BACKGROUND: The results of rotator cuff (RC) repair surgery can be influenced by the presence of muscle atrophy and fatty infiltration. Three-dimensional (3D) quantitative data regarding those degenerative muscle changes after successful or failed RC repair are rare in the current literature. HYPOTHESIS/PURPOSE: The purpose of this study was to analyze muscle volume and fatty infiltration of the supraspinatus muscle after successful and failed arthroscopic RC tendon repair, with a minimum follow-up of 5 years. It was hypothesized that RC muscle volume and fatty infiltration would improve after successful repair and only to a limited extent after failed repair. STUDY DESIGN: Cohort study
Level of evidence 2. METHODS: A total of 115 patients (mean age, 59 ± 8 years
33% women) with RC repair for full-thickness supraspinatus tendon tear were prospectively followed at 3 and 12 months. Of them, 18 patients with unsuccessful RC repairs were matched to 21 patients with successful repairs and reevaluated at a minimum follow-up of 60 months. All patients underwent quantitative 2-point Dixon magnetic resonance imaging at all time points to evaluate full 3D muscle volume and 3D fatty infiltration. The clinical examination included the full Constant-Murley score (CS) and subjective shoulder value. RESULTS: The relative changes in supraspinatus muscle volume were statistically significant between the 2 groups over time ( CONCLUSION: Successful RC repair was associated with relevant improvement of supraspinatus muscle mass and an unchanged fatty infiltration at a midterm follow-up of 5 years. However, failed repairs achieved only mild improvement of supraspinatus muscle volume and showed deterioration of fatty infiltration.