Oral Presentation 50th International Society for the Study of the Lumbar Spine Annual Meeting 2024

Introduction.
As non-specific low back pain (LBP) likely is multifactorial, it is appealing to investigate relationships between multiple potential factors. Modic changes (MC), annular fissures, and endplate changes are all commonly found in LBP patients, and they may coexist in the same individual. The association between MC, annular fissures and endplate changes is, however, complex and requires further investigation to fully understand the association between these entities. The aim of this study was to investigate to what extent MC, annular fissures, vertebral and endplate changes coexists in LBP patients by using multiple imaging modalities.

Methods.
Sixty-two LBP patients (mean age 45 years, range 24-63, 53% men) were examined with same-day CT-discography and MRI. Intervertebral discs (IVDs) punctured for discography (n=204) were evaluated on MRI [Pfirrmann grade, High-Intensity Zone (HIZ)] and on CT-discograms [Modified Dallas Discogram Score (DDS)]. IVDs with DDS≥ 1, i.e., fissures involving outer annulus, were further digitiomized into delimitable fissure (<50% of annulus affected) or a non-delimitable annular fissuring. Using both MRI and CT, adjacent vertebras and endplates were assessed for MC, vertebral sclerosis, and a modified Endplate defect Score (EPS).

Results.
In 194 discs, the contrast agent was adequately injected during discography, of which 160 (83%) displayed outer annular fissures with 91 (47%) of the latter being delimitable fissures. Most discs with delimitable fissures were moderately degenerated; 68% Pfirrmann grade ≤3, 71% EPS≤2 and 12% displayed MC. Majority (76%) of MC were associated with advanced adjacent disc degener-ation; 84% Pfirrmann grade ≥4, 76% with non-delimitable annular fissuring and 59% EPS≥ 4 and 34% EPS 3.95 HIZ´ (47%) were found of which 54 had delimitable fissure while remaining displayed non-delimitable fissuring. Vertebral sclerosis was commonly observed (26%), both with MC (73%) and without MCs (27%), and not specifically linked to MC type 3. 97% of segments with vertebral sclerosis displayed outer annular fissures. The co-existence of the different investigated MR findings were significant  (0.046>p>0.0001) (Figure 1), except between HIZ and adjacent sclerosis (p=0.303).

Discussion

A close interplay between the IVD and adjacent vertebra and endplate was confirmed. That a majority of IVDs with delimitable annular fissures did not coexist with pronounced endplate changes and/or MCs, however, support the theory that disc fissuring is an early event in the degenerative cascade. This was further supported by the fact that MCs were strongly linked to extensive IVD fissuring and to advanced endplate damage. Present result also highlights that it is unrealistic to look at a single marker in the search for features linked to pain and that a multiparametric approach is necessary to characterize this complex interplay between spinal degenerative findings. Moreover, in the clinical setting, one should be aware that HIZ is a marker for annular disruption but non-specific. Minor endplate defects and MCs indicate a more pronounced deteriorating process in that segment. Also, vertebral sclerosis is a common morphological feature without MCs and not specifically found in MC type 3.

Figure 1. Covariation between morphological features at MR, CT and Discograms