Multi-dimensional assessment of vertebral endplate breaks on MRI: implications in spine degeneration and pain/ disability

Abstract

Introduction: The vertebral endplate is a critical component of the motion segment. The endplate is vulnerable to extensive wear and tear during one’s life-time. Magnetic resonance imaging (MRI) is an effective tool to detect the structural endplate dimensions and changes. Previous studies have noted endplate abnormalities/defects or “breaks” to be associated with intervertebral disc degeneration. However, such endplate findings were not always synonymous with disc degeneration severity or pain and disability. Endplate breaks vary in morphology and size. However, the role of such variation in endplate dimensions upon disc integrity and other MRI phenotypes (e.g. Modic changes, facet joint degeneration) remains speculative, and their implications upon pain and disability debatable. As such, the aim of the current study was to investigate the role of endplate dimensions in disc degeneration, and their relationship with other MRI phenotypes as well as the clinical profile. Methods: One hundred and eight Southern Chinese subjects were recruited (50% male; mean age: 53 years) and underwent T2W 3T MRI of the lumbar spine (n=1,080 endplates). Any structural endplate breaks were identified and their dimension was measured in terms of maximum width and depth using RadiAnat Dicom software. These measurements were then standardized with actual width of the endplate and depth of the vertebral body, respectively. Both width and depth of all endplate breaks in each subject were added separately and scores were assigned on the basis of size from 1 to 3. Combining both width and depth scores gave cumulative endplate break scores. Disc degenerative scores and associated disc degenerative changes based on Pfirrmann grading, posterior disc bulge, Modic changes, HIZ and facet joint profiles were also assessed. Subject demographics, low back pain (Visual Analog Scale: VAS) and disability profiles (Oswestry Disability Index: ODI) were obtained and correlated to the endplate and other MRI phenotype profiles. Results: Intra-rator reliability for all measurements were found to be excellent. Endplate breaks were observed in 67.5% of the subjects (51% males; mean age: 52 years) and in 14% of the endplates (58% males; 57% upper two lumbar levels; 67% inferior endplate). Standardized width and depth of the endplate breaks were found to be increased with age (p=0.02 & p=0.007, respectively), Modic changes (p<0.001 & p=0.003, respectively), Pfirrmann grades (p<0.001 both cases) and posterior disc bulge (p=0.03 & p=0.005, respectively). Width of the endplate breaks was also seen to be increased with irregular and narrow facet joints (p<0.05 & p=0.01, respectively). Cumulative endplate break scores showed strong positive association with ODI (ODI; p<0.05) and VAS compared to disc degenerative scores. Discussion: This is the first study to assess the multi-dimensional morphology of endplate breaks. Different sizes of endplate breaks may represent different etiologies. Large size endplate breaks were strongly associated with degenerative spine changes and other MRI phenotypes as well as more back-related disability. Findings from this study stress the need to assess endplate findings from a multi-dimensional perspective, whose role may have clinical utility