Are GLP-1 (Glucagon-like peptide-1) medications suitable for weight loss after knee replacement surgery?

GLP-1 Medications for Weight Loss After Knee Replacement

Yes, GLP-1 receptor agonists are appropriate for weight loss after knee replacement surgery, but you must continue them throughout the perioperative period rather than stopping them, contrary to older guidance. 1

Current Perioperative Management Guidelines

The most recent 2025 multidisciplinary consensus statement from major anesthesia and surgical societies fundamentally changed the approach to GLP-1 medications around surgery:

• Continue GLP-1 medications throughout the perioperative period - do not stop them before or after surgery 1
• This represents a significant shift from 2024 guidance that recommended holding these medications for three half-lives before elective procedures 1
• The newer evidence recognizes that the benefits of continuing therapy outweigh aspiration risks when proper precautions are taken 1

Why GLP-1s Are Beneficial for Orthopedic Surgery Patients

Weight loss before and after joint replacement improves surgical outcomes:

• GLP-1 agonists produce 15-25% average body weight reduction after approximately 1 year, with semaglutide and tirzepatide being most effective 2
• Preoperative use improves glycemic control, potentially reducing postoperative complications 3
• These medications may have disease-modifying effects on osteoarthritis and osteoporosis, providing additional orthopedic benefits 4

Important Caveats for Post-Surgical Use

Aspiration risk management is critical:

• GLP-1s delay gastric emptying, creating pulmonary aspiration risk during anesthesia 1
• If you need any future procedures, adhere strictly to fasting guidelines and inform your anesthesiologist about GLP-1 use 1
• Point-of-care gastric ultrasound should be considered before any future anesthesia to assess gastric contents 1

Muscle mass considerations:

• GLP-1-induced weight loss includes 15-60% lean body mass loss depending on the study, though this appears largely adaptive rather than pathological 5
• After knee replacement, maintaining muscle strength is crucial for rehabilitation 5
• Combine GLP-1 therapy with resistance exercise and adequate protein intake to preserve muscle during weight loss 5

Practical Implementation

Starting therapy post-operatively:

• Begin once you've recovered from surgery and can tolerate oral intake normally 1
• Semaglutide (Wegovy) weekly injections or tirzepatide (Mounjaro) weekly injections are the most effective options 1, 2
• Common gastrointestinal side effects (nausea, vomiting, diarrhea) occur but typically improve with dose titration 2

Long-term considerations:

• Weight regain is common if GLP-1s are discontinued, so plan for extended or indefinite use 2
• These medications carry a boxed warning for personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia syndrome type 2 2
• Cost and insurance coverage may limit accessibility for some patients 3

Realistic expectations:

• GLP-1s may not produce sufficient weight loss alone to meet BMI cutoffs if additional joint replacement is needed 3
• Combine with lifestyle modifications including dietary changes and physical therapy exercises for optimal results 3