Predictors of flexion contracture progression following total knee arthroplasty: role of global sagittal alignment and patient age
Bibliographic record
Abstract
BACKGROUND: Knee flexion contracture (KFC) progression after total knee arthroplasty (TKA) can significantly affect functional outcomes through disruption of the biomechanical knee-hip-spine kinetic chain. This study was conducted to investigate whether preoperative global sagittal alignment parameters, particularly the center of the acoustic meatus-sagittal vertical axis (CAM-SVA), could predict short-term KFC progression after TKA. METHODS: A retrospective case-control study was performed on 760 consecutive TKA cases, with 347 knees meeting inclusion criteria. KFC progression was defined as > 5° increase in knee flexion angle between immediate postoperative and final follow-up radiographs. Demographic factors and radiographic parameters were analyzed using univariate and multivariate logistic regressions. Patient-reported outcomes were assessed using the American Knee Society Score (AKSS) and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Potential sources of bias were addressed through standardized measurement protocols and inter-observer reliability testing. RESULTS: KFC progression was observed in 39 knees (11.2%), with mean progression of 8.0 ± 3.8° over 23.5 ± 13.1 months. Multivariate analysis revealed that CAM-SVA and age were independently associated with KFC progression (odds ratio: 1.02 [95% CI 1.01-1.04], p < 0.05; and 1.09 [95% CI 1.02-1.17], p < 0.01, respectively). At 12 months, the KFC progression group demonstrated significantly lower AKSS scores and higher WOMAC scores (p < 0.05) as compared to the nonprogression group. CONCLUSIONS: CAM-SVA and advanced age were identified as independent predictors of KFC progression following TKA, supporting the hypothesis that global sagittal malalignment contributes to compensatory knee flexion through biomechanical interdependence of the knee-hip-spine kinetic chain. Assessment of preoperative global sagittal alignment may help identify patients at risk for KFC progression and inform individualized treatment strategies.
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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 | 0.004 | 0.004 |
| 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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".