INVESTIGATING SITE-SPECIFIC CHANGES IN THE MECHANICAL PROPERTIES OF THE ANNULUS FIBROSUS FOLLOWING DISC HERNIATION
Bibliographic record
Abstract
Introduction: Disc herniations transpire when the nucleus pulposus (NP) within the intervertebral\ndisc (IVD) breaks through the surrounding annulus fibrosus (AF) (Gooyers et al., 2015). Disc\nherniations have been demonstrated to be a result of cumulative damage brought on by repeated\nflexion under compressive stresses (Aultman et al., 2005). Limited research has investigated the\nchanges in mechanical properties that occur as a consequence of disc herniation to the AF. Further,\nit is not known if these changes are isolated to only the region of the herniation or the entire AF.\nAims: The purpose of the current work is to investigate if site specific changes to the mechanical\nproperties of the AF fibrosus post disc herniation.\nMethods: A total of 30 porcine cervical spines were used (10 control, 10 static, 10 experimental).\nThe C3/4 and C5/6 functional spine units (FSUs) were excised from these spines and randomized\ninto groups via block randomization for each condition. The experimental porcine FSUs were\nloaded into a uniaxial material testing system (MTS Systems Corporation, Eden Prairie, MN,\nUSA) under a compressive load of 1200 N, with repetitive cycles of off-axis bending at 30°, at 0.5\nHz to create herniation in the 10 experimental spines. The static FSUs were also loaded at 1200 N\ncompression but did not undergo repetitive flexion-extension. The control FSUs only underwent\npreloading. The reasoning for the off-axis herniation protocol was to force the migration of the\nnucleus (i.e., prolapse) to one side of the posterolateral region of the AF (Aultman et al, 2005).\nThis yielded a herniated region, and an internal control region of the posterolateral AF. Following\nloading, two AF samples were excised from each of the herniated and the intact regions. Similarly,\nfrom the control FSUs, two AF samples were excised from the left and right posterolateral region\nof the disc. A lamellar adhesion peel test was conducted on one AF sample and a single lamellae\nlayer test was conducted on the other sample using the UStretch (Cellscale, Waterloo, Ontario)4\nand Biotester (Cellscale, Waterloo, Ontario), respectively. Mechanical properties were quantified\nfrom both tests. A two-way repeated measures ANOVA was conducted to examine the main effect\nof condition (experimental, control, and static) and posterolateral side (ipsilateral and contralateral\nsides), and the interaction between these two variables.\nResults: 3/10 of the experimental IVDs showed evidence of nucleus tracking and thus herniation\nin the posterior, and contralateral region to the bending axis. There was a statistically significant\n(p= 0.03) difference in stress at toe region (mPa) when comparing the experimental group to the\ncontrol group. The control group had greater stress (M=0.29 MPa) at toe region than the\nexperimental group (M=0.068 MPa). There was also a statistically significant (p= 0.02) difference\nin strain at toe region (mPa) when comparing the experimental group to the control group. The\ncontrol group had greater strain (M=0.19%) at toe region when compared to the experimental\ngroup (M=0.13%). There was found to be a statistically significant difference between the\ncontralateral and ipsilateral sides of the IVD for peel stiffness regardless of loading condition\n(p=0.01).\nDiscussion/Conclusion: The toe region of the stress-strain curve is where elastin largely\nfunctions. From the current study, it is possible that fatigue-related degradation to the elastin\nfibres occurred, which could have contributed to the separation of lamellae, eventually leading to\nNP prolapse. The shorter toe region in the current study could be explained by damage to the\nelastin fibres in the experimental group, which resulted in a disruption to elastin.
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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 | 0.001 |
| 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".