Reduced Shear Modulus and Altered Lamellar Morphology of the Outer Annulus Fibrosus in Painful Intervertebral Disc Degeneration Compared With Tissue From Non‐Surgical Controls
Bibliographic record
Abstract
ABSTRACT Background Stability of the spine and intervertebral disc (IVD) integrity is enabled by the highly organized fibrocartilaginous annulus fibrosus (AF). The shear properties of the AF are important in maintaining IVD integrity. AF shear mechanics in degenerative disc (DD) remain underexplored, especially in comparing minimally degenerative (non‐DD) and symptomatic DD individuals. This study measured tissue mechanical properties (AF simple shear modulus and dynamic shear properties) and examined structure (with optical coherence tomography (OCT)) in surgical DD and non‐DD control individuals. Methods Whole AF tissue samples were collected from non‐DD donors ( N = 13) and DD surgical individuals ( N = 30). Two anterior outer AF (OAF) 5 mm cubes were sectioned from each sample and subjected to shear in two orientations, radial (coronal plane, G1) and circumferential (sagittal plane, G2). Tissues underwent static shear and dynamic shear protocols to a maximum of 10% shear strain. Following mechanical tests, average lamellar thickness was assessed using OCT. Results Static shear moduli were significantly reduced for DD tissue compared to non‐DD in both the radial (G1) (non‐DD: 83.0 ± 41.3 kPa, DD: 24.1 ± 23.7 kPa) and the circumferential (G2) (non‐DD: 226.2 ± 81.9 kPa, DD: 54.0 ± 40.2 kPa) orientations ( p < 0.05). Further dynamic mechanical alterations were detected in hysteresis, phase shift, and dynamic modulus. Shear moduli correlated negatively with lamellar thickness (G1: r s = −0.63, G2: r s = −0.71). Conclusions There were significant alterations in AF shear moduli and dynamic properties in DD individuals when compared to non‐DD controls. Structural correlations highlight the role of the highly organized AF lamellar structure on shear modulus values. These findings suggest that altered AF mechanics may contribute to DD pathology and associated low back pain, warranting further investigation into structural and functional AF changes in symptomatic individuals.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".