This 40-year-old female presents with right shoulder pain that started two weeks prior. There is no known source of injury. Movement has limited range, and there have been no injections or physical therapy.
Q1 – What are the primary abnormal features of this case?
Q2 – Which common diagnosis could be easily misdiagnosed in this case?
Q3 – What is the significance of an os acromiale?
A1 – Thickening of the inferior glenohumeral ligament and anterior rotator interval.
A2 – Primary rotator cuff abnormality / tendinopathy.
A3 – It predisposes to microinstability.
This is a case of adhesive capsulitis masquerading as rotator cuff tear. On initial inspection, it appears as though the supraspinatus tendon demonstrates abnormal signal due to tendinopathy (images 1 and 5, blue arrows). This would be a commonly “overcalled” diagnosis, but on closer inspection, there is capsular thickening and infiltration / inflammation at the inferior glenohumeral ligament (IGHL) (images 1 and 2, green arrows).
There is also capsular thickening and diffuse intermediate signal on the T1-weighted sequences at the anterior rotator interval (images 3 and 4, yellow arrows) between the subscapularis and the supraspinatus. This abnormal signal at the anterior rotator interval does extend to involve and infiltrate the supraspinatus, and to a lesser extent, the subscapularis, which is a common feature of moderate to marked adhesive capsulitis.
The other features of adhesive capsulitis in this case are thickening of the coracohumeral ligament (CHL) (image 8, pink arrow), and eccentrically displaced joint fluid (images 6 and 7, red arrows) with the fluid tracking along the long head of the biceps tendon and the subscapularis tendon.
Therefore, the diagnosis of fibroinflammatory “dry” capsulitis, which is consistent with the clinical entity of adhesive capsulitis, is made rather than primary rotator cuff / supraspinatus tendinopathy. In other words, the cuff is infiltrated secondarily rather than torn.
Unrelated, but an interesting feature of this case is the presence of an os acromiale (image 9, orange arrow).
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