Changes in rib cage geometry during childhood.

Age related changes in rib cage geometry were found from measurements made on chest radiographs from 38 individuals aged from 1 month to 31 years and on computed tomography (CT) scans in another 28 individuals, aged from 3 months to 18 years. Chest radiographs were taken for minor respiratory symptoms or fever and only films showing no abnormality were used. CT scans were obtained in children undergoing staging for solid tumours in whom no intrathoracic deposits were found. In infants and very young children the ribs were found to be more horizontal and the sternal clavicular heads and diaphragmatic domes higher than in older children and young adults. Most of these changes were observed in the first two years of life, with something close to the adult pattern by the age of 2 years. Similarly cross sectional chest shape changed from the rounded infantile form to the more ovoid adult form by the same age. The configuration of the ribs observed in infancy and early childhood reduces the potential for thoracic expansion and may contribute to the frequency of respiratory problems found in the very young.