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

Abstract

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.

Keywords: Cervical sagittal balance; Intervertebral disc degeneration; Rang of motion; Retro-odontoid pseudotumor; Retro-odontoid soft-tissue thickness; T1 slope.