Sickle cell disease and silent avascular necrosis of the hip.

We reviewed the prevalence of avascular necrosis (AVN) in a series of patients with sickle cell disease, using radiography and magnetic resonance imaging. We found AVN of at least one hip in 11 of 27 patients (41%). This is a significantly greater prevalence than reported. MRI was not as helpful in patients with sickle cell disease as it is in patients with AVN from other causes; it detected no more cases than radiography.