Exercise
Swimming and walking on soft ground are generally some low impact exercises I have done and had great success with. Walking and exercising on cement and sidewalks always makes my knees and body hurt.
I have posted a couple links to this site BraceAbility, but they are great and offer great choices for use larger people for knee braces and have a couple options for arthritis braces made of neoprene. Check out some of these big knee braces.
I have a torn menicus (sp) in my knee and it hurts like crazy to walk. I'm supposed to exercise and it presents a problem. I was water walking before the surgery and had looked forward to doing that again however, one of my incisions became infected and I can't do that again until it is healed. (currently on a wound vac what a pain!). I'm looking forward to getting back to the water since it doesn't put any real strain on my joints. You might see if your local Y has a pool, I'm sure they would offer water walking.