The link between lumbar subcutaneous edema and soft tissues composition in patients with low back pain: an observational study on MRI

RATIONALE AND OBJECTIVES: The purpose of this study was to evaluate the relationship between lumbar subcutaneous edema (LSE) and parameters on MRI indicative of soft tissue composition. PATIENTS AND METHODS: Ninety-four consecutive patients with low back pain underwent MRI examination of the lumbosacral spine between November 2019 and March 2022. All exams were performed on a 1.5 T magnet. Data were collected regarding the presence or absence of LSE, the thickness of the posterior subcutaneous adipose tissue of the lumbar region, the area of the paravertebral muscles and the psoas muscles and the intramuscular fat. RESULTS: Statistical analysis showed a significant correlation between LSE and age (OR: 1.10; 95% CI: 1.03, 1.20) and BMI (OR: 1.23; 95% IC: 1.01, 1.50). A logarithmic increase in the Paravertebral/fat ratio was associated with a possible protective effect against LSE (OR: 0.37; 95% CI: 0.13, 1.04). The marginal probability analysis showed that an increased risk of edema is detectable in patients over the age of 40 who have a BMI > 25 and a z-score > 0 (for both superficial and deep fat). CONCLUSION: The study showed a statistically significant relationship between LSE and BMI and age. Promising data indicate a possible positive association between LSE and deep and superficial fat and a protective effect of the paravertebral area/fat ratio on LSE. The age of 40 seems to be a critical threshold concerning the relationship between LSE, BMI and superficial or deep fat.