The Canadian Arthroplasty Society’s experience with hip resurfacing arthroplasty
Bibliographic record
Abstract
The purpose of this study was twofold: first, to determine whether the five-year results of hip resurfacing arthroplasty (HRA) in Canada justified the continued use of HRA; and second, to identify whether greater refinement of patient selection was warranted. This was a retrospective cohort study that involved a review of 2773 HRAs performed between January 2001 and December 2008 at 11 Canadian centres. Cox's proportional hazards models were used to analyse the predictors of failure of HRA. Kaplan-Meier survival analysis was performed to predict the cumulative survival rate at five years. The factors analysed included age, gender, body mass index, pre-operative hip pathology, surgeon's experience, surgical approach, implant sizes and implant types. The most common modes of failure were also analysed. The 2773 HRAs were undertaken in 2450 patients: 2127 in men and 646 in women. The mean age at operation was 50.5 years (sd 8.72; 18 to 82) and mean follow-up was 3.4 years (sd 2.1; 2.0 to 10.1). At the last follow-up a total of 101 HRAs (3.6%) required revision. Using revision for all causes of failure as the endpoint, Kaplan-Meier survival analysis showed a cumulative survival of 96.4% (95% confidence interval (CI) 96.1 to 96.9) at five years. With regard to gender, the five-year overall survival was 97.4% in men (95% CI 97.1 to 97.7) and 93.6% in women (95% CI 92.6 to 94.6). Female gender, smaller femoral components, specific implant types and a diagnosis of childhood hip problems were associated with higher rates of failure. The most common cause of failure was fracture of the femoral neck, followed by loosening of the femoral component. The failure rates of HRA at five years justify the ongoing use of this technique in men. Female gender is an independent predictor of failure, and a higher failure rate at five years in women leads the authors to recommend this technique only in exceptional circumstances for women.
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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 | 0.001 | 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 | 0.005 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.002 |
| 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".