Assessing the Correlation Between the Lumbar Disc Herniation Degree and Multifidus Muscle Fatty Degeneration in Chronic Low Back Pain.

Background: Chronic low back pain (LBP) is a common condition primarily associated with lumbar disc herniation. Fatty degeneration of the multifidus muscle is also observed in the majority (>80%) of patients with LBP.

Methods: This retrospective study included 140 patients (72 females and 68 males) with chronic LBP. 3T lumbar magnetic resonance imaging (MRI) T1- and T2-weighted fast spin-echo sequences were used for radiological evaluation. Disc herniations were graded according to the degree of bulging, protrusion, extrusion, and sequestration. Multifidus fatty infiltration was semiquantitatively graded from grade 1 (normal) to grade 4 (severe).

Results: Multifidus fatty degeneration was more common in females compared to males at the L4-L5 and L5-S1 levels (p-values <000.1 and <000.1, respectively). There was no correlation between disc herniation at the L4-L5 and L5-S1 levels and fatty degeneration of the multifidus muscle (p values 0.426 and 0.170). There was a statistically significant positive correlation between multifidus fatty degeneration at L4-L5 and L5-S1 levels and increasing age (p<000.1, r-values 0.462 and 0.357, respectively). In contrast, there was no correlation between age and L4-L5 and L5-S1 herniation grades (p values 0.167 and 0.723, respectively). Fatty degeneration grades were generally higher in females and increased with age at L4-L5 and L5-S1 levels in both genders (p<0.001).

Conclusions: The frequency and degree of fatty degeneration of the multifidus muscle increase with age, especially in women, and do not correlate with the presence of a herniated disc.