Proximally Versus Fully Porous-coated Femoral Stems: A Multicenter Randomized Trial
Bibliographic record
Abstract
UNLABELLED: There are two broad-based categories of cementless femoral component designs: proximally porous-coated and fully porous-coated. While both have been widely used, there remains debate regarding differences in clinical outcome scores, relative incidence of thigh pain, and development of stress shielding. We investigated these variables in a multicenter prospective randomized blinded clinical trial of 388 patients from three centers: 198 patients had a proximally porous-coated tapered cementless femoral component and 190 patients had a fully porous-coated cementless femoral component. A minimum followup of 2 years (mean, 6.7 years; range, 2.0-8.65 years) was available in 367 of the 388 patients (95%). We observed no differences in age at surgery, body mass index, or preoperative clinical outcome scores (WOMAC, SF-12, Harris hip score, UCLA activity, thigh pain) with the two groups. We determined serial bone density changes in a subcohort of 72 patients from two of the three centers. The postoperative clinical outcome scores were similar at all followup intervals, and we observed no differences in the incidence of thigh pain at any time. Bone density reduction in Gruen Zone 7 was greater with the fully coated stem than the proximally coated stem (24% versus 15% reduction, respectively). Both fully and proximally coated stems performed well, with no clinical differences at 2 years' followup, except in bone mineral density evaluations. LEVEL OF EVIDENCE: Level I, therapeutic study. See Guidelines 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 | 0.005 | 0.006 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.004 | 0.003 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.003 | 0.002 |
| Insufficient payload (model declined to judge) | 0.006 | 0.001 |
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".