In 2019, Bricca and colleagues reviewed the research to see what impact exercise had on the articular cartilage (the cartilage covering the bone in our joints) in the knee of people at risk of, or currently diagnosed as having, knee OA. If exercise and activity were detrimental to our joints, the studies reviewed should show that people who regularly partake in exercises show negative changes in the articular cartilage.
From the studies reviewed, no evidence was found that participating in exercise with an arthritic knee, or a knee prone to become arthritic, made the articular cartilage worse. In fact, many studies showed a positive change in the articular cartilage from the exercise programs. The authors state that "knee joint loading exercise seems not to be harmful for articular cartilage in people at increased risk of, or with, knee OA."
If you believe that you should stop being active, or have been told by your health care provider to stop doing things because you have, or may develop, knee OA, this is likely not the best thing for you. Now, that is not to say that every type of exercise is right for everyone. Exercise can be very beneficial if it is specific to what you need and can currently tolerate. I wrote about this more specifically here: