NEUTRAL MECHANICAL ALIGNMENT: STICKIN' WITH THE ONE THAT BRUNG YA! – OPPOSES
Bibliographic record
Abstract
Conventional total knee arthroplasty aims to place the joint line perpendicular to the mechanical axis resulting in an overall neutral mechanical alignment. This objective is promulgated despite the fact healthy adult populations are on average in varus with few proximal tibias being neutral to the mechanical axis. The goal of a neutral mechanical axis is based largely on historical studies and the fact that it is easier to make a neutral tibial cut with conventional jigs and the eye. In order to balance the flexion and extension gap to accommodate a neutral tibial cut, in most patients, asymmetrical distal and posterior femoral cuts are required. The resulting position of the femoral component could be considered to be “mal-rotated” with respect to the patient9s soft tissue envelope. Soft tissue releases are often required to “balance” the knee. Planning and execution of the surgery are largely based off 2-dimensional radiographs which grossly oversimplifies the concept of alignment to the coronal plane, largely ignoring what happens to the knee in 3 dimensions through range of motion and 4 dimensions with respect to gait, stair climbing, etc. Subsequently, sticking with neutral mechanical for all engenders the “looks9 good, feels bad” phenomenon seen in many patients that may in part drive the higher dissatisfaction rates seen in knee arthroplasty globally compared to hip arthroplasty. New imaging and surgical techniques allow for the identification of patient specific alignment targets and the ability to more precisely execute the surgical plan with respect to 3-dimensional placement of the components. Long-term outcomes studies as well as more recent studies on “kinematic” positioning suggest that deviation away from a neutral mechanical target may in fact be safe with respect to survivorship and provide better function with a more “natural” feeling knee.
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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 | 0.002 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.003 | 0.004 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.001 | 0.003 |
| Research integrity | 0.002 | 0.003 |
| Insufficient payload (model declined to judge) | 0.017 | 0.010 |
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".