SUBSCAPULARIS ANATOMY

SOME ANATOMY TO BEGIN: To more accurately find subscapularis tears we need to have a good understanding of the anatomy of its insertion. These are the key landmarks for understanding the insertion.

1. Lesser Tuberosity ( Blue arrow in image below).
2. Bicipital Groove ( Green arrow in image below).
3. Surgical Neck of Humerus ( Yellow arrow in image below).

Image adapted from Subscapularis Footprint Anatomy Revisited with a 3-Dimensional Perspective and its Relationship with the Supraspinatus Yoo J C et al

The important things to note from the anatomy we can use in imaging

1.  Subscapularis tendon inserts onto the Lesser Tuberosity ( yellow arrows) and a smaller portion on the surgical neck ( Pink arrow).
2. The tendon insertion occupies the entire lesser tuberosity  ( So on MRI between the tendon and bone there should be no fluid from the joint space).
3. The Insertion is broadest superiorly ( this is also where most of the tears occur).
4. The Bicipital Groove ( Green Arrow) forms the lateral margin of the insertion.

SUBSCAPULARIS WHAT AND WHERE TO LOOK FOR:

1.  Start with a sagittal PDFS/ T2FS scan lateral most aspect.
2. Find the Biceps tendon ( Green Arrow) in the bicipital groove.
3. On the next slice the anterior aspect of the humerus will have an oblique configuration ( Yellow Dashed Line) . This marks the beginning of the Lesser Tuberosity where Subscap inserts ( Pink arrows).
4. There should be NO fluid signal between subscapularis tendon and bone. If there is fluid = Tear.
5. As you keep going medially Subscapularis tendon will lift off bone and fluid will be seen deep to it ( Orange Arrows)  which is normal joint fluid.