If I had chronic pain, I wouldn't even think of doing exercises, I would be more determined to reduce pain and that would give your body alot less "stress", to deal with. I have found that pain drains the body of energy anyways...
I have osteoarthritus in the feet (big toe joints, both feet). With arthritis, exercising is like a double-edged sword....not too much and not too little. Your body will let you know, just listen. And easy does it as first too!
Just my two cents worth.... Good luck with your knees, too!
ps...I take 2 or 3 fish oil caps per day (omega 3's, salmon oil). 1000 mg per capsule. That helps with pain, acts as a anti-inflammatory.