Impact of paravertebral muscular atrophy in acute work-related low back pain: a retrospective cohort study

This study aims to assess whether paravertebral muscle atrophy, evaluated through MRI, is associated with longer disability periods in patients with acute work-related low back pain (LBP).

This retrospective observational study reviewed cases of adult patients evaluated foracute work-related LBP who underwent lumbar MRI between January 2021 and August 2023. Exclusion criteria included pre-existing spinal disorders, major trauma, systemic conditions affecting recovery, or radicular symptoms. Disability was quantified using total temporary incapacity (TTI), absolute incapacity (AI), and follow-up (FU) durations. Paraspinal muscle morphology was assessed at the L4-L5 level using cross-sectional area (CSA) and fatty infiltration grading with Goutallier, Mercuri, and Kader scales. Associations were tested using t-tests, ANOVA, and chi-square, with significance set at p < 0.05.

A total of 87 patients (77.0% male; mean age, 36.4 ± 14.9 years) were included. The mean TTI was 30.2 ± 21.9 days. No significant associations were found between CSA or most morphological scores and disability duration. Only higher Goutallier scores in the multifidus muscle were weakly associated with longer follow-up (p = 0.037). A modest correlation was observed between psoas CSA and follow-up/TTI duration (p < 0.05).

Paravertebral muscle atrophy, as assessed by MRI, does not appear to significantly influence short-term disability in acute work-related LBP. These findings suggest that muscle morphology plays a minor role in acute LBP recovery, contrasting with its known impact in chronic cases.