GLP-1s Before Joint Replacement: The 90-Day Outcome Data

If you take a GLP-1 medication and a hip or knee replacement is on your horizon, you have probably wondered whether the drug helps you through the operation or complicates it. Until now the answer came from scattered single-hospital record reviews.

In the August 2026 issue of The Bone & Joint Journal, a group led by researchers at the University of Oxford published the first pooled analysis of that question. They combined ten matched cohort studies covering 96,356 hip and knee replacements and looked at what happened in the 90 days after surgery.

What the analysis actually pooled

The team screened 78 studies and kept ten. Together those studies covered 96,356 primary joint replacements: 30,350 hips and 66,606 knees. Mean patient age was 61.9 years, and 60.1% of patients were female.

One detail shapes everything that follows. In every study included, the GLP-1 receptor agonist had been prescribed for type 2 diabetes or for obesity. Nobody was given one in order to prepare for surgery. This is a picture of people already on the medication for another reason who then had a joint replaced.

The primary outcome was tightly defined. A 90-day surgical complication meant one of six specific things: periprosthetic joint infection, wound dehiscence, periprosthetic fracture, haematoma, nerve injury, or surgical site infection. Medical complications, readmissions, revision surgery, length of stay, and healthcare costs were secondary.

"Matched cohort" means the researchers paired each GLP-1 user with a non-user who resembled them on recorded characteristics such as age, diabetes status, and comorbidity burden, then compared what happened to each. It approximates a fair comparison out of records that were never collected for research. It is not a randomised trial, and that distinction drives everything below.

What the pooled numbers showed

Across hips and knees combined, the 90-day surgical complication rate was lower in the GLP-1 group, with a pooled risk ratio of 0.73.

A risk ratio of 0.73 means the rate in the GLP-1 group was 27% lower than the rate in the matched comparison group. It describes a gap between two groups of records. It is not a reduction any individual person can expect to receive.

Medical complications came in at a risk ratio of 0.78, and readmissions at 0.79. The readmission figure carried substantial heterogeneity (I² of 61.6%), which means the ten studies disagreed with each other considerably on that outcome rather than all pointing the same way with the same force.

Revision rates at two years overlapped between groups: 1.7% to 3.3% across the GLP-1 cohorts, and 1.7% to 4.5% across the controls.

Hips and knees did not behave the same way

The subgroup analysis is where the picture splits.

• In hip replacement, GLP-1 use was associated with significantly lower 90-day surgical complications (RR 0.63), medical complications (RR 0.55), and readmissions (RR 0.82).
• In knee replacement, only the readmission rate reached statistical significance (RR 0.77). Surgical and medical complications did not.

The paper reports that difference but does not establish why it exists, and any confident explanation of it is currently guesswork.

How much confidence the authors put in their own result

This is the part worth reading twice.

The authors graded their evidence using GRADE, the standard system for rating how much a body of evidence should move your beliefs. Their verdict was very low confidence for every outcome except healthcare cost, which was rated moderate. Two of the ten included studies carried a serious risk of overall bias, and the other eight a moderate risk. The authors' own conclusion is worded carefully: GLP-1 treatment before surgery "potentially reduces" these complications.

The core problem is one that statistical matching cannot solve. Someone who was prescribed a GLP-1, filled it, tolerated it, and stayed on it long enough to reach the operating room may differ from a matched non-user in ways no database captures: engagement with their care, access to that care, general resilience. Any of those could produce better surgical outcomes on their own, with the medication just along for the ride.

A 2026 editorial in Knee Surgery, Sports Traumatology, Arthroscopy, written by an international group of arthroplasty surgeons, makes the same argument. It notes that the evidence here remains largely observational and is limited by residual confounding, indication bias, inconsistent timing of treatment, and inconsistent reporting of which drug was used, at what dose, for how long. Its position is that GLP-1 receptor agonists belong in the conversation about broader metabolic optimisation before surgery, but that prospective studies are needed before they enter standardised pre-surgery pathways.

The access question underneath all of this

A separate 2026 audit in the Annals of the Royal College of Surgeons of England shows why this argument has teeth. Researchers took a 30% random sample of one UK centre's knee replacement waiting list in August 2025, 300 patients. Of those, 120 (40%) had a BMI of 35 or above. Among that group, 45% were initially denied or only conditionally listed for surgery, rising to 74.1% of those above a BMI of 40. Women were denied more often than men (52% versus 28%).

Only 13 of those 120 patients (10.8%) were taking a GLP-1 receptor agonist. The authors call current pathways for obese patients with knee osteoarthritis inadequate and identify these medications as a promising route to reduce barriers to surgery, while stating plainly that further research is needed. This is one centre, one snapshot, describing UK practice.

What this means if you are weighing it

The honest summary: in a large body of medical records, people already taking a GLP-1 for diabetes or obesity had fewer complications in the 90 days after a hip or knee replacement than matched people who were not taking one, the signal was clearer for hips than for knees, and the researchers themselves rate their confidence in it as very low.

That is a reason to have a specific conversation, not a reason to change anything on your own.

If you are already on a GLP-1 and surgery is being planned, whether to continue it and how to handle it around the date of the operation is a decision for your surgeon and anaesthesia team. Note what this analysis did not measure: its outcomes were complications of the surgery, not side effects of the medication, so nothing here says a GLP-1 is safe or free of risk for you. Every GLP-1 receptor agonist carries side effects and cautions of its own, and those belong in the same conversation with the provider who prescribes it. If you are not on one and have been told your BMI is a barrier to being listed, this evidence is not strong enough to be the reason to start one, though your weight and metabolic health may already be reasons your provider wants to talk with you.

Not one patient in this analysis was randomised. Every finding here is an association observed in medical records, and the authors say so themselves.