Effect of Anterior Acromial Coverage on Functional and Radiological Outcomes After Arthroscopic Repair of Anteroposterior Massive Rotator Cuff Tears

Background: Rotator cuff tear size, fatty infiltration, and scapular morphology are correlated with tendon healing and functional outcomes after arthroscopic repair; however, the association between anteroposterior acromial coverage and the clinical outcomes of anteroposterior massive rotator cuff tears (AP-MRCTs; involving all 3 tendons) remains unclear. Purpose: To identify the association between AP acromial coverage and functional and radiological outcomes after arthroscopic repair of AP-MRCTs. Study Design: Cohort study; Level of evidence, 3. Methods: A total of 98 patients who underwent arthroscopic repair of AP-MRCTs between January 2015 and December 2020 were included in the study and classified according to whether anterior acromial coverage (AAC) was anterior (46 patients; positive AAC group) or posterior (52 patients; negative AAC group) to the scapular line on true lateral shoulder radiographs. Demographic characteristics, surgical details, and functional outcomes were prospectively collected. Acromial morphological features, global tear extension (GTE), the global fatty infiltration index (GFII), tendon integrity after repair, proximal humeral migration, and glenohumeral abduction were measured and calculated on radiographs or magnetic resonance imaging scans preoperatively and at 2 years post-operatively. Multivariate logistic regression was performed to identify the independent risk factors of a rotator cuff retear. Results: The positive AAC group showed larger AAC, posterior acromial tilt, and anterior acromial slope as well as smaller posterior acromial coverage compared with the negative AAC group. Postoperatively, the American Shoulder and Elbow Surgeons score (82.5 +/- 8.3 vs 77.2 +/- 11.5, respectively; P =.013), active abduction (157.8 degrees +/- 27.1 degrees vs 142.7 degrees +/- 39.6 degrees, respectively; P =.048), and glenohumeral abduction (45.6 degrees +/- 10.4 degrees vs 39.7 degrees +/- 14.9 degrees, respectively; P =.041) in the positive AAC group were significantly higher than those in the negative AAC group, while the retear rate (23.9% vs 44.2%, respectively; P =.035) and proximal humeral migration (1.7 +/- 1.0 vs 2.3 +/- 1.2 mm, respectively; P =.006) were significantly lower in the positive AAC group than in the negative AAC group. Smaller AAC (odds ratio [OR], 0.93 [95% CI, 0.87-1.00]; P =.040), larger GTE (OR, 1.03 [95% CI, 1.01-1.06]; P =.017), and a higher GFII (OR, 3.49 [95% CI, 1.09-11.19]; P =.036) were associated with an increased risk of a rotator cuff retear. Conclusion: Increased AAC was associated with a lower retear rate and better functional outcomes after arthroscopic repair of AP-MRCTs. A preliminary risk evaluation integrating GTE, the GFII, and AAC is recommended to consider the necessity of additional procedures for patients in need of arthroscopic rotator cuff repair.