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, 10 (6), 1132-1140

Analysis of the Relationship Between Ligamentum Flavum Thickening and Lumbar Segmental Instability, Disc Degeneration, and Facet Joint Osteoarthritis in Lumbar Spinal Stenosis


Analysis of the Relationship Between Ligamentum Flavum Thickening and Lumbar Segmental Instability, Disc Degeneration, and Facet Joint Osteoarthritis in Lumbar Spinal Stenosis

Toyomi Yoshiiwa et al. Asian Spine J.


Study design: Cross-sectional study.

Purpose: To investigate the relationship between ligamentum flavum (LF) thickening and lumbar segmental instability and disc degeneration and facet joint osteoarthritis.

Overview of literature: Posterior spinal structures, including LF thickness, play a major role in lumbar spinal canal stenosis pathogenesis. The cause of LF thickening is multifactorial and includes activity level, age, and mechanical stress. LF thickening pathogenesis is unknown.

Methods: We examined 419 patients who underwent computed tomography (CT) myelography and magnetic resonance imaging after complaints of clinical symptoms. To investigate LF hypertrophy, 57 patients whose lumbar vertebra had normal disc heights at L4-5 were selected to exclude LF buckling as a hypertrophy component. LF thickness, disc space widening angulation in flexion, segmental angulation, presence of a vacuum phenomenon, and lumbar lordosis at T12-S1 were investigated. Disc and facet degeneration were also evaluated. Facet joint orientation was measured via an axial CT scan.

Results: The mean LF thickness in all patients was 4.4±1.0 mm at L4-5. There was a significant correlation between LF thickness and disc degeneration; LF thickness significantly increased with severe disc degeneration and facet joint osteoarthritis. There was a tendency toward increased LF thickness in more sagittalized facet joints than in coronalized facet joints. Logistic regression analysis showed that LF thickening was influenced by segmental angulation and facet joint osteoarthritis. Patient age was associated with LF thickening.

Conclusions: LF hypertrophy development was associated with segmental instability and severe disc degeneration, severe facet joint osteoarthritis, and a sagittalized facet joint orientation.

Keywords: Disc degeneration; Facet orientation; Ligamentum flavum thickness; Lumbar spine.

Conflict of interest statement

No potential conflict of interest relevant to this article was reported.


Fig. 1
Fig. 1. Measurement of ligamentum flavum thickness on axial T2-weighted images at the facet joint level.
Fig. 2
Fig. 2. Measurement of the facet angle on an axial computed tomography scan at the facet joint level.
Fig. 3
Fig. 3. The morphology of facet joints was classified into four groups. (A) sagittalized facet indicating a smaller facet angle. (B) Coronalized facet (angle of nearly 90°). (C) C-shaped facet (facet angle of nearly 45°). (D) J-shaped facet (facet angle of nearly 30°).
Fig. 4
Fig. 4. Mean ligamentum flavum (LF) thickness of each grade of disc degeneration. The average thickness of grade II was 3.2±0.1 mm, grade III was 3.9±0.7 mm, and grade IV was 4.8±1.0 mm. LF thickness was greater in grade IV than in grade II (p<0.01) and grade III (p<0.01).
Fig. 5
Fig. 5. Age significantly correlated with disc degeneration (r=0.67, p<0.01) and facet joint osteoarthritis (r=0.56, p<0.01).
Fig. 6
Fig. 6. The average thickness in the four groups. LF, ligamentum flavum.

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