Evaluation of axial and flexural stresses in the vertebral body cortex and trabecular bone in lordosis and two sagittal cervical translation configurations with an elliptical shell model
Bibliographic record
Abstract
BACKGROUND: Osteoarthritis and spinal degeneration are factors in neck and back pain. Calculations of stress in clinically occurring configurations of the sagittal cervical spine are rare. OBJECTIVE: To calculate and compare combined axial and flexural stresses in lordosis versus cervical configurations in anterior and vertical sagittal head translated positions. DESIGN: Digitized measurements from lateral cervical radiographs of 3 different shapes were used to calculate axial loads and bending moments on the vertebral bodies of C2-C7. METHODS: An elliptical shell model was used to model horizontal cross-sections of the vertebral bodies of C2 through T1. Axial and flexural stresses were calculated with short compression block equations. Elliptical shell modeling permitted separation of stresses into cortical and inner medullary regions. Digitized radiographic points were used to create polynomials representing the shape of the sagittal cervical curvatures from C1 to T1. To calculate bending moments at each vertebral segment, moment arms from a vertical line through C1 were determined from digitizing. RESULTS: Compared with the normal lordosis, stresses on the anterior vertebral body cortical margins of C5-T1 in the sagittal translated postures are compression rather than tension. At the posterior vertebral bodies in the anteriorly translated position and vertically translated postures, the stresses change from compression to tension at C5 through T1. In absolute value (ABS) compared with values at the same segments in a normal lordosis, the magnitude of the combined anterior stresses in the sagittal postures are higher at C5-C7 (eg, ABS[sigma(straight)/sigma(normal)] approximately 1.25 to 4.25). CONCLUSIONS: Vertebral body stresses are reversed in direction at C5-T1 in sagittal translated postures compared to a normal lordosis. Stress analysis, with implications for bone remodeling, indicates that both sagittal head translation postures, anterior head carriage, and vertical head translation, are undesirable configurations in the cervical spine.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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".