Factors Affecting Modular Acetabular Ceramic Liner Insertion: A Biomechanical Analysis
Bibliographic record
Abstract
BACKGROUND: Ceramic liner fracture is a concern in THA. However, it is unclear what factors influence the risk of facture. To study these factors under controlled conditions, we created a laboratory model to avoid fractures in vitro. QUESTIONS/PURPOSES: We determined (1) whether misaligned liner insertion, acetabular shell deformation, entrapment of soft tissue within the locking taper area, and damage to the taper during engagement of the ceramic liner on the locking taper influenced fracture at light and medium impaction forces; and (2) whether the number and force of impactions affect the locking taper force between the ceramic liner and acetabular shell and fracture of the ceramic liner. METHODS: Impaction and pushout tests were performed with each of five ceramic inserts in titanium shells per test to simulate clinical intraoperative situations of misaligned inserts (Test 1), deformed shells (Test 2), soft tissue within the locking taper area (Test 3), simulated cup taper damage (Test 4), and a combination of misaligned insert, deformed shells, and simulated taper damage to create an overall worst-case condition (Test 5). RESULTS: Higher pushout forces occurred with increased impact force and an increased number of strikes. Insert fractures only occurred where inserts were misaligned in the shell. No fractures occurred with deformed shells, soft tissue in the taper, or with simulated taper damage in the absence of misaligned inserts. CONCLUSION: The data suggest a misaligned ceramic insert in an acetabular increases the potential for insert fracture. Shell deformation, soft tissue in the taper, or simulated taper damage seemed well tolerated even with very forceful impaction. Forceful and repetitive impaction is favorable for engagement of the taper and improving pullout strength.
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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 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| 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".