Forces in spinal cannulation and breaches ex vivo
Bibliographic record
Abstract
BACKGROUND: Pedicle screw insertion, to stabilize or correct the spine, relies on creating a probe path with the correct trajectory to prevent unsafe breaching of the cortical wall. Safe pedicle cannulation is aided when the surgeon can feel the difference between a safe and unsafe path. Pedicle probe forces and torques are currently unknown. The purpose of this study was to investigate the forces and torques encountered while cannulating the pedicle tract in both correct and incorrect cannulations. METHODS: Two experienced surgeons used a standard lumbar probe modified to incorporate a 6 degree-of-freedom load cell to cannulate and breach the T12 to S1 vertebrae of six fresh frozen cadavers (3 males, 3 females, ages 65 to 92). A total of 76 pedicles were tested. FINDINGS: Cannulation axial forces averaged 48 N (standard deviation = 13 N), medial breach 129 N (standard deviation = 25 N), and lateral breach 86 N (standard deviation = 27 N). Cannulation values were significantly lower than the breach values in all 6 degrees of freedom (p < 0.001). There were significant differences between specimens, including males and females, and between degrees of freedom, but no significant right and left differences or by vertebral level. CONCLUSION: A large range of cannulation and breach forces and torques were measured due to variations in bone quality and geometry, as experienced clinically. This is the first time that the absolute and relative force and torque levels have been reported, to our knowledge.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| 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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".