To Estimate MRI Findings in Chronic Low Back Pain Due to Degenerative and Paraspinal Muscle Changes and Its Correlation with Modified Oswestry Disability Index

Abstract

Background: Chronic low back pain (CLBP) is a leading cause of disability and reduced quality of life worldwide, often arising from degenerative changes in the lumbar spine and associated paraspinal musculature. Magnetic Resonance Imaging (MRI) provides critical insight into both osseous and soft tissue alterations in CLBP, including disc degeneration, Modic changes, facet joint arthropathy, spinal canal narrowing, and fatty infiltration or atrophy of the paraspinal muscles. However, the clinical impact of these MRI findings remains controversial, particularly in relation to the patient's functional disability as measured by tools like the Modified Oswestry Disability Index (mODI).

Aim: To evaluate MRI-based degenerative changes and paraspinal muscle alterations in patients with chronic low back pain and correlate these findings with the Modified Oswestry Disability Index.

Materials and Methods: A prospective cross-sectional study was conducted at a tertiary care center involving 100 patients aged 20–70 years presenting with CLBP (pain duration >12 weeks). MRI of the lumbosacral spine was performed using a 1.5T system. Parameters assessed included intervertebral disc degeneration (Pfirrmann grading), Modic changes, presence of Schmorl’s nodes, facet joint hypertrophy, spinal canal or foraminal stenosis, and cross-sectional area and fatty infiltration of paraspinal muscles (particularly multifidus and erector spinae). The severity of disability was assessed using the Modified Oswestry Disability Index (mODI). Correlations between imaging findings and mODI scores were analyzed using Spearman’s rank correlation and logistic regression.

Results: Degenerative disc changes were present in 91% of patients, with Pfirrmann grade III and IV being the most common. Modic changes were observed in 48% of cases, predominantly type II. Facet joint arthropathy was seen in 57%, and spinal canal stenosis in 32% of patients. Paraspinal muscle atrophy was evident in 66% of the sample, with multifidus muscle fatty infiltration graded as moderate to severe in 43%. A significant positive correlation (r = 0.61, p < 0.001) was noted between higher mODI scores and severity of paraspinal muscle changes. Disc degeneration and Modic changes also showed moderate correlation with mODI (r = 0.42 and r = 0.38, respectively). Regression analysis identified multifidus fatty infiltration and spinal stenosis as independent predictors of higher disability.

Conclusion: MRI plays a crucial role in identifying structural and muscular abnormalities in CLBP. Paraspinal muscle atrophy and fatty infiltration, more than bony degenerative changes, showed stronger correlation with functional disability. These findings suggest that targeted rehabilitation focused on muscle preservation may be key in managing chronic low back pain and improving quality of life.