Determining the relation between total knee arthroplasty surgery site drainage in two weeks after surgery with periprosthetic joint infection (PJI) in two years.

Background: Prosthetic joint infection (PJI) is a devastating complication in total knee arthroplasty (TKA) surgeries and prompt diagnosis and treatment are vital; however, no study has been conducted to determine the relationship between characteristics and duration of surgical site discharge and PJI.

Methods: This is a longitudinal observational study that was performed at Al-Zahra and Kashani and Sadi university hospitals from 2017 until 2019. A total of 961 elective TKA were performed on 850 consecutive patients. Patients were followed up for two years after surgery. Data regarding the occurrence of discharges, types of discharges, duration of discharges, the incidence of PJI and superficial infections were collected.

Results: The rate of superficial and prosthetic joint infection was 0.3% and 0.3%. Patients with infections (either PJI or superficial) had a longer duration of discharge (14.6 days and 13.3 days in PJI and superficial infections respectively, compared to 7.7 days in all of the study population); Bloody-purulent discharge was associated with the development of prosthetic and superficial infections.

Conclusion: Bloody purulent discharge reaching seven days postsurgical in TKA patients is highly suggestive of an underlying infection (PJI or superficial infection) but type and duration of discharge could not be used to differentiate between PJI and superficial infection. Other risk factors for PJI or superficial infection include women's gender, longer surgical duration, longer hospitalization and longer discharge duration.