Bibliographic record
Abstract
According to the Canadian Joint Replacement Registry, in 2010–2011 there were 17,303 hip replacements performed in Canada of which 10% were revisions. More than 73% of these revisions were for aseptic loosening, wear, and instability which suggests that hip biomechanics may be anomalous. The hip joint is often described as a ball-and-socket joint, which implies congruent interacting bony joint surfaces and purely rotational relative motion. This study challenges the accepted kinematic description by analysing detailed motion of the hip joint using surgical navigation technology. An in-vitro study was conducted using twelve fresh frozen cadaveric human hemi-pelvises in three soft-tissue states. Three dimensional digital models of each specimen were generated from segmentation of computed tomography images. Local coordinate reference devices, mounted on the proximal femur and anterior-superior iliac spine, were registered and tracked with an active optical localisation system. Positions and orientations were imported to custom virtual surgery software. The study used soft-tissue states as one variable and twelve combinations of flexion/extension, abduction/adduction and internal/external rotation as the other variable. The entire series of motions were repeated for (I) soft tissues intact, (II) capsule intact and (III) completely disarticulated joint. Translation of the femoral head with respect to the acetabular cup at each frame was extracted from the recorded data. An Analysis of Variance (ANOVA) was used to determine whether the means of translations in each dissection states were significantly different. Translatory motion was observed in all specimens. Significant differences were found between magnitudes of translation in distinct soft tissue states (p The highly accurate surgical navigation system detected subtle translatory behaviour in hip motion. The data provided evidence that the femoral head translates with respect to the acetabular cup with or without any contact between the two bones; such impingements were previously thought to be the main reason for femoral excursion. The statistical significance found between translations exhibited at different soft tissue states indirectly supports an aspherical model of the adult hip, with kinematics driven by both soft tissue and the anatomy. This work towards an improved biomechanical model of the hip could help guide both surgical intervention and implant design, leading to improved outcomes for the hundreds of thousands of hip surgeries performed globally each year.
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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 | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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".