Timing of periprosthetic joint infections following primary and revision arthroplasty in Ontario: a population-based retrospective cohort study using administrative databases from 2003-2017

Background — Periprosthetic joint infections (PJIs) of the hip and knee are a devastating outcome of arthroplasty, resulting in profound morbidity. As more arthroplasties are performed, there is a need to monitor the long-term risk and trends of infection.

Methods — A population-based retrospective cohort of all primary hip and knee arthroplasties performed in Ontario from April 1, 2003, until March 31, 2017, was created using linked administrative databases with patients followed postoperatively until March 31, 2018. There were 504,332 primary hip and knee arthroplasties performed, with the number of annual procedures increasing an average of 5.8% annually over the study. The primary outcome was hospital readmission for a PJI. Poisson models were used to determine trends over time.

Results — Overall, 7,331 PJIs were identified. The incidence of a PJI following primary arthroplasty was 0.59 out of 100 (95% confidence interval (CI): 0.57 to 0.61) at 90 days and 1.29 of 100 (95% CI: 1.26 to 1.33) at five years, whereas following revision arthroplasty, it was 1.93 of 100 (95% CI: 1.70 to 2.16) at 90 days and 4.89 of 100 (95% CI: 4.52 to 5.26) at five years. The one-year incidence of PJI following primary arthroplasty increased from 0.70 of 100 in 2003 to 0.97 of 100 in 2016 (P < 0.001).

Conclusion — The PJIs are increasing, both because of an increase in the numbers of primary arthroplasties and due to an increase in PJIs occurring within 90 days. There is a need to understand the reasons for the rise in PJIs.