Purpose: Coracoid morphology has been related to coracoid impingement mainly resulting in anterior shoulder pain aggravated by forward flexion and internal rotation. However, the coracoid process morphology can also affect the inclination of the coracoacromial ligament and subsequently the subacromial space in the same way that acromial slope does. The purpose of this study was to evaluate the influence of the coracoid body-glenoid surface, coracoid tip-glenoid surface, and coracoid body-coracoid tip angles (coracoid inclination angles) on rotator cuff tears (RCTs).
Methods: Fifty patients with documented RCT and 50 patients with normal rotator cuff (control) were included. The coracoid inclination angles were determined in both groups by measuring on computed tomography scans the angle created by the coracoid body and the glenoid surface (A1), the angle created by the coracoid tip and the glenoid surface (A2), and the angle created by the coracoid body and the coracoid tip (A3).
Results: All angles were significantly lower in the RCT group compared to the control group: mean A1 angle of 49.7° and 54.61°, respectively ( p = 0.011); mean A2 angle of 76.45° and 93.6°, respectively ( p < 0.001); and mean A3 angle of 132.33° and 144.34°, respectively ( p < 0.001).
Conclusions: Decreased coracoid body-glenoid surface, coracoid tip-glenoid surface, and coracoid body-coracoid tip angles are associated with RCT. Decreased angles may reduce subacromial space by projecting the coracoacromial ligament more vertically.
Keywords: coracoacromial ligament; coracoid impingement; coracoid inclination angle; rotator cuff.