Relationship between Anterior Extension of the Acromion and Rotator Cuff Tear

Abstract

The aim of this study was to investigate the relationship between anterior acromial extension beyond the clavicle and the presence of rotator cuff tears. Images of 1156 patients who underwent shoulder MRI examination due to shoulder pain were reviewed. Two groups were formed from 284 patients included in the study. Group 1 included 142 patients with anterior acromial extension beyond the clavicle, whereas Group 2 consisted of 142 patients without anterior acromial extension. The presence of a rotator cuff tear was recorded in all patients. The relationship between the size of the acromion's anterior extension and rotator cuff tear was statistically evaluated. In Group 1, the length of the anterior acromial extension was found to be an average of 7.7 mm (95% CI for median 6.8–8.5 mm). Anterior acromial extension was significantly associated with a higher incidence of rotator cuff tears compared with the control group (p < 0.001). Supraspinatus and subscapularis tears were more frequent in Group 1 (p = 0.020 and p = 0.011, respectively). During forward elevation, the contact between the acromion and the rotator cuff becomes more pronounced especially in cases with a prominent anterior acromial extension. This could potentially lead to inflammation in the rotator cuff, particularly in the supraspinatus and subscapularis muscles, and the method used in our study to measure anterior acromial coverage is relatively simple and reliable.