Influence of Body Mass Index (BMI) on Functional Improvements at 3 Years Following Total Knee Replacement: A Retrospective Cohort Study
Bibliographic record
Abstract
BACKGROUND: The number of patients presenting for total knee replacement who are classified as obese is increasing. The functional benefits of performing TKR in these patients are unclear. AIM: To assess the influence pre-operative body mass index has upon knee specific function, general health status and patient satisfaction at 3 years following total knee replacement. DESIGN: Retrospective comparative cohort study using prospectively collected data from an institutional arthroplasty register. METHODS: 1367 patients were assessed using the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) and Medical Outcomes Trust Short Form-36 (SF-36) scores supplemented by a validated measure of satisfaction pre-operatively and subsequently at 1,2 and 3 year post-operatively. Comparisons were made by dividing the cohort into 4 groups based on body mass index (BMI) 18.5-25.0 kg/m(2) (n = 253);>25.0-30.0 kg/m(2) (n = 559);>30.0-35.0 kg/m(2) (n = 373);>35.0 kg/m(2) (n = 182). RESULTS: Despite lower pre-operative, 1 and 3 year WOMAC and SF-36 scores patients with the highest BMIs >35.0 kg/m(2) experienced similar improvements to patients with a 'normal' BMI (18.5-25.0 kg/m(2)) at 1 year (Difference in WOMAC improvement = 0.0 (95%CI -5.2 to 5.2), p = 1.00) and this improvement was sustained at up to 3 years (Difference in 1 year to 3 year improvement = 2.2 (95%CI: -2.1 to 6.5), p = 1.00). This effect was also observed for the SF-36 mental and physical component scores. Despite equivalent functional improvements levels of satisfaction in the >35.0 kg/m(2) group were lower than for any other BMI group (>35.0 kg/m(2) = 84.6% satisfied versus 18.5-5.0 kg/m(2) = 93.3% satisfied,p = 0.01) as was the proportion of patients who stated they would have the operation again (>35.0 kg/m(2) = 69.6% versus 18.5-25.0 kg/m(2) = 82.2%,p = 0.01). CONCLUSION: Obese and morbidly obese patients gain as much functional benefit from total knee replacement as patients with lesser body mass indexes. This benefit is maintained for up to 3 years following surgery. However, these patients are less satisfied with their knee replacement and almost a third would not have the operation again.
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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 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 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".