Cervical spine balance: postoperative radiologic changes in adult scoliosis surgery

Cervical spine alignment interests appeared recently and relationships between the pelvis and the cervical spine have been reported but remain unclear. In this study, postoperative changes for cranial, cervical, lumbar and sagittal balance parameters have been measured in adult scoliosis surgery without major sagittal malalignment to appreciate the adaptation of the cervical spine.

Twenty-nine consecutive patients with a surgical adult degenerative scoliosis treated with a T8-T11 to iliac fusion without PSO or multiple Ponte's osteotomies had preoperative and postoperative full spine EOS radiographies to measure spino-pelvic parameters. Correlation analysis between the different parameters was performed.

Lower cervical, lordosis, lumbar lordosis and thoracic kyphosis were increased in postoperative as no changes were observed for upper cervical lordosis. C1-C7 CL highly correlated (0.85 in preoperative and 0.87 in postoperative) with C7 slope, which highly correlated itself with global balance parameters (0.74 in preoperative and 0.71 in postoperative for CAM-PL) underlining the relationship between cervical spine alignment and global malalignment.

Modifications of lower CL are observed, as upper CL remains constant. If no correlation was found for LL, TK and CL changes, CL appears to be highly correlated with C7 slope, which highly correlated itself with sagittal global balance parameters. C7 slope appears as a base for CL influenced by the spine global alignment.