Dynamic Fluctuation of Truncal Shift Parameters During Quiet Standing in Healthy Young Individuals
Bibliographic record
Abstract
STUDY DESIGN: Retrospective analysis. OBJECTIVE: To describe the dynamic fluctuation of truncal shift parameters during quiet standing in healthy young individuals using biomechanical analyses. SUMMARY OF BACKGROUND DATA: Coronal decompensation (CD) and sagittal vertical axis (SVA) are the key radiographic parameters to assess static truncal stability, with the known cut-off value of 4 cm for SVA in determining severity of spinal deformity. These values are obtained at a specific moment during quiet standing, when the posture innately changes. Thus, unassessed truncal sway could potentially compromise the reliability of these measurements. METHODS: Previously obtained biomechanical data with 11 male, healthy participants aged 16 to 29 were used to quantify the dynamic sway of standing posture. The participants were instructed to quietly stand with surface reflective markers for 130 seconds. The midpoint of bilateral acromia was used as a surrogate for C7 vertebral body. The time series of coronal and sagittal shifts of C7 to sacrum were measured as quasi-coronal decompensation (CD) and quasi-sagittal vertical axis (SVA) to simulate CD and SVA on radiographs. A force platform was also used to measure the center of pressure (COP) displacement. RESULTS: The group averages of the dynamic sway range were 20.2 ± 4.1 mm (range: 15.1-28.6) in the sagittal plane (quasi-SVA) and 9.8 ± 3.2 mm (range: 5.5-15.2) in the coronal plane (quasi-CD). There were significant correlations between quasi-CD sway and medial-lateral COP velocity (Pearson r = 0.65, P = 0.03), as well as between quasi-SVA sway and COP sway area (r = 0.65, P = 0.03). CONCLUSION: Given the considerable fluctuation of quasi-SVA and quasi-CD during quiet standing, the reliability of radiographic measurement using CD and SVA at a specific moment can be substantially compromised. The assessment based on the currently proposed cut-off values should be interpreted with caution, and repeat examinations are warranted. LEVEL OF EVIDENCE: 4.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| 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) | 0.001 | 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".