Rotator Interval Anatomy

There are two regions in the shoulder where Capsulo Synovitis can occur

  1. The IGHL
  2. Rotator Interval

In the last section  we looked at the IGHL. In this part, we look at the Rotator Interval.

The full anatomy of the Rotator Interval is quite complex and we will cover more of it when we look at the Biceps Pulley. However, the three essential components that we need to assess for Capsulo Synovitis are the

  1. Coraco Humeral Ligament ( CHL) and the fat around it.
  2. Sub Coracoid fat
  3. Rotator Interval Capsule: This is the the anterior superior capsule between the Supraspinatus and Subscapularis tendons and merges with the CHL.

WHAT IS THE BEST WAY TO ASSESS THE ROTATOR INTERVAL

  1. These are best assessed on sagittal PD and PDFS scans.
  2. Start medially at the coracoid and scroll laterally.
  3. The first structure to identify is the coracoid process ( Pink circle)
  4. Then find a straight dark line from the coracoid going towards the humerus ( Blue Arrows) which is the Coraco Humeral Ligament
    • Normal CHL is well defined, low signal and thin.
  5. Above the CHL is fat ( Purple circle) and below is fat in the Sub Coracoid space ( Orange circle)
    • On PD will be bright and on PDFS will saturate and be dark.
  6. More laterally we get to the Rotator Interval Capsule ( Yellow Arrow).
    • This extends between Supraspinatus ( red circle) and Subscapularis ( Green circle).
    • Capsule should be thin, well defined and low signal.
  7. The Rotator Interval is the space between Supraspinatus and Subscapularis.

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