Associations between multifidus muscle morphology and degenerative pathologies have been implied in patients with non-specific low back pain, but it is unknown how these are influenced by pathology severity, number, or distribution. MRI measures of pure multifidus muscle cross-sectional area (CSA) were acquired from 522 patients presenting with low back and/or leg symptoms in an outpatient clinic. We explored cross-sectional associations between the presence, distribution, and/or severity of lumbar degenerative pathologies (individually and in aggregate) and muscle outcomes in multivariable analyses (beta coefficients [95% CI]). We identified associations between lower pure multifidus muscle CSA and disc degeneration (at two or more levels): - 4.51 [- 6.72; - 2.3], Modic 2 changes: - 4.06 [- 6.09; - 2.04], endplate defects: - 2.74 [- 4.58; - 0.91], facet arthrosis: - 4.02 [- 6.26; - 1.78], disc herniations: - 3.66 [- 5.8; - 1.52], and when > 5 pathologies were present: - 6.77 [- 9.76; - 3.77], with the last supporting a potential dose-response relationship between number of spinal pathologies and multifidus morphology. Our findings could hypothetically indicate that these spinal and muscle findings: (1) are part of the same degenerative process, (2) result from prior injury or other common antecedent events, or (3) have a directional relationship. Future longitudinal studies are needed to further examine the complex nature of these relationships.
© 2022. The Author(s).