Progression of vertebral and spinal three-dimensional deformities in adolescent idiopathic scoliosis: a longitudinal study.

STUDY
DESIGN: The evolution of scoliotic descriptors was analyzed from three-dimensionally reconstructed spines and assessed statistically in a group of adolescents with progressive idiopathic scoliosis.
OBJECTIVES: To conduct an intrasubject longitudinal study quantifying evolution of two- and three-dimensional geometrical descriptors characterizing the scoliotic spine and vertebral deformities. SUMMARY OF BACKGROUND DATA: The data available on geometric descriptors usually are based on cross-sectional studies comparing scoliotic configurations of different individuals. The literature reports very few longitudinal studies that evaluated different phases of scoliotic progression in the same patients.
METHODS: The evolution of regional and local descriptors between two scoliotic visits was analyzed in 28 adolescents with scoliosis. Several statistical analyses were performed to determine how spinal curvatures and vertebral deformities change during scoliosis progression.
RESULTS: At the thoracic level, vertebral wedging increases with curve severity in a relatively consistent pattern for most patients with scoliosis. Axial rotation mainly increases toward curve convexity with scoliosis severity, worsening the progression of vertebral body deformities. No consistent evolution is associated with the angular orientation of the maximum wedging. Thoracic kyphosis varies considerably among subjects. Both increasing and decreasing kyphosis are observed in nonnegligible proportions. A decrease in kyphosis is associated with a shift in the plane of maximum deformity toward the frontal plane, which worsens the three-dimensional shape of the spine.
CONCLUSIONS: The results of this study challenge the existence of a typical scoliotic evolution pattern and suggest that scoliotic evolution is quite variable and patient specific.