T1 Pelvic and Lumbar Pelvic Angles Normative Values
Bibliographic record
Abstract
STUDY DESIGN: Cross-sectional analysis of a prospectively enrolled cohort. OBJECTIVE: Determine the normative values of the T1 pelvic angle (TPA) and lumbar pelvic angle (LPA) in an asymptomatic cohort of volunteers. SUMMARY OF BACKGROUND DATA: The TPA and LPA have been introduced as sagittal spinopelvic parameters to guide correction of adult spinal deformity. Suggested values for these parameters were derived from linear regressions based on Oswestry disability index scores from adult spinal deformity patients. While a few studies have evaluated the normative value of TPA, none have evaluated the LPA in asymptomatic individuals. MATERIALS AND METHODS: TPA and LPA were measured on radiographs of 472 asymptomatic volunteers between 20 and 40 years old. TPA and LPA were calculated as originally described from the centroid of T1 and L1, respectively, to the center of the femoral head to the midpoint of the sacral endplate. TPA and LPA were also evaluated using the midpoint of the superior endpoint as a surrogate to the centroid of the vertebra to compare these two measurement techniques. RESULTS: TPA and LPA normative values were, respectively, 7.3° (6.8-7.8) and 6.3° (5.9-6.7). There was no statistically significant difference between using the centroid of T1 or L1 versus using the midpoint of the superior endplate with respective results of 7.5° (7.0-8.0) ( P =0.55) and 6.1° (5.6-6.5) ( P =0.43). TPA was significantly different between Roussouly types 1, 2, 3, versus type 4 with respective results of of 6.7°, 7.2°, 6.5°, and 9.2° ( P <0.001). The same difference was observed for the LPA with normative results of 3.8°, 5.1°, 5.8°, and 9.3° ( P <0.001), respectively, for Roussouly types 1, 2, 3, and 4. CONCLUSIONS: TPA and LPA normative values are 7° and 6°, respectively, and vary between Roussouly morphotypes 1, 2, and 3 versus type 4. Using the midpoint of the superior endplate of T1 and L1 versus the centroid yielded similar results and therefore could be easier to use intraoperatively.
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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 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".