Development of radiographic references for skeletal maturity in Indian children

OBJECTIVES: The Tanner-Whitehouse 3 (TW3) method recognized globally for assessing skeletal maturity are based primarily on Western and East Asian populations, limiting their accuracy when applied to Indian children. The objective of present study was to develop population-specific reference values for Skeletal Maturity Scores (SMS) in Indian children aged 1-18 years using the TW radius-ulna-short bones (RUS-13) system, and to validate these data against the in vogue TW3 system. METHODS: This retrospective study analysed 3,549 left-hand radiographs (1,741 boys; 1,808 girls) from healthy Indian children obtained from previously approved bone age studies conducted between 2021 and 2024. Radiographs were scored using the TW3 RUS-13 method by two trained observers. Age- and sex-specific median SMS values were computed and smoothed using Gaussian curve fitting. The Indian SMS was validated prospectively in 50 children (20 healthy, 30 with endocrine disorders) and retrospectively for adult height prediction by substituting Indian bone ages into TW3 adult height prediction equations. RESULTS: SMS values increased progressively with age, showing earlier skeletal maturation in girls than boys. Indian children reached full skeletal maturity (SMS=1,000) at ∼16.5 years in girls and ∼17.5 years in boys. Comparison with TW2 and TW3 references indicated that Indian maturation patterns lie between these datasets. Validation demonstrated strong agreement between Indian and TW3 bone ages (ICC>0.95) and improved accuracy in adult height prediction using Indian SMS (mean absolute error = -0.1 cm for Indian vs. -0.9 cm for TW3). CONCLUSIONS: This study provides the first comprehensive Indian reference for skeletal maturity assessment. The Indian SMS enhances clinical accuracy for growth evaluation, endocrine diagnosis, and height prediction, supporting region-specific references for pediatric skeletal maturity.