Bone density is a measure of how much material is in bone per unit volume of bone. Bone density is one of many things that can affect bone strength. In general, bones that are denser are less likely to fracture (break).
What is Low Bone Density?
Low bone density is a condition in which bones are less dense than is normal for age and sex. Low bone density used to be called osteopenia. However, this term is no longer used in children.