Fig. 1

True-anteroposterior radiographs of a patient diagnosed with rotator cuff tear (RCT) of the right shoulder. a The critical shoulder angle (CSA of 38.8°), which was measured by drawing one line connecting the superior and inferior osseous margins of the glenoid cavity and then another line from the inferolateral border of the acromion and intersected the first line at the inferior glenoid margin. The angle between the two lines results in the CSA. b The acromion index (AI of 0.72) was calculated by dividing the distance of the glenoid plane to the lateral acromion border (GA) by the distance of the glenoid plane to the lateral margin of the humeral head (GH). c The lateral acromion angle (LAA of 76.05°) was assessed at the intersection of two lines representing the glenoid cavity and the acromion’s undersurface