The influence of gravity to the vertebral rotation in AIS patients: a study based on EOS imaging system

English Keywords:Adolescent idiopathic scoliosis  Vertebral rotation  EOS imaging system  Standing position  Supine position

English Abstract:

  【Abstract】 Objectives: To investigate the changes of the vertebral rotation from standing position to supine position of the thoracic adolescent idiopathic scoliosis(T-AIS) patients, by comparing the different vertebral rotation obtained by standing EOS 3D full spine reconstructions and supine CT scans. Methods: Twenty-five female AIS patients with Lenke type 1A and Lenke type 5C curve who underwent posterior spinal fusion surgery in our hospital in May 2017 were included. All patients underwent EOS 3D full spine reconstructions and CT scans. The sterEOS software was used to obtain the apical vertebral rotation, the rotation of the upper and lower end vertebrae and the relative rotation of every vertebral body of patients in standing position. The apical vertebral rotation(AVR) and the relative rotation of every vertebral body were also measured on the CT images scanned in supine position. The difference of the rotation parameters of each axial plane in different positions was compared by the paired sample t test. Results: A total of 15 T-AIS patients and 10 lumbar adolescent idiopathic scoliosis(L-AIS) patients were included in this study. The AVR of the T-AIS was 22.3°±6.4° in standing position, significantly greater than 18.7°±6.1° in supine position, and the average difference was 3.6°. Similarly, the difference of AVR between standing position and supine position in L-AIS patients was statistically significant(28.4°±7.5° vs. 22.6°±7.2°), with an average difference of 5.8°. The end vertebral rotation of T-AIS and L-AIS patients in standing position was also significantly larger than that in supine position. In addition, the changes of the lower end vertebral rotation in T-AIS patients and the upper end vertebral rotation in L-AIS patients were larger. Correlation analysis showed that all vertebral rotation parameters in T-AIS and L-AIS patients had significant correlations in both standing position and supine position. Conclusion: The vertebral rotation in AIS patients is influenced by gravity, all the vertebral rotations were reduced but the relative vertebral rotation of the adjacent vertebrae did not change significantly, when idiopathic scoliosis patients changed from standing position to supine position.