Bone Development In Children

ln children, the most unique feature of bone development is the growth plate or physis which contributes to the longitudinal growth of the bone. The physis and its adjacent area called the metaphysis is the most active part of the growing bone in children. physiological and biochemical interactions take place mainly in the metaphysis and physis and contribute to the development of bones. Any disorders in these areas can impact bone development.

Metabolic Bone Disorders

These are a group of conditions where there is a disturbance in the biochemical composition of the bone, thus affecting its.integrity and strength. Deficiency of bone vitamins (vitamin D3), calcium insufficiency and hormonal disturbances during childhood affect the mineral part of bone composition. Tissue disturbances (collagen framework) are seen in osteogenesis imperfecta or fragile bone disease, fibrous dysplasia and other collagen disorders also affect bone development.

ln osteogenesis imperfecta or fragile bones, the tissue matrix is weaker and less durable, resulting in collapse or breakage of the bone under trivial stress. Children born with these disorders are rarely diagnosed and often treated only for a fracture rather than the underlying disorder.

The causative mechanism for this disorder in unknown but there are different varieties of fragile bone diseases. The disorder can also affect two or more members of the same family. Some children have a mild disease and it is hard to distinguish this from a normal fracture. Others may present with fractures about three_four times a year and the incidence of fractures decreases towards adolescence.

Osteogenesis Imperfecta (fragile bones)

Although osteogenesis imperfecta has been around for centuries, it is only in the last two decades that knowledge about it has increased sufficiently to be able to use both medical and surgical therapy for this rare yet debilitating condition.

Vitamin D3 Deficiency

The most common metabolic disorder seen in children is vitamin D3 deficiency which impacts bone and muscle development. There are several types of rickets, but most children are afflicted by the nutritional type wherein either poor intake or poor absorption of vitamin D3 occurs. ln severe cases, bone development is delayed and children exhibit deformities in the lower limb like bow legs or knock knees. Even lack of parathyroid hormone and thyroid hormones can cause faulty bone development  but there is preponderance of other symptoms causing a delay in diagnosis.

Skeletal Dysplasia Or Congenital Disorders

These cause particular type of developmental defects in the bone leading to short stature, deformities of limb and spine and visceral manifestations. Thus, normal bone development is regulated by inherent growth factors and external forces on the body. Any pathology that interferes with this delicate interplay will lead to developmental disorders in the bones.