Do more MRI findings imply worse disability or more intense low back pain? A cross-sectional study of candidates for lumbar disc prosthesis

Abstract

Objective: To examine whether combined magnetic resonance imaging (MRI) findings are related to the degree of disability and low back pain (LBP) in candidates for lumbar disc prosthesis surgery.

Materials and methods: This cross-sectional study included 170 disc prosthesis candidates (mean age 41 years; 88 women) with chronic non-radicular LBP and localized disc degeneration. Experienced radiologists rated Modic changes and disc findings at L4-S1 on pre-treatment MRIs. An MRI total score (0-10) for findings at L4/L5 plus L5/S1 was calculated for Modic type I and/or II changes, a posterior high intensity zone (HIZ) in the disc, dark/black nucleus pulposus signal, and ≥40 % disc height decrease. We analyzed the relationship of the MRI total score to the Oswestry Disability Index (ODI) (n = 170) and LBP intensity scores (0-100 visual analogue scale, n = 165) using multiple linear regression and adjusting for age, gender, body mass index, smoking, and anxiety/depression.

Results: The MRI total score was not related to ODI (regression coefficient 0.12, p = 0.79) or LBP intensity (regression coefficient 0.64, p = 0.37). When individual MRI findings were analyzed, patients with HIZ at L5/S1 had slightly lower ODI scores (4.7 points, p = 0.02). In post hoc analyses, results remained unchanged after adding facet arthropathy to the MRI total score and adjusting also for physical workload and physical leisure-time activity.

Conclusions: The combined MRI findings were not related to the degree of disability or the intensity of LBP. These degenerative MRI findings cannot explain variation in pre-treatment disability and pain in patients with chronic LBP accepted for disc prosthesis surgery.