Characterizing the Rotational Profile of the Distal Femur: A Roadmap for Distal Femoral Replacement Surgery
Bibliographic record
Abstract
INTRODUCTION: Standard references for determining rotational alignment are often unavailable when performing distal femoral replacement (DFR) surgery. This study aimed to describe the rotational profile of the distal femoral osteology at common resection levels. METHODS: Adults with CT scans of the bilateral legs were included. Exclusion criteria included fractures, congenital deformity, prior arthroplasty, or inadequate imaging. Referencing the transepicondylar axis, angles were measured in the axial plane using the following reference lines: anterior condylar axis or anterior femoral cortex axis (AFCA), posterior condylar axis or posterior femoral cortex axis (PFCA), lateral projection of the linea aspera (LAA), and Whiteside line (WL). These rotational measurements were assessed at 3, 5, 7, and 9 cm proximal of the joint line. External and internal rotation were denoted as positive and negative, respectively. RESULTS: Fifty-one patients (102 femora) were included (mean age: 62.6 ± 13.4 years; mean body mass index: 26.0 ± 6.7 kg/m 2 ). Proximally, the anterior condylar axis/anterior femoral cortex axis became increasingly internally rotated (3-cm: -13.1 ± 3.5°, 9-cm: -21.2 ± 6.6°), whereas the posterior condylar axis/PFCA became increasingly externally rotated (3-cm: -6.7 ± 2.3°, 9-cm: 9.6 ± 6.1°). WL remained nearly perpendicular (3-cm: 88.8 ± 2.3°, 5-cm: 89.8 ± 3.7°) but was not reliably measured beyond 5 cm. The LAA was measurable proximal to 5 cm from the joint line and was internally rotated (5-cm: -58.5 ± 14.3°, 9-cm: -45.6 ± 13.4°). CONCLUSION: Distally, WL is a reliable anatomic landmark for femoral implant rotation. At more proximal resection levels, the posterior cortex may be a valuable landmark as referencing the linea aspera may lead to gross internal rotation of the femoral implant.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".