Thickness of Ligamentum Flavum at Different Levels of Lumbosacral Spine using Magnetic Resonance Imaging at a Tertiary Care Center

Introduction: Low back pain is a common global problem with lumbar stenosis, facet hypertrophy, degenerative changes in disc and thickening of ligamentum flavum being some of the reasons. A clear anatomic description is important to surgeons who frequently enter the spinal canal at this anatomic site and also the thickness of ligamentum flavum is to be carefully measured before surgery in case of suspected spinal canal stenosis. This study aims to study the thickness of ligamentum flavum using Magnetic Resonance Imaging at a tertiary care center. Methods: A descriptive cross-sectional study was conducted in a Department of Radiology of a tertiary care centre during the period from June 2023 to November 2024 after the acceptance of ethical approval. Convenience sampling technique was used to collect imaging data of 385 patients meeting the inclusion criteria. Measurements were taken on the axial T2 weighted images at the level of L3-L4, L4-L5 and L5-S1. Minimum, maximum, mean thickness and standard deviation at various levels of lumbosacral spine was measured using descriptive statistics. Statistical analysis was done with IBM SPSS Statistics version 23. Results: The mean thickness of ligamentum flavum measured was L3-L4: right 1.88 mm ± 0.40, left 1.98 mm ± 0.40, L4-L5: right 2.23 mm ± 0.50, left 2.30 mm ± 0.51 and L5-S1: right 2.33 mm ± 0.53, left 2.39 mm ± 0.53. The ligamentum flavum thickness was found to be greater on the left side. The spinal level with maximum thickness of ligamentum flavum was found at L5-S1 level and then at L4-L5 level. Conclusions: This study concluded that the mean thickness of ligamentum flavum was found to be greater on the left side.