Temporal Trends in Revision Burden Ratio for Hip and Knee Arthroplasty: A Comparative Analysis of Large National Registries.

BACKGROUND: The proportion of revision surgeries among all arthroplasties performed annually suggests a higher revision burden for total knee arthroplasty (TKA) than for total hip arthroplasty (THA). This study analyzed temporal trends in the knee-to-hip (K/H) revision burden ratio (RBR) over the past decade; evaluated hip and knee RBRs separately; compared trends across four national arthroplasty registries; and assessed changes in revision causes for THA and TKA over time.

METHODS: A retrospective, registry-based observational study was conducted using publicly available annual reports from four national arthroplasty registries in the United Kingdom (UK), Australia, the United States, and Sweden. Annual numbers of primary and revision THA and TKA procedures were extracted. Hip and knee Revision Burden Ratios (RBR) and Knee to Hip Revision Burden Ratios (K/H RBR) were calculated annually. Temporal trends were assessed using linear regression, and revision causes common to all registries were analyzed for the 2018 to 2023 period.

RESULTS: Across registries, primary arthroplasty volumes increased substantially, with knee procedures exceeding hip procedures. Globally, the K/H RBR increased significantly (β = 3.63 percentage points/year, R2 = 0.876, P < 0.001), driven by a decrease in hip RBR (β = -0.165, P = 0.006) and an increase in knee RBR (β = 0.207, P < 0.001). Similar trends were observed in the UK, Australia, and Sweden, whereas no significant temporal change was identified in the United States. The proportion of revisions due to aseptic loosening declined significantly, whereas infection and periprosthetic fractures increased over time, particularly after TKA.

CONCLUSION: Revision burden is progressively shifting from hip to knee arthroplasty, driven by declining aseptic loosening and a concomitant rise in infection-related revisions, particularly after TKA, where infection is becoming the predominant failure mechanism. These findings have major implications for clinical practice and highlight the need for infection-focused prevention and treatment strategies.