Automated Determination of Bone Age in a Modern Chinese Population

Rationale and Objective. Large studies have previously been performed to set up a Chinese bone age reference, but it has been difficult to compare the maturation of Chinese children with populations elsewhere due to the potential variability between raters in different parts of the world. We re-analysed the radiographs from a large study of normal Chinese children using an automated bone age rating method to establish a Chinese bone age reference, and to compare the tempo of maturation in the Chinese with other populations. Materials and Methods. X-rays from 2883 boys and 3143 girls aged 2–20 years from five Chinese cities, taken in 2005, were evaluated using the BoneXpert automated method. Results. Chinese children reached full maturity at the same age as previously studied Asian children from Los Angeles, but 0.6 years earlier than Caucasian children in Los Angeles. The Greulich-Pyle bone age method was adapted to the Chinese population creating a new bone age scale BX-China05. The standard deviation between BX-China05 and chronologic age was 1.01 years in boys aged 8–14, and 1.08 years in girls aged 7–12. Conclusion. By eliminating rater variability, the automated method provides a reliable and efficient standard for bone age determination in China. 1. Introduction Globalization is not a new trend in auxology. For decades, researchers have compared growth and maturation in populations across the world, exploring racial and regional differences and studying the effects of changes in lifestyle. In particular, there has been a longstanding interest in the differences in tempo of maturation among populations and their secular trend. Such studies have preferentially been performed using bone age (BA) determinations. Unlike secondary sexual characteristics, BA can reveal the entire course of maturation from birth to adulthood. However, bone age rating is associated with considerable operator variability, and it is particularly difficult to ensure consistency between raters from widely separated parts of the world. The emergence of a fully automated and therefore rater-independent BA rating method [1] has the potential to overcome this problem and, thereby, revitalize comparative studies of maturation across the world. We present a reanalysis of a large study of hand radiographs involving modern, normal Chinese children using this automated bone age system. The study could also have considerable impact on clinical practice in China. Due to the one-child policy, parents have a strong focus on growth and development of their child, and currently, there are