Relationship between the surgical epicondylar axis and the articular surface of the distal femur: an anatomic study
Bibliographic record
Abstract
Many authors presented the epicondylar axis as the fixed axis of rotation of the femoral condyles during flexion of the knee. Positioning of the femoral component of a total knee arthroplasty (TKA) based on the epicondyles has been proposed. This work is a critical analysis of this concept. Metallic bodies were inserted at the level of collateral ligament insertions on 16 dried femurs, allowing us to locate the surgical epicondylar axis. The dried femurs were studied using standard radiographs and CT-scan. CT cuts were made perpendicular to the epicondylar axis. The medial mechanical femoral angle and the epicondylar angle were measured on the radiographs. The posterior and distal epiphyseal rotations relative to the epicondylar axis (Posterior Condylar Angle, PCA, and Distal Condylar Angle, DCA, respectively) were measured on the CT-scans. PCA and DCA values were compared. The centre of the posterior femoral condyles was located on sagittal reconstructions using the tangent method and was confirmed with circular templates, and then compared to the location of the epicondyles. Circle-fitting of the entire femoral condylar contours centred on the epicondyles was also tried. The mechanical femoral axis was nearly perpendicular to the epicondylar axis but with important variations. The average PCA and DCA were 1.9 degrees +/- 1.8 degrees and 3.1 degrees +/- 2.1 degrees , respectively. No relationship could be established between the mechanical femoral angle and the PCA. The individual differences between the PCA and the DCA averaged 2.2 degrees . A significant distance was found between the centre of the condylar contours and the epicondyles: 6.5 mm in average on the lateral side (range 2.3-11.3 mm) and 8.4 mm on the medial side (range 4.0-11.6 mm). Circle-fitting of the entire medial or lateral femoral condylar contours centred on the epicondyles was not possible. The centre of the posterior femoral condyles is significantly different from the epicondylar axis, thus refuting the conclusions of previous authors. Furthermore, considering the differences between the distal and posterior condylar angles shown here, as well as the difficulty of repeatably locating the epicondyles during surgery, using the epicondylar axis as the only landmark to position the femoral component during a first intention TKA is not recommended. The surgical epicondylar axis does not appear to be an adequate basis for the understanding of the shape of the distal femur.
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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 | 0.002 |
| 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 | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".