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

Objective To evaluate the predictive accuracy of the Global Fatty Degeneration Index (GFDI) for retear risk following rotator cuff repair (RCR). 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 (GFDI) from magnetic resonance imaging, were analyzed in patients undergoing primary RCR between January 2014 and December 2018. Results Among 334 patients, 42 (12.6%) experienced retears. No significant differences were found in age, sex, or BMI, except for diabetes mellitus, which was more prevalent in the retear group (P = 0.012). The mean GFDI was significantly higher in the retear group (2.3 ± 0.7 vs. 1.3 ± 0.5, P < 0.001). ROC analysis demonstrated strong predictive capability (AUC = 0.866). A GFDI of ≥1.875 yielded a sensitivity of 77.6% and specificity of 89.4%. Logistic regression showed an odds ratio (OR) of 18.059 for retears at GFDI ≥1.875 (P < 0.001), with significant associations for subscapularis (OR = 4.530, P = 0.019) and infraspinatus (OR = 2.928, P = 0.043) GFDI ≥3. Conclusion GFDI is a reliable quantitative predictor of retear following RCR, with clinical relevance for risk assessment.