Evaluation of the relationship between critical shoulder angle and acromial index measurements with rotator cuff rupture on three-dimensional models

Objective: The relationship between rotator cuff tears (RCTs) and morphological features of the shoulder joint has yet to be fully explained. The earlier studies were usually done with two-dimensional radiography images, but joint positions and bone formations could not be thoroughly evaluated in two-dimensional images. This study aims to assess the relationship between RCTs and critical shoulder angle (CSA) and acromial index (AI) values in three dimensions. Methods: In our study, computerized tomography of 24 RCTs (RCT group) and 20 Bankart lesions, and no RCTs (control group) were examined. CSA and AI were measured on three-dimensional (3D) glenohumeral joint models obtained by 3D reconstructions of computed tomography examinations. Results: The RCT group's CSA was significantly higher than the control group (P = 0.002). AI values did not differ significantly (P = 0.151) between the groups. In addition, there was a moderate positive correlation between the AI and CSA values and the age of patients with RCTs (r = 0.309, r = 0.367). Conclusion: This study differs from earlier studies in some significant respects, such as AI values were not found to be associated with RCTs. CSA values were associated with RCTs in parallel with earlier studies. This difference may be because we performed our study on 3D models. We anticipate that our results will guide clinicians in revealing the etiology of rotator cuff degeneration and determining the surgical method for treatment.