Comparative Analysis of Critical Shoulder Angle and Acromion Index in Patients with or without Rotator Cuff Tear

Background: Recent evidence suggests that a high value of radiographic acromial indices such as critical shoulder angle (CSA) and acromial index (AI) may be associated with a higher incidence of rotator cuff tears (RCTs). The objective of this observational study was to evaluate the relationship between RCTs, CSA, and AI. Materials and Methods: We divided 68 patients with shoulder pain into two groups: Group 1, RCT and Group 2, normal cuff. Patients were evaluated with standard true anteroposterior (AP) radiographs. CSA and AI were calculated on true AP X-ray. Twenty-four males and 10 females were selected for Group 1 whereas 23 males and 11 females for Group 2. Results: The mean age for Group 1 was 53.23 years and for Group 2 was 47.53 years. CSA findings (mean ± standard deviation [SD]) were 37.5 ± 4.37 for Group 1 and 32.23 ± 3.19 for Group 2. Mean ± SD for AI were 0.72 ± 0.07 and 0.66 ± 0.09 for Groups 1 and 2, respectively. CSA and AI revealed a statistically significant P < 0.0001 for both groups. Logistic regression confirmed CSA and AI to be strong predictors of an RCT. Conclusions: Higher CSA and AI are associated with degenerative RCT. Level of Study: Level III. Keywords: Acromion index, critical shoulder angle, degenerative rotator cuff tear