Comparison of the Anatomical Risk for Vertebral Artery Injury Associated With the C2-Pedicle Screw and Atlantoaxial Transarticular Screw
Bibliographic record
Abstract
In Brief Study Design. We evaluated the trajectories of atlantoaxial transarticular and C2-pedicle screws in 3 dimensions using computerized tomography. Objective. To compare the anatomic risk for vertebral artery injury associated with C2-pedicle and atlantoaxial transarticular screws. Summary of Background Data. The atlantoaxial fixation technique using C1-lateral mass screws combined with C2-pedicle screws is considered a safer technique for preventing vertebral artery injury than atlantoaxial transarticular fixation. However, few reports have compared the anatomic risk of vertebral artery injury associated with C2-pedicle screws with that of transarticular screws. Methods. A total of 62 consecutive patients with cervical lesions were evaluated using 3-dimensional images reconstructed by a computer-assisted navigation system. We compared the maximum possible diameters of the atlantoaxial transarticular screw and C2-pedicle screw trajectories, and examined whether the maximum possible diameters were limited by the height or width of the bony structure in screw trajectories ≤4 mm in diameter. Results. Mean maximum possible diameters did not differ significantly between the trajectories of 124 atlantoaxial transarticular and 124 C2-pedicle screws. In screw trajectories ≤4 mm in diameter, 57.1% of transarticular screw trajectories were limited by the height of the bony structure, and all pedicle screw trajectories were limited by the width. Conclusions. C2-pedicle screw placement has nearly the same anatomic risk of vertebral artery injury as transarticular screw placement. Preoperative 3-dimensional evaluation may be useful for choosing the best surgical technique. Three-dimensional computerized tomography was used to compare the screw trajectories of atlantoaxial transarticular and C2-pedicle screw placement. C2-pedicle screw placement had nearly the same risk for vertebral artery injury as transarticular screw placement. Preoperative 3-dimensional evaluation may assist in choosing the best surgical technique.
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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 | 0.001 |
| 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 | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".