Disc deformation as a potential biomarker of nonspecific low back pain.

Nonspecific low back pain (nLBP) lacks clear biomarkers, making diagnosis challenging. The disorder is commonly associated with annular fissures, which are hypothesized to trigger nerve endings to signal pain during disc deformation. Although symptoms worsen with load, MRI is typically performed in a relaxed state. Herein, a novel loading-based MRI method for non-invasive quantification of disc deformation was applied on 76 discs from 28 nLBP-patients to determine whether specific deformation patterns reflect fissures and pain using computer tomography and low-pressure discography during the same day as references. Discs without fissures and those with posterior fissures only displayed compression of annulus fibrosus posteriorly and expansion anteriorly, while discs with fissures both anteriorly and posteriorly and those with severe fissuring displayed elevated deformation and larger within-group variance (p = 0.001-0.04). Notably, discs with elevated anterior and low posterior deformation were more likely pain-signaling, whereas those with elevated posterior and low anterior deformation were often non-pain-signaling. At model probability thresholds below 0.38, all discs were correctly identified as non-painful and above 0.65, 86% were correctly identified as pain-signaling. Conclusively, this study provides in vivo evidence of a close interplay between disc deformation, fissures and pain, supporting the hypothesis that disc deformation contributes to nLBP.