Bone Age Study (1)

  A bone age study can help doctors estimate the maturity of a child's skeletal system. It's usually done by taking a single X-ray of the left wrist, hand, and fingers. It is a safe and painless procedure that uses a small amount of radiation. The bones on the X-ray image are compared with X-rays images in a standard atlas of bone development, which is based on data from large numbers of other kids of the same gender and age.
      A child's bones, such as those in the fingers and wrist, contain "growing zones" at both ends called growth plates. These plates consist of special cells responsible for the bones' growth in length. Growth plates are easy to spot on an X-ray because they're softer and contain less mineral, making them appear darker on an X-ray image than the rest of the bone.
      As kids grow, growth plates change in appearance on the X-ray images and become thinner, eventually disappearing (this is what is called "closed growth plates"). Because they look different at each age, a doctor can assign a bone age based on the appearance of the bones and growth plates. A child's bone age (also called the skeletal age) is assigned by determining which of the standard X-ray images in the atlas most closely match the appearance of the child's bones on the X-ray.
      A difference between a child's bone age and his or her chronological age might indicate a growth problem. But such differences don't always mean there's a problem, because perfectly healthy kids can have bone ages that differ from their chronological ages.