Irreversible Perforations in Vertebral Trabeculae?
Bibliographic record
Abstract
UNLABELLED: In human cancellous bone, osteoclastic perforations resulting from normal remodeling were generally considered irreversible. In human vertebral samples, examined by backscatter electron microscopy, there was clear evidence of bridging of perforation defects by new bone formation. Hence trabecular perforations may not be irreversible. INTRODUCTION: Preservation of the trabecular bone microarchitecture is essential to maintain its load-bearing capacity and prevent fractures. However, during bone remodeling, the osteoclasts may perforate the platelike trabeculae and disconnect the structure. Large perforations (>100 microm) are generally considered irreversible because there is no surface on which new bone can be laid down. In this work, we investigated the outcome of these perforations on human vertebral cancellous bone. MATERIALS AND METHODS: Using backscatter electron microscopy, we analyzed 264 vertebral bone samples from the thoracic and lumbar spine of nine subjects (44-88 years old). Nine fields (2 x 1.5 mm) were observed on each block. Several bone structural units (BSUs) were visible on a single trabecula, illustrating a dynamic, historical aspect of bone remodeling. A bridge was defined as a single and recent BSU connecting two segments of trabeculae previously separated by osteoclastic resorption. They were counted and measured (length and breadth, microm). RESULTS AND CONCLUSION: We observed 396 bridges over 2376 images. By comparison, we found only 15 microcalluses on the same material. The median length of the bridge was 165 microm (range, 29-869 microm); 86% being longer than 100 microm and 35% longer than 200 microm. Their breadth was 56 microm (range, 6-255 microm), but the thinnest were still in construction. Bridges were found in all nine subjects included in the study, suggesting that it is a common feature of normal vertebral bone remodeling. These observations support the hypothesis that perforation could be repaired by new bone formation, and hence, might not be systematically irreversible.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".