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Retatrutide Knee Osteoarthritis Results: Pain Down Up to 76%

November 5, 2026 · 5 min read · By the Sharpy team
The short answer

In Eli Lilly's TRIUMPH-4 trial of 445 adults with knee osteoarthritis and obesity, retatrutide cut knee pain by up to 75.8% on average over 68 weeks, and more than 1 in 8 people on the drug had no knee pain at the end, versus 4.2% on placebo. TRIUMPH-1 showed a similar 73.1% drop over 80 weeks. Full results are being presented at ACR Convergence 2026 in Orlando (November 6 to 11). Retatrutide is still investigational and not approved anywhere. Strong thigh muscles matter for knees too, and Sharpy gives you one protein target and one 20-minute workout a day.

Does retatrutide help knee osteoarthritis pain? In Eli Lilly's TRIUMPH-4 trial, it cut knee pain by up to 75.8% on average over 68 weeks, and more than 1 in 8 people taking it had no knee pain at all by the end. A second trial, TRIUMPH-1, found a 73.1% drop over 80 weeks. Lilly announced on November 5, 2026 that the full data are being presented at ACR Convergence 2026, the American College of Rheumatology meeting in Orlando. Retatrutide is still an experimental drug. It is not approved anywhere.

Here is what the trials found, what the numbers mean, and what you can do for your knees today.

Retatrutide knee osteoarthritis results at a glance

TRIUMPH-4 TRIUMPH-1 (knee data)
Who 445 adults with obesity or overweight and knee osteoarthritis, no diabetes Adults with knee osteoarthritis and obesity
Length 68 weeks 80 weeks
Doses tested 9 mg and 12 mg once a week vs placebo Three doses vs placebo
Knee pain drop (best result) Up to 4.5 points (75.8%) from 6.0 Up to 4.3 points (73.1%) from 6.0
No knee pain at the end 14.1% (9 mg), 12.0% (12 mg), 4.2% placebo More than 1 in 6 on retatrutide
Weight loss Up to 28.7% (71.2 lbs) on average Not given in the ACR release
At ACR 2026 Plenary talk, Sunday, Nov. 8 Poster, Tuesday, Nov. 10

Pain was measured with the WOMAC pain score, a standard knee questionnaire. The "up to" numbers are Lilly's best results, from people who stayed on treatment.

Retatrutide knee pain study: what the numbers really mean

The headline numbers are strong, but read them with three points in mind.

Placebo helped too. When Lilly counted everyone who started, including people who stopped early, pain fell 67.2% on 9 mg and 62.6% on 12 mg. On placebo it fell 35.1%. So the drug's real extra benefit is the gap between those numbers, which is still large.

The lower dose did as well on pain. On the all-patient count, 9 mg relieved pain slightly more than 12 mg, even though 12 mg caused more weight loss (23.7% vs 20.0%). More people stopped the higher dose because of side effects, which may explain it.

These were heavy patients. In TRIUMPH-4, 84% had a BMI of 35 or more. Results may differ for people with less weight to lose.

How does retatrutide help knee osteoarthritis?

Retatrutide acts on three hormone receptors: GLP-1, GIP and glucagon. That combination drives large weight loss. Less weight means less force on the knee with every step and stair.

That fits what doctors already know. The American College of Rheumatology's knee osteoarthritis guideline strongly recommends exercise for everyone with knee osteoarthritis and weight loss for those who have overweight or obesity.

TRIUMPH-4 also lowered hsCRP, a blood marker of inflammation, and dropped systolic blood pressure by 14 mmHg on the top dose. The trials did not test cartilage, so there is no proof the drug repairs the joint.

Retatrutide side effects in the knee trial

Side effect 9 mg 12 mg Placebo
Nausea 38.1% 43.2% 10.7%
Diarrhea 34.7% 33.1% 13.4%
Constipation 21.8% 25.0% 8.7%
Vomiting 20.4% 20.9% 0.0%
Less appetite 19.0% 18.2% 9.4%
Dysesthesia (odd skin feeling) 8.8% 20.9% 0.7%
Stopped due to side effects 12.2% 18.2% 4.0%

Lilly said stopping was closely tied to starting weight, and some people stopped because they felt they were losing too much weight. Our retatrutide guide covers side effects across all the trials.

Does weight loss on retatrutide risk your muscles, and your knees?

Fast weight loss takes some muscle with it. For knees, that matters. The quadriceps on the front of the thigh act like a shock absorber, and weak quads are linked to worse knee pain. Losing fat while keeping thigh strength is the goal.

Two habits help most:

  • Eat enough protein every day, spread over meals.
  • Do short, knee-friendly strength work: sit-to-stands from a chair, wall sits, step-ups on a low step and glute bridges. Stop if a move causes sharp pain, and ask a physical therapist to adjust it.

Sharpy is built for this. It gives you one daily protein target, one 20-minute workout and a Shape Score so you can see that you are losing fat, not muscle. For more ideas, see our beginner strength program and walking on GLP-1 guides.

Retatrutide vs Wegovy for knee osteoarthritis

Semaglutide (Wegovy) has its own knee trial, STEP 9, published in the New England Journal of Medicine in 2024. Over 68 weeks, pain improved more on semaglutide than on placebo, and weight fell 13.7% vs 3.2%. STEP 9 used a 0 to 100 pain scale, so its numbers cannot be lined up against TRIUMPH-4's. There is no head-to-head knee trial. For the closest direct comparison, see retatrutide vs Ozempic.

Can you get retatrutide for knee pain now?

No. Retatrutide is not approved for any use. Lilly says it plans to file with the FDA for weight loss in early 2027, so knee pain patients are unlikely to get it before late 2027 at the earliest. Vials sold online as "research peptides" are illegal to sell for human use and may not contain what the label says. See is retatrutide legal? and retatrutide clinical trials if you want a safe way in.

If knee pain is limiting you today, talk to your doctor about approved options, physical therapy and whether a GLP-1 medicine already on the market fits you. Meanwhile, Sharpy can help you build the leg strength your knees rely on, 20 minutes at a time.

Sources

Questions people ask

Does retatrutide help knee pain?

In two Phase 3 trials, yes. In TRIUMPH-4, adults with knee osteoarthritis and obesity saw knee pain fall by up to 4.5 points (75.8%) on a pain scale that started at an average of 6.0. In TRIUMPH-1, pain fell by up to 4.3 points (73.1%). People on placebo also improved, by about 35% in TRIUMPH-4, so part of the drop is not from the drug.

How does retatrutide help knee osteoarthritis?

Mostly through weight loss. Every pound you lose takes load off the knee with each step. Retatrutide also lowered hsCRP, a blood marker of inflammation, in TRIUMPH-4. The trials were not designed to show whether the drug helps the knee in other ways, so treat that as unproven.

Does retatrutide rebuild knee cartilage?

There is no evidence of that. TRIUMPH-4 and TRIUMPH-1 measured pain, function and weight, not cartilage. No GLP-1 drug has been shown to regrow cartilage.

What are the side effects of retatrutide in the knee osteoarthritis trial?

In TRIUMPH-4, the most common were nausea (38% to 43%), diarrhea (about 33% to 35%), constipation (22% to 25%), vomiting (about 20%) and less appetite. Dysesthesia, an odd skin sensation, affected 8.8% on 9 mg and 20.9% on 12 mg versus 0.7% on placebo. About 12% to 18% stopped because of side effects, versus 4% on placebo.

Is retatrutide approved for knee osteoarthritis?

No. Retatrutide is not approved for any use anywhere. Lilly says it cannot be legally sold or marketed for human use. The company has said it plans to ask the FDA to approve it for weight loss, with a filing planned for early 2027.

Is retatrutide better than Wegovy for knee pain?

There is no head-to-head knee trial. Semaglutide (Wegovy) was tested in the STEP 9 knee osteoarthritis trial and also reduced pain, but the trials used different scales, so you cannot compare the percentages directly. Your doctor can tell you what is approved and right for you now.

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