Correlation between multifidus fatty atrophy and lumbar disc degeneration in low back pain

BACKGROUND: Chronic low back pain (LBP) is common and associated with lumbar disc herniation. The purpose of this study was to investigate if the grade of lumbar disc degeneration correlates with the degree of lumbar multifidus muscle (LMM) fatty atrophy. METHODS: A retrospective analysis on 16 males and 19 females with chronic LBP and a mean age of 47.2 years. Using MRI, the grade of lumbar intervertebral discs degeneration was assessed according to the Pfirrmann classification at L4/L5 and L5/S1 levels. Fatty infiltration of the LMM was graded as normal, mild, moderate and severe. Adobe Photoshop CS6 was used for qualitative image analysis by measuring the Cross-sectional area (CSA) of the pure fat component of LMM. RESULTS: There was a low correlation (R = 0.37) and significant association (ANOVA, p = 0.001, 95% CI 2.07–8.14) between the grade of lumbar disc degeneration and the degree of LMM fatty atrophy. Mean value of intervertebral disc degeneration was 2.9 for the L4/L5 level and 3.2 for L5/S1 respectively. The percentage of fat infiltration of the LMM at both studied levels showed a mean value of 22.91+/− 13.19% for L4/L5 and a higher mean value of 26.37+/− 12.89% for L5/S1. There were higher fatty atrophy scores in women and more disc degeneration in men. CONCLUSION: The percentage of LMM atrophy is higher in the lower levels (L5/S1) and shows a low correlation with the grade of disc degeneration.