Thickness of the Ligamentum Flavum: Correlation with Age and Its Asymmetry-An Magnetic Resonance Imaging Study

Study Design: A retrospective radiological study of the ligamentum flavum (LF). Purpose: This study is an attempt to measure and compare the thickening of the LF on both the sides with the use of magnetic resonance imaging, to investigate if there is a predominant tendency to thicken a specific side and also to determine if a correlation between the thickening of the LF and increasing age exists. Overview of Literature: Even though many studies measured the thickness of the LF, very few have compared it on each side, or determined its correlation with age. Methods: The thickness of LF was measured at the L3-4, L4-5, L5-S1 levels on both sides using the magnetic resonance images of 200 patients (n=1,200). The sample population was divided into three groups: 21-40 years, 41-60 years, and 61-80 years. The data was analyzed statistically, comparing the thickness of LF on both sides and in various age-groups. Results: The thickness of the LF was found to increase with age; however, there were several younger instances with thicknesses >4 mm. The mean thickness of the right LF at different spinal levels was measured (L3-L4=3.38 +/- 0.94 mm, L4-L5=3.70 +/- 1.16 mm, and L5-S1=3.65 +/- 1.16 mm) while the mean thickness of the left LF was higher (L3-L4=3.52 +/- 0.99 mm, L4-L5=3.84 +/- 1.12 mm, and L5-S1=3.78 +/- 1.24 mm). Conclusions: The LF thickness does not appear to have any side dominance; however, it tends to thicken with increasing age.