Modeling of the Sagittal Cervical Spine as a Method to Discriminate Hypolordosis
Bibliographic record
Abstract
STUDY DESIGN: Computer analysis of digitized vertebral body corners on lateral cervical radiographs. OBJECTIVES: Using elliptical and circular modeling, the geometric shape of the path of the posterior bodies of C2-C7 was sought in normal, acute pain, and chronic pain subjects. To determine the least squares error per point for paths of geometric shapes, minor axis to major axis elliptical ratios (b/a), Cobb angles, sagittal balance of C2 above C7, and posterior tangent segmental and global angles. SUMMARY OF BACKGROUND DATA: When restricted to cervical lordotic configurations, normal, acute pain, and chronic pain subjects have not been compared for similarities or differences of these parameters. Conventional Cobb angles provide only a comparison of the endplates of the distal vertebrae, while geometric modeling provides the shape of the entire sagittal curves, the orientation of the spine, and segmental angles. METHODS: Radiographs of 72 normal subjects, 52 acute neck pain subjects, and 70 chronic neck pain subjects were digitized. For normal subjects, the inclusion criteria were no kyphotic cervical segments, no cranial-cervical symptoms, and less than +/- 10 mm horizontal displacement of C2 above C7. In pain subjects, inclusion criteria were no kyphotic cervical segments and less than 25 mm of horizontal displacement of C2 above C7. Measurements included segmental angles, global angles of lordosis (C1-C7 and C2-C7), height-to-length ratios, anterior weight bearing, and from modeling, circular center, and radius of curvature. RESULTS: In the normal group, a family of ellipses was found to closely approximate the posterior body margins of C2-C7 with a least squares error of less than 1 mm per vertebral body point. The only ellipse/circle found to include T1, with a least squares error of less than 1 mm, was a circle. Compared with the normal group, the pain group's mean radiographic angles were reduced and the radius of curvature was larger. For normal, acute, and chronic pain groups, the mean angles between posterior tangents on C2-C7 were 34.5 degrees, 28.6 degrees, and 22.0 degrees, C2-C7 Cobb angles were 26.8 degrees, 16.5 degrees, and 12.7 degrees, and radius of curvature were r = 132.8 mm, r = 179 mm, and r = 245.4 mm, respectively. CONCLUSIONS: The mean cervical lordosis for all groups could be closely modeled with a circle. Pain groups had hypolordosis and larger radiuses of curvature compared with the normal group. Circular modeling may be a valuable tool in the discrimination between normal lordosis and hypolordosis in normal and pain subjects.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".