The Development of Thoracic Vertebral Sagittal Morphology During Childhood.

STUDY DESIGN: This is a cross-sectional descriptive study objectives to describe normal development of thoracic vertebrae during childhood and document contribution of individual vertebral shape to the sagittal alignment.

SUMMARY OF BACKGROUND DATA: Sagittal spinal alignment changes during growth. The changes in sagittal alignment during adolescent growth spurt as well as the individual shapes of thoracic vertebrae have been implicated as factors for the development of adolescent idiopathic scoliosis (AIS). The contribution of individual vertebral shape to the sagittal alignment and the changes in the vertebral shape with growth is not known.

METHODS: Sagittal computed tomographic (CT) scans of thoracic vertebrae were examined in children without any evidence of spinal deformity. Vertical distances between the endplates at the most anterior and most posterior sides of vertebral body were measured as anterior vertebral height (aVH) and posterior vertebral height (pVH), respectively.

RESULTS: There were a total of 133 CT scans done on 71 male and 62 female children. The children were grouped as follows: Group I (0-2 years of age), Group II (3-6 years of age), Group III (7-9 years of age), Group IV (10-12 years of age), and Group V (13-16 years of age). A-P ratios of vertebral heights were grouped as T1-T5, T6-T8, and T9-T12. Measurements demonstrated that the anterior and posterior heights in each vertebra grew longitudinally and consistently with increasing age. The aVH/pVH ratio of each individual vertebra showed no significant difference according to age. Measurements of thoracic vertebrae on sagittal spinal CT images did not show any differences in the relative growth and heights of the anterior versus posterior walls of the vertebral bodies in any of the segments in any age or age group.

CONCLUSIONS: The sagittal alignment changes during growth are likely related to maintenance of sagittal balance rather than the shapes of individual vertebrae.

LEVEL OF EVIDENCE: Level II.