You might ask your doctor for a referral to a physical therapist (which your insurance then might pay for) who can design an exercise program for you. After my cycling accident I had a problem with my SI joint and general back weakness. The PT gave me a back strengthening program which I found more helpful than general yoga/pilates classes since due to the nature of my injuries not all exercises one might do in a gym or yoga class were appropriate. At her suggestion, I purchased a balance ball which came with a workout DVD and found that also did wonders for my back and core, and can be done in the convenience of your own home. Good luck with healing. At least you can still ride, and at least surgery is off the table right now. I think eating healthy food and doing the right exercise (i.e. what your med experts say is safe) will be good for your to heal, and perhaps slow the progression of your arthritis. Perhaps others with more experience in this area can chime in. Healing thoughts are going your way!