Radiographic Study on the Acromion Index and Its Relationship with Rotator Cuff Tears.

OBJECTIVE The purpose of this study was to evaluate the relationship between the lateral projection of the acromion and rotator cuff tears (RCTs) in the Brazilian population. METHODS The lateral projection of the acromion was measured using anteroposterior radiographs of the shoulders, carried out with the glenoid cavity in absolute profile and the humeral head in the neutral position or with internal rotation. The acromion index (AI) was defined as the ratio between the distance from the plane of the glenoid cavity to the lateral edge of the acromion and the distance from the plane of the glenoid cavity to the lateral edge of the humeral head. This index was measured in 83 patients (mean age of 54 years) with RCTs and compared with a group of 28 individuals (mean age of 48 years) without RCTs. The presence or absence of RCTs was determined by means of magnetic resonance imaging. RESULTS The mean AI was 0.7194 for the patients with RCTs and 0.6677 for the individuals without RCTs, in the Brazilian population. This difference was statistically significant, with P < 0.001. CONCLUSION A relationship can be established between AI and rotator cuff tears in the Brazilian population.