Not sure if it's a bone problem

I had surgery on my knee a long time ago. Lo.n.g time ago. At that time the surgeon removed part of the soft tissue (cartilage) and I lived ok enough for maybe 20 years after that, BUT -- I am pretty old now, 40 years later and I feel the swelling plus can't walk without a walker. Question is: aside from seeing the surgeon, what supplements might help, because I don't think it's a bone problem but I'm not sure. Two surgeons advised me to have a knee replacement, but now I'm 81 and have concerns about going through an operation. I had a hip replacement two years ago and am still recovering but the knee problem is not good.
So the question is: what about supplements, and might green lipped mussel oil help with the pain?
P.S. I don't have pain when I sit on my lovely recliner, only when I stand or walk.