Objective: Determination of skeletal or bone age is often used in pediatrics and orthopedics. The most commonly used bone age standards in the United States, those published by Greulich and Pyle, were derived from white children of the upper socioeconomic class in 1931-1942. We examined whether these standards apply to the current assessment of bone age in children of diverse ethnicity.
Materials and methods: Hand radiographs of children less than 19 years old at our institution were evaluated for bone age using the standards of Greulich and Pyle. Differences between bone age and chronologic age were calculated, and the mean differences were compared among subgroups of children on the basis of sex, age, and ethnicity.
Results: In Asian and white girls, bone age approximated chronologic age throughout childhood, with the only significant discrepancy being in adolescent white girls, in whom bone age exceeded chronologic age by an average of 4 months. In black girls, bone age exceeded chronologic age except during middle childhood. In late childhood and adolescence, bone age exceeded chronologic age by approximately 10 months. In Hispanic adolescent girls, bone age exceeded chronologic age by nearly 9 months. In black adolescent boys, bone age exceeded chronologic age by 5 months, with no significant discrepancies between bone age and chronologic age at other ages. In white preadolescent boys, bone age lagged behind chronologic age to a statistically significant degree, ranging from approximately 4 to 8 months. Preadolescent Asian boys also showed significant delays in bone age, particularly in middle childhood, when bone age lagged behind chronologic age by nearly 15 months. In adolescent Asian boys, bone age exceeded chronologic age by 9 months 15 days. In adolescent Hispanic boys, bone age exceeded chronologic age by 11 months 15 days. In younger Hispanic boys, delays in bone age occurred but were significant only in early childhood (4-month delay).
Conclusion: Using the standards of Greulich and Pyle to determine bone age must be done with reservations, particularly in black and Hispanic girls and in Asian and Hispanic boys in late childhood and adolescence, when bone age may exceed chronologic age by 9 months to 11 months 15 days.