Osteonecrosis (ON) (Avascular Necrosis; Aseptic Necrosis; Ischemic Necrosis of Bone) By Stuart B Goodman, MD, PhD, Stanford University Reviewed / Revised Mar 2023 View Patient Education Etiology Pathophysiology Symptoms and Signs Diagnosis Treatment Prevention Key Points Osteonecrosis is a focal infarct of bone that may be caused by specific etiologic factors or may be idiopathic.