Poster Presentation 50th International Society for the Study of the Lumbar Spine Annual Meeting 2024

INTRODUCTION

The evaluation of patients with low back pain (LBP) often requires repeated magnetic resonance imaging (MRI) examinations of the lumbosacral spine. The specific role of soft tissues, particularly muscles, in LBP remains unclear, and a detailed exploration of each MRI-derived parameter's contribution to LBP intensity is lacking. This study seeks to examine the relationship between soft tissue status, as derived from MRI parameters, and LBP. The focus is on evaluating the individual impact of parameters such as the paravertebral and psoas muscle area, the extent of intramuscular fatty infiltration, and disc degeneration from L1 to S1 on LBP.

METHODS

This retrospective observational study, conducted at a University Hospital, involved 94 patients experiencing LBP due to degenerative disc disease who underwent MRI scans of the lumbosacral spine. Imaging was performed with a 1.5 Tesla scanner. LBP intensity was assessed using the Visual Analogue Scale (VAS). VAS scores were classified as mild, moderate, or severe, with cutoff values of 3.8 and 5.7 based on the literature. Biometric data, encompassing weight and height, were recorded to calculate the body mass index (BMI). The ratios between intramuscular fatty infiltration and net muscle area were computed (Fig. 1).

RESULTS

The stepwise analysis revealed that increasing psoas net area was associated with lower VAS levels [odds ratio (OR): 0.94: 95% confidence interval (CI): 0.90-0.98; p = 0.005], and an increase of one square centimeter of total psoas area resulted in a greater probability of reporting a mild (+1.21%; 95% CI: 0.37, 2.05%) or a moderate VAS (+0.40%; 95 % CI: -0.02, 0.82%), Furthermore, a more severe VAS was associated with a higher BMI (OR: 1.13; 95% CI: 1.00-1.27; Fig. 2).

DISCUSSION

Our research revealed a connection between LBP and the status of paravertebral and psoas muscles as indicated by MRI parameters. The significance of the psoas muscle in spine stabilization is underscored, and its correlation with clinical symptoms in LBP patients is evident. These insights have the potential to inform future studies and enhance treatment strategies for individuals with LBP, with the prospect of mitigating the effects on disability, quality of life, and socio-economic burdens.

Figure 1: Representative image showing the cross-sectional total muscle area of the paravertebral and psoas muscles,  the intramuscular fatty infiltration and the maximum thickness of the posterior subcutaneous adipose tissue.

Figure 2: Marginal effects of total psoas area (one square centimeter increase) (A) and BMI (one point increase) (B) on the probability of mild, moderate, and severe VAS score.