Therefore, we must consider what the final leg length difference will be at maturity. Not all children mature at the same time or rate. For example, a child who is 12 years old may have bones that are as mature as a child who is 15 years old. We would then say the child has a chronological age of 12 years, but a skeletal age of 15 years. It is for this reason that we look primarily at skeletal age of the child when calculating the amount of growth remaining so that we can predict the final leg length difference.
Skeletal age is determined by taking an x-ray of the wrist or the pelvis.
Other factors considered are family history of growth patterns and degree of physical maturity observed on physical exam. Leg length discrepancies are caused by changes in bone growth. Mild amounts of leg length differences frequently go undetected. These differences may be noticed by such things as limping, abnormal rotation of the leg during walking, or unequal shoe wear. Children do not complain about pain in association with leg length differences.