Average Models and 3-dimensional Growth Patterns of the Healthy Infant Cranium

Treatment of cranial deformity is often performed during infancy in cases such as craniosynostosis and deformational plagiocephaly. To acquire morphologic standards for the treatment goals of these conditions, we created cranial average models and elucidated the growth patterns of the cranium of healthy infants in 3-dimension (3D) using homologous modeling. METHODS: Homologous modeling is a technique that enables mathematical analysis of different 3D objects by converting the objects into homologous models that share the same number of vertices with the same spatial relationships. Craniofacial computed tomographic data of 120 healthy infants ranging in age from 1 to 17 months were collected. Based on the computed tomographic data, we created 120 homologous models. Six average 3D models (20 individuals each for 6 different age groups) were created by averaging the vertices of the models. Three-dimensional growth patterns of the cranium were clarified by comparing the 6 average models. RESULTS: We successfully created 6 average models and visualized the growth patterns of the cranium. From 1-month-old to 5-month-old infants, the entire cranium except for the occipital region grows, and the cranium tended to be brachycephalic (cephalic index at 4–5 months: 87.1–97.3), but the growth was thereafter localized to specific areas. CONCLUSIONS: Three-dimensional growth patterns of the cranium of healthy infants were clarified. These findings will support the understanding and treatment of the conditions that cause cranial deformity. To our knowledge, this is the first report to visualize the growth patterns of the entire cranium of healthy infants in 3D.