Background Lumbar spinal canal stenosis (LSCS) is a common degenerative spinal condition, and its diagnosis relies significantly on accurate assessment of spinal canal dimensions. Population-specific reference values are essential, especially in diverse regions like India where normative data remain limited. Objective To evaluate the anteroposterior (AP) diameter of the lumbar spinal canal using MRI and identify gender-based differences among patients at a tertiary care hospital in Mandya, India. Methods This was a retrospective study conducted using MRI scans of 54 adult patients (22 males, 32 females) from the hospital’s imaging archives. Measurements of the AP diameter were taken at five lumbar levels (L1-L2 to L5-S1) using T2-weighted axial and sagittal images. Descriptive statistics and independent t-tests were used to analyse the data. Results Significant gender-based differences were observed at the L2-L3 and L3-L4 levels, where females exhibited larger mean AP diameters compared to males (p = 0.003 and p = 0.002, respectively). A marginally significant difference was noted at L4-L5 (p = 0.051). No significant differences were found at L1-L2 or L5-S1. The mean AP diameter at L4-L5 in males (0.90 cm) was below the commonly accepted threshold for stenosis, suggesting a higher risk of LSCS in this subgroup. Conclusion This study highlights important gender-specific anatomical differences in lumbar spinal canal dimensions in the Indian population. These findings underscore the need for localized reference standards to aid in the early diagnosis of LSCS. Further multicentric research with larger sample sizes is recommended to validate these observations.

Lumbar spinal canal, MRI, spinal stenosis, AP diameter, gender differences, Indian population.