Has the bacteriology of periprosthetic joint infection after total knee arthroplasty changed over time? A retrospective cohort study of 2171 patients

INTRODUCTION: Periprosthetic joint infection (PJI) is an uncommon but serious complication of total knee arthroplasty (TKA). A previous retrospective cohort study at our institution reported a PJI incidence of 1.34% between 1993 and 2013. The present study aimed to determine whether the incidence of PJI after TKA has changed at our hospital and to evaluate changes in microbiological patterns between 2014 and 2021. METHODS: In total, 2171 primary TKAs were performed at Queen Mary Hospital in Hong Kong between 1 January 2014 and 31 December 2021. All cases of PJI were identified using the Musculoskeletal Infection Society criteria. Patient demographics, PJI occurrence, and microbiological data were collected and compared with the previously published findings from the 1993-2013 PJI cohort. RESULTS: The incidence of PJI after TKA was 0.64% between 2014 and 2021, representing a significant decrease from the incidence of 1.34% observed at our institution between 1993 and 2013 (P=0.018). There was no significant difference in the incidence of early-onset infection (P=0.095). Methicillin-sensitive Staphylococcus aureus was the most common causative organism, accounting for 57.1% (n=8) of our cohort and 26.5% (n=9) in the previous cohort. CONCLUSION: The incidence of PJI decreased significantly from 1.34% to 0.64% between the two study periods, suggesting the effectiveness of infection-reduction measures implemented at our institution. Minimal differences were observed in the microbiological patterns of PJI between the cohorts.