The Acromiohumeral Center-Edge Angle and Risk of Rotator Cuff Tear: A Plain Radiograph and MRI Study

The acromiohumeral center-edge angle (ACEA) is a parameter that can be measured on plain shoulder radiographs and has been found to be associated with increased risk of sustaining a rotator cuff tear. The aim of this study was to investigate this association using plain radiographs and to explore its applicability on shoulder magnetic resonance imaging (MRI) in the same patients. This retrospective study compared 45 patients who underwent rotator cuff repair between September 2021 and April 2022 and 41 patients with normal shoulders. The ACEA was measured by 2 independent observers on anteroposterior radiographs and shoulder MRI. The collected data were analyzed and P values of <.05 were considered statistically significant. The ACEA was found to be higher in patients with rotator cuff tears (23.48° ± 7.11°) when compared with the control group (15.54° ± 4.4°). On shoulder MRI assessment, a higher ACEA was also seen in the rotator cuff tear group (18.93° ± 6.7°) than in the control group (13.79° ± 4.9°). The ACEA measurement on MRI showed strong intrarater reliability (0.965), but weak interrater reliability (0.251). This retrospective study found an association between increased ACEA and risk of rotator cuff tear when measured on plain radiographs. In addition, we found an association between increased ACEA measurement on shoulder MRI and rotator cuff tears, thus suggesting the applicability of ACEA measurement on shoulder MRI.