here at the top. It looks really, really normal. I didn't even bother putting in a video of scanning it because it's in Blake's scan anyways. But he's got a nice big lesser saphenous vein. And then the sural nerve is right here. Nice little honeycomb appearance with the fascicular structure. So visualized, found to join together to form the sural nerve. No evidence of entrapment, focal thickening, or fascicle changes. Whereas the SPN also showed no evidence of thickening or entrapment. And I just kind of followed it. So it starts off inside the peroneus longus here and then penetrates out through the fascia. And I call this the shark fin. It's just the fibula. But it kind of points you in the direction of where the superficial peroneal nerve is going. So if for some reason you can't find it, find the point where the shark fin shows up. And it's usually kind of pushing the nerve out of the fascia there. And then this is just following it down further. So we can see it branch into a couple separate little branches. So we see one branch there, one branch there. And they're separating out. So I could follow that down the rest of the way. But his looked normal. So we did not do that further. I'm not going to go through these scans because I didn't do them for this case. But just know that these exist. There's something called a lateral talocalcaneal ligament, which courses from the talus inferiorly when it converges with the calcaneofibular ligament often. So this is our dissection that we did last year. And then this is just the different positioning. So CFL. And then you just kind of tilt the probe a little bit anterior to the fibula and land on that lateral process of the talus. And you should be able to find it. So this is from a Doring paper. And then the same thing with the bifurcate ligament. It's this kind of Y or V shaped structure that connects the calcaneus to the cuboid laterally and the navicular medially. And it is often, it can be injured in somebody with sinus tarsi syndrome. So if you're looking for that, then that's something else that you should be looking at. So to find that, to find this portion of it, place the probe in transverse plane at the calcaneal cuboid joint and then move the probe superiorly towards the superior margin of the calcaneus. And you should see this really skinny little linear structure. These are tough to find practice. That's all there is to it.

2nd Edition, CASE 10

2nd Edition

Foot and Ankle

ankle examination

ligament diagnosis

dynamic scanning

ultrasound techniques

tendon injuries

neurovascular identification