Posterolateral Dislocation of the C1–C2 Articulation Associated With Fracture of the Anterior Arch of C1: A Case Report
Bibliographic record
Abstract
STUDY DESIGN: Case report. OBJECTIVE: To report a rare traumatic C1-C2 dislocation associated with fracture of the anterior arch of the atlas in a neurologically intact patient. SUMMARY OF BACKGROUND DATA: Isolated fractures of the anterior arch of C1 are very rare. There have been reports of horizontal fractures of the anterior arch thought to occur secondary to hyperextension injuries with subsequent avulsion of the anterior tubercle of the atlas. To our knowledge, however, there are no previously reported cases of isolated anterior arch fractures of C1 associated with posterolateral dislocation of the C1-C2 articulation. METHODS: A 53-year-old patient who presented with a posterolateral dislocation of the C1-C2 articulation and an associated anterior arch fracture of C1 is reported. Details of the initial presentation, diagnostic strategy, and initial and definitive management are provided. RESULTS: Closed reduction with halo ring application and gentle manipulation was followed with definitive internal fixation consisting of Magerl C1-C2 transarticular screw fixation coupled with modified Brooks fusion. CONCLUSIONS: Posterolateral C1-C2 dislocation associated with atlantal anterior arch fracture is a rare injury that can be effectively treated with gentle closed reduction under fluoroscopic guidance followed by internal fixation with or without halo vest immobilization. Recognition of associated conditions including vertebral artery compromise, concomitant cervical spine fractures, and life-threatening injuries is paramount to the successful treatment of these patients.
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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 | 0.004 |
| Meta-epidemiology (narrow) | 0.003 | 0.002 |
| Meta-epidemiology (broad) | 0.002 | 0.002 |
| Bibliometrics | 0.003 | 0.002 |
| Science and technology studies | 0.003 | 0.003 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.007 | 0.003 |
| Insufficient payload (model declined to judge) | 0.005 | 0.002 |
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".