GLP-1RA Reduces Supraspinatus Fatty Infiltration and Promotes Functional Recovery in a Rat Model of Rotator Cuff Repair

Background: Despite rotator cuff (RC) tendon repair surgery, fatty infiltration (FI) often progresses due to muscle unloading. Purpose: To evaluate the effects of liraglutide on enhancing muscle quality and function in a rat model of RC tendon repair. Study Design: Controlled laboratory study. Methods: A total of 40 male Sprague-Dawley rats were randomly divided into the control and liraglutide groups and subjected to RC tendon repair surgery. After surgery, rats in the liraglutide group were administered liraglutide (250 µg/kg) for 12 weeks and then sacrificed. Oil Red O staining was used to evaluate the FI of the supraspinatus muscle. The expression of biomarkers related to muscle atrophy, FI, and fat browning was measured by quantitative real-time polymerase chain reaction. Range of motion tests, a wire hanging test, and electromyography were performed to evaluate shoulder function. Results: The liraglutide treatment group demonstrated a significantly lower body mass index and reduced FI compared with the control group. However, no significant differences were observed in the expression levels of genes related to muscle atrophy and FI. Similarly, there was no significant difference in the expression of uncoupling protein 1 (UCP1), a gene associated with fat browning. In the evaluation of shoulder motor function, internal rotation improved early after RC surgery, while external rotation showed improvement at a later stage. In the assessment of muscle strength, the liraglutide group exhibited significant improvement. Furthermore, in the evaluation of compound muscle action potential (CMAP), the liraglutide treatment group showed significant improvement in CMAP both early and late after surgery. Conclusion: The systemic administration of liraglutide suppresses FI without causing muscle loss after RC tendon repair. Furthermore, liraglutide has significant potential to improve shoulder function and quality. Clinical Relevance: This multifaceted mechanism of liraglutide in RC tear treatment may be a powerful clinical strategy for postoperative prognosis management in obese patients with RC tear.