Semaglutide and knee pain: the STEP 9 findings

The short answer

In people with obesity and painful knee osteoarthritis, semaglutide improved average weight and pain scores more than placebo.

Who took part?

STEP 9 assigned 407 adults to weekly semaglutide 2.4 mg or placebo for 68 weeks. Everyone received diet and physical-activity counseling. Participants had moderate knee osteoarthritis with at least moderate pain; most were women.

What changed?

Average weight fell 13.7% with semaglutide versus 3.2% with placebo.

Pain improved by 41.7 points versus 27.5 points on a 100-point questionnaire, where a higher score means worse pain. These are point reductions, not percentages. Physical-function scores also improved more with semaglutide.

Adverse events led 6.7% to permanently stop the semaglutide regimen, versus 3.0% with placebo; digestive problems were the most common reason.

What does it mean?

The findings suggest benefits people may notice in everyday movement. They do not prove that semaglutide repairs cartilage or treats every cause of knee pain. Both groups improved, and this trial studied a specific combination of obesity and osteoarthritis.