Liraglutide Prevented Fatty Degeneration and Improved Function After Rotator Cuff Tears in Rats | Research

The takeaway

Liraglutide dramatically reduced fatty infiltration in torn rotator cuff muscles and improved range of motion and nerve function in rats — suggesting GLP-1 drugs could help with muscle degeneration after tendon injuries.

1.1% vs 11.8% fat infiltration
Liraglutide reduced fatty infiltration in torn rotator cuff muscles by roughly 90% compared to controls

What the researchers found

Liraglutide produced striking improvements across all measured outcomes in the chronic rotator cuff tear model:

- **Fatty infiltration**: 1.11 ± 0.75% vs 11.82 ± 3.89% (P<0.001) — a roughly 90% reduction

- **Internal rotation**: 79 ± 38° vs 70 ± 2° (P<0.001)

- **External rotation**: 55 ± 2° vs 48 ± 3° (P<0.001)

- **Nerve-muscle signal strength**: 19.43 ± 8.77 mV vs 7.61 ± 3.15 mV (P=0.028) — more than doubled

Histological analysis confirmed markedly decreased adipocyte deposition and preserved muscle fiber morphology in the liraglutide group. These results suggest GLP-1 receptor agonists can attenuate the otherwise irreversible muscle degeneration following rotator cuff tears.

Why it matters

Fatty infiltration after rotator cuff tears is one of the most vexing problems in orthopedic surgery. Once muscle turns to fat, it doesn't come back — even after surgical repair. No drug has been validated to prevent or reverse this degeneration. If GLP-1 agonists can be repurposed for this indication, it would represent a paradigm shift for millions of rotator cuff patients. The fact that liraglutide is already FDA-approved for other conditions could accelerate clinical translation.

How the study worked

Adult male rats underwent unilateral supraspinatus tendon transection with a silicone tube placed to prevent healing. After 2 weeks to allow the chronic tear to establish, rats were randomly assigned to receive daily intraperitoneal liraglutide (250 μg/kg/day) or saline for 4 weeks. At 6 weeks post-surgery, outcomes were assessed via Oil Red O staining (fatty infiltration), H&E histology (muscle morphology), goniometer (passive range of motion), and compound muscle action potential recordings (neuromuscular function).

What this study cannot tell us

This is a preclinical rat model, and the rotator cuff anatomy differs from humans. The silicone tube interposition creates a specific injury model that may not perfectly replicate all types of human rotator cuff tears. Treatment started 2 weeks post-injury — it's unclear whether starting later (as often happens clinically) would be effective. Liraglutide was given systemically, so effects on body weight and metabolism could confound the musculoskeletal outcomes. Sample size was not reported in the abstract.

How to read the evidence

This is a controlled animal study with randomization and multiple outcome measures. While the results are striking and consistent across endpoints, it remains preclinical and has not been tested in humans. The rat model is a simplified representation of human rotator cuff pathology.

When this study was published

Published in 2026, this is a very recent study exploring a novel application of GLP-1 agonists in orthopedic medicine.

The bigger picture

This study adds to a growing list of unexpected benefits being discovered for GLP-1 receptor agonists beyond diabetes and obesity — from cardiovascular protection to kidney disease to now musculoskeletal degeneration. The anti-adipogenic (fat-preventing) properties of GLP-1 drugs are well established in metabolic contexts, but applying them to prevent fatty infiltration in damaged muscles represents a novel therapeutic concept. If validated in larger animals and humans, this could change how orthopedic surgeons manage rotator cuff injuries.

Questions still open

Would GLP-1 agonists also improve outcomes when combined with surgical rotator cuff repair, not just in the no-repair setting?
Does the anti-fatty infiltration effect work at the lower doses used clinically for diabetes, or are higher orthopedic-specific doses needed?
Could local injection of GLP-1 agonists at the rotator cuff site provide targeted benefit without systemic metabolic effects?

Common questions

Why does muscle turn to fat after a rotator cuff tear?

When a rotator cuff tendon tears, the muscle it connects to is no longer used properly. Over time, the muscle fibers waste away and are replaced by fat cells — a process called fatty infiltration. This change is largely considered irreversible and is one of the main reasons rotator cuff repairs sometimes fail, because the muscle has already degenerated too much to function normally after reattachment.

Could patients on GLP-1 drugs for weight loss also benefit for their shoulders?

That's an interesting possibility this research raises. Patients already taking liraglutide or semaglutide for weight loss or diabetes might coincidentally experience some protection against fatty infiltration in damaged muscles. However, this has only been shown in rats so far, and dedicated human studies would be needed to confirm whether the doses used for metabolic conditions provide meaningful musculoskeletal benefits.

Read the original research

GLP-1 receptor agonist suppresses fatty infiltration while improving range of motion and electromyographic function in a chronic rotator cuff tear rat model.

Journal of shoulder and elbow surgery

View on PubMed ↗Publisher’s paper ↗

Citation

Yoon, Jong Pil; Park, Sung-Jin; Kim, Dong-Hyun; Lee, Hyun Joo; Kim, Jun-Young; Pham, Dinh The; Cho, Chul-Hyun; Chung, Seok Won. (2026). GLP-1 receptor agonist suppresses fatty infiltration while improving range of motion and electromyographic function in a chronic rotator cuff tear rat model.. Journal of shoulder and elbow surgery. https://doi.org/10.1016/j.jse.2025.12.019