INTRODUCTION:
Accurate characterization of total knee arthroplasty (TKA) failure mechanisms may inform strategies to reduce failure rates. National joint registries report revision causes, however these are limited by incomplete capture of acute procedures and non-standardized classification of revision indications. This study aimed to combine detailed patient chart review with a standardized failure characterization protocol to: 1) determine the cumulative incidence of failure indications following contemporary TKA, and 2) evaluate temporal trends over the last 23 years.
METHODS:
We analyzed 20,523 primary TKAs performed between 2000 and 2023 across three tertiary hospitals. Failure was defined as revision surgery or reoperation for confirmed periprosthetic joint infection (PJI). Clinical notes, radiographs, and laboratory investigations were reviewed to identify failures and characterize indications using a standardized protocol. Patients who underwent revision outside the study institutions were identified through national joint registry linkage, with external clinical records and imaging retrieved to ensure accurate capture and classification of failures. Competing-risk cumulative incidence analyses were performed.
RESULTS:
At 23 years, cumulative failure incidence was 10.7% (95% confidence interval (CI) 8.4-13.4). The most common cause of failure was PJI (2.9%, 95% CI 2.3-3.6), followed by aseptic loosening (1.5%, 95% CI 1.1-2.1) and patellofemoral arthrosis (0.8%, 95% CI 0.7-1.0). Compared with TKAs performed between 2001-2010, those performed between 2011-2020 showed a small increase in PJI incidence (2.2% vs. 2.0%) at 12-year follow-up, with small decreases in aseptic loosening (0.6% vs. 0.8%) and tibiofemoral instability (0.3% vs. 0.5%). Rates of patellofemoral
arthrosis and polyethylene wear remained unchanged over time.
DISCUSSION AND CONCLUSION:
In this large cohort with comprehensive long-term follow-up, PJI is now the leading cause of TKA failure and has not improved over time despite reductions in mechanical failure mechanisms. These findings identify PJI as the key unresolved challenge in contemporary knee arthroplasty and reinforce the need for targeted prevention strategies.
