Critical Shoulder Angle and Its Clinical Correlation in Shoulder Pain

Introduction The critical shoulder angle is defined as the angle formed between the plane of the glenoid and the line connecting the most lateral border of the acromion process, as seen on the true anteroposterior radiograph of the shoulder. The purpose of this study was to determine the association between the critical shoulder angle and shoulder pathologies like rotator cuff tears and glenohumeral osteoarthritis. It was also to assess the reproducibility and accuracy of critical shoulder angle values, which were measured with radiographs.  Objective The aim of the study was to find out the association between the critical shoulder angle and shoulder injuries in a rural population cohort. The secondary aims were to assess clinical and radiological correlations between the critical shoulder angle and the symptomology of shoulder pain. Materials and methods Our study analysis was a prospective design conducted at R L Jalappa Hospital & Research Centre, Karnataka, South India. After meeting the inclusion and exclusion criteria, 100 patients were recruited for the study. Forty-five patients had glenohumeral osteoarthritis and 55 patients had a diagnosis of rotator cuff tears. The majority of the patients were male (70%) in both the glenohumeral osteoarthritis and rotator cuff tear groups. The mean critical shoulder angles in the glenohumeral osteoarthritis and rotator cuff tear groups were 30.31 and 33.62, respectively. Conclusions Our data aid in demonstrating that glenohumeral osteoarthritis is associated with a significantly narrower critical shoulder angle and wider critical shoulder angles in rotator cuff disease. Further studies, however, should determine whether this association has a cause-and-effect relationship.