Characteristics of cervical sagittal parameters in healthy cervical spine adults and patients with cervical disc degeneration

BACKGROUND The cervical sagittal parameters of the normal population and the impact of disc degeneration on cervical sagittal alignment have not been clearly defined yet. This study is applied to investigate the characteristics and relationships of cervical sagittal parameters in normal adults and patients with cervical disc degeneration. METHODS We reviewed 50 normal control subjects (normal group, NG) and 50 patients with cervical disc degeneration (degeneration group, DG), who had both cervical MRI and radiographs obtained together, between January 2010 and September 2015. Data including C2-7 lordosis (CL), T1 slope (T1S), thoracic inlet angle (TIA), neck tilt (NT), C2-7 sagittal vertical axis (C2-7 SVA), cervical tilting, and cranial tilting on cervical radiographs were collected and analyzed. RESULTS T1S in the NG was significantly greater than in the DG (P < 0.05), while NT and C2-7 SVA in the NG were significantly lower than in the DG (P < 0.01 and P < 0.05, respectively). T1S positively correlated with CL in both groups (Pearson correlation coefficients of 0.588 in the NG and 0.504 in the DG). No significant difference was seen in TIA between the NG and DG. CONCLUSIONS T1S was involved in the occurrence and development of cervical disc degeneration, and TIA could be considered as a constant morphological parameter in both the normal population and cervical disc degeneration patients.