I am 31 with avn in both knees and hips i recently had a total knee replacement. is there anything i can do to stop the progression?

Don't believe so: The best thing you can do is keep up your exercise. It is imperative to keep your muscles in top shape. This may delay the inevitable joint replacement.

Depends on the cause: There are several conditions that cause avn. Corticosteroid use is the most common. Once the bone has lost the blood supply, there is a regenerative process that starts and can lead to pain and collapse of the articular surface. This will depend on the extent of involvement in the affected joint. Not all cases go on to joint replacement as some will resolve over time.