Strong association between vertebral endplate defect and Modic change in the general population

Abstract

Modic change (MC) is considered an independent risk factor for low back pain (LBP) but its aetiology remains unclear. In this cross-sectional, large-scale population-based study we sought to characterise associations between endplate defect (ED) and MC in a population sample of broad age range. The study population consisted of 831 twin volunteers (including 4155 discs and 8310 endplates) from TwinsUK. Lumbar T2-weighted MR images were coded for ED and MC. Total endplate (TEP) score was calculated at each intervertebral disc while receiver operating curves (ROC) were calculated to define critical endplate values predictive of MC. MC was detected in 32.1% of the subjects, with a significantly higher prevalence at lower lumbar levels (3.5% at L1/2-L3/4 vs. 15.9% at L4/5-L5/S1, p < 0.001). TEP score was strongly and independently associated with MC at each lumbar level (risk estimates from 1.49 to 2.44; all p ≤ 0.001) after adjustment for age, sex, BMI and twin pairing. ROC analysis showed a TEP score cut-off of 6 above which there was a significantly higher prevalence of MC. In conclusion, ED were strongly associated with MC at every lumbar level. These findings support the hypothesis that endplate defect is a major initiating factor for the cascade of events that may include disc degeneration (DD) and MC.

Figure 1

Endplate grading. (A) Grade 1: Normal endplate, no breaks or defects, (B) Grade 2: Focal thinning (white arrow) of the endplate, no breaks or defects, (C) Grade 3: Focal disc marrow contacts (white arrow), but with maintained endplate contour, (D) Grade 4: Endplate defects up to 25% of the endplate area (white arrow), (E) Grade 5: Endplate defects up to 50% of the endplate area (white arrow), (F) Grade 6: Extensive damaged endplates up to total destruction (white arrows). From Rade M. et al. Vertebral endplate defect as initiating factor in intervertebral disc degeneration: Strong association between endplate defect and disc degeneration in the general population. Spine 43, 412–419 (2018). With permission.

Figure 2

Prevalence and distribution of Modic change (MC) in the lumbar spine. The majority of MC is found in the lower lumbar spine (L4-S1) indicating a possible role of mechanical forces acting on the adjacent intervertebral discs and endplates of this anatomical region.

Figure 3

Survival analysis paired with Cox proportional hazards models analysis. Probability of having Modic change (MC) by TEP score ≥6 (denoted ‘Teps – Yes’ in the Figure) and <6 (denoted ‘Teps – No’ in the Figure). The probability is significantly increased in TEP score positive age subgroups at each disc level. The probabilities increase with age, and the influence of TEP score on MC is least at L5/S1. HR = hazard ratio.

Figure 4

MRI scan showing endplate defect grade VI both at the L4/L5 rostral and caudal endplates, with associated Modic changes (MC) over both rostral and caudal bone marrows adjacent to endplates and disc degeneration evaluated as Pfirrmann grade 5. As the endplate is a fundamental part of the vertebral body-endplate-intervertebral disc motion segment, one could consider endplate defects to be an initiating factor not only for disc degeneration, but also for MC. MRI indicates magnetic resonance imaging. From Rade M, et al. Vertebral endplate defect as initiating factor in intervertebral disc degeneration: Strong association between endplate defect and disc degeneration in the general population. Spine 43, 412–419 (2018). With permission.