Evaluation of a CT-Based Patient Specific Femoral Alignment Guide for Hip Resurfacing Arthroplasty
Bibliographic record
Abstract
Introduction: Alignment of the initial femoral guidewire is critical in avoiding technical errors that may increase the risk of failure of the femoral component. A novel alternative to conventional instrumentation for femoral guidewire insertion is a computed tomography (CT) based alignment guide. The aim of this study was to assess the accuracy of femoral component alignment using a CT-based, patient specific femoral alignment guide. Methods: Between March 2010 and January 2011, 25 hip resurfacings utilizing a CT-based femoral alignment guide were performed by three surgeons experienced in hip resurfacing. Stem-shaft angle (SSA) accuracy was assessed using minimum 6 week post-operative digital radiographs. A benchside study was also conducted utilizing six pairs of cadaveric femora. Each pair was divided randomly between a group utilizing firstly a conventional lateral pin jig followed by computer navigation and a group utilizing a CT-based custom jig. Guidewire placement accuracy for each alignment method was assessed using AP and lateral radiographs. Results: In the clinical series, the post-operative SSA differed from the planned SSA by a mean of 1.3° (SD 4.8, range −9–14). The final SSA measured within ± 5° of the planned SSA in 20 of 24 cases (83%). There was no significant difference between surgeons in post-operative SSA accuracy (p = 0.697). In the benchside study, the custom jig (mean error 6.4°, SD 2.9) provided a comparable level of accuracy to that of the conventional jig (mean error 5.5°, SD 3.6, p = 0.851). Guidewire version using the custom jig (mean error 1.0°, SD 0.4) was comparable to computer navigation (mean error 3.9°, SD 2.1, p = 0.101) and was superior to the conventional jig (mean error 5.6°, SD 2.9, p = 0.008). Conclusion: CT-based, patient specific guidewire alignment jigs provide a satisfactory level of accuracy for alignment of the femoral component. A custom guidewire alignment jig is comparable to computer navigation and may be a better alternative to conventional instrumentation for placement of the initial femoral guidewire in hip resurfacing. Accuracy results of the device approach those previously established for imageless computer navigation in hip resurfacing (1).
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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 | 0.003 | 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) | 0.001 | 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".