Risk Factors of Multifidus Muscle Fat Infiltration in Patients with Single-segment (L4-5) Degenerative Lumbar Spinal Stenosis：A retrospective cohort study

Study design: A retrospective cohort study Objective :To investigate the risk factors for multifidus muscle (MF) fat infiltration in patients with L4-5 degenerative lumbar spinal stenosis (DLSS). Methods :A total of 118 surgical patients diagnosed with single-segment (L4-5) DLSS between January 2019 and February 2023 were retrospectively enrolled. MF fat infiltration at the L4-5 level was evaluated on T2-weighted MRI using the Kjaer scale. Facet joint degeneration (Grade 0–3) was assessed using the Weishaupt classification on CT, and spinal canal stenosis severity (Grade 1–3) was rated with the Lee classification on MRI. Univariate and multivariate ordinal logistic regression analyses were performed to identify risk factors. Results :The patients had a mean age of 61.43±8.63 years, with 66.95% being female. Multivariate analysis showed that female gender (P<0.001, OR = 5.00, 95% CI: 2.03 ~ 12.32), older age (P=0.003, OR = 1.08, 95% CI: 1.03 ~ 1.14), L4 spondylolisthesis (P=0.034, OR = 2.75, 95% CI: 1.08 ~ 7.01), severe facet joint degeneration (P=0.040, OR = 6.60, 95% CI: 1.09-39.78), and severe spinal canal stenosis (P=0.001, OR = 5.90, 95% CI: 1.99 ~ 17.48) were independent risk factors for aggravated MF fat infiltration. Conclusion :In patients with single-segment (L4-5) DLSS, female gender, older age, degenerative spondylolisthesis, severe facet joint degeneration, and severe spinal canal stenosis are independent risk factors for aggravated MF fat infiltration, with severe spinal canal stenosis exhibiting the strongest risk effect.