2feelbetter - getting in the water is an awesome way to avoid the knee/foot issues. There's water aerobics - if touching the bottom hurts the feet, you can do Deep Water classes - you get a noodle or flotation device and you work out in the deep end - NO impact at all!
I have osteo-arthritis in both knees.....up until May, I was able to Spin. Then I hurt my ankle, and it's still bothering me to pedal. Stinks, because I sure ATE like I took Spin, if you know what I mean....