Intra-Rater Reliability of In-Vivo Measurements of Lumbar Spine Force Displacement Properties
Bibliographic record
Abstract
PURPOSE: The intra-rater reliability of manual methods to characterize the postero-anterior loading response of spinal tissues is modest at best. Should the use of technology increase measurement reliability when assessing the spine's response to postero-anterior loading, the use of this technology in clinical practice may be beneficial. METHODS: Asymptomatic subjects between the ages of 18–30 years were recruited for this study. An indenter device was placed perpendicularly over the spinous process of the 4th lumbar vertebrae in each prone subject. The indentation device consisted of moveable piston connected in-series to a load cell and linear velocity displacement sensor. The piston was moved manually to apply indentation to the spine to a maximum of 100N. The resulting load and displacement of the indenter were quantified in real time. Ten indentations were then performed at two minute intervals. From the resulting force-displacement data, two variables were calculated: the mean maximal stiffness (MMS, peak force divided by peak displacement) and global stiffness (GS, the slope of the force-displacmeent data between 30 and 100 N). From these data, intraclass correlation coefficients (ICC) were calculated to determine reliability. Error values (using the difference between consecutive trials) were computed for each subject. Finally, a paired t-test was used to determine if the 2nd and 10th indentation differed significantly. RESULTS: Twelve male and eleven female subjects participated in this study. Both MMS and GS had ICC values greater than 0.90 (ICC = 0.93 and 0.91, respectively). Mean error values were calculated to be 7.70% (+/− 5.33%) for MMS and 6.24% (+/−4.52%) for GS. Paired t-tests demonstrated a significant difference between indentation trials 2 and 10 for GS values only (p = 0.003). CONCLUSIONS: Measurement of spinal stiffness using indentation demonstrated excellent reliability in a single rater, much greater than the reliability afforded by manual assessment of spinal stiffness. Given that the indentation is performed manually, rate-dependant variables such as GS showed greater between-trial variation than MMS. Further research is required in this area to compare the reliability of stiffness quantification using multiple raters and at different anatomic sites.
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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 | 0.018 | 0.035 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".