The greater tuberosity angle: a new predictor for rotator cuff tear

Background: The implication of scapular morphology in rotator cuff tears has been extensively studied. However, the role of the greater tuberosity (GT) should be of equal importance. The aim of this study was to propose a new radiographic marker, the ur angle (GTA), which measures the position of the GT in relation to the center of rotation of the humeral head. The hypothesis was that a higher angle value would be associated with a higher likelihood in detecting a rotator cuff tear. Methods: During 1 year, patients were prospectively recruited from a single institution specialized shoulder clinic in 2 different groups. The patient group consisted of individuals with a degenerative rotator cuff tear involving at least the supraspinatus. The control group consisted of individuals with no rotator cuff pathology. Individuals in both groups with congenital, post-traumatic, or degenerative alterations of the proximal humerus were excluded. The CITA was measured on an anteroposterior shoulder x-ray image with the ann in neutral rotation by 3 observers at 2 different times. Results: The study recruited 71 patients (33 patients, 38 controls). Mean GTA value was 72.5 degrees (range, 67.6 degrees-79.2 degrees) in patients and 65.2 degrees (range, 55.8 degrees-70.5 degrees) for controls (P < .001). A value above 70 degrees resulted in 93-fold higher odds of detecting a rotator cuff tear (P < .001). Interobserver and intraobserver reliability were high. Conclusions: GT morphology is implicated in rotator cuff tears. The GTA is a reliable radiographic marker, with more than 70 degrees being highly predictive in detecting such lesions. (C) 2018 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved.