Estimation of pedicle screw fixation strength from probe indentation force and screw insertion torque: A biomechanical study on bone surrogates of various densities
Bibliographic record
Abstract
Posterior pedicle screw fixation is commonly used for patients with spinal disorders. However, failure of fixation is reported in many cases and surgeons have only little information. The objective of this study was to assess the correlation between the probe indentation force, screw insertion torque and the pullout force using bone surrogates of different densities. The indentation force and insertion torque were measured using a custom made test bench during screw insertion into polyurethane foam blocks. The two variables were significantly correlated to pullout force and to density. A high correlation was also found between indentation force and the peak insertion torque. The proposed methods for measuring indentation force and screw insertion torque were reproducible. This study suggests that the peak screw insertion torque and the indentation force can predict the screw fixation strength in synthetic bone models. Additional tests should be performed on animal and human specimens to confirm and to translate these findings to clinical applications.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 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".