The three most important uses of bone age in clinical practice are:

1) To assess whether the child is advanced or delayed in maturation

  • The problem with manual rating: Rater variability in the form of random errors and due to variation in the emphasis on the various bones.
  • BoneXpert rating is standardised and objective, and uses modern reference curves to compute bone age SDS (standard deviation scores), which accurately describes the child's bone age relative to healthy children of the same age, sex and ethnicity.

2) To assess increase of bone age between visits

  • The problem with manual rating: Rater variability: The random errors are 0.58 years (SD), Kaplowitz 2011
  • BoneXpert rating is very precise: The random errors are 0.19 years (SD)

3) To perform adult height prediction

  • The problem with the traditional Bayley-Pinneau method: It is based on very old studies and it divides the children too crudely into advanced, normal and delayed bone age
  • BoneXpert uses a more accurate model developed and validated on modern data. It also allows the inclusion of parental height.

BoneXpert bonuses:

  • Assesses Bone Health Index (BHI), and gives BHI-SDS relative to modern healthy children of the same bone age and sex
  • Saves rating time, and can provide the result as soon as the X-ray has been recorded.


The workflow is usually divided into two steps:

First, the X-ray is recorded in the radiology department and the bone age is determined by the PACS Server version - this can be done by the radiographer as soon as the image has been recorded.

Second, the pediatrician brings up the processed image using a suitable PACS image viewer, and reads the bone age value and performs the adult height prediction using the web-based calculator. Optionally the parental height can be used in the prediction.