Sex Disparity in the Canal-to-Body Ratio of the Cervical Spine Indicating the Prevalence of Cervical Myelopathy: A Cross-Sectional Study

Background A narrow spinal canal and large vertebral body have been thought to be risk factors for cervical myelopathy. It is generally known that males are more likely to develop cervical myelopathy than females. Thus, sex is also a factor that contributes to myelopathy. The anteroposterior (AP) diameter of the cervical spinal canal is well-established as a primary factor of myelopathy. Objective To investigate the sex discrepancy in the canal-to-body ratio of the cervical spine on magnetic resonance imaging (MRI). Materials and Methods This cross-sectional study included 59 males and 59 females, all aged between 20 and 40 years. Morphological parameters, including height, AP diameter of the vertebral body, and AP diameter of the spinal canal, were measured on sagittal T2-weighted MRI cervical spine images for each participant. The canal-to-body ratio, obtained by dividing the spinal canal's AP diameter by the vertebral body's AP diameter, served as a key metric. The average canal-to-body ratio values compared between male and female groups at each spinal level (C3–C7) elucidate potential gender-related differences. Results The height and the AP diameter of the vertebral body were larger in males than in females throughout C3–C7. There was a statistically significant difference between males and females. The AP diameter of the spinal canal was similar for both genders, with no statistically significant difference between them. The mean canal-to-body ratio was significantly larger in females than in males, with a statistically significant difference between males and females at each spinal level. Conclusion Females had a larger canal-to-body ratio, and men had a significantly lower one. The canal-to-body ratio method was thought to be superior to the absolute value of the AP diameter of the spinal canal for the diagnosis of canal stenosis.