[header] How to prevent avascular necrosis [title] Manage the conditions that cause avn. [step] Preventing this condition requires treating the underlying conditions that cause it and managing the potential conditions from which it may arise. Generally, speaking avn is a result of thrombosis, emboli, or general bone fractures. 
[substeps] Thrombosis, and emboli mostly arise post-operatively, or after fractures and prolonged immobilization of fractured limbs. They both can be prevented by proper rehabilitation, and, if necessary, administration of anti-coagulant therapy, such as heparin.