REPRODUCIBILITY OF IN VIVO FEMORO-PELVIC JOINT ANGLE MEASUREMENTS UPON REPOSITIONING ASSESSED USING OPEN MRI IMAGING UNDER WEIGHTBEARING CONDITIONS, WITH APPLICATIONS TO FEMOROACETABULAR IMPINGEMENT
Bibliographic record
Abstract
This paper presents a methodology for measuring the femoro-pelvic joint angle based on in vivo magnetic resonance imaging (MRI) images taken under weight-bearing conditions. We assess the reproducibility of angle measurements acquired when the subject is asked to repeatedly assume a reference position and perform a voluntary movement. We scanned a healthy subject in a lying position in a 3T MRI scanner to obtain high resolution (HR) images including two transverse T1-weighted TSE sequence scans at the pelvis and knee and a sagittal T1-weighted dual sense scan at the hip joint. We then scanned the same subject in a weight-bearing configuration in a 0.5T open MRI scanner to obtain related low resolution (LR) images of the femur and acetabulum. Four scan cycles were obtained with the subject being removed and reinserted between cycles in the Open MRI scanner. In each cycle, a block was inserted (up position) and removed (down position) under the subject9s foot. The femur and acetabulum bone models were manually segmented and the models from the LR (sitting) images were registered to the HR (supine) images. The femoroacetabular angles relative to the LR scanning plane for four cycles were calculated. The femoral angle relative to the scanner were quite repeatable (SD We found that the femoral position could be accurately re-acquired upon repositioning, while the pelvic position was notably more variable. Limb position changes induced by inserting a block under the subject9s foot were consistent (standard deviations in the relative attitude angles under 2°). Overall, our measurement method produces plausible measures of both the femoroacetabular angles and the changes induced by the block, and the reproducibility of relative joint changes is good. ACKNOWLEDGMENTS: Dr. Kang was supported by the National Science and Engineering Research Council of Canada (NSERC) through a Postdoctoral Fellowship and conducted her research at the Centre for Hip Health and Mobility at Vancouver General Hospital, Canada.
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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 | 0.005 |
| 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 | 0.001 |
| 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".