The Biomechanical Effect of Notch Size, Notch Location, and Femur Orientation on Hip Resurfacing Failure
Bibliographic record
Abstract
For hip resurfacing, this is the first biomechanical study to assess anterior and posterior femoral neck notching and femur flexion and extension. Forty-seven artificial femurs were implanted with the Birmingham hip resurfacing (BHR) using a range of notch sizes (0, 2, and 5 mm), notch locations (superior, anterior, and posterior), and femur orientations (neutral stance, flexion, and extension). Implant preparation was done using imageless computer navigation, and mechanical tests measured stiffness and strength. For notch size and location, in neutral stance the unnotched group had 1.9 times greater strength than the 5-mm superior notch group (4539 N versus 2423 N, p=0.047), and the 5-mm anterior notch group had 1.6 times greater strength than the 5-mm superior notch group, yielding a borderline statistical difference (3988 N versus 2423 N, p = 0.056). For femur orientation, in the presence of a 5-mm anterior notch, femurs in neutral stance had 2.2 times greater stiffness than femurs in 25° flexion (1542 N/mm versus 696 N/mm, p = 0.000). Similarly, in the presence of a 5-mm posterior notch, femurs in neutral stance had 2.8 times greater stiffness than femurs in 25° extension (1637 N/mm versus 575 N/mm, p = 0.000). No other statistical differences were noted. All femurs failed through the neck. The results have implications for BHR surgical techniques and recommended patient activities.
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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) | 0.000 | 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".