Effect of Fatty Infiltration of the Infraspinatus Muscle on Outcomes and Graft Failure After Arthroscopic Superior Capsule Reconstruction for Irreparable Posterosuperior Rotator Cuff Tears

Abstract

Background: Superior capsule reconstruction (SCR) was developed as an alternative treatment for irreparable rotator cuff tears to restore superior stability of the glenohumeral joint. Although fatty infiltration (FI) of the rotator cuff muscles, especially the infraspinatus, has been implicated as a predictor of outcomes and graft integrity after rotator cuff repair, it has not been fully investigated in cases of SCR. Purpose: To evaluate the effect of FI of the infraspinatus muscle on clinical and radiological outcomes after SCR. Study Design: Cohort study; Level of evidence, 3. Methods: A total of 55 consecutive patients with irreparable posterosuperior rotator cuff tears who underwent SCR between January 2013 and August 2020 were included retrospectively. Preoperative and postoperative clinical and radiological findings (median follow-up of >2 years), including magnetic resonance imaging results, were thoroughly reviewed. The patients were divided into 2 groups: group 1 with mild FI of the infraspinatus (Goutallier grades 0-2) and group 2 with severe FI of the infraspinatus (Goutallier grades 3-4). The American Shoulder and Elbow Surgeons score, Constant score, visual analog scale score for pain, and range of motion were evaluated. Acromiohumeral distance and rotator cuff tear arthropathy using the Hamada classification were assessed on plain radiography. Postoperative graft integrity was evaluated by magnetic resonance imaging. Graft failure was defined as complete discontinuity. Univariate and multivariable logistic regression analyses were performed to evaluate clinical and radiological findings that might be associated with successful SCR. Results: Clinical and radiological outcomes significantly improved after SCR. Graft failure was noted in 15 (27.3%) patients and was more frequent in group 2 than in group 1 (50.0% vs 14.3%, respectively; P = .004). Univariate analysis indicated a significant association between severe FI in the infraspinatus (group 2) and graft failure after SCR (odds ratio, 6.00 [95% CI, 1.65-21.80]; P = .006). Multivariable analysis indicated that FI of the infraspinatus was the only factor associated with graft failure (odds ratio, 6.37 [95% CI, 1.63-24.90]; P = .008). Conclusion: Severe FI of the infraspinatus muscle was a factor indicating a poor prognosis for graft integrity after SCR. Preoperative evaluation of FI in the rotator cuff muscles can help predict postoperative outcomes and may help guide therapeutic options.