Could using steriods from chemo cause avascular necrosis?

Yes: This is a known complication of taking steroids, especially if you had to take prolonged courses during your chemo regimen (for acute lymphoblastic leukemia, for example). Depending on the location and extent, treatment ranges from physical therapy and waiting, to some orthopedic surgery procedures. If you are still on steroids, you and your oncologist will have the risk/benefit ratio of stopping.