1. A 3D Analysis of Scoliosis Progression in Non-Idiopathic Scoliosis: Is it similar to Adolescent Idiopathic Scoliosis? Keith R. Bachmann, MD; Burt Yaszay, MD; Fredrick G. Reighard, MPH; Tracey Bastrom, MA; Carrie E. Bartley, MA; Vidyadhar V. Upasani, MD; Peter O. Newton, MD

2. Introduction
AIS progression is believed to be associated with a relative overgrowth of the anterior spine resulting in progressive hypokyphosis with increasing curve magnitude.
The purpose of this study was to evaluate patients with non-idiopathic scoliosis to determine if a similar 3D relationship exists between the coronal and sagittal planes of deformity.

3. Methods Cohorts Identified
28 patients with neural axis (NA) abnormalities (Chiari 1, syrinx)
20 patients with connective tissue disorder (CTD)(Marfan’s, Beal’s, Ehlers-Danlos syndrome, mixed)
284 AIS patients with a similar range of coronal deformity.

4. Methods
The 3D parameters of the coronal, sagittal and axial planes were compared between the groups
3D sagittal values were obtained by individual segmental measures that were summed in the local sagittal plane of each vertebra.

5. Results
The average Cobb magnitude was similar between all three group (48°, p = 0.4).
The NA patients had a significantly greater 3D thoracic kyphosis (20° vs 10°, p = 0.001) and smaller apical vertebral rotation deformity (-5° vs -12°, p = 0.003) when compared to AIS.
The CTD group’s 3D thoracic kyphosis (p = 0.7) and apical vertebral rotation (p = 0.09) did not significantly differ from AIS.

6. Results
All three cohorts demonstrated decreasing thoracic kyphosis with increasing Cobb angle, all p <
AIS r = -0.49
CTD r =
NA r =

7. Conclusions
Scoliotic patients with neural axis abnormalities have a more kyphotic, less rotated 3D profile compared to AIS patients.
Scoliosis patients with CTD have 3D curve features similar to AIS.

8. Conclusions
All 3 groups demonstrated a similar pattern of thoracic kyphosis reduction with increasing coronal deformity.
Irrespective of the underlying diagnosis, the progression of the scoliotic curve is associated with increasing loss of intersegmental kyphosis, suggesting a similar biomechanical pathophysiology for curve progression.