Bone marrow lesion on magnetic resonance imaging indicates the last chance for hip osteonecrosis treated with vascularized fibular grafting before collapse.

BML indicates the last chance for a reproducible improvement in the treatment of hip osteonecrosis with FVFG before collapse. However, the concomitant lower pre-operative HHS (< 80) is a poor prognostic factor for BML-positive hips.