GLP-1 drugs are safer than bariatric surgery for weight loss before knee replacement | Research

The takeaway

In 4,652 propensity-matched patients, GLP-1 receptor agonist use before total knee arthroplasty had significantly fewer 90-day complications than prior bariatric surgery, including lower rates of infection, fracture, revision, cardiac events, and readmissions.

2.4x more fractures with bariatric
Prior bariatric surgery before knee replacement was associated with significantly higher complication rates across all measured outcomes vs GLP-1 drugs

What the researchers found

Compared to GLP-1 RA use, prior bariatric surgery before TKA was associated with significantly higher 90-day rates of periprosthetic fractures (RR 2.4, p=0.016), infections (RR 1.7, p=0.002), revisions (RR 1.9, p=0.005), cardiac events (RR 1.255, p<0.001), readmissions (RR 1.316, p=0.015), and ED visits (RR 1.2, p<0.001).

Why it matters

Obesity is a major risk factor for knee replacement complications, and preoperative weight loss improves outcomes. This large study provides the first comparative data between the two main weight loss strategies, strongly favoring GLP-1 drugs.

How the study worked

Retrospective review of national research network data (May 2005-Feb 2025), propensity score matching of 4,652 patients per cohort who had bariatric surgery or GLP-1 RA prescriptions within 18 months before TKA.

What this study cannot tell us

Retrospective observational design. Cannot determine how much weight was lost by each method. Bariatric surgery patients may have had more severe obesity. Different time periods may introduce temporal confounding. Propensity matching cannot account for all unmeasured confounders.

How to read the evidence

Large retrospective propensity-matched study (4,652 pairs) from a national database. Strong for observational evidence but limited by unmeasured confounders.

When this study was published

Published in 2025; covers data through February 2025.

The bigger picture

This study may reshape how orthopedic surgeons approach obese patients needing knee replacement. Instead of recommending bariatric surgery first—which carries its own surgical risks—GLP-1 drugs offer a less invasive weight loss approach with better post-TKA outcomes.

Questions still open

Do the better outcomes reflect the weight loss method or the degree of initial obesity?
How much preoperative weight loss with GLP-1 drugs is optimal before TKA?
Would similar findings apply to hip replacement?

Common questions

Should I take GLP-1 drugs or get bariatric surgery before knee replacement?

This study suggests GLP-1 drugs may be safer before knee replacement, with significantly fewer complications at 90 days compared to patients who had bariatric surgery first. GLP-1 drugs avoid the additional surgical risks of bariatric procedures while still achieving meaningful weight loss.

Why does bariatric surgery lead to more knee replacement complications?

Bariatric surgery involves major changes to the GI tract that can affect nutrient absorption, bone health, and metabolic reserves. These changes may compromise healing after knee replacement. GLP-1 drugs achieve weight loss without these anatomical alterations, potentially preserving better surgical recovery capacity.

Read the original research

Short-Term Complications of Preoperative Weight Loss Strategies in Total Knee Arthroplasty: Bariatric Surgery Versus Glucagon-Like Peptide-1 Receptor Agonists.

The Journal of arthroplasty

View on PubMed ↗Publisher’s paper ↗

Citation

Sharma, Aadi; Lieu, Brigitte A; Velichala, Suhas R; Ernst, Brady; Satalich, James; Smith, Matthew; Golladay, Gregory J. (2025). Short-Term Complications of Preoperative Weight Loss Strategies in Total Knee Arthroplasty: Bariatric Surgery Versus Glucagon-Like Peptide-1 Receptor Agonists.. The Journal of arthroplasty. https://doi.org/10.1016/j.arth.2025.08.073