Construction of a Statistical Cervical Vertebrae Geometric Model for Children 3-10 Years Old

Cervical spinal injuries of children in motor vehicle crashes have high morbidity and mortality rates. Cervical vertebrae change rapidly in both size and shape during growth. To accurately assess the risk of spinal injury for children of different ages, it is necessary to understand how the spatial geometric features of vertebrae change with the child's age and neck size. In this study, an innovative semi-automated method was developed that can extract and align geometric points from computed tomography scans to accurately represent complex three-dimensional vertebral geometry. Based on these spatial geometric points, a statistical cervical vertebrae geometry model for children aged 3-10 YO was established based on principal component analysis and multivariate regression. According to this model, the vertebra spatial geometries for children of different ages and neck circumferences were represented, and its variation with age were accounted for. Statistical results show that age has a significant effect on anterior-posterior length (APL), transverse process width (TPW), vertebral body circumference (VBC) and height (VBH), whereas the significance of location and its interaction with age effects on these four parameters are different. The VBC and VBH increase more rapidly with age than the APL and TPW. In addition, the APL of C6 and C7 increase significantly faster than that of C3. As for the shape changes with child growth, the inclination angle of the upper surface of the lateral mass for C1 and the tilt angle of the articular process of the articular facet joint for C3-7 increase; and the shape of odontoid process of C2 becomes higher and steeper. This study can provide geometric basis for developing multiple pediatric cervical finite element models and anthropomorphic test devices to further quantify child neck injury risk with different ages and neck geometries.