Magnetic Resonance Imaging Evaluation of Lumbar Multifidus Muscle in Early Degenerative Changes of Lumbar Spine: a...

Low back pain (LBP) is a leading global cause of disability, with lumbar paraspinal muscle degeneration playing a key pathophysiological role. Lumbar multifidus muscle (LMM) atrophy, detectable on magnetic resonance imaging (MRI) as fatty infiltration, is closely associated with degenerative lumbar pathology. However, the relationship between LMM fat infiltration and co-existing degenerative changes - disc herniation, intervertebral disc degeneration (IVDD) and facet joint degeneration (FJD) - requires further characterisation.

This hospital-based cross-sectional study was conducted from March 2023 to February 2024. Eighty-six patients (38 males, 48 females; age 20-60 years) with clinically diagnosed LBP of ≥ three month-duration underwent 1.5 Tesla MRI lumbar spine in Assam Medical College and Hospital (AMCH), Dibrugarh, India. Lumbar multifidus muscle fat infiltration at the L4/L5 mid-disc level was graded using Goutallier's classification (Grades 0-4). Intervertebral disc degeneration was graded using Pfirrmann's system and facet joint changes by Pathria's grading. Statistical analysis was performed using Fisher's exact test.

The majority of patients had Grade 2 LMM fat infiltration (45.34%), followed by Grade 3 (23.26%), Grade 1 (18.61%), Grade 4 (8.14%) and Grade 0 (4.66%). Disc herniation was present in 67.44% of patients, with Grade 3 being the most frequently seen (36.04%). A progressive increase in disc herniation grade was observed with increasing LMM atrophy grade. Pfirrmann Grade 3 IVDD was most prevalent (27.90%). Grade 1 facet joint degeneration predominated (50.0%). Higher grades of LMM fat infiltration correlated significantly with higher grades of IVDD and FJD (p < 0.05).

MRI-based qualitative assessment of LMM fat infiltration using Goutallier's grading is a reliable, clinically practical method that should be incorporated into routine lumbar spine reporting. Increasing LMM atrophy correlates significantly with progressive degenerative changes including disc herniation, IVDD and FJD. Targeted lumbar muscle rehabilitation should be considered as an integral component of LBP management.