title: [Reference values of differences between TW3-C RUS and TW3-C Carpal bone ages of children from five cities of China].
abstract: OBJECTIVE
  The determination of skeletal maturity has an important role in pediatric clinical practice, especially in relation to endocrinological problems and growth disorders, and it is frequently useful in diagnosis and monitoring treatment. It has been suggested that the difference between radius, ulna and short bonse (RUS) and carpal may be of differential diagnostic significance. However, no data on comparison among bone ages of Chinese children are available. The differences between TW3-Chinese RUS (TW3-C RUS) and TW3-Chinese Carpal (TW3-C Carpal) bone age of Chinese children were observed in this study to provide references for skeletal development estimation.
  
  
  METHODS
  Totally 9408 Han healthy children (5066 boys, 4302 girls) aged 1.5 - 13.5 years from 5 cities of China were enrolled in this study. The bone ages of the children were estimated by TW3-C RUS and TW3-C Carpal. The Z score curves of the differences between them were fitted by BCPE distribution and the goodness-of-fit of Box-Cox power exponential distribution (BCPE) models were assessed by Q-test and percents of cases of sample below the fitted percentile curves.
  
  
  RESULTS
  The means of the differences between TW3-C RUS and TW3-C Carpal were -0.19 - 0.17 over the age 2.0 - 13.5 years in boys and -0.12 - 0.13 from age 1.5 - 11.5 years in girls. The standard deviations were respectively 0.47 - 1.01 years for boys and 0.49 - 0.82 years for girls. The degrees of freedom, with respect to the parameter curves from BCPE distribution, were selected and the percentile curves were fitted by BCPE. The differences between percents of cases below the fitted percentile curves and expected values were all under 0.66%, exception of difference for 90th percentile in girls.
  
  
  CONCLUSIONS
  The differences between TW3-C RUS and TW3-C Carpal varied with age, the standard deviations increased gradually before 4.5 years of age in boys and 4 years of age in girls, and afterwards the variations decreased steadily until the TW3-C Carpal has reached full maturity. However, there was sex diversity in the extent of the variations. The differences between TW3-C RUS and TW3-C Carpal for boys were evidently greater than that for girls. The sex difference decreased progressively after 10 years. The proposed Z scores curves charts should provide reference for clinical practice.
authors.affiliation: Hebei Sports Science Research Institute, Shijiazhuang 050011, China.
authors.forename: Shao-yan
authors.initials: SY
authors.lastname: Zhang
authors.forename: Li-juan
authors.initials: LJ
authors.lastname: Liu
authors.forename: Yi-san
authors.initials: YS
authors.lastname: Han
authors.forename: Gang
authors.initials: G
authors.lastname: Liu
authors.forename: Zhen-guo
authors.initials: ZG
authors.lastname: Ma
authors.forename: Xun-zhang
authors.initials: XZ
authors.lastname: Shen
authors.forename: Rui-long
authors.initials: RL
authors.lastname: Xu
authors.forename: Ji-qing
authors.initials: JQ
authors.lastname: Hua
mesh_terms: D000293:Adolescent; D000365:Age Determination by Skeleton / Q000706:statistics & numerical data*; D044466:Asian People; D001846:Bone Development; D002348:Carpal Bones / Q000033:anatomy & histology*; D002648:Child; D002675:Child, Preschool; D002681:China; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D011884:Radius; D012016:Reference Values; D014457:Ulna; D014505:Urban Population