Periprosthetic proximal femoral fractures in cemented and uncemented stems according to Vancouver classification: observation of a new fracture pattern
Bibliographic record
Abstract
BACKGROUND: Periprosthetic fractures are increasingly encountered in hip arthroplasty. The Vancouver classification system is widely used. Little knowledge exists regarding the association of the Vancouver classification with either cemented or uncemented stems. The aim was to analyse a series of fractures and determine associations. METHODS: A series of consecutive patients over 8 years was identified including only post-operative fractures of primary hip arthroplasties. Baseline and radiographic characteristics were recorded including the type of stem fixation (cemented or uncemented) and Vancouver classification. Statistical analysis was performed to determine the association of the Vancouver classification between cemented and uncemented stems. RESULTS: A total of 172 patients were identified (84 cemented stems, 88 uncemented stems). There were 30 Vancouver A fractures (12 cemented vs.18 uncemented, p > 0.05), 125 Vancouver B fractures (63 cemented vs. 62 uncemented, p > 0.05) and 17 Vancouver C fractures (9 cemented vs. 8 uncemented, p > 0.05). The Vancouver B2 fracture occurred most frequently (N = 95; 44 cemented vs. 51 uncemented, p > 0.05) and consists of four distinct fracture patterns: the previously described comminuted 'burst', clamshell and spiral patterns and the newly observed 'reverse' clamshell. The burst and spiral fracture patterns are significantly associated with cemented stems, and the clamshell pattern is significantly associated with uncemented stems. CONCLUSIONS: Vancouver A, B and C fractures occur equally in cemented and uncemented stems. Awareness of four distinct Vancouver B2 fracture patterns, including the newly observed reverse clamshell, will aid surgeons in predicting stem instability.
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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 | 0.004 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 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 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".