I can feel cracking sound from my knees once I bend my knees between 135- 90 degrees The doctor has diagnosed osteoarthritis and advised not to climb stairs. I do not have constant pain, but If I walk 2-3 km, I feel pain on my back/pelvis. My mother has acute OA and she find it difficult to move and cannot travel more than 5-10 meters that to with support. What exercise do you suggest to delay any surgery or knee transplant op in future ?