Three-dimensional spine parameters can differentiate between progressive and nonprogressive patients with AIS at the initial visit: a retrospective analysis.

BACKGROUND

Knowledge concerning morphology of the spine is reported in 2-dimensional (2D) or focuses on modification of parameters with progression of spinal deformation. The objective of this study was to compare 3-dimensional (3D) morphologic parameters of the spine at the first visit between progressive and a nonprogressive group of immature adolescent idiopathic scoliosis (AIS).

METHODS

The first group was made up of surgically corrected AIS patients (E) (n=19), whereas the second group was composed of nonprogressive AIS that had reached skeletal maturity (n=18). Computerized measurements were undertaken on reconstructed 3D spines. There were 5 categories of measurement: Cobb angles (scoliosis, kyphosis, lordosis), 3D wedging (apical vertebra, mean 2 apical disks), rotation (upper and lower junctional vertebra, apical vertebra, and disk), torsion, and slenderness (height/width ratio of T6, L4, and T1-L5). Nonparametric Mann-Whitney tests were also undertaken.

RESULTS

There was no statistical difference between the 2 groups for age, 3D Cobb angle, lordosis, and kyphosis. Mean 3D wedging of the apical disks, lower junctional vertebral axial rotation, torsion and T6, and whole spine height/width ratio were all significantly affected.

CONCLUSIONS

This study supports the theory that wedging begins in the disks and then in the vertebral body and identifies 3D morphologic parameters that could be used in the prediction of AIS evolution. The findings in the junctional area illustrate that a torsional deformity seems to occur distally from the apex and creates a progressive scoliosis. Curve progression could be predicted based on 3D morphometric parameters, as early as the initial visit.