Avascular necrosis of the femoral head in sickle cell disease in pediatric patients suffering from hip dysfunction.

Objective: The aim of this study is to verify the prevalence of avascular necrosis (AVN) in pediatric patients with sickle cell anemia and hip dysfunction, and to evaluate the presence of associated risk factors.

Method: A cross-sectional study was conducted in a group of 92 patients with sickle cell disease and hip dysfunction. Clinical and sociodemographic characteristics were collected, and laboratory variables were evaluated. All the subjects underwent radiographic and clinical evaluation of the hip. The participants were divided into two groups: the "AVN Group" consisting of patients with AVN, and the "Comparison Group" without AVN. Both groups were evaluated in search of factors associated with osteonecrosis of the femoral head.

Results: 43 (46.7 %) out of 92 individuals presented hip dysfunction, and 13 were diagnosed with AVN (30.2 %). Comparison between groups showed significant differences in time of diagnosis, previous trauma, presence of pain, and mean values of functional scores. Higher percentage rates of fetal hemoglobin, higher platelet counts and lower rates of total hemoglobin were perceived in the Comparison Group.

Conclusions: Pediatric patients with sickle cell anemia with hip dysfunction present a prevalence of 39.4 % of osteonecrosis of the femoral head. This was associated with a longer time of diagnosis (97 months), previous trauma in 92 % of patients, and a mean Charnley score of 15 points. Also, an association with lower rate of fetal hemoglobin (7.2 versus 11.8) was found, which supports the hypothesis that fetal hemoglobin may function as a protective factor against avascular necrosis.