The bones are composed of hard, mineralized material held together by the tough, elastic protein collagen. Abnormalities in the production, metabolism or structure of either of these components can lead to infant bone diseases, often characterized by deformities and fractures. Infant bone diseases can be inherited or acquired and vary in severity from asymptomatic to life threatening.
Osteogenesis Imperfecta
Osteogenesis imperfecta is a group of inherited diseases that lead to brittle bones, easy fractures and other abnormalities. The defective genes associated with osteogenesis imperfecta lead to decreased or defective bone collagen. Eight types of osteogenesis imperfecta can occur, designated I through VIII. Each type involves a different genetic mutation and disease characteristics.
Type I osteogenesis imperfecta accounts for approximately 50 percent of cases of the disorder, reports the Osteogenesis Imperfecta Foundation. Decreased production of bone collagen causes fragility and easy fractures, which most commonly occur in the long bones of the arms and legs and in the spine bones. Children with type I osteogenesis imperfecta often exhibit hearing loss and a bluish tint of the whites of the eyes. Children with type I osteogenesis imperfecta generally do not have significant bone deformities.
Type II osteogenesis imperfecta is the most severe form of the disorder. Abnormal development of the bones while in the womb leads to skeletal deformities, including an abnormally small ribcage and short, misshapen arms and legs. Bone fractures commonly occur before birth. Underdevelopment of the lungs, severe breathing problems and swallowing difficulties typically manifest at birth. Babies with type II osteogenesis imperfecta often die of complications within a few weeks to months of life, according to the American Academy of Orthopaedic Surgeons.
Enchondromatosis
Enchondromatosis, also known as Ollier's disease, involves the development of noncancerous cartilage tumors in the bones, causing deformities and bone fragility. The disorder occurs in approximately one in 100,000 births, report Drs. Caroline Silve and Harald Juppner in an article on enchondromatosis posted by OrphaNet. Tumors often arise in the bones of the fingers, hands, arms, legs and pelvis, and characteristically cluster on one side of the body. The first tumors typically arise in infancy to early childhood. Enchondromas often cause discrepant limb growth in which the affected arm or leg remains significantly shorter than the opposite limb.
Osteopenia of Prematurity
Babies born prematurely often have inadequate calcium and phosphorus in the bones, leading to bone fragility. This condition, known as osteopenia of prematurity, occurs because the baby has not had the full advantage of the normal process of bone mineralization, which occurs in the last three months of pregnancy, notes the University of Maryland Medical Center. Accidental bone fractures can occur in babies with severe osteopenia of prematurity, also known as neonatal rickets. With calcium, phosphorus and vitamin D supplementation, the bones typically gain a normal level of mineralization and strength.
