Application of the Ames–International Spine Study Group radiographic modifiers to an asymptomatic population: are the thresholds for "normal" appropriate?
Bibliographic record
Abstract
OBJECTIVE: The Ames-International Spine Study Group (ISSG) classification is a tool for stratifying severity in adult cervical spine deformity. The Ames-ISSG sagittal modifiers include C2-7 sagittal vertical axis (cSVA), T1 slope-cervical lordosis mismatch (TS-CL), and chin-brow vertical angle (CBVA). Each modifier stratifies patients as grade 0, 1, or 2. The study aimed to classify an asymptomatic population according to the Ames-ISSG sagittal modifier grades and assess differences in health-related quality of life (HRQOL) between grades. METHODS: A cross-sectional analysis of a prospectively collected database was performed. Five hundred healthy, asymptomatic volunteers between 20 and 40 years of age without prior surgery or diagnosed spinal pathology were enrolled and underwent EOS imaging to measure their Ames-ISSG sagittal modifiers (cSVA, TS-CL, and CBVA). HRQOL questionnaires (the Oswestry Disability Index and Neck Disability Index) were also completed. RESULTS: Four hundred seventy-seven patients were included. The cSVA was not analyzed because 475 of 477 individuals were grade 0 (< 4 cm). The TS-CL modifier was not analyzed because 472 of 477 individuals were grade 0 (< 15°). The CBVA was grade 0 (1°-10°) in 64% of individuals and grade 1 (-10° to 0° or 11°-25°) in 36%. There was no significant difference between grades in HRQOL. CONCLUSIONS: The Ames-ISSG classification sagittal modifiers cSVA and TS-CL grade 0 describe normal anatomy. A CBVA grade of 1 is present in 36% of asymptomatic individuals with no difference in HRQOL scores. This study validates the threshold for grade 0 in a normative population for TS-CL and cSVA. It also highlights inconsistency in CBVA and the importance of specific instructions for appropriate evaluation.
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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 | 0.005 | 0.018 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".