I have degenerative arthritis in both knees. I can't take glucosamine, because the supplement is always seafood based (oyster shells, etc.) and I'm allergic to fish... it gives me a nasty allergic reaction. However, in my experience, moderate (low-impact to knees, so running is right out) exercise helps more than rest. Keeping the weight off, which you have obviously done, is also helpful.

That's my experience anyway.