The maturity of a child's skeletal system might be estimated by using a bone age study. It consists of taking a single X-ray of the left wrist, hand, and fingers. It is a painless procedure that exposes the individual to a very small amount of radiation. Afterward, the image is compared to standard images from a bone development atlas created from studies on a large number of kids. Bone age is measured in years.

The growth of bones is possible thanks to a particular area within two ends of long bones – the growth plate. This is a hyaline cartilage plate, which consists of actively growing cells. These plates can be found in children's bones, and in adolescents, they turn into an epiphysial line (a residue of the growth plate). This replacement is called epiphysial closure or growth plate fusion. The fusions are complete in ages 12-16 for girls and 14-19 for boys.

Growth plates are easy to identify on an X-ray because they are softer and contain less mineral content than standard bone. That makes them appear darker than the rest of the skeleton on the X-ray image. They look different at each age – thanks to that, a doctor can determine bone maturity by simply reviewing its appearance. Then, the image is compared with the closest matching image from an atlas.

Observing the difference between a child's bone age and chronological age may point to a growth problem, but it is not the rule. Some kids with perfect health can have a disparity in skeletal and chronological age.

The control of bone age is done to assess the tempo of the maturing process of a child's skeleton. This allows doctors to diagnose conditions that delay or accelerate physical growth. Using the skeletal age, physicians may predict the following:

The study is also used to monitor the treatment process of kids with growth deficiencies. There are plenty of factors that may affect growth: