The Impact of Cervical Degeneration and Sagittal Balance on Retro-Odontoid Soft-Tissue Thickness.

OBJECTIVE

To investigate whether retro-odontoid soft-tissue thickness (ROSTT) is associated with cervical degeneration, cervical spine mobility, and sagittal balance of cervical spine.

METHODS

The data of 151 patients who presented at our hospital with cervical spondylosis were reviewed. The ROSTT was measured using T1-weighted sagittal cervical magnetic resonance imaging findings. The assessment of the degree of cervical intervertebral disc degeneration (IVDD) was conducted using sagittal T2-weighted imaging. The T1 slope (T1S), C0-C2 angle, C1-C2 angle, C2-C7 angle, C1-C7 sagittal vertical axis and C2-C7 sagittal vertical axis were measured. The range of motion was assessed by measuring the flexion-extension radiographs. According to the ROSTT, those measuring less than 3 mm were classified as normal group and those measuring larger than 3 mm were classified as thickened group.

RESULTS

The thickened group had larger cervical IVDD grade, age, C2-C7 angle, and T1S compared to the normal group (all P < 0.05). Additionally, the C0-C2 angle was significantly smaller in the thickened group than in the normal group (P < 0.05). ROSTT showed a negative correlation with C0-C2 angle (r = -0.181, P < 0.05), but positive correlations with both C2-C7 angle (r = 0.255, P < 0.05) and T1S (r = 0.240, P < 0.05). Furthermore, ROSTT was positively correlated with age (r = 0277, P < 0.05) and cervical IVDD grade (Spearman, r = 0.299, P < 0.05).

CONCLUSIONS

Cervical sagittal balance and cervical degeneration have a significant impact on ROSTT. Patients with a higher T1S and severe cervical degeneration are more likely to result in greater ROSTT.