Registry-based cohort study reveals infection rates after knee replacement, indicating arthroplasty registries miss substantial non-revision reoperations.
Key Points
To estimate the incidence of early infection-related reoperations after primary and revision knee replacements using linked nationwide register data.
Searched the Finnish Arthroplasty Register (FAR) for primary unicompartmental knee arthroplasties (UKAs), primary total knee arthroplasties (TKAs), and revision TKAs performed between 1997 and 2003.
Cross-referenced FAR revision data with the national Hospital Discharge Register (HDR) to capture additional reoperations including debridements, partial/total revisions, resection arthroplasties, arthrodeses, and amputations.
Within the first postoperative year, reoperation rates due to infection were 0.33% (95% CI: 0.13–0.84) for primary UKAs, 0.52% (95% CI: 0.45–0.60) for primary TKAs, and 1.91% (95% CI: 1.40–2.61) for revision TKAs.
The overall 1-year infection rate was 0.77% (95% CI: 0.69–0.86) using FAR data alone versus 0.89% (95% CI: 0.80–0.99) when combining FAR and HDR records.
Annual infection rates remained constant across all knee arthroplasty cohorts over the observation period, with FAR reliably capturing full revisions but missing other infection-related surgical interventions.