The tangent sign is useful in helping to quantify supraspinatus muscle belly fatty atrophy with a negative sign implicated with a poorer outcome after supraspinatus tendon tear repair.
On a sagittal oblique plane, a line is drawn between the upper surface of the scapular spine and the upper surface of the coracoid process (medial aspect). A normal supraspinatus muscle belly lies above this line (positive sign) and an abnormal supraspinatus muscle belly (small from fatty atrophy) lies below this line (negative sign) 1-3.
- 1. Yoav Morag, Jon A. Jacobson, Bruce Miller, Michel De Maeseneer, Gandikota Girish, David Jamadar. MR Imaging of Rotator Cuff Injury: What the Clinician Needs to Know1. (2006) RadioGraphics. 26 (4): 1045-65. doi:10.1148/rg.264055087 - Pubmed
- 2. Zanetti M, Gerber C, Hodler J. Quantitative assessment of the muscles of the rotator cuff with magnetic resonance imaging. (1998) Investigative radiology. 33 (3): 163-70. Pubmed
- 3. Schaefer O, Winterer J, Lohrmann C, Laubenberger J, Reichelt A, Langer M. Magnetic resonance imaging for supraspinatus muscle atrophy after cuff repair. (2002) Clinical orthopaedics and related research. Pubmed