Ultrasound of the Shoulder - HD

Introduction

Hi, I'm Dr. Neri. I am from the Mayo Clinic, Arizona. The lecture you're going to listen to today is on musculoskeletal ultrasound, focusing on the shoulder ultrasound. We will discuss the normal anatomy and then some of the pathological conditions. Thank you.

Rotator Cuff Disease Overview

Today we are going to talk on the ultrasound of the shoulder. I have no relevant financial disclosures.

When you look at the rotator cuff disease, it is the number one cause of shoulder pain and disability. And if you look at the gamut of MSK causes for disability and loss time from work, it ranks number two.

Before we look at the abnormal findings of rotator cuff, we will go through the shoulder anatomy in a detailed fashion.

Normal Shoulder Anatomy

The posterior superior part of the rotator cuff includes tendons from the supraspinatus and infraspinatus and the teres minor. The anterior cuff is composed of the subscapular tendon, and then we have the long head of the biceps that we image.

When we look at the rotator cuff as an illustration of anatomy from posteriorly, this is the scapular spine, and above that you have the supraspinatus muscle. Inferior to that, you have the infraspinatus muscle and they all move laterally to form the rotator cuff.

The function of the tendons based on where they're located, is either the rotation of the humeral head or the abduction and dependent on which tendon you are trying to assess. You can do dynamic evaluation by simulating similar movements.

If you cut out the biceps tendon, then under the acromion you can find a virtual space that is a subdeltoid bursal space. And additionally, you can look at the subscapular tendon as it comes and versus the bicipital groove wherein lies the biceps tendon.

We are going to look at anatomy in a little bit of a detailed fashion here.

So if you look at the x-ray, it's easy to identify the landmarks. That's the glenoid fossa, that's the subacromial space where the supraspinatus resides. That's the greater tuberosity, that's the acromioclavicular joint, and that's the coracoid process.

So that way if you now look at the humerus, we again identify the lesser tuberosity and the greater tuberosity, and then we understand that within the groove lies the bicep tendon as the tendon becomes extra articular. This wave wavy line is the humeral head anatomical neck, and the second line is demonstrating surgical neck.

So as we go further, this is just an illustration to show how the subscapularis muscle tendons cross the bicipital groove and keep the tendon inside.

Now, if you look at the bony structure from posteriorly, one of the easier palpable abnormality or the palpable structure is the spine of the scapula. Inferior to that, again, you have the infraspinatus muscle and superior to that you have the supraspinatus muscle, and then you have the teres minor originating from the lateral side.

Now, it's easy to imagine how the tendons reverse to go to their facets, and in the process they construct the rotator cuff.

If you look at this illustration, which is fairly bare of the muscles, here are these blue lines demonstrating how the fibers from the subscapular and then the supraspinatus tendon, they all come and insert onto the tuberosities. And in this process they construct the rotator cuff.

The rotator cuff obviously has one gap, that's the rotator cuff interval from where passes the bicep tendon.

Now this is what I call the bird's eye view. This is if you are standing behind the patient and looking down, and this is an important view to understand. We'll talk a little bit more about that view.

Ultrasound Examination Technique

Once we are looking at patient scanning, essentially the ultrasound exam of the rotator cuff is performed either with the patient having a Crass position or a modified Crass position in either positions. What happens is that we are trying to pull out the supraspinatus tendon from under the acromion so that we can evaluate it in a clearer fashion.

Going back to our bird's eye view, you have the patient here who's sitting down on a stool, and at least in our lab, I like to scan from standing behind the patient from the top. If you look down, you can clearly palpate the bony structure, which is the acromion.

Once you've identified the acromion, then it's easy to visualize the anatomy going back to our bird's eye view, and you have to understand that under this acromion lies the supraspinatus tendon above the spine of the scapula lies the supraspinatus muscle.

So as the muscle traverses laterally from under the acromion, it becomes a tendon just at the insertion. Similarly, you can visualize the infraspinatus tendon at the posterior part of the cuff and you can visualize the subscapular tendon at the anterior part of the cuff.

So this is a good view to kind of memorize, to understand how the tendon will look once you make the patient go into a modified grasp position, because once you are bringing this shoulder back, what you're doing is aggravating and pulling out this tendon to be in full view.

So now imagine that if you are having the patient to be scanned in the modified Crass position, you are looking for the tendon as it tries to come out from under the acromion.

So when we scan, the ultrasound transducer is actually put in this oblique plane or oblique fashion where it lines up itself up along the long axis of the supraspinatus muscle, which becomes a tendon as it emerges from under the acromion for insertion onto the greater tuberosity. And this is a good way to kind of construct a virtual three-dimensional understanding of the rotator cuff.

In your mind, patient is sitting on a stool. You're standing at the back, this is the acromion and the spine of the scapula. This is your bird's eye view. This is the orientation of the transducer so that you can look at the long section of the supraspinatus tendon.

And if everything is perfect, then this is what you should see. There is no shadowing from the acromion because of the modified grasp position. We have pulled out the tendon far laterally.

Now in this structure, it is very easy to understand the anatomy. Here is the rotator cuff, this is the humeral head, and this is the greater tuberosity where the tendon has inserted above the rotator cuff. We have the deltoid muscle, then we have the subcutaneous fat, and then we have the skin.

And it always makes sense when you start out doing the shoulder ultrasound to count the layers because if there is one layer missing, for example, the rotator cuff, then you know you might be dealing with a full thickness rotator cuff tear where the traction to sub acromial location.

Now there's a virtual space that exists on between the deltoid muscle and the rotator cuff, and this is a subdeltoid bursal space. If there is fluid in here, or if it is thickened, then it becomes more easier to appreciate.

Here is an MR correlate of the same issue and you realize that the MR does not struggle at all with the acromion. So you can image the rotator cuff really well as it goes laterally to its insertion. But in ultrasound, we definitely need to do the modified transposition at a minimum to try and get a good visualization of the rotator cuff.

This dark line, which is covering the humeral head, is the articular cartilage. And it is important to recognize this because if you do not, then many times you can make a mistake of calling this as fluid.

In the joint space, this portion where the articular cartilage ends is correlating to the anatomy neck of the rotator cuff as demonstrated by this line on this humerus and on the MR. Also you see it, here's the correlative positions of the anatomical neck of the humerus on the ultrasound image, on the MR image and on the humeral image.

Now this line, which starts from the point where the articular cartilage ends, is the insertion of the rotator cuff. At this point, the rotator cuff has come laterally as an inserting onto the greater tuberosity.

When you turn the transducer 90 degrees, you get a transverse view of the rotator cuff. Again, this is the humeral head, the rotator cuff, the deltoid muscle, subcutaneous fat and skin. And in this patient you can see that there is some sick thickening of the subdeltoid bursal space.

The virtual space on the prior image is not virtual anymore, and you actually can put cursors and measure the thickness of the subdeltoid. Here has the MR correlate of the same, and once you understand anatomy, it's relatively easy.

Now, because this is a transverse image of the rotator cuff, you would expect to cut the humeral head in a transverse fashion. And this hyper echoic structure is the humeral head, which lies in this little defect within the rotator cuff, which is called the rotator cuff interval.

Many times in this position, the bicep tendon might seem to be surrounded by a little bit of a fluid, but this is okay and normal because there might be a physiological fluid within the sheath at this point, and this is not a tear immediately near the bicep tendon.

Now, when we start the examination, you understood now the anatomy of the rotator cuff, at least in the area of the supraspinatus tendon and the infraspinatus tendon. But when we start the exam on a general, general basis, we start anteriorly by trying to find the biceps tendon.

The transducer is kept in a transverse plane. You get the lesser tuberosity and the greater tuberosity in view. You find the bicipital groove, and you are clearly able to see the hyper echoic biceps tendon within the groove.

When you turn your transducer 90 degrees, you can lay out this entire biceps tendon as a hyper echoic fibrillar structure where you have multiple hyper echoic lines running parallel to each other.

When you want to look at the subscapular tendon, then you have to perform the external rotation of the arm. Once you perform the external rotation, the subscapular tendon comes into view as it's demonstrated on this longitudinal image of the tendon and on the transverse image of the tendon.

It is important to see and remember that in the transverse images, many times you will find these hypoechoic areas within the cuff, which are not tears, but these are just sort of artifacts created because of interdigitation of the fibers as they come laterally for insertion.

So when you do a shoulder exam, you do a couple of things. You look at the bicep tendon, look at the subscapular tendon, look at the supraspinatus and the infraspinatus tendon, and you look at the transverse images.

Now, it is important to know that you should look at the bicep tendon in a way that the biceps tendon, or rather any tendon is hyperechoic rather than hypoechoic. And this is demonstrating the angulation of the transducer as you are trying to image the tendon itself.

When the tendon is hypoechoic, that means the transducer is at 90 degrees and is able to show a good representation of the tendon. When you see a hypoechoic tendon, you are worried that you might be getting misled by the artifact of anisotropy, which can happen when the sound beams are intersecting the tendon in an angular fashion and thus not getting reflected back.

Usually we end the exam by looking at the muscles. Okay, this is the transverse image of the supraspinatus muscle above the spine of the scapula. This is the infraspinatus muscle below the spine of the scapula. This sees the teres minor muscle a little bit more laterally beyond the lateral edge of the scapula.

And you can see the muscles are fairly hypoechoic and somewhat homogeneous, which means that there is no atrophy and there's no fatty infiltration.

You could go behind and look at the glenohumeral joint, although in thick patients or bigger patients, it's sometimes really difficult to see as a part of the labrum, which is visualized here. This also is a good section if you're doing any kind of intervention procedure or if you're checking for fluid.

Some people also look at the acromioclavicular joint to assess for any synovial hypertrophy or any arthritis changes.

Pitfalls in Imaging

Here's a slide that explains the pitfall of anisotropy, somewhat details if this is the source of sound, and if this is a reflector or the tendon, if the tendon is at 90 degrees to the beam, then all the sound gets reflected back to the transducer, in which case there is no anisotropy.

If the tendon is going at an angle to the source of sound, then some part of the sound does not go back to the transducer and gets reflected away. Because of this, this tendon may look hypoechoic and thus abnormal.

In this example, we are looking at the rotator cuff. If you look at the middle of the rotator cuff, it seems hypoechoic with good fibrillar pattern, but then at the insertion you see this hypoechoic wedge like appearance, and you could be tempted to call this as a tear.

But when you move your transducer laterally so that you hit this area in a 90 degree fashion, realize there is no hypoechoic area because you got rid of the anisotropy. So this is an important point to understand because anisotropy can mislead you into making a diagnosis when there is no pathology.

Pathological Conditions

Now we look at the abnormal cuff. One of the most frequently encountered pathology is a tendinosis. Then we see patients who have full thickness or partial thickness tears, the partial thickness tears could be articular, could be bursal or could be intrasubstance tears.

We also look at the biceps, either is the biceps located in the groove, is it subluxated, is it dislocated? Does it have tears or is it inflamed and just has tenosynovitis? We look at a few cases of acromioclavicular joint arthritis, and then we look at the appearance of a postoperative cuff, which is fairly challenging.

Tendinosis

So tendinosis is a degenerative process. However, there is very little evidence of inflammation. All the inflammation may play a role in the initiation of the process itself.

Currently, the terms tendinosis and tendinopathy are used to describe the chronic tendon disorders and calling them as tendonitis has somewhat fallen by the wayside.

The intrinsic mechanism for osis is tendon overload or inherent degeneration, sometimes just age related. An extrinsic mechanism could be a compressive force due to a surrounding structure like an osteophyte or a spur or bone itself.

When you think of tendinosis, the appearance of the tendon is very heterogeneous, as in this image. You can see we've lost that normal hyperechoic fibrillar pattern of the tendon. There is no tear, but the tendon itself is somewhat heterogeneous and just to the eye it seems somewhat thicker too.

There are not many good numbers to go for, but I generally think if a tendon is more than five millimeters in thickness, then it probably is a thickened tendon. You can alternatively just compare this tendon with the opposite side and see if there is a difference between the two sides.

And a difference of more than two millimeters between the two tendon thicknesses can be significant.

Now, if you have chronic tendinopathy, secondary to calcification, it becomes much more easier and obvious. This is a large chunk of calcification within a cuff. And here's a little video, which again shows huge calcification in the subscapular tendon, very close to its insertion.

So this is calcific tendinopathy. In this case, you can see that the bursa is slightly thickened and the underlying tendon itself is heterogeneous. It can be sometimes confusing to know where is the bursa and where is the tendon, and make sense that you do some abduction movements to find out if the whole thing is a tendon or a bursa.

If you do abduction, then the bursa stays in its place, whereas the tendon is going to show movement.

Bursitis

Significant chronic bursitis. You can see the tendon is way down there and fairly normal thickness, although it might be slightly heterogeneous, but the subdeltoid bursa is really thick. Here's another example of chronic bursitis.

You can see that's the deltoid and this is the rotator cuff. And you can see significant thickening of the subdeltoid bursal space depending on how much fat is present within the bursa. Sometimes it can have a really varied appearance.

This bursa has these hyperechoic areas and all that is just inflamed fat apart from some debris within the bursa.

Subacromial Impingement

When you have a thickened tendon secondary to either tendinopathy or you have a tendon that is having a very thick bursa and it makes sense to look for subacromial impingement. And subacromial impingement is basically trying to abduct the arm and to see how the rotator cuff slides under the acromion in a coronal plane, keep the acromion in view and then make sure you have part of the cuff and the arm is hanging by the side.

When the arm abducts, you're looking for how much of this cuff actually goes under the acromion, and here you can see the entire cuff including the bony landmarks, slides under the acromion really well. So in this case, there is no impingement.

Now, if you look at this case, we can see that the cuff is somewhat heterogeneous. You can see fairly heterogeneous and very thick, and you have the acromion here. And when you do the abduction, you don't go all the way. You kind of go to this point.

And if you look carefully in the video when the impingement occurs, there is somewhat more prominent finding of the subdeltoid bursal space because the bursa is getting compressed by something under the acromion.

Here again, you can see the video that's slight prominence of this bursal space here at the end of this abduction. And you can see the entire cuff does not slide completely under the acromion.

Full Thickness Tears

So we look at the full thickness tears. Now these originate in the junctional area of the supraspinatus and the infraspinatus, and they progress sideways. They usually represent as a focal defect within the cuff, and you sometimes can obviously see the retraction of the torn ends. Underlying degenerative bony changes are pretty apparent.

Now, if you are dealing with a massive tear, you sometimes will not see the retracted end at all because of subacromial retraction. The cuff literally disappears from view.

Now, we did the studies a few years back in which we looked at the origination of tears. In this diagram, you can see when we looked at all the full thickness tears, most of the tears, the common number where the tear existed was between the 13 to 17 millimeters from the bicep tendon posteriorly.

When we looked at small full thickness tears, we again saw the predominant of these small full thickness tears to be around 13 to 17 millimeters from the bicep tendon. This led us to believe that the origin of the tears must be taking place at least 12 to 13 millimeters posterior to the bicep tendon, and then the tear over a period of time progresses anteriorly and posteriorly as it grows within the rotator cuff crescent.

Now here is an image of a full thickness tear. You can see this is the deltoid muscle. This is the degenerative underlying bony changes in the humeral head, and this is where the cuff should have been, but the cuff has gone off its insertion and retracted, and you can see the retracted end of the cuff.

So this is a fairly large full thickness tear with the defect being occupied by fluid. If you compress with your transducer, you can generally displace that fluid away and change the contour of the rotator cuff.

When the rotator cuff contour is changed, that's a good evidence that you're dealing with a full thickness tear. As a transverse view of the same. You can see that this is the cross-section view of the biceps tendon and the tear pretty much extends right immediately behind the bicep tendon all the way posteriorly.

This is the image again, with compression, you can displace the fluid. Now, if you don't have the fluid, it can become somewhat more difficult and that is where in small full thickness tears, you have to concentrate on trying to find out what's the contour of the rotator cuff.

Now in this case, you can see the contour is not completely convex, it is concave, and this is an indirect evidence that you are dealing with an underlying full thickness tear.

If you do an MR arthrogram in this patient, you will see the contrast will be in the joint space and also in the subdeltoid space.

Sometimes we can get fooled by subdeltoid fat herniation. If you look at this cuff initially, you might think that the cuff is intact, but there is one big problem when you draw the contour of the cuff, it keeps going beyond the insertional site.

So that tells you that you might be getting fooled by the bursa itself. The actual contour of the cuff is somewhat like this, and this defect has been replaced by the subdeltoid fat herniation.

So this is an important pitfall to keep in mind as you do rotator cuff ultrasound. Here's another example. Again, pretty much showing the same thing. There's a large amount of subdeltoid bursal fat, which is occupying the defect of the full thickness rotator cuff tear.

Another sign that helps sometimes with small full thickness tears is called the cartilage interface sign or the bare cartilage sign. If there is a absence of cuff material, then what happens is that the underlying articular cartilage over the humeral head becomes really well seen, and you can see the edge of the articular cartilage becomes hyper reflective.

So that's a good sign, which helps you focus as to where the full thickness tear exists.

Now in this instance, it is really difficult to say what's going on. You know that this is a subdeltoid, this is the deltoid muscle, you know, this is the bone and you have a lot of degenerative change. And what you're not sure is that are you dealing with a very thin cuff or has the cuff torn?

And in such an instance, it's really good to go and compare with the opposite side. When we compare with the opposite side, we see that the opposite side has a pretty big cuff and the cuff is intact.

On this side, there actually is a full thickness tear, and what has happened is that the defect is now occupied by some subdeltoid fat herniation and some debris, and this can simulate a tear, so it always makes good practice to compare with the opposite side.

Again, this is a full thickness tear. There is no cuff present, and when the cuff is not present, sometimes the articular cartilage can look much more prominent than what we are used to seeing. This hypoechoic line is the articular cartilage.

Here's the comparison shot from the opposite side, and you can see there's a fairly good cuff and the articular cartilage is not well-defined here because the cuff is intact.

Partial Thickness Tears

This is the biceps tendon on the transverse view of the rotator cuff. When you deal with partial thickness tears, most of them will be seen on the articular side. Again, you look for a distinct hypoechoic or a mixed defect. It'll be present regardless of the transducer's angulation.

You can try and find it in longitudinal and transverse plane and should be able to demonstrate it in both the planes. You can also look for the echogenic tendon fragments. They can help you understand what's the size of the tear and look for degenerative bony changes in the underlying bony contour.

An extensive partial thickness tear in which more than 50% of the cuff is involved can be mistaken for a full thickness tear. And we are not very sensitive in differentiating between an extensive partial thickness tear or a full thickness tear.

Here's a small articular side partial thickness tear, which is occupying almost about 50% or even 60% of the thickness of the cuff. However, when you compress the cuff does not change its contour. The contour is maintained and that tells us that we are dealing with a partial thickness tear.

Now, if we had somewhat of a similar appearance, but the contour changed, then we would suspect that we might be dealing with a full thickness tear and just are not able to see the connection all the way up. So concentrating on the contour of the rotator cuff is really important.

Here's a partial thickness tear. Seems to be an articular side tear, which is extending into the substance of the cuff. This is a transverse view of the cuff.

Now, one important concept for people to understand is your transverse image is a representation of where your transducer is on the rotator cuff. If your transducer is a little bit more medial on this rotator cuff, then the representative image can under call the tear, right?

This looks much smaller than the prior image, so it really depends where you keep your transducer. The other big pitfall is that you look at this in longitudinal and then when you do transverse, your transducer has slid off more medially than you expect.

And when that happens, you don't see any tear. So many times when you're looking at the rotator cuff, you actually get fooled into thinking that there is no tear.

It is really important to get in the habit when you are examining the transverse views of the rotator cuff that you slide your transducer medially and laterally so that you understand what's going on in the entire cuff.

Here's an example of a partial thickness tear, kind of having an intrasubstance extension, somewhat delaminated in its appearance. There's a large amount of subdeltoid fluid collection within the bursal space.

Postoperative Rotator Cuff

Now, post-surgical cuffs are even more difficult to see. One of the big problems is that there is a lot of material in there because of the rotator cuff repair, the suture material, the anchors, they make it difficult to see the cuff because of the artifacts.

Additionally, the rotator cuff is not a watertight repair, so you can see a little bit of fluid within the cuff or what seems like a partial thickness tear, but it may be just because you have to remember that it's not a watertight repair.

As a post-op cuff, somewhat more difficult to see that shadow is that reverberation shadow coming from the metal head is a good indicator that this is where the humeral head is. And then you have tuberosity here where the cuff is inserting.

So look for this to get your landmarks accurately. In the second image, you can look at the anchor. This is the anchor which has been put within the bone after the repair, and then within the cuff you can see these hyperechoic material kind of conglomeration is because of the suture material.

The cuff is intact, the anchor is visualized, the suture material is visualized within this cuff. The suture material can also look a little bit more linear in its appearance. And here few more images of the anchors.

This anchor seems to have come out significantly because this is a cortical outline and you can see that almost half of this anchor is already out. But this is a good image to understand how these screws or anchors look on the ultrasound.

These linear hyperechoic lines parallel to each other. Now, here is a rotator cuff that has been repaired. You can see this is the anchor, but there is no cuff. You have the deltoid muscle sitting on the humeral head.

The rotator cuff has broken off and gone medially into the subacromial location. So this is a recurrent full thickness tear.

This is also a postoperative rotator cuff, very heterogeneous in appearance and there was suspicion that we might be dealing with some kind of tear. However, we know that the rotator cuff is not watertight once it's been repaired.

So we also felt that this might be just a little bit fluid in there. Now the advantage of evaluating a post-op rotator cuff by ultrasound over MR is that you can do dynamic maneuvers.

So we decided to abduct the arm. And if you look at the abduction concentrate here at the point where we had a little bit of a suspicion of fluid and we see that there actually is a full thickness tear.

Now this was not apparent on the exam when we started, but once you abduct the rotator cuff, you realize that this is joint fluid communicating through the entire cuff.

So what happened here that this is a non-insertional tear. The tear has taken place at the myotendinous junction. The suture material and the anchors which are holding the repair are intact.

However, this patient returned with a new tear at the myotendinous junction. One of the reasons that can happen is if before the surgery patient did not have a good structure of the muscles itself, that is why we look at all the muscles.

Now, you know how a normal muscle appearance should be hypoechoic and somewhat homogeneous, but when you look at a muscle which is so hyperechoic and somewhat heterogeneous, then you think that this is how fatty infiltration manifests.

Additionally, you can see that the muscle bulk is much lesser than you would expect, at least in the case of infraspinatus tendon. And it also tells that there is some muscle atrophy taking place.

This is a supraspinatus tendon, which is of somewhat of a better appearance. You can see that it's much more hypoechoic when compared to these hyperechoic muscles.

Muscle Atrophy and Nerve Impingement

Isolated teres minor atrophy can be visualized as in this case, this is the fatty atrophy of the teres minor. This is the MR correlate of the same, and sometimes this might be because of the nerve impingement.

You know, this is a quadrilateral space. If there is a space occupying lesion here or a paralabral cyst that is inferior, then the axillary nerve gets compressed and that can lead to isolated fatty changes within the teres minor muscle. And that is one of the big reasons.

In rotator cuff ultrasound, we tend to examine the muscle structures. The nerve impingement based on where the nerve is impinged, you can deal with isolated muscle atrophy or fatty change.

If the axillary nerve is impinged in the quadrilateral space, then we get the teres minor atrophy. If the suprascapular nerve is impinged in the suprascapular notch, then you get atrophy of the infraspinatus and the supraspinatus muscles.

However, if you get the suprascapular nerve impingement to take place in the spinoglenoid notch, then you get isolated atrophy of the infraspinatus muscle and or including the teres minor muscle.

If the cyst is large and has an inferior component, we will now look at some bicep tendon pathology, mostly dealing with inflammation, instability, tear and rupture.

Biceps Tendon Pathology

When you look at a biceps tendon that is inflamed, you're either dealing with tenosynovitis, which is more acute or a chronic tendinosis. In either case, the tendon is heterogeneous and there is increased flow within the tendon or the surrounding sheath.

Here's a case of a tendon that is inflamed. There is significant amount of vascularity within the tendon, and in this case you can see the synovium around it is hypoechoic and shows increased flow.

So this is a good case of the good look for a bicep tendon tenosynovitis.

Biceps tendon instability. The biceps tendon is really well located within the biceps tendon groove. Now, if you look at it, apart from the fact that it gets some fibers from the subscapular tendon to hold it in the groove, it also has fibers from the coracohumeral ligament and the superior glenohumeral ligament.

And all these try and keep this biceps tendon within the groove. Any compromise that takes place in these structures because of trauma or degeneration then can lead to instability of the bicep tendon and the bicep tendon might subluxate or dislocate.

In this case, you can see this is a bicep tendon groove, and this biceps tendon is somewhat subluxated trying to come out of the groove. In this case, you can see the tendon is now overriding the lesser tuberosity, and this has really left the groove.

And in this case, you can see the biceps tendon is now anterior to the subscapular tendon insertion. Here's a little video that demonstrates the biceps tendon. You can also look at the property of anisotropy as you angulate the transducer, but this is a bicep tendon out from its groove and anterior to the subscapular tendon.

Sometimes the bicep tendon gets really dislocated, far medially than you expect. In this instant, we can see that the bicep tendon groove actually was empty. This hyperechoic structure is not the bicep tendon. This was just some fat in that fluid.

We could not have any representation of it in the longitudinal image. This is the bicep tendon sheath without the tendon, some debris or hemorrhage within the tendon sheath.

But as we went more medially, we looked at the bicep tendon, we found it far more medial than we think. This is the more lateral aspect. This is the coracoid process, and this is the biceps tendon.

Here's an example of an intrasubstance biceps tendon tear. You can see it's heterogeneous and hypoechoic. Here's a more obvious intrasubstance biceps tendon tear.

A full rupture of the biceps tendon leads to the Popeye sign. You know, there is no biceps tendon in the groove. And as you come inferiorly, you find a bulging of the biceps muscle itself. Self has a little video which again demonstrates the empty biceps tendon groove and the bunched up biceps tendon more distally.

Other Joint Assessments

The glenohumeral joint posteriorly is sometimes looked at because we want to evaluate for any joint fluid and it is also a good position to do any interventions. As you can see here, we are doing some medial rotation and external rotation, and as we do that, a sliver of fluid in the joint space is appreciated and you really have to do that maneuvering to look for minimal joint effusion.

Sometimes when you're looking at the glenohumeral joint, you can find a paralabral cyst and you can see this is a paralabral cyst extending more laterally. And if you keep scanning, it seems to have multiple septations as it extends along the inferior side of the infraspinatus muscle.

The acromioclavicular joint. In this lecture we're not going to talk much in detail, but generally you can quickly finish your shoulder exam by looking for any obvious synovial hypertrophy or separation or degenerative changes within the underlying bone.

Conclusion

So in conclusion, on this lecture, we've understood that the rotator cuff lends itself really well to the ultrasound examination because of its relative superficial location. Dynamic evaluation is extremely important, and especially where you're looking at cases in which the MR was equivocal or postoperative rotator cuff.

The dynamic evaluation helps us to hone down to the areas of interest. Pitfalls like anisotropy need to be recognized to avoid making a wrong diagnosis.

Learning how to do a rotator cuff ultrasound does have a learning curve. It takes a little bit of a practice and however this is a great tool and can be a very good first line examination for rotator cuff disease. Thank you.