Increased Mortality Following Periprosthetic Joint Infection After Total Knee Arthroplasty: A Microbiologically Verified Nationwide Cohort of 916 Cases

BACKGROUND: Periprosthetic joint infection (PJI) following total knee arthroplasty (TKA) is a serious complication with potential implications for patient mortality. We assessed mortality associated with PJI revisions compared to major aseptic revisions using a microbiologically verified, population-based, nationwide cohort. METHODS: We used data from the Danish Knee Arthroplasty Register and the Danish Microbiology Database. We included patients who underwent PJI revisions between January 1, 2010, and November 9, 2023, and compared them with patients undergoing major aseptic revisions in the same period. The follow-up period was until April 4, 2024. Mortality was calculated using the Kaplan-Meier method. The inverse probability of treatment weighting method was utilized to calculate adjusted hazard ratios with 95% confidence intervals (CIs) comparing PJI and aseptic revisions in terms of mortality. Confounders included in the weighting were age, sex, weight, Charlson Comorbidity Index, and marital status. Estimates were reported with 95% CIs. We identified 916 PJI revisions and 4,129 major aseptic revisions following primary TKA. The mean follow-up time was 7.0 years for PJI revisions and 7.3 years for aseptic revisions. Patients undergoing PJI revisions had a higher proportion of men, older age, greater prevalence of obesity, and higher comorbidity compared to those who had aseptic revisions. RESULTS: The PJI revisions had a crude mortality rate of 5.7 deaths per 100 person-year, and major aseptic revisions had a crude mortality rate of 2.4 deaths per 100 person-year. The adjusted Kaplan-Meier 10-year cumulative mortality was 36% for PJI and 24% for aseptic revisions. Cox proportional hazards analysis demonstrated an adjusted hazard ratio of 1.48 (CI: 1.26 to 1.74, P < 0.001), for PJI-associated mortality. CONCLUSIONS: A PJI following TKA was associated with a significantly higher mortality risk compared to major aseptic revisions.