You must be in a dark room to get the best image quality.
Ambient light from the US machine will usually allow you to see the shoulder.
Make sure you have both shoulders completely exposed.
Use an ample amount of gel between the probe and the skin.
Use 3 or 4 fingers to hold the probe, leave 1 or 2 to steady your hand on the body.
Sit next to or behind the patient so you can both see the US screen.
I begin the exam over the anterior aspect of the shoulder centered over the bicipital groove with the probe held in the transverse position. You will visualize an axial view of the biceps tendon. It is as if you are looking at the biceps from above or end on like it has been transected.
You will note here the fine detail of the tendon on the axial view. This is a view equivalent to an axial cut on an MRI. The tendon is the circular structure surrounded by fluid. Note the transverse bicipital ligament overlying the tendon and a small amount of fluid in the bicipital sheath.
Next rotate the probe 90 degrees. Keep the probe over the biceps and make sure it is rotated to be parallel with the tendon. This will give you the equivalent of a sagittal cut on an MRI. It is as if you are looking at the arm and tendon from the side.
The tendon is visualized as if you were looking at it from the side as it runs down the arm. You can see the tendon just superficial to the humeral cortex, and a small amount of fluid in the bicipital sheath.
Next, place the probe back to the transverse position and externally rotate the arm. This brings the subscap into view. If you slide the probe medially, you will see the tendon coming out from under the shadow of the corocoid and the conjoined tendon.
Here you can see the transverse view of the subscap as it attaches to the lesser tuberosity. The anterior humeral cortex is the underlying hyperechoic line. Note the biceps is no longer visible, as it has been rotated out of the field of view.
Next, rotate the probe 90 degrees to get a sagittal view of the subscap. Keep the arm externally rotated during this part of the exam.
Now you are seeing the subscap as if you are looking at it from the side. To the far left is the corocoid process and the upper border of the subscap is just adjacent to the right. This view allows you to see the upper and lower part of the subscap.
Next move the probe to the posterior aspect of the shoulder in the transverse position. This will allow you to see the infraspinatus and the posterior labrum. The teres minor can also be visualized if you wish.
This view shows the muscular portion of the infraspintus as it transitions into a tendon to insert to the posterior greater tuberosity. The gleno-humeral joint can be visualized to the left of the image with the dense glenoid bone and attached posterior labrum. This is the view you utilize if you are performing an ultrasound guided glenohumeral injection from the posterior approach.
The final portion of the exam is dedicated to visualizing the supraspinatus and subacromial space. The patient's hand is placed behind their back, or have them place their hand on their hip with the arm adducted towards the torso. This will deliver the supraspinatus out from under the acromian.
This is the ideal view of the supraspinatus. This is the equivalent of a coronal MRI cut. It is as if you are looking at the shoulder from the front. Note the tendon as it attaches to the greater tuberosity and the uniform thickness of the tendon. The deltoid is overlying the tendon.
Next turn the probe 90 degrees. This allows you to visualize the equivalent of a sagital view on an MRI.
Here you will see the circular biceps tendon in the cuff interval between the subscap and the supraspinatus on the left of the image. Just to the right of the biceps is the anterior portion of the supraspinatus where most tears occur. To the right of that is the middle and posterior aspects of the supraspinatus.
Visualizing the AC joint is simple. Place lots of gel over the joint and hold the probe in a transverse fashion.
Here you see the distal clavicle, the joint itself, and the end of the acromian. You can also visualize the meniscal component of the joint and a small amount of fluid. This view makes AC injections easier than doing it blind.
A key component to the complete exam is isometric contraction of the cuff muscles against resistance. This allows you to see contracting fibers, and you can catch some non-displaced full thickness cuff tears that can't be diagnosed with static images alone.
This image is of an acute full-thickness tear of the supraspinatus viewed in the coronal plane. It was not clearly evident until I had the patient contract against resistence. The fibers retracted to the left revealing the full-thickness defect seen adjecent to the greater tuberosity on the right.