Mean difference between skeletal and chronological age in prepubertal children of African descent was 0.09 ± 0.66 y, while that in children of European descent was −0.17 ± 0.67 y (t = 3.13 p = 0.0019). Comparisons between skeletal and chronological age only reached statistical significance in EA prepubertal girls, whose skeletal ages were delayed, on average, by three months (t = −2.9 p = 0.005). The range of values for differences in skeletal and chronological ages was very wide, indicating great individual variability. Skeletal age determinations by the two radiologists showed a high degree of agreement by intraclass correlation coefficient (r = 0.994). One group t-tests were performed to verify the hypothesis that the mean difference score was equal to zero. A difference score was calculated for each subject by subtracting chronological age from the mean bone ages scores provided by the two raters. The hand and wrist radiographs of 534 children (265 boys, 269 girls 260 European-Americans, 274 African-Americans ), ages 0 to 19 y, were analyzed by two experienced pediatric radiologists blinded to the chronological age of the subjects. This study assesses the value of the Greulich and Pyle method in determining the skeletal ages of healthy American children of European and African descent born after the year 1980.

Bone age greater than chronological age