Aseptic/Avascular necrosis
From FOAM EMed Index
Overview of AVN from Mayo Clinic:
http://www.mayoclinic.org/diseases-conditions/avascular-necrosis/basics/definition/con-20025517
Overview from Johns Hopkins
http://www.hopkinsmedicine.org/healthlibrary/conditions/bone_disorders/avascular_necrosis_85,P00108/