Research Study Looking at How Well Semaglutide Works in People Suffering From Obesity and Knee Osteoarthritis

This study will look at participants body weight from the start to the end of the study. It will also look at how much pain participants have in participants knee from the start to the end of the study and how this affects participants daily life. This is to compare the effect on body weight and pain in the knee in people taking semaglutide with people taking "dummy" medicine. Participants will either get semaglutide or "dummy" medicine. Which treatment participants get is decided by chance.

Participants will need to take 1 injection once a week. The study medicine is injected with a thin needle in a skin fold in the stomach, thigh or upper arm. During the study, participants will have talks with study staff about how to eat healthy food and how to be more physically active. The study will last for about 1 ½ years. Participants will have 14 clinic visits with the study staff. At the first clinic visit participants will have a blood sample taken. Participants will have an X-ray of participants knee taken at the first visit. If participants have had an X-ray recently, this may not be needed.

At 6 of the clinic visits participants cannot take pain medications for 3 days before the visit. Participants cannot take part if participants have had a joint replacement surgery in participants knee. Participants cannot take part if participants have or have had diabetes. Women: Women cannot take part if pregnant, breast-feeding or plan to become pregnant during the study period.