Risk of avascular necrosis of the femoral head in children with sickle cell disease on hydroxyurea: MRI evaluation.

The frequency and rate of progression of AVNFH in this study is much less than that previously reported for our patients not treated with HU. There is no evidence that HU therapy is a risk factor for AVNFH. It may, in fact, prevent new lesions and deter the progression of existing AVNFH.