Reference values for radiological evaluation of cervical vertebral body shape and spinal canal

Background. Defining normal values is essential for reliable evaluation of growth disturbances. Previous studies of the cervical spine have mainly focused on the sagittal canal diameter and interpedicular distances. Values for vertebral body height and depth have been published only in adult men and cadavers. Objectives. To define normal values for vertebral body height (H)/vertebral body depth (D) ratio (H/D ratio) and sagittal canal diameter (S)/ vertebral body depth ratio (S/D ratio) in C2-7. Materials and methods. Lateral cervical spine radiographs were available from 441 children and 192 adults. Subjects' ages varied from newborn to 39 years. Vertebral body height and depth and sagittal canal diameter were measured and ratios were calculated. This was a cross-sectional and retrospective study. Results. Vertebral bodies grow relatively more in height than in depth, most actively at puberty. At all levels, the H/D ratio remains below 1, indicating that vertebral body depth is greater than height. The SD ratio is quite stable until 7-8 years of age and then it starts to decline slowly. Conclusions. When estimating platyspondyly, the age of the patient must be taken into consideration because vertebral body height is lower in children. Growth of the spinal canal declines after 7-8 years of age.