Medial Pivot Designs Versus Conventional Bearing Types in Primary Total Knee Arthroplasty: A Systematic Review and Meta-Analysis of Randomized Controlled Trials
Bibliographic record
Abstract
BACKGROUND: Medial pivot (MP) designs are growing in popularity. They provide increased sagittal plane stability and theoretically replicate some aspects of native joint kinematics, which may improve total knee arthroplasty outcomes. METHODS: A systematic review was performed of randomized controlled trials (RCTs) that compared MP designs with cruciate-retaining, posterior-stabilized (PS), ultracongruent, or mobile-bearings in primary total knee arthroplasty, according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The primary outcome measures were all clinical function scores, patient-reported outcome measures, and range of motion. The secondary outcome was complications. Two authors independently selected studies, performed data extraction, and risk-of-bias assessment. Studies at high risk of bias were excluded from meta-analysis. Treatment effects were assessed using random-effects meta-analysis and quantified using pooled mean differences or incidence rate differences as appropriate. RESULTS: Eight RCTs met inclusion criteria. Five compared MP with PS, two with ultracongruent, and one with cruciate-retaining and mobile-bearing. In total, 350 knees were randomized to MP and 375 to conventional bearings. One RCT was excluded from meta-analysis because of high risk of bias. Meta-analysis comparing MP with PS only was possible and found no differences at any time points for any outcome measure, including 2-year follow-up for Oxford Knee Score (MD = 0.35 favoring PS; 95% CI -0.49 to 1.20) and range of motion (MD = 1.58 favoring MP; 95% CI -0.76 to 11.92, P = 0.30) and 12 months for Western Ontario Arthritis Index (MD = 4.42 favoring MP; 95% CI -12.04 to 3.20, P = 0.09). CONCLUSIONS: There is no difference in clinical outcomes, with contemporary measurement tools, at any time points, between MP and PS. There are insufficient RCTs comparing MP with other bearings.
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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 | 0.065 | 0.075 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.076 | 0.012 |
| Bibliometrics | 0.001 | 0.003 |
| 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) | 0.002 | 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; both teacher heads agree on what is shown here.
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".