In previous studies, where the measured skeletal age was compared with the chronological bone age in children with no evidence of growth abnormalities, the normality of the study populations was mainly verified by a lack of clinical suspicion of abnormalities. This was not confirmed, or correlated with the actual growth values, to guarantee normal growth. Our study was therefore designed to include only those children with known values of growth and weight between the 25th and 75th percentile of a normal age-related population. The subjects could thus be reliably assumed to be normal
9.
The Greulich and Pyle atlas is based on T.Wingate Todd’s investigation of left hand and wrist radiographs5. The method involves directly comparing the radiograph to be assessed with series of standard plates of the same sex by analyzing characteristics such as the appearance of ossification centers, contours of bones, and thinning of growth plates. The standards are stratified by sex and represent the median skeletal maturity for the chronologic age.
The bone-specific approach (Tanner-Whithouse II) assigns a separate rating for each bone of the hand and wrist, with the mean or median rating used as the skeletal age4. This approach is more accurate, but rarely done. More commonly, the bone age is determined by the closest overall match using a generalized approach and is considered normal if the bone age is within two standard deviations (as provided by the Greulich and Pyle atlas) of chronologic age. Because skeletal development provides the only means of assessing rates of maturational change throughout the growth period, it is imperative to determine the degree of skeletal maturity as accurately as possible1.
The two methods of bone age assessment as used in clinical practice do not give equivalent estimates of bone age and Bull et al.10 suggest that one method only should be used when performing serial measurements on an individual patient.
Greulich and Pyle published their data after an analysis of hand radiographs of white upper - class North American children in the 1930s5. Recent reports show that skeletal maturation may vary over time, between ethnic subgroups, or between children in different geographical locations11-14.
Mora et al.12 determined statistically significant difference about skeletal maturity between children of European and African descent in their study. Prepubertal American children of European descent have significantly delayed skeletal maturation when compared with those of African descent. The bone ages of 10% of all prepubertal African descent children were 2 SD above the normative data in the Greulich and Pyle atlas, while the bone ages of 8% of all prepubertal European descent children were 2 SD below. They concluded that the Greulich and Pyle standards imprecise for American children of European and African descent born after 1980.
In a study of Groell et al.9 the differences between chronological age and bone age were within the normal variations of skeletal maturation as reported by Greulich and Pyle. The mean intraobserver and interobserver variations were lower for experienced readers than for radiology residents in their study. They concluded that Greulich and Pyle method may be used for European children confidentally. Also, Van Rijn et al.2 reported that Greulich and Pyle atlas may be used for Holland children.
In our study, there was not statistically significant difference between observers according to knowledge of chronological age. There was an intraobserver concordance in both basal and second interpretations. There was a statistically significant correlation between chronological ages and estimated ages in both basal and second interpretations with and without knowledge of chronological ages. When chronologic age was known, all the observers interpreted radiographs as having normal findings more than when the chronologic age was not known, but this was not statistically significant.
If one wants to increase sensitivity, then observers should not know chronologic age when evaluating bone age. However, if one wants to maximize specificity, knowledge of chronologic age is recommended. Ultimately, the decision of whether to access chronologic age before assessment should depend on the consequences of the diagnosis of normal or abnormal1.
Knowledge of chronologic age does not affect the reliability of bone age assessments. However, observers are more likely to interpret the radiograph as normal when chronologic age is known than when it is not. Therefore, it is important that each radiologist, group, or institution adopt a policy indicating whether each will consistently interpret bone age studies with or without knowledge of the patient’s chronologic age1.
Greulich and Pyle standards is the most common method that preferred for determination of skeletal maturity because it is a basic, rapid and accurate method. As a result, we think that Greulich and Pyle method can be used for determination of Turkish children’s skeletal maturity.
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