A comparative study of three bone age assessment methods on Chinese preschool-aged children

BACKGROUND: Bone age assessment (BAA) is an essential tool utilized in outpatient pediatric clinics. Three major BAA methods, Greulich–Pyle (GP), Tanner–Whitehouse 3 (TW3), and China 05 RUS–CHN (RUS–CHN), were applied to comprehensively compare bone age (BA) and chronological age (CA) in a Chinese sample of preschool children. This study was designed to determine the most reliable method. METHODS: The BAA sample consisted of 207 females and 183 males aged 3–6 years from the Zhejiang Province in China. The radiographs were estimated according to the GP, TW3, and RUS–CHN methods by two pediatric radiologists. The data was analyzed statistically using boxplots, the Wilcoxon rank test, and Student’s t-test to explore the difference (D) between BA and CA. RESULTS: According to the distributions of D, the boxplots showed that the median D of the TW3 method was close to zero for both male and female subjects. The TW3 and RUS–CHN methods overestimated the age of both genders. The TW3 method had the highest correct classification rate for males but a similar rate for females. The GP method did not show any significant difference between the BA and CA when applied to 3-year-old males and 4-year-old females while the TW3 method showed similar results when applied to 6-year-old females. The RUS–CHN method showed the least consistent results among the three methods. CONCLUSION: The TW3 method was superior to the GP and RUS–CHN methods but not reliable on its own. It should be noted that a precise age diagnosis for preschool children cannot be easily made if only one of the methods is utilized. Therefore, it is advantageous to combine multiple methods when assessing bone age.