Ossification of Femoral Head: Normal Sonographic Standards

Abstract

The aim of the study was to establish normal reference standards for the appearance of the femoral head ossification center according to age, sex, and gestational age. Sonographic examination of the hip was performed in 1,800 healthy Indian and Israeli infants (900 each) aged 2 to 24 weeks. There were an equal number of boys and girls. The ossification center was noted at 2 weeks of life in the Israeli infants and at 8 weeks in the Indian infants. However, from 10 to 16 weeks, it was noted in 81% or more of the Indian infants but only 22% to 74% of the Israeli ones. In both groups, between 20 and 24 weeks of age, it was noted in more than 90% of the infants. An association was found between gestational age at birth and chronologic age of appearance of the femoral head ossification center, but only among the Israeli infants. There were no differences between genders. Knowledge of the normal sonographic appearance of the femoral head ossification center by age and ethnicity will help clinicians in the diagnosis of hip disorders.