Similar femoral stem fixation but less metaphyseal loss of bone mineral density with a taper-wedge design and diaphyseal bone preservation with a long and round-tapered design: a 5-year randomized RSA and DXA study of 50 patients
Bibliographic record
Abstract
BACKGROUND AND PURPOSE: The new Tri-Lock bone -preserving stem with a collarless proximal-coated tapered-wedge design was compared with a classic well-proven collarless proximal-coated long and round-tapered design. Our primary aim was to compare femoral stem fixation (subsidence) of the Tri-Lock stem with the classic Summit stem, and secondarily to compare the change in periprosthetic bone mineral density (BMD) and PROMS between stem groups. METHODS: In a patient-blinded randomized controlled trial, 52 patients at mean age 60 (SD 6) received cementless Tri-Lock (n = 26) or Summit (n = 26) femoral stems with a cementless Pinnacle cup, a cross-linked polyethylene liner, and a CoCr head. Patients were followed for 5 years with radiostereometric analysis (RSA), dual-energy X-ray absorptiometry (DXA), and patient-reported outcome measures (PROMs). We measured mean (CI) values of migration and periprosthetic bone mineral density and calculated between group differences. RESULTS: At 2-year follow-up, the mean difference in subsidence was 0.14 mm (95% confidence interval [CI] -0.27 to 0.56) and below the chosen minimal clinically important difference of 0.6 mm. At 5-year follow-up, for the Tri-Lock and Summit stems, the mean subsidence was 0.38 (CI 0.04-0.72) and 0.24 (CI 0.09-0.57), and the mean retroversion was 1.68° (CI 0.80-2.55) and 1.53° (CI 0.68-2.37), respectively. There was initial periprosthetic BMD loss for both stems. At 5-year follow-up, the mean metaphyseal bone loss was minimal for the Tri-Lock stem (zone 1: -2.8% vs -11.5%) while the Summit stem preserved the medial diaphyseal bone better (zone 6: -7.1% vs -13.6%). At the medial stem tip, BMD was increased with the Summit stem (zone 5: +3.4% vs -1.5%). At 5-year follow-up, median EQ5D was 1 in both groups and median Oxford Hip Score was 47 (Tri-Lock) and 45 (Summit) with no statistical significant differences between groups. CONCLUSION: The Tri-Lock and the Summit stems displayed similar migration until mid-term follow-up. At 3 months both stems had lost metaphyseal periprosthetic bone mineral density (BMD). During the following years, the new design regained more metaphyseal BMD. Contrarily, the long and round-tapered stem design regained or even increased diaphyseal BMD. PROM scores improved beyond the reference level for both groups.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".