Effect of stem preheating and precooling on residual stress formation at stem/cement interface for cemented hip implants
Bibliographic record
Abstract
PMMA polymerization is an exothermic phenomenon during which stresses and porosity are observed. An experimental model is devised to directly measure radial forces, to be converted to radial stresses, at the stem/cement interface, and temperatures at both interfaces during cement curing. The effects of stem and bone cement initial temperatures (preheating or precooling vs. room temperature) as well as mixing method (hand vs. vacuum mixing) and cement type (Simplex P vs. Palacos R) on radial stress and temperatures are investigated. Compressive radial residual stresses at the stem/cement interface are measured for hand mixed PMMA with preheated stem, with a maximum magnitude of 1.0 MPa. No radial residual stresses are observed when the stem is initially at room temperature or precooled, suggesting that during curing, bone cement can polymerize away from the stem/cement interface generating radial stress in tension or gaps. The results demonstrate the reverse direction of polymerization for preheated stems. Stem preheating significantly increases transient temperatures at the bone/cement interface and also the risk of bone thermal necrosis, because the exposure time to high temperature is prolonged. The results provide interfacial characteristics for accurate modeling of bone cement polymerization to better understand the debonding process of cemented hip prostheses.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.008 | 0.000 |
| 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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".