Revision Hip Arthroplasty Using a Porous-coated or Taper ZMR Implant: Minimum 10-year Follow-up of Implant Survivorship
Bibliographic record
Abstract
INTRODUCTION: The Zimmer Modular Revision hip (ZMR) system is available in two stem options, a porous-coated cylindrical (PCM) and a taper (TM) stem. Several concerns have been reported regarding modular implants. Specifically, because of early junctional fractures, the ZMR system was redesigned with a wider modular interface. As such, we designed a study assessing long-term ZMR survivorship and functional and radiographic outcomes. METHODS AND MATERIALS: A search of our institutional research database was performed. A minimum 10-year follow-up was selected. The following two cohorts were created: PCM and TM stems. The Kaplan-Meier survival analysis was performed, and causes of stem failure requiring revision surgery were collected. Functional outcomes as per the Harris Hip Score and radiographic stem stability were assessed as per the Engh classification. RESULTS: A total of 146 patients meeting the inclusion criteria were available for follow-up (PCM = 68, TM = 78). The mean follow-up was 13.4 years clinically and 11.1 years radiographically for the PCM cohort. Similarly, the TM cohort had a follow-up of 11.1 years clinically and 10.5 years radiographically. The Kaplan-Meier survivorships were 87.1% and 87.8% at 15 years for the PCM and TM cohorts, respectively. The most common cause of failure requiring revision surgery overall was aseptic loosening (PCM = 1.4%, TM = 5.6%). The mean postoperative Harris Hip Score was as follows: PCM = 71.2 and TM = 64.7. Engh type I or II stem ingrowth was as follows: PCM = 85% and TM = 68%. DISCUSSION: Good survivorship using the ZMR stem system can be expected at up to 15 years. Aseptic loosening remains the most commonly encountered problem for both PCM and TM stems. Previously identified modular junctional weakness seem to have been addressed.
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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 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| 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".