Effect of body mass index on postoperative mechanical alignment and long-term outcomes of residual varus after total knee arthroplasty: a retrospective cohort study of 671 knees
Bibliographic record
Abstract
Abstract Background High body mass index (BMI) is associated with increased rates of complications after total knee arthroplasty (TKA). Here, we aimed to investigate the potential association between high BMI and incidence of postoperative misalignment in patients undergoing TKA for varus osteoarthritis. We also evaluated whether higher BMI is associated with shorter prosthetic survival and worse clinical function in patients with postoperative residual varus. Methods We retrospectively reviewed 671 patients who underwent primary TKA for varus osteoarthritis between January 2010 and December 2015. The mean follow up was 8.16 years (± 1.45 years). Patients were divided into five groups depending on their BMI: normal weight (< 25.0 kg/m2), overweight (25.0–29.9 kg/m2), class I obese (30.0–34.9 kg/m2), class II obese (35–39.9 kg/m2), and class III obese (> 40 kg/m2). All patients underwent standing, full-length radiography before and after surgery in order to measure the mechanical hip-knee-ankle axis angle (HKA). After excluding 496 non-varus knees, we followed up 175 residual varus knees. Among the BMI subgroups, we compared prosthetic survival and knee function scores, including Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, Knee Society Knee Score (KS-KS), Knee Society Function Score (KS-FS), Forgotten Joint Score (FJS), and range of motion (ROM). Results Multivariate and logistic regression revealed that preoperative alignment and higher BMI were associated with higher risk of postoperative misalignment. ROM and KS-FS were similar among all groups. WOMAC was higher in the normal and overweight groups than in the other groups. FJS and KS-KS gradually decreased with increasing BMI. Kaplan-Meier survival analysis showed a non-significant trend towards lower prosthetic survival with higher BMI. Conclusions Higher BMI is associated with greater risk of misalignment after TKA. Among patients with postoperative residual varus, those with class II and III obesity had worse long-term clinical outcomes. However, long-term prosthetic survival was similar between among the BMI subgroups. Trial registration: The trial was registered in the Chinese Clinical Trial Registry (ChiCTR2000038360).
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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 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| 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 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".