Assessing the Accuracy of Rotator Cuff Muscular Fat Infiltration Status in Predicting Symptomatic Retear After Repair Surgery

OBJECTIVE: The aim of the study was to evaluate the predictive accuracy of the Global Fatty Degeneration Index for retear risk after rotator cuff repair. DESIGN: A single-cohort longitudinal study using historical data was conducted. Data on patient demographics, clinical comorbidities (e.g., diabetes mellitus), and preoperative rotator cuff fatty infiltration, quantified by the Global Fatty Degeneration Index from magnetic resonance imaging, were analyzed in patients undergoing primary rotator cuff repair between January 2014 and December 2018. RESULTS: Among 334 patients, 42 (12.6%) experienced retears. No significant differences were found in age, sex, or body mass index, except for diabetes mellitus, which was more prevalent in the retear group ( P = 0.012). The mean Global Fatty Degeneration Index was significantly higher in the retear group (2.3 ± 0.7 vs. 1.3 ± 0.5, P < 0.001). Receiver operating characteristic analysis demonstrated strong predictive capability (area under the curve = 0.866). A Global Fatty Degeneration Index of ≥1.875 yielded a sensitivity of 77.6% and specificity of 89.4%. Logistic regression showed an odds ratio of 18.059 for retears at Global Fatty Degeneration Index ≥1.875 ( P < 0.001), with significant associations for subscapularis (OR = 4.530, P = 0.019) and infraspinatus (odds ratio = 2.928, P = 0.043) Global Fatty Degeneration Index ≥3. CONCLUSIONS: The Global Fatty Degeneration Index is a reliable quantitative predictor of retear after rotator cuff repair, with clinical relevance for risk assessment.