Human lumbosacral root and ligamentum flavum thicknesses: a magnetic resonance study

Background: This study investigated the lumbosacral plexus (LSP) nerve root thickness and ligamentum flavum (LF) thickness and correlated them with age and sex. These findings provided a useful data for spinal nerve root micro-anastomosis surgery and lumbar decompression surgery. Materials and methods: This retrospective study was conducted with 350 individuals with ages ranging from 21 to 80 years under magnetic resonance imaging to evaluate the possible cause of a lower back pain. Results: According to the morphometric measurements of the LSP root thickness, the diameter gradually increased from L1 to S1. L1 has the thinnest root (3.9 ± ± 0.81 mm) while S1 has the thickest root (5.45 ± 0.8 mm). The measurements revealed inconsiderable differences in the LSP thickness in relation to age, sex in the study population. Regarding the LF, the thickness of the LF was found to insignificantly increase with age. Besides, the LF thickness was inconsequentially higher in female. The mean thickness of the right LF at different spinal levels was measured (L2–L3 = 3.19 ± 0.27, L3–L4 = 3.38 ± 0.11 mm, L4–L5 = 3.71 ± ± 0.29 mm, and L5–S1 = 3.64 ± 0.21 mm). The mean thickness of the left LF was non-significantly higher. Conclusions: The LSP root and LF thicknesses not related to age or sex.