Predictive accuracy of RSA migration thresholds for cemented total hip arthroplasty stem designs
Bibliographic record
Abstract
INTRODUCTION: Radiostereometric analysis (RSA) migration thresholds for cemented total hip stems have been established beyond which an unacceptably high risk of revision is likely to occur. These thresholds are subsidence >0.23 mm or >1.2 mm after 2 years. The purpose of this study was to retrospectively examine after long-term follow-up the predictive accuracy of the two thresholds. METHODS: Data from two previous prospective RSA trials with 2 year follow-up for which minimum 10 year survivorship data was available were used. Thirty-six patients received a Spectron stem, 17 patients received an Exeter stem, and 17 patients received a CPCS stem. Subsidence after 2 years was compared to the migration thresholds, and long-term survivorship and clinical outcome scores were obtained. RESULTS: At 2 years, the Spectron stem subsided 0.046 ± 0.160 mm, the Exeter stem subsided 1.218 ± 0.320 mm, and the CPCS stem subsided 0.681 ± 0.246 mm ( p < 0.0001). The Spectron stem passed both thresholds, the Exeter stem failed both thresholds, and the CPCS stem passed 1 and failed 1 threshold. At 10 years, survivorship exceeded 90% for all stems. CONCLUSION: All stems demonstrated strong 10 year survivorship and equivalent clinical outcome scores, but this success would not have been equally predicted across RSA migration thresholds. Although RSA is a useful predictive tool, care should be taken in applying migration thresholds only to those stem designs they are indicated for, with the threshold of 1.2 mm of subsidence at 2 years being most broadly applicable.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 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) | 0.001 | 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 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".