The Reliability of Using Greulich-Pyle Method to Determine Children's ...

Child bone age determination in Taiwan

ORIGINAL ARTICLE

The Reliability of Using Greulich-Pyle Method to Determine Children's Bone Age in Taiwan 1

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Kuo-Hsien Chiang , Andy Shau-Bin Chou , Pao-Sheng Yen , Chang-Ming Ling , Chao-Chun Lin , 1 1 Chau-Chin Lee , Pau-Yang Chang 1

Department of Radiology , Buddhist Tzu Chi General Hospital, Hualien, Taiwan; College of Medicine and Graduate Institute of Clinical Medical Research2, Chang Gung University, Taoyuan, Taiwan

ABSTRACT Objective: The Greulich-Pyle Atlas of skeletal maturation has been prepared using data from children born between 1917 and 1942 in the USA, and is frequently used for assessment of skeletal maturity. In this study, we investigated whether or not the GreulichPyle method is sufficient for the determination of the skeletal age of children in Taiwan. Materials and Methods: Plain radiographs of the left hand and wrist were obtained from 478 children who came to the emergency department or orthpedic outpatient department because of suspected trauma. The study group consisted of 370 children (140 girls, 230 boys), with a mean age of 10.31 years. These radiographs were analysed by two radiologists who were unaware of the age of the children. Results: Mean skeletal ages were delayed by approximately 0.22 to 1.86 years compared to the mean chronological ages in boys aged 2 to 12 years and advanced by 0.13 to 1.28 months in boys aged 13 to 18 years. Mean skeletal ages were delayed by approximately 0.19 to 0.84 months compared to the mean chronological ages in girls aged 2 to 8 years and advanced by 0.18 to 1.48 months in girls aged 9 to 17 years. Conclusions: Our results show a retardation of bone age before puberty followed by an increase at puberty, resulting in advancement by the end of puberty. Also, there is a discrepancy of more than one year between the chronological age and the measured bone age in some age groups. We believe that some modification of the Greulich-Pyle Atlas is necessary to enhance our ability to determine skeletal maturation with accuracy, reliability and consistency. (Tzu Chi Med J 2005; 17:417-420) Key words: bone age, Greulich-Pyle method, radiography

INTRODUCTION Bone age determination is usually performed by comparing the plain left-hand radiograph of a patient with findings in a normal reference population. The Greulich-Pyle (GP) standards are the most commonly used method for bone age assessments throughout the world [1]. However, it was compiled solely from data from Caucasians who lived in the 1930s. There is evidence that skeletal maturation may vary between different ethnic and socioeconomic groups of children or

among children living in various geographical locations [2-6]. In this study, we investigated to what extent the GP method is adequate for determining the skeletal maturity of children in Taiwan.

MATERIALS AND METHODS Plain radiographs of the left hand were obtained from 478 children who came to the emergency department or orthopedic outpatient clinic because of suspected trauma. These radiographs were taken using the same

Received: June 1, 2005, Revised: July 11, 2005, Accepted: November 15, 2005 Address reprint requests and correspondence to: Dr. Pau-Yang Chang, Department of Radiology, Buddhist Tzu Chi General Hospital, 707, Section 3, Chung Yang Road, Hualien, Taiwan

Tzu Chi Med J 2005 17 No. 6

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We found no statistically significant difference in the interpretation of bone age between the two radiologists. Paired t test of the boys group and the girls group yielded a p value of 0.4562 and 0.4879. The computed correlation coefficients of the two groups between the two radiologists were both 0.997 (Fig. 1,2). Mean chronological and bone ages of children according to age groups are given in Tables 1 and 2. Mean skeletal ages were delayed by 0.22 to 1.86 years when compared to mean chronological ages in boys aged 2 to 12 years and advanced by 0.13 to 1.28 months in boys aged 13 to 18 years (Fig. 3). Mean skeletal ages were delayed by approximately 0.19 to 0.84 months when compared to mean chronological ages in girls aged 2 to 8 years and advanced by 0.18 to 1.48 months in girls aged 9 to 17 years (Fig. 4).

DISCUSSION In the determination of physical development, skeletal maturity has proved to be a graded and accurate indicator. Bone age is a frequently used diagnostic tool for the evaluation of endocrine, orthopedic, genetic and renal disorders. It is also used to monitor response to medical therapy and to determine the growth potential of children. The method most widely used for bone age determination is the reference atlas of Greulich and Pyle,

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Fig. 1.

Graph showing interobserver agreement when estimating bone age of boys using the Greulich and Pyle standard.

Bone age of girls estimated by radiologist 1 (months)

RESULTS

Bone age of boys estimated by radiologist 2 (months)

Bone age of girls estimated by radiologist 2 (months)

Fig. 2.

Graph showing interobserver agreement when estimating bone age of girls using the Greulich and Pyle standard.

Difference (year)

projection and exposure parameters as for the primary assessment of bone age. Subjects included in this study fulfilled the following criteria: (1) normal findings on the radiograph of the left hand with neither bone (including fracture) nor soft tissue abnormalities; (2) no medical record of congenital disorder or developmental disturbances. Bone ages were rated using the GP Atlas by two radiologists separately, without any knowledge of the children's chronological ages. When the appearance lay between two standards, a bone age between these was given. If the interobserver variation was more than 12 month, the radiographs were excluded. One hundred and eight cases are excluded: 58 cases due to poor film quality, 40 cases due to interobserver difference, and the others due to microcephaly, developmental delay, polydactyly, seizure and facial tumor. The study group consisted of 370 children (140 girls, 230 boys), ranging in age from 10 days to 17.9 years, with a mean age of 10.31 years.

Bone age of boys estimated by radiologist 1 (months)

K. H. Chiang, A. S. B. Chou, P. S. Yen, et al

Age group (year)

Fig. 3.

Mean differences in years for the deviation between chronological ages for boys. Mean skeletal ages were delayed by 0.22 to 1.86 years when compared to the mean chronological ages in boys aged 2 to 12 years and advanced by 0.13 to 1.28 months in boys aged 13 to 18 years.


Child bone age determination in Taiwan

consisting of radiological examinations of the left hand and wrist of subjects at different stages of skeletal maturation [1]. Another widely used method is the Tanner and Whitehouse score [2]. However, it appears to be

Table 1.

more time-consuming. Many reports show that skeletal maturation may vary over time, between ethnic groups and between children in different geographical locations [3-7]. The ref-

Mean Chronological and Bone Ages of Boys According to Age Group

Age groups (year)

N

0-0.9 1-1.9 2-2.9 3-3.9 4-4.9 5-5.9 6-6.9 7-7.9 8-8.9 9-9.9 10-10.9 11-11.9 12-12.9 13-13.9 14-14.9 15-15.9 16-16.9 17-17.9

9 13 10 8 6 12 9 6 7 9 9 7 18 20 17 18 24 28

chronological ages (year) Mean ± SD 0.40 ± 0.25 1.43 ± 0.25 2.41 ± 0.32 3.45 ± 0.30 4.45 ± 0.27 5.42 ± 0.21 6.44 ± 0.28 7.44 ± 0.37 8.59 ± 2.57 9.40 ± 0.23 10.41 ± 0.24 11.39 ± 0.36 12.57 ± 0.23 13.51 ± 0.29 14.53 ± 0.27 15.59 ± 0.29 16.50 ± 0.27 17.50 ± 0.27

skeletal ages (year) Mean ± SD 0.31 ± 0.34 1.54 ± 0.67 2.19 ± 0.41 2.63 ± 0.68 3.10 ± 0.75 4.59 ± 1.16 4.97 ± 1.48 5.58 ± 1.26 7.10 ± 1.31 8.44 ± 1.51 8.80 ± 1.25 10.55 ± 2.41 13.20 ± 1.26 13.97 ± 2.27 14.66 ± 3.86 16.87 ± 1.15 17.32 ± 0.75 17.71 ± 0.62

Difference (year) Mean ± SD 0.09 ± 0.21 -0.11 ± 0.65 0.22 ± 0.47 0.83 ± 0.80 1.35 ± 1.00 0.83 ± 1.26 1.47 ± 1.62 1.86 ± 1.29 1.48 ± 1.16 0.95 ± 1.43 1.61 ± 1.19 0.84 ± 2.35 -0.63 ± 1.24 -0.46 ± 2.21 -0.13 ± 3.92 -1.28 ± 1.20 -0.82 ± 0.73 -0.22 ± 0.59

Z

P value

-1.24 -0.59 -1.48 -2.10 -2.20 -1.88 -2.19 -2.20 -2.03 -1.72 -2.31 -0.68 -2.68 -1.98 -2.68 -2.85 -3.60 -2.08

0.214 0.552 0.139 0.036 * 0.028 * 0.06 0.028 * 0.028 * 0.043 * 0.086 0.021 * 0.499 0.007 * 0.048 * 0.007 * 0.004 * < 0.001 * 0.037 *

Z

P value

-0.11 -1.78 -2.20 -1.18 -1.86 -1.60 -1.10 -1.12 -1.60 -0.52 -0.94 -1.01 -1.75 -2.67 -2.76 -2.82 -2.13 -0.14

0.917 0.075 0.028 * 0.237 0.063 0.11 0.273 0.263 0.109 0.60 0.345 0.31 0.08 0.008 * 0.006 * 0.005 * 0.033 0.893

* : p < 0.05 statistical significance

Table 2.

Mean Chronological and Bone Ages of Girls According to Age Group

Age groups (year)

N

0-0.9 1-1.9 2-2.9 3-3.9 4-4.9 5-5.9 6-6.9 7-7.9 8-8.9 9-9.9 10-10.9 11-11.9 12-12.9 13-13.9 14-14.9 15-15.9 16-16.9 17-17.9

6 13 7 7 7 9 4 8 3 6 5 7 5 12 13 12 11 5

chronological ages (year) Mean ± SD 0.47 ± 0.26 1.53 ± 0.25 2.55 ± 0.28 3.45 ± 0.27 4.45 ± 0.31 5.43 ± 0.32 6.64 ± 0.39 7.39 ± 0.25 8.44 ± 0.44 9.46 ± 0.30 10.72 ± 0.17 11.68 ± 0.32 12.45 ± 0.24 13.43 ± 0.29 14.50 ± 0.28 15.46 ± 0.32 16.50 ± 0.29 17.77 ± 0.14

skeletal ages (year) Mean ± SD 0.52 ± 0.48 1.66 ± 0.42 2.07 ± 0.51 3.24 ± 0.66 3.84 ± 0.67 4.77 ± 1.27 6.45 ± 0.73 6.91 ± 0.75 7.60 ± 0.70 9.63 ± 1.00 11.25 ± 0.79 12.14 ± 1.38 13.55 ± 0.89 14.85 ± 1.49 15.81 ± 1.11 16.94 ± 1.22 17.36 ± 1.03 17.70 ± 0.41

Difference (year) Mean ± SD -0.05 ± 0.30 -0.13 ± 0.37 0.48 ± 0.33 0.21 ± 0.42 0.61 ± 0.64 0.66 ± 1.15 0.19 ± 0.47 0.47 ± 0.77 0.84 ± 0.64 -0.18 ± 0.96 -0.53 ± 0.90 -0.46 ± 1.18 -1.10 ± 1.00 -1.42 ± 1.38 -1.30 ± 1.08 -1.48 ± 1.01 -0.87 ± 1.07 0.07 ± 0.47

* : p < 0.05 statistical significance


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K. H. Chiang, A. S. B. Chou, P. S. Yen, et al

Difference (year)

CONCLUSION

Age group (year)

Fig. 4.

Mean differences in years for the deviation between chronological ages for girls. Mean skeletal ages were delayed by approximately 0.19 to 0.84 months when compared to the mean chronological ages in girls aged 2 to 8 years and advanced by 0.18 to 1.48 months in girls aged 9 to 17 years.

erence population, which formed the basis of the atlas of Greulich and Pyle, consisted of white upper-class North American children in the 1930s. Due to variations between populations, a match between skeletal and chronological age can be expected only if the population examined does not deviate from the population on which the scoring system was standardized. In an attempt to overcome ethnic and racial differences in skeletal maturations, standards have been developed for the German, Scandinavian and Japanese populations [6-9]. Our radiographs were obtained from children who came to the emergency department or orthopedic outpatient department because of suspected trauma. Socioeconomic status was not controlled in this study. However, with the increased realization (in the mid1950s) that medically unnecessary radiation should be avoided, serial roentgen examinations of study populations were discontinued and later studies of skeletal maturation have become cross-sectional. We excluded patients with congenital disorders or developmental disturbances noted in their medical records, to minimize their influence on our results. Further, the children enrolled in this study were mostly from the Hualien county, where many aborigines live. Theoretically, differences between our results and the standards of Greulich and Pyle could in part be due to the effects of ethnic differences. A larger population is necessary for establishing a bone age atlas for children in Taiwan.

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Our results show a retardation of bone age before puberty followed by an increase at puberty, resulting in advancement by the end of puberty. There is a discrepancy of more than one year between the chronological age and the measured bone age in some age groups. We believe that some modification of the GP Atlas is necessary to enhance our ability to determine skeletal maturation with accuracy, reliability and consistency.

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