Intermediate to Long-Term Outcomes of Total Ankle Replacement with the Scandinavian Total Ankle Replacement (STAR)
Bibliographic record
Abstract
BACKGROUND: The Scandinavian Total Ankle Replacement (STAR) prosthesis has been in clinical use since 1981, with investigational use in the U.S. since 1998. Few studies of the North American version of the STAR are available. This prospective cohort study analyzed intermediate to long-term outcomes of total ankle arthroplasty with use of the STAR prosthesis at two Canadian centers. METHODS: Consecutive patients who received the STAR prosthesis between 2001 and 2005 were enrolled at two large, urban teaching hospitals. Patients were annually evaluated clinically, and the Ankle Osteoarthritis Scale (AOS) and the Short Form (SF)-36 were administered. RESULTS: One hundred and eleven ankles underwent arthroplasty with the STAR prosthesis. One-half of the patients were male; the mean age was 61.9 ± 11.7 years. Sixty-eight of the ankles underwent a total of 121 additional procedures during ankle arthroplasty, including gastrocnemius release, subtalar arthrodesis, triple arthrodesis, tendoachilles lengthening, and removal of hardware. The mean duration of follow-up for all living patients without revision (seventy-three ankles) was 9.0 ± 1.0 years. Thirteen (12%) of the ankles required metal component revision at a mean of 4.3 ± 3.0 years (range, 0.6 to 10.2 years). Twenty (18%) of the prostheses underwent polyethylene bearing exchange, mostly due to fracture, at a mean of 5.2 ± 2.1 years (range, 1.5 to 9.3 years). Most (97%) of the revisions and exchanges occurred in patients with a diagnosis of primary, secondary, or posttraumatic osteoarthritis (p = 0.0003). The mean change from baseline to final follow-up was -36.5 ± 23.3 points for AOS pain, -38.6 ± 26.8 points for AOS disability, and 9.6 ± 10.3 points for the SF-36 physical component summary score. The SF-36 mental component summary score was unchanged. CONCLUSIONS: Intermediate patient-reported outcomes were good after ankle arthroplasty with the STAR prosthesis performed by experienced surgeons, and long-term outcomes demonstrated a 12% rate of metal component revision and 18% rate of polyethylene bearing failure. The revision rate was substantially higher among the first twenty ankles than among subsequent ankles, but the early ankles had nearly two years' longer follow-up than subsequent ankles. Additional study to elucidate possible reasons for polyethylene bearing failure is warranted. LEVEL OF EVIDENCE: Therapeutic Level IV. 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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| 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".