Study on the Application Value of the Novel Acromial Angle in Diagnosing Rotator Cuff Tears

Objective: To investigate the associations between the novel acromial angle (NAA), critical shoulder angle (CSA), acromial index (AI), and rotator cuff tears. Design: Retrospective cohort study. Setting: A single hospital with complete imaging data (scapular anteroposterior radiography, scapular outlet radiographs, and shoulder magnetic resonance imaging). Participants: A total of 207 patients (100 males, 107 females) aged 57.73 ± 16.74 (normal group) and 59.48 ± 13.00 (injury group) years were included. Independent Variables: NAA, CSA, AI. Main Outcome Measures: Rotator cuff tears. Results: The NAA in the normal group was (149.1 ± 5.96)°, and in the injury group was (142.3 ± 6.56)°, with a statistically significant difference ( P < 0.001); the CSA in the normal group was (37.61 ± 5.83)°, and in the injury group was (42.4 ± 7.56)°, with a statistically significant difference ( P < 0.001); the AI in the normal group was (0.745 ± 0.088), and in the injury group was (0.779 ± 0.117), with a statistically significant difference ( P = 0.03). On the receiver operating characteristic curve, the area under the curve for NAA was 0.749, for CSA 0.683, and for AI 0.585. Conclusions: The NAA in the injury group was generally lower than in the normal group, whereas the CSA and AI were generally higher in the injury group than in the normal group. The measurement value of NAA was better than that of CSA and AI. Therefore, NAA, CSA, and AI are risk factors for rotator cuff tears, and measuring NAA, CSA, and AI helps predict the probability of rotator cuff tears occurrence.