Bulging of the Inner and Outer Annulus During In Vivo Axial Loading of Normal and Degenerated Discs
Bibliographic record
Abstract
STUDY DESIGN: Comparison of in vivo biomechanical outcomes between experimental and control group animals. OBJECTIVE: To quantify the in vivo bulging response of the inner and outer annulus in animals with and without disc degeneration. SUMMARY OF BACKGROUND DATA: Prior attempts to quantify the load-deformation response of the inner annulus have most often relied on in vitro preparations. Unfortunately, to visualize the inner annulus, these in vitro approaches rely on disc modifications that may result in nonphysiologic behaviors. In response to this problem, in vivo techniques were developed to quantify regional bulging of the inner and outer annulus during applied axial loading. METHODS: Two groups of pigs were tested: a normal group and a group having disc degeneration that was induced surgically 3 months earlier. Eight adolescent pigs were evaluated and for each animal, a miniature servohydraulic actuator was attached to the third and fourth lumbar vertebrae to deliver a cyclic axial loading protocol (300 N, 1 Hz, 10 cycles) whereas regional deformations of the annulus were visualized ultrasonically via retroperitoneal access. RESULTS: For the normal animals, image analysis demonstrated a significantly greater bulging of the inner annular region when compared with the outer annular region. In animals with disc degeneration, the inner and outer annular regions were equal in their bulging response, which ranged from 0 bulging to 37% greater than the average response of the normal animals. CONCLUSIONS: This work supports prior in vitro studies that observed maximal disc bulging in the inner annulus and minimal bulging in the external annulus. Results for this in vivo study suggest that this normal bulging gradient is lost with degenerative disc disease. Compared with in vitro approaches, this new in vivo technique has the potential to demonstrate disc behavior in a variety of loading conditions and/or with a variety of induced disc pathologies.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 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) | 0.000 | 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 teacher head, 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".