A vascular necrosis(AVN)
Rare but severe complication of certain fractures when the blood supply to a segment of bone is affected
Most common sites
Head of femur-in neck of femur fracture and posterior dislocation of hip.
Body of talus - in fracture through the neck of talus.
Proximal pole of scaphoid-in fracture through waist of the scaphoid.
No traumatic cause are
Idiopathic
Steroids
Sickle cell disease
Caissons disease
Gaucher’s disease
Lupus erythematosis
Radiation therapy
Alcoholism
Hyperlipidemia