Ultrasound-guided L5 dorsal ramus block: validation of a novel technique
Bibliographic record
Abstract
BACKGROUND: Although the value of ultrasound-guided (USG) lumbar medial branch blocks (MBB) has previously been examined in several clinical trials, blocking the L5 dorsal ramus (DR) remains a technical challenge and we sought to examine the accuracy of a novel technique targeting this level. METHODS: In this prospective cohort study, 115 patients scheduled for an L4 MBB and L5 DR block underwent an ultrasound scan to assess their lower spine sonoanatomy. Subjects in whom the necessary landmarks could be visualized underwent a USG L5 DR block using a pivot technique, which involved redirecting a needle from its position on the L5 transverse process after an L4 MBB. Success was determined by a blinded observer who examined the contrast distribution on postprocedural X-ray images. In addition to the final needle position, performance time, the number of needle passes, and any complication were recorded. RESULTS: , p=0.004). A total of five failures were noted (95% success rate), this included three patients with transitional anatomy in whom needles were placed at the wrong level and two cases of incomplete contrast coverage possibly related to the partial intravascular injection. Performance time was 153.93±41.56 s and the median number of needle passes was 2 (range 4). No significant complications were noted. CONCLUSION: The pivot technique provides a reliable approach for USG L5 DR ramus blocks. TRIAL REGISTRATION NUMBER: NCT03805906.
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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 | 0.007 | 0.010 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 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".