Computed tomography morphometry of the vertebral body, spinal canal, and torg ratio of the sub-axial cervical spine of adult Ugandans

Abstract

Background: Sagittal dimensions of the vertebral body and the spinal canal in the sub-axial cervical spine are key in screening for developmental cervical stenosis and preoperative planning for cervical spine surgery. However, these vary with age, sex, and ethnicity necessitating population-specific baseline values. Objective: To describe the morphometry of the vertebral body, spinal canal, and the Torg ratio of adult Ugandans’ sub-axial cervical spine using computed tomography (CT) scans. Methods: This was a cross-sectional study conducted at Mulago and Nsambya Hospitals. Computed Tomography (CT) scan images of the cervical spine in electronic archives were retrieved from 1st April 2021 to 30th April 2022. Consecutive sampling was done for participants fulfilling eligibility criteria. Mid-sagittal diameter of the vertebral body (Dv) and spinal canal (Ds) were measured from reformatted images and the Torg ratio (TR) was computed by dividing Ds by Dv. Data were collected with a structured data collection tool and analyzed using STATA version 17. Categorical data were compared using Chi-square or Fischer’s exact tests and numerical data using Mann-Whitney U or Kruskal Wallis tests. A p< 0.05 was considered statistically significant. Results: A total of 2110 vertebrae for levels C3 to C7 from CT scan images of 422 individuals, with a median age of 31 (interquartile range: 25-41) years were examined. The average median value for Dv was 15.89 (15.07 — 16.67) mm and was wider among male compared to female participants [16.03 (15.30 — 16.81) versus 15.19 (14.46 — 16.11) mm p<0.001]. The average median Ds was 13.83 (13.10 — 14.60) mm and was wider among male compared to female participants [14.01 (13.29 — 14.74) versus 13.38 (12.85-14.17) mm, p<0.001]. However, TR was similar among both sexes, [male; 0.88 (0.82 — 0.95) versus females; 0.89 (0.82 — 0.97), p=0.460]. Dv increased between C3 and C6 across all decades (p<0.05) except at C7 where it remained stable (p=0.129). The median Ds and TR decreased between C3 and C7 across all decades (p<0.05). Conclusions: The Dv and Ds of Ugandan adults were widest among males while TR was similar in both sexes. These parameters also showed significant variation with age. The measurements from this study are comparable to the rest of the world and can be used in preoperative surgical planning and screening for developmental cervical stenosis