How can bone age be estimated from X-rays of a child's hands and wrists?

Bone age is estimated by using X-rays of a child's hands and wrists to examine the maturation of the epiphyses, which are the growth centers of the bones.1

The process relies on the fact that the appearance of epiphyseal ossification centers and their eventual fusion follow an orderly, predictable sequence as a child develops. By observing the extent of this maturation, clinicians can compare the child's skeletal development against the expected bone age of healthy children of the same chronological age.21

This assessment is a valuable tool for evaluating growth and development, as bone age often deviates from chronological age in children with endocrine or metabolic disorders. For instance, bone age may be delayed in cases of growth hormone deficiency or hypothyroidism, while it may be advanced by conditions such as hyperthyroidism or the excess production of sex steroids.12