44 y/o man with history of steroid use for Crohn's Disease
The left hip shows the "double-line sign" that is characteristic of AVN; a hypointense line adjacent to a hyperintense line. The right hip shows extensive hypodensity and deformity of the femoral head in keeping with sclerosis and mild subchondral collapse.
Avascular necrosis is secondary to vascular obstruction and commonly involves the hips. Predisposing conditions to AVN include steroid use as in this case, pancreatitis, alcoholism, sickle cell disease, rheumatoid arthritis, and systemic lupus erythematosis.