Acromiohumeral center edge angle for predicting degenerative rotator cuff tear in aging patients: a retrospective...

The etiology of degenerative rotator cuff tears (DRCTs) is unclear, although certain distinct acromion morphologies may correlate with degenerative processes. Numerous radiographic measurements attempting to describe acromion morphology have been described previously. This study aimed to validate and study the relationship between the acromiohumeral center edge angle (ACEA) and DRCTs. We also aimed to compare the predictive value of ACEA to more widely studied parameters, including acromion index (AI), lateral acromion angle (LAA), and critical shoulder angle (CSA). We hypothesize that ACEA is a valid and reliable method for predicting DRCTs. Patients who have higher ACEA are more likely to experience DRCTs.

We conducted a retrospective review of 204 shoulder radiographs obtained from patients aged ≥ 40 years. The study population was divided into 2 groups based on rotator cuff status as identified by magnetic resonance imaging. We compared various radiologic parameters in 108 patients with partial and full-thickness DRCTs to 96 patients with intact rotator cuffs. Two independent authors measured the ACEA, AI, LAA, and CSA values on a standardized anteroposterior shoulder radiograph.

The mean ACEA was significantly higher in the DRCT group than in the intact group (33.11° vs. 24.56°, P < .001). The ACEA has excellent reliability (intraclass correlation coefficient, 0.99). The cutoff value was determined to be > 29.88° (sensitivity, 0.69; specificity, 0.78). ACEA had the best predictive value (area under the curve: 0.76) and reliability compared with AI, LAA, and CSA.

Our study shows that ACEA is an effective predictor of DRCTs. Patients with an ACEA > 29.88° on plain radiography were more likely to have DRCTs.