Axial plane dissimilarities of two identical Lenke-type 6C scoliosis cases visualized and analyzed by vertebral vectors

Purpose The global appearance of scoliosis in the horizontal plane is not really known. Therefore, the aims of this study were to analyze scoliosis in the horizontal plane using vertebral vectors in two patients classified with the same Lenke group, and to highlight the importance of the information obtained from these vertebral vector-based top-view images in clinical practice. Methods Two identical cases of scoliosis were selected, based on preoperative full-body standing anteroposterior and lateral radiographs obtained by the EOS™ 2D/3D system. Three-dimensional (3D) surface reconstructions of the spinal curves were performed by using sterEOS™ 3D software before and after surgery. In both patients, we also determined the vertebral vectors and horizontal plane coordinates for analyzing the curves mathematically before and after surgery. Results Despite the identical appearance of spinal curves in the frontal and sagittal planes, the horizontal views seemed to be significantly different. The vertebral vectors in the horizontal plane provided different types of parameters regarding scoliosis and the impact of surgical treatment: reducing lateral deviations, achieving harmony of the curves in the sagittal plane, and reducing rotations in the horizontal plane. Conclusions Vertebral vectors allow the evolution of scoliosis curve projections in the horizontal plane before and after surgical treatment, along with representation of the entire spine. The top view in the horizontal plane is essential to completely evaluate the scoliosis curves, because, despite the similar representations in the frontal and sagittal planes, the occurrence of scoliosis in the horizontal plane can be completely different. Graphical abstract These slides can be retrieved under Electronic Supplementary Material.