THE EFFECT OF SEGMENTAL PEDICLE SCREW INSTRUMENTATION ON ACTIVELY GROWING SPINE: A LONG-TERM EXPERIMENTAL STUDY*
Bibliographic record
Abstract
Objectives. To determine the biological response of growing spine to rigid segmental fixation. Summary of background data. Pedicle screw is gaining popularity in pediatric deformities. Yet, biological response of actively growing spine to rigid pedicle screw fixation remains unclear. Methods. Twelve mini pigs in actively growing period were subjected to posterior segmental screw-rod instrumentation spanning 9 levels and creation of experimental scoliosis. There was no attempt of posterior arthrodesis. The pigs were subjected to periodic radiological examinations and were euthanized at 18 months for analysis. Results. There was no significant fixation failure despite conspicuous growth of the animals. Initial scoliosis of 31 ± 5° was reduced to 27 ± 8° at 18months, but there was no statistical significance (p=0.37). Though there was no change in length of the implant construct, the vertebrae within the instrumented section showed mean longitudinal growth of 6 ± 3 mm (p = 0.000). The growth occurred at expense of the disc spaces that progressively narrowed with time. On necropsy, the instrumented region was completely fused posteriorly with crossing of the osseous traberculae across the former facet joints. Intervertebral discs were severely atrophic in all the discs with occasional spontaneous fusion. Conclusions. Even in the actively growing spine, the force of growth does not overcome the fixation offered by segmental pedicle screws. Longitudinal growth occurs at the expense of the joint spaces and leads to spontaneous intervertebral fusion. Our results may explain the favorable outcomes in pedicle fixations in pediatric population, showing little implant failure or nonunion.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".