Multifidus degeneration correlates with the extent of L4 translation in degenerative lumbar spondylolisthesis.

INTRODUCTION: While the role of paravertebral muscles has increasingly been studied in the pathogenesis and outcome of spinal pathologies, their role in the development of degenerative lumbar spondylolisthesis (DLS) remains poorly understood. Our study's aim was to analyze whether the extent of L4 translation is associated with changes in paraspinal muscle morphology. MATERIAL AND METHODS: We retrospectively included patients treated surgically for degenerative lumbar spondylolisthesis at the L4/5 level, all of whom underwent single-level surgical intervention solely at this segment. Muscle measurements were performed in magnetic resonance imaging (MRI) and included the cross-sectional area (CSA), functional CSA (fCSA), and fatty infiltration (FI) of the multifidus, erector spinae, and psoas muscles. Radiographs were analyzed for the degree of spondylolisthesis according to Meyerding and the extent of L4 translation in mm. Pearson correlation coefficient was determined to assess the relationship between muscle parameters and L4 translation. A multiple linear regression model was performed, with L4 translation as the dependent variable. RESULTS: Ninety-six patients were included, 61 (63.5%) were female. Female patients showed a significantly higher frequency of spondylolisthesis Meyerding grades > 1 (p = 0.018). In the psoas, female patients showed a significantly lower CSA (9.61 ± 3.18 vs. 12.32 ± 3.47, p < 0.001) and fCSA (9.50 ± 3.12 vs. 12.12 ± 3.44, p < 0.001). The multiple linear regression model showed a significant positive association between the multifidus FI and L4 translation (b = 0.084, p = 0.009). CONCLUSIONS: We demonstrate an association between multifidus FI with the degree of L4 translation in DLS. Muscle morphology therefore needs to be taken into consideration in both the conservative and the surgical treatment which may be supported by specific multifidus strengthening.