Background: It is not yet clear whether muscle atrophy and fat degeneration have improved after successful arthroscopic rotator cuff repair. Therefore, in this study, the quantitative MRI measurement was performed to evaluate the changes of muscle atrophy and fat degeneration before and after surgery more accurately and to analyze the correlation between changes in muscle atrophy and fat degeneration and clinical outcome.
Materials and Methods: From March 2013 to March 2017, 40 patients who had no retear up to 1 year after rotator cuff repair were taken before surgery, 3 days after surgery, and 1 year after surgery. Supraspinatus muscle atrophy and fat infiltration were measured quantitatively in Conventional Y view and Supraspinatus origin view. The measurement items were muscle area , occupation ratio, degree of fat degeneration (%) and area of fat degeneration (㎣). Postoperative clinical results were measured by ASES score and Constant score at 1 year. Correlation between values and scores was analyzed.
Results: Inter-measurement reliability was high (ICC = 0.933, Cronbach-α = 0.963). There was no significant change in muscle atrophy in Conventional Y-view at 1 year after surgery (Occupation ratio:P = 0.2770; Muscle area(㎣) P = 0.3049) and muscle atrophy in Supraspinatus origin view(Muscle area(㎣) P = 0.5953). Fatty Infiltration (%) and fat area (㎣) measured with conventional method on Y-view and showed significant difference (P = 0.0001). Fatty Infiltration (%) and fat area (㎣) measured with modify method on Y-view and SOV-view showed no significant difference (all P ＞0.05). Postoperative constant score and ASES showed significant improvement compared to preoperative (P = 0.0001), but there was no correlation between fat infiltration and muscle atrophy. (P = 0.653)
Conclusion: Clinical outcome (ASES, Constant score) was significantly improved after rotator cuff repair surgery. Clinical outcome (ASES, Constant score) does not have correlation with FI & MA. Muscle Atrophy does not have change 1-year after surgery. Fatty Infiltration was improved in Y-view measured by conventional method. Keywords: Fatty infiltration, Muscle atrophy, Arthroscopic rotator cuff repair, Supraspinatus origin view, Y-view