Infection After Total Knee Arthroplasty: Does Timing of Pre-operative Antibiotics Matter?

Background: Since the 2003 NIH consensus statement, the use of prophylactic antibiotics in total knee arthroplasty (TKA) has been the standard of care. Some studies recommend antibiotic administration within 1 h of skin incision, but no specific time frame has been delineated. The objective of this study was to determine if timing of pre-operative antibiotics is associated with post-operative infection after TKA. Materials and Methods: An institutional database from a multi-center health-care system was queried with ICD-10 codes and reviewed for patients undergoing primary TKA between March 2020 and December 2020. The rate of superficial surgical site infection (SSI) and periprosthetic joint infection (PJI) was compared with pre-operative antibiotic timing. PJIs were defined based on 2018 MSIS criteria and superficial SSIs were other infections that did not meet MSIS criteria. Antibiotic timing was separated into 15-min cohorts from 0 min before skin incision to over 45 min before incision. Further comparison between patients who received antibiotics within 30 min of incision with those who received antibiotics greater than 30 min prior was performed. Results: Of the 2511 patients who underwent primary TKA, 19 were found to have post-operative infections. There were 7 SSIs, and 12 PJIs, 16 of the post-operative infections occurred when patients received antibiotics <30 min before incision. There was no significant difference in SSIs or PJIs between each 15-min time interval of antibiotic administration (P = 0.45) or between the 30-min time intervals (P = 0.09). Conclusion: Our study demonstrates no difference in post-operative infection based on pre-operative antibiotic timing. As long as antibiotics are given within 60 min of incision, preferentially 30–60 min before incision, their timing does not have a significant effect on post-operative infection following TKA. Keywords: Pre-operative antibiotics, periprosthetic joint infection, superficial skin infection, total knee arthroplasty, complications