Bone age, or skeletal age, is the maturity of bone at all ages in children and is determined by the degree of calcification of the child’s bones. Bone age can more accurately reflect the level of development at each age from birth to full maturity, and is a good indicator to evaluate the development of children.
The orthopantomograph of the left wrist, metacarpal and finger bones is usually taken to determine the age of the bones, as this area concentrates the long bones, short bones and round bones and can reflect the growth and maturity of the whole body. The number and size of ossification centers, the morphological changes of ossification centers and epiphysis, and the healing of epiphysis and diaphysis are the three main points to determine the degree of bone calcification.
To evaluate the bone age, the most used methods at home and abroad are G-P method (Greulich}Pyle) and TW3 (Tanner-Whitehouse), and the G-P method is mostly used in our clinic. The bone age film of the examined child is compared with the standard chart, and the age that is most similar to the standard chart is the bone age of the examined child. Under normal circumstances, the difference between the bone age and the actual age should be between ±1 year, and being too far behind or too far ahead is considered abnormal.
Bone age can reflect the level of growth and maturity of a child more accurately, so that we can determine the growth potential of the child and the tendency of sexual maturity. Bone age can also be used to predict lifetime height. For example, if two girls of the same age have the same height, but there is a difference in bone age, with one having the same bone age as her age and the other being 2 years ahead of her actual age, the former may reach her genetic height, while the latter’s lifetime height will be impaired, meaning that the latter’s epiphysis will close two years earlier than her actual age, shortening her growth period and eventually failing to reach her genetic height.
It will appear that the parents’ height is very tall while the child’s height is short. Precocious puberty, a common endocrine disorder in clinical practice, is such a condition. The early sexual development of the child accelerates the maturation of the bone, resulting in early bone age and early epiphyseal closure, which impairs height. Therefore, bone age is an important auxiliary test for endocrinologists to diagnose certain endocrine diseases. For example, in cases of hypothyroidism and growth hormone deficiency, bone age may be significantly behind the actual age. Bone age also provides the physician with a basis for evaluating the prognosis during the course of the diagnosis and treatment.