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

Abstract

Background There are conflicting reports on the role of hydroxyurea (HU) in the pathogenesis of avascular necrosis of the femoral head (AVNFH) in patients with sickle cell disease (SCD). Procedure The present study is a prospective cohort study of Kuwaiti children with SCD who were treated with HU. They had magnetic resonance imaging of the hips before starting HU and at regular intervals during a follow‐up period, ranging from 1 to 15 years. Results There were 40 patients (18 SS, 19 Sβ0‐thalassemia, and three SD genotypes), aged 6–20 years. Pre‐HU, 11 (27.5%) had varying grades of AVNFH, while post HU, the prevalence was 32.5%. Two patients developed new lesions during the study, while five (45.5%) that had lesions pre‐HU remained static, another five (45.5%) progressed, and one (9%) improved radiologically. The older patients who had been on HU the longest were more likely to deteriorate. The only hematological parameter that was consistently associated with AVNFH was the reticulocyte count. Conclusions 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.

Occult ischemic bone lesions in children with sickle cell disease: A study of prevalence

“…The prevalence of hip necrosis was comparable with previously published data, while the number of occult lesions of the vertebrae and humeri is surprisingly high. Bone infarcts may be present also in children without bone pain, with a consequent underestimate of these complications 6,7,23–26 …”

Multifocal Osteonecrosis in a 3-Year-old Child With Sickle Beta Plus Thalassemia

“…Some reports postulated that HU can be a risk factor for OST given it increases HbF and hematocrit leading to increased blood viscosity and sickling in the microcirculation of the femoral head 13. However, a recent prospective study reported there is no evidence that HU therapy is a risk factor for avascular necrosis of the femoral head and that it may prevent new lesions and deter the progression of existing lesions 14. There is no evidence that supports the use of HU to treat or prevent OST.…”

The Genetic and Clinical Significance of Fetal Hemoglobin Expression in Sickle Cell Disease

“…We have followed many patients on HU for upwards of 15 years. Pre-and post-HU MRI of the hips have not suggested any increased predisposition to avascular necrosis of the femoral head; if anything, it tends to deter the appearance of new or progression of existing necrotic lesions [54,55,66].…”