Comma sign of subscapularis tear

Last revised by Henry Knipe on 24 Feb 2022

The comma sign of subscapularis tear was first described on arthroscopy but recognized later on MRI. The comma sign represents a full thickness partial width superior subscapularis tear along with torn superior glenohumeral and coracohumeral ligament insertional fibers vertically retracted via adherent fibers to a medially-displaced anterior supraspinatus tear 1,2. Two series have shown a sensitivity of ~75% (range 63-91%) and specificity of ~97% (range 94-99%) 1,2.

Radiographic features


The comma sign can be identified on any plane but best assessed in the coronal plane 2, where it is described as a low T1/T2 signal comma-shaped fibrous band anteromedial to the anterior glenoid extending vertically from the subscapularis tendon lateral to the coracoid process to the superior glenohumeral capsule 1,2.

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