No Discernible Difference in Revision Rate or Survivorship Between Posterior Cruciate-Retaining and Posterior Cruciate-Substituting TKA
Bibliographic record
Abstract
BACKGROUND: Many authors and the data of multiple registries have suggested that the use of posterior cruciate-substituting (posterior stabilized [PS]) total knee arthroplasty (TKA) leads to a higher risk of revision compared with the use of posterior cruciate-retaining (CR) TKA. The aim of the present prospective, randomized, long-term study was to compare PS and CR TKA with regard to the clinical, radiographic, and computed tomography (CT) results; the prevalence of osteolysis; revision rate; and survivorship. METHODS: This study included a consecutive series of 300 patients (mean age [and standard deviation], 63.6 ± 6 years) who underwent simultaneous, bilateral TKA in the same anesthetic session. Each patient received a NexGen CR-Flex prosthesis on 1 side and a NexGen LPS-Flex prosthesis on the contralateral side. The mean follow-up period was 18 years (range, 17.5 to 19.5 years). RESULTS: There were no significant differences between the NexGen CR and LPS-Flex TKA groups at the latest follow-up with regard to the mean Knee Society knee score (93 versus 92 points, respectively); the Western Ontario and McMaster Universities Osteoarthritis Index score (19.1 points for both); the University of California Los Angeles activity score (6.1 points for both); range of motion (125° ± 6.1° versus 126° ± 6.5°); radiographic and CT results; and revision rate (6.0% versus 6.3%). No knee had osteolysis. The estimated survival rate at 19.5 years was 94% (95% confidence interval [CI], 91% to 100%) for the NexGen CR-Flex prosthesis and 93.7% (95% CI, 91% to 100%) for the LPS-Flex prosthesis, with revision or aseptic loosening as the end point. CONCLUSIONS: The findings of the present, long-term (minimum follow-up of 17.5 years) clinical study showed that NexGen CR-Flex and NexGen LPS-Flex implants produced excellent clinical and radiographic results. There was no notable clinical advantage of a NexGen CR-Flex implant over a NexGen LPS-Flex implant. LEVEL OF EVIDENCE: Therapeutic Level II . See Instructions for Authors for a complete description of levels of evidence.
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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 | 0.006 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".