Introduction: Over time, the body, including the spine, undergoes anatomical and morphological changes. Magnetic resonance (MR) imaging is a good modality to analyse degenerative processes by evaluating joint deformity and fat accumulation in bone and muscle. We studied MR images from 22 patients diagnosed with spondylolisthesis at level L4-5 to characterise the factors that cause spondylolisthesis, including disc degeneration, facet joint osteoarthritis, fatty infiltration of the multifidus muscle and thickening of the ligamentum flavum. Materials and Methods: Twenty-two patients with degenerative spondylolisthesis diagnosed by MR imaging were enrolled in this study to characterise the following factors in the degenerative spine at level L4-5: intervertebral disc, facet joint, multifidus muscle and ligamentum flavum. Results: None of the evaluated factors were normal at level L4-5; all had degenerated to various degrees. Twelve discs (54.5%) showed a significant decrease in disc height with a hypointense signal, indicating grade IV. Fifteen cases (68.1%) showed narrowing and irregularity of the facet joint with marked osteophytes, suggesting severe joint osteoarthritis. In 11 cases (50%), fat had already infiltrated the multifidus muscles such that there was an equal amount of fat and muscle tissue, indicating grade III on the Goutallier classification. Thickening of ligamentum flavum was also observed, with maximal thickening of 6.7 mm (right) and 7.1 mm (left). Conclusion: Our study confirms that degeneration of the intervertebral disc, facet joint osteoarthritis, multifidus muscle fatty infiltration and thickening of ligamentum flava are present in patients with spondylolisthesis at level L4-5.

intervertebral disk

degenerative spondylolisthesis

MR Imaging

Facet Joint

Lumbar multifitus

Ligamentum flavum