166. Can C7 slope be used as a substitute for T1 slope? A radiographic analysis

Sagittal imbalance in the cervical spine is a major cause of neck pain, headache, fatigue, and disability. While parameters such as C2-C7 lordosis and C2-C7 sagittal vertical axis have been extensively studied, they do not fully characterize cervical sagittal balance. T1 is an important new paramete...

Full description

Saved in:
Bibliographic Details
Published inThe spine journal Vol. 19; no. 9; pp. S80 - S81
Main Authors Ye, Ivan B., Tang, Ray, Cheung, Zoe B., Cho, Brian, Erdman, John, Schwartz, John T., Taree, Amir, Warburton, Andrew, Kim, Jun, Cho, Samuel K.
Format Journal Article
LanguageEnglish
Published Elsevier Inc 01.09.2019
Online AccessGet full text

Cover

Loading…
More Information
Summary:Sagittal imbalance in the cervical spine is a major cause of neck pain, headache, fatigue, and disability. While parameters such as C2-C7 lordosis and C2-C7 sagittal vertical axis have been extensively studied, they do not fully characterize cervical sagittal balance. T1 is an important new parameter of both cervical as well as global spinal sagittal balance. However, the T1 superior end plate can be difficult to visualize on standard lateral radiographs due to overlying anatomical structures. C7 slope has therefore been proposed as a potential substitute for T1 slope when the T1 superior end plate is not well visualized. The objectives of this study were: (1) to assess the correlation between C7 slope and T1 slope on upright lateral cervical spine radiographs, and (2) to evaluate the inter-rater reliability of C7 slope. This was a retrospective cohort study of cervical spine radiographs taken between December 2017 and June 2018 at a single institution. Only radiographs with visible C7 superior and inferior end plates, and T1 superior end plate were included. Radiographs with cervical instrumentation were excluded. Two independent observers measured upper C7 slope, lower C7 slope, and T1 slope. The correlations between upper C7 slope and T1 slope, as well as between lower C7 slope and T1 slope were evaluated. Linear regression analyses were also performed. Inter-rater reliability of C7 slope as assessed. A total of 650 radiographs were reviewed. The superior end plate of C7, inferior end plate of C7, and superior end plate of T1 were visible in 72.9%, 50.2%, and 31.2% of these radiographs, respectively. After applying our exclusion criteria, 152 patients remained and were included in our analysis. The average age was 48.1 years, with 70.4% females. The average upper C7 slope, lower C7 slope, and T1 slope was 23.5°±9.1°, 22.9°±9.0°, and 27.5°±8.7°, respectively. There was a strong correlation between upper C7 slope and T1 slope (r=0.91, p<0.001), as well as between lower C7 slope and T1 slope (r=0.90, p<0.001). Linear regression analyses showed that T1 slope could be estimated from C7 slope based on the equation, T1 slope = 0.87 x C7 slope + 7, with an overall model fit of R2=0.8. There was strong inter-rater reliability for upper (ICC=0.95, p<0.001) and lower (ICC=0.96, p<0.001) C7 slope. Both the upper and lower C7 slope are strongly correlated with T1 slope and can be used as a substitute to estimate T1 slope when the superior end plate of T1 is not well visualized. This abstract does not discuss or include any applicable devices or drugs.
ISSN:1529-9430
1878-1632
DOI:10.1016/j.spinee.2019.05.183