Purpose: The purpose of this study is to determine the accuracy of biplanar radiography in calculating vertebral axial rotation in patients with adolescent idiopathic scoliosis (AIS).
Methods: A single-center retrospective review of patients with AIS who received a preoperative CT and biplanar imaging (EOS imaging, Paris, France) was performed. Axial rotation of each vertebra was assessed by EOS and by true axial CT images. The relative vertebral rotation difference (VRD) of each vertebra in relation to the apex was calculated to standardize the reference plane. Paired testing and correlations were used to compare the VRD between the two imaging modalities.
Results: 32 patients were reviewed. The average major curve cobb was 66° ± 10°. There was no significant difference between modalities on paired analysis except at T3, T4, T5, and T6 (p = 0.03; p = 0.01; p = 0.02; p = 0.01). Despite these differences, there were moderate to strong correlations between both modalities at every level.
Conclusion: Despite minor differences in VRD in the proximal thoracic spine, our findings suggest that axial rotation measured by EOS is an accurate representation of rotational deformity in the uninstrumented AIS spine.
Keywords: 3D reconstruction; Adolescent idiopathic scoliosis; Axial rotation; Biplanar radiography; Computed tomography; EOS imaging.
© 2026. The Author(s), under exclusive licence to Scoliosis Research Society.