The Effects of Antibiotic-Impregnated Spacers on Bone Healing in an Animal Model of the Induced Membrane Technique
Bibliographic record
Abstract
Background: Surgeons performing the induced membrane technique (IMT) often incorporate antibiotics into the spacer at the first stage of the surgical procedure to prevent or treat infection. However, the effect of antibiotic use on subsequent bone healing is not clear. This study aimed to investigate if antibiotic-impregnated spacers impact subsequent bone healing in a rat model of the IMT. Methods: Inbred male rats (Fischer 344) were randomly divided into 3 groups according to the antibiotic dose in the spacer: (1) control (no antibiotics), (2) low-dose (1.2 g tobramycin and 1.0 g vancomycin per 40 g of polymethylmethacrylate [PMMA]), and (3) high-dose (3.6 g tobramycin and 3.0 g vancomycin per 40 g of PMMA). We created a 5-mm segmental defect in the right femoral diaphysis. The bone was stabilized with a plate and screws, and the assigned spacer was inserted into the defect. Four weeks later, the spacer was removed and bone graft was placed within the defect. Radiographs made 12 weeks after grafting were scored according to union status and degree of bone healing. Micro-computed tomographic (CT) analysis and biomechanical testing were also performed at 12 weeks. Results: Full radiographic union was achieved in 10 (83%) of 12 control animals, 13 (100%) of 13 low-dose animals, and 8 (62%) of 13 high-dose animals (high-dose compared with low-dose: risk ratio, 11.0; p = 0.039). The control group demonstrated higher bone volume compared with the high-dose group (mean difference, 9.0 mm 3 ; p = 0.039), and there was a trend toward higher bone volume in the low-dose group compared with the high-dose group (mean difference, 8.1 mm 3 ; p = 0.06). The biomechanical results demonstrated that maximum stiffness was significantly higher in the low-dose group compared with the high-dose group (mean difference, 14.1 N*mm/degree; p = 0.009). Conclusions: Our results demonstrated that low doses of antibiotics in PMMA spacers used for the IMT did not impair bone healing. However, high doses of antibiotics demonstrated inferior bone healing. Clinical Relevance: The addition of high-dose antibiotics to the PMMA spacers used for the IMT may result in impaired bone healing and should be used with caution.
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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 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".