Ultrasound of the Shoulder - Anatomy - SD

Introduction to the Thomas Jefferson University Eating Edge Ultrasound Lectures

Greetings everyone and welcome to the Thomas Jefferson University Eating Edge ultrasound lectures.

I'd like to present to you today the ultrasound of the shoulder and one of the best ways to look at musculoskeletal ultrasonography is to separate your learning structure into modules.

We're going to look at each joint as a module and within that joint, for example, the shoulder, we're going to have some sub-folders. In this case we'll start by showing you anatomy and then go into techniques. From here, of course we'll be going into pathology.

Shoulder Anatomy Overview

Let's begin by taking a look at the anatomy of the shoulder. For the ultrasonography of the shoulder, basic anatomy of course, will be essential, so you need to know exactly where to park your transducer.

Here you see it on the patient's right shoulder in a long axis view, long axis view as you go along the greater axis or length of the supraspinatus.

Once we have learned about the surface anatomy in individuals, we will eventually end up by looking at the gray scale images of ultrasound. Here you could see the par beak appearance of the fibrillar pattern of the supraspinatus as it inserts into the greater tuberosity in a long axis, tomographic cut, the normal anatomy of the shoulder has to be looked at by identifying on the skin surface where you think the shoulder would be.

Once you have appreciated the fact that you are on top of the shoulder itself, then you try to possibly go back to your first year medical school or in our first years of education. If you're a sonographer, you can now look at skeletal anatomy.

Once you know the bones, try to remember that they're connected to each other and they will have a joint in between them and therefore you should get to know a little bit of joint anatomy from there.

Now try to remember that you may vary the position of your patient in order to see different points of the anatomy and so you might have to rotate his arm, you might have to elevate his arm. And of course it's not uncommon for us to spin the whole patient so we can move from the anterior to the posterior part of the patient.

I'd like to look at each articulation or joint as regions and almost universally now you could actually look at any joint into four areas. In case of the shoulder, we will approach it by taking a look at the anterior superior and posterior approaches.

Anterior Approach

So for example, let's begin by doing an anterior approach. This is probably the most natural because then you introduce yourself to the patient and then from here you talk to the patient a bit and begin to identify on the skin surface where the patient's shoulder should be anteriorly, which is going to be the first region that you're going to explore.

We're going to be taking a look at two structures. First you'll be looking for the long head biceps tendon within its bicipital groove and, and then with a bit of shoulder positioning, you're going to be looking at these subscapularis from the anterior region.

Superior Region

We are going to go into the superior region and there's only one structure that we really are going to be concerned with in this area, and that's going to be the acromioclavicular joint from the superior shoulder.

Anterolateral Region

We down tune our cells into the lateral region, but for the shoulder we'd like to think of it as anterolateral because the patient is going to be in a hyperextension internal rotation position, which will show you later during the shoulder technique. So instead of a true lateral, it actually is an anterolateral position or region.

And we're going to be looking at the most important parts of the rotator cuff, which is going to be the supraspinatus and the infraspinatus.

Posterior Region

From there, like I said, we usually rotate the patient who's sitting on a revolving stool to look at the posterior part of the shoulder. The last part, this region, we're going to be looking at a couple of structures, namely the glenohumeral joint for some joint effusion, and then the glenoid labrum pathology here would include not only the effusion of the glenohumeral joint, but also a tear of the labrum, which can create a suprascapular ganglion once we have our regions identified and know how to approach them and park the transducer with the patient's skin.

Like I warned you, let's go back to our introductory days of medicine. We're in, we looked at basic anatomy for the anterior shoulder, you'll have to be prepared to look for the coracoid process. From there, a bit lateral to it, you'll see the lesser tuberosity. And finally, probably one of the easiest structures to identify in a long axis view would be the greater tuberosity.

After doing so, try to remember that the greater tuberosity is, or both tuberosities, the greater and lesser tuberosity are separated from the proximal humeral head, which is covered with hyaline cartilage.

Remember that I told you that shoulder positioning will matter, and so we're going to look now at a shoulder that's slightly abducted and a little bit externally rotated in this position. Now you clearly begin to see that it exposes a groove in between the greater tuberosity and lesser tuberosity. This is the bicipital groove or in the longhand the biceps tendon courses right through. And once you have seen this groove, then you should be readily positioned to look at the long head, the biceps tendon, the bicipital groove.

When you look at it, more or less and on or on axis, you'd appreciate the fact that it's got different depths. That's going to be important because sooner or later you'll appreciate the fact that musculoskeletal radiologists, who do perform ultrasound studies and therefore are anatomists, will begin to identify the structures at different levels.

Case in point, note that as the long head of the biceps tendon runs to the groove and you look at the proximal portion of the groove, notice that the floor of the bicipital groove is quite deep. On the other hand, as you go, a little bit more distal note that the groove of the bicipital or intertubercular sulcus now is a bit shallower in comparison to the deeper proximal portion of the groove.

We're going to look at a patient who has completely abducted his shoulder and we're now looking more or less, at the patient lying down and we're looking up through his axilla. This is, quite an important silhouette for us and to identify the skeletal anatomy because this is where one of the larger rotator cuff tendons, inserts, namely the subscapularis.

So once you have, placed a patient in this position or you take this excellent approach, you can identify the paramedical silhouette of the lesser tuberosity, and then you have the coracoid process from the lesser tuberosity with paramedical silhouette arises the subscapularis or rather that's where the subscapularis inserts. And so after identifying this bony landmark, now you can readily see and look for the soft tissues that too pertain to it.

Remember that I told you for the superior shoulder, there's only one structure that we need to concern ourselves with, and that's going to be the acromioclavicular joint. Of course, more often than not, you are approaching the patient a little bit more anterior, but it is the bird's eye view that probably will make you appreciate more the length and the extent of the acromioclavicular joint.

Note that from the anterior portion of the joint to the posterior, it's at least two or three centimeters. So while most of the examples that we'll be showing you are static images, it'll behoove you to make a sweep across the entire joint from anterior to posterior. And then one more time going backwards from posterior to anterior.

Once you have finished the superior portion of the shoulder, now you go back to the lateral area, but like I told you, because we're going to reposition the patient, we're going, we'd rather call it as anterolateral shoulder on profile. You'll get to see the ledge of the greater tuberosity and the down sloping part of the lateral deltoid shelf separating the greater tuberosity from the convexity of the humerus is the anatomic neck.

It is another groove you already to learn about the bicipital groove. Now you have the anatomic neck, which itself is a distinct anatomic line that separates the tuberosities from the convexity of the humerus. This is going to be an important landmark because remember that hyaline cartilage or articulating cartilage only caps the humerus and not that of the greater tuberosity.

Remember though that we've told you that because ultrasound is a tomographic type of modality, you have to be prepared to look at it at 90 degrees. Any structure has to be visualized at 90 degrees. So from the face, if you look at an individual face on, then you have to look at him also in profile. Likewise, same thing with the bony structures on the profile view.

Note that the convexity of the greater tuberosity equals the convexity of the humeral head, which also will equal not shown here the convexity of the rotator cuff. We can identify bone landmarks because the anterior portion of the greater tuberosity has a deeper and more wedge shape anatomic neck in comparison to the posterior anatomic neck.

So it should be readily clear to a lot of people that this is why if we can identify the point of bony anatomy, we should be able to identify exactly where our transducers are. Identifying that single slice of the soft tissue structures leading the profile view.

Remember what I told you about the convexity, upwards of the humerus, but this time the difference between that the humeral surface and that of the greater tuberosity surface is that now you have a hyaline cartilage capping it completely. This will appear as a hypoechoic black line over the subchondral plate of the humerus once we've seen the anterior superior and anterolateral regions of the shoulder.

Let's finish by taking a look at the posterior shoulder. In the posterior shoulder. As you approach the patient from behind, you have to identify the convexity of the humerus with its hyaline cartilage, and then you're going to look at the rim of the bony glenoid.

The bony glenoid. If you're an engineer, probably well said that it's got an O-ring in order to keep the humeral head inside its socket and the O-ring is known as the glenoid labrum. This will appear as a hyperechoic structure around the rim of the bony glenoid.

The other region that we have to familiarize ourselves with the posterior shoulder is the spinoglenoid groove. The spinoglenoid groove is directly medial to the glenoid fossa, or you could consider it as the neck of the glenoid. It's got several parts. It's going to have the spinoglenoid groove as the neck of the bony glenoid. Then at the base of the scapular spine, you can name that as the spinoglenoid notch.

If you look at this area, therefore you create a groove coming from the top portion of the scapula all the way down to the bottom portion of the neck of the glenoid approaching it. In another way, you could get to see the entire conduit of this structure. Note that at the very superior portion is the scapular notch, and you go through the spinoglenoid notch and finally ending up in the spinoglenoid groove.

Thus, you should be able to identify at what level the lesions are going to be now that you've familiarize yourself with the bone anatomy of the shoulder.

Soft Tissues of the Shoulder

Let's take a look at some of the soft tissues, the following slides or courtesy of Dr. Zung Vu, who is a professor at the New South Wales University in Sydney, Australia. As anatomist, he wanted to learn ultrasound because it helped him identify the dynamic portions of the anatomy that he needed to know.

So let's begin by taking a look at the first soft tissue structure that you probably would also identify on your ultrasound examination. And this is going to be the long head biceps tendon. Note that the long head biceps tendon originates at the 12 o'clock position of the glenoid labrum has an intracapsular portion and then the extracapsular portion, well within the bicipital groove, which we've already talked about, and the bicipital groove lies between the lesser tuberosity and the greater tuberosity.

From there, let's add more soft tissue structures and the all important supraspinatus, which now inserts on the anterior portion of the greater tuberosity. Dr. Vu included the glenohumeral ligaments and anterior capsule, which we don't see much on ultrasound, but as the machines get better, we probably will identify sooner or later.

Overlying of the capsule is the subscapularis, one of the four rotator cuff tendons as you could see, and like we already said, that it inserts into the lesser tuberosity. From there, the subscapularis donates the transverse humeral ligament, which tacks down the long head biceps tendon as it exits its intracapsular portion to its extracapsular portion.

Note to that, there are additional ligaments, and in this case you have the coracohumeral ligaments, which can be identified on ultrasound. From there, let's go a little bit more superior and identify the coracoclavicular ligament and finally, the capsule of the acromioclavicular joint.

Let's swing the patient around and take a look at the skeleton from behind. One more time. Looking at the glenoid labrum, like we said, it's an O ring that keeps the head of the humerus well within the socket of the glenoid fossa.

From there, there's a neurovascular bundle that runs the gamut of the scapular notch through the spinoglenoid notch into the spinoglenoid groove. Of course, nerves are usually accompanied by its artery and veins. This is going to be important because if there is a tear of the glenoid labrum, there may be a giant cyst created known as the suprascapular cyst or ganglion, which may impinge on this neurovascular bundle, causing some denervation of the infraspinatus muscle in its accompanying tendon.

Let's look at the teres minor and the smallest of the rotator cuffs, and this is going to be the teres minor. It is largely a muscle and it's got very, it's very short tendon extent that inserts on the posterior most portion of the greater tuberosity.

Below it, you'll see some other muscle groups, which are the triceps, and of course we can get to see the latissimus dorsi, but let's concern ourselves only right now with the rotator cuff. The teres minor is of course a part of the rotator cuff, and the one you've seen before was the supraspinatus, which as you could see inserted on the anterior portion.

Because we're doing a posterior approach, it appears that the infraspinatus will be a larger tendon, no doubt, however, that the rotator cuff is a conjoint tendon and that we only arbitrarily separate them in this illustration, much like what Dr. Vu wanted us to look at. So you have the supraspinatus, the infraspinatus, and the teres minor, but all of these is considered one unit and known as the rotator cuff.

Most of your patients might come in with referred pain to the deltoid muscle, and so we'd like to show how it overlies the rotator cuff. Of course, once there is some instability or weakness of the rotator cuff, much as the work is done by the deltoid muscle, therefore the referred pain that the patients will point to their deltoid muscle.

Aside from the deltoid muscle, one other muscle that gets overworked is going to be the trapezius, and so now we'd like to show you its relation to the shoulder and to the rotator cuff.

Remember that once you know the anatomy, please recall where the topographical sites are 'cause that is going to be the approach you're gonna be taking and where you're going to plant your transducer. From there, you begin to appreciate the exact skeletal anatomy, which will come out as grayscale images on your ultrasound.

Finally, remember that we are working with soft tissue structures, and once you have everything in place, then the soft tissue structure should be readily identified after you localize it by knowing about the bone anatomy and where to plant your transducer. On the topographical spot.