Is There a Time-Dependent Contamination Risk to Open Surgical Trays During Total Hip and Knee Arthroplasty?

Background: Periprosthetic joint infection (PJI) after total hip and knee arthroplasty (TJA) is a devastating complication and intraoperative contamination can be a source for PJI. Currently, many measures are performed intraoperatively to reduce the risk of contamination. The primary purpose of this study was to determine if there is a time-dependent risk of contamination to open sterile surgical trays during TJA cases. Methods: A prospective intraoperative culture swab study was performed. Standard sterile operating room trays without instruments were utilized as the experimental trays. These were opened simultaneously with all other surgical instrumentation needed for the procedure. These trays were left on an isolated Mayo stand next to the scrub tech's table and swabbed at 30-minute intervals. The first swab was performed immediately after opening all sets and the last swab performed on closure of the incision. A new section of the grid-lined tray was swabbed for each data point and the culture analysis was conducted by our institutions' microbiology lab for both quantitative and qualitative analysis. Operating suite room temperature and humidity data was also gathered. Results: Twenty-three consecutive primary TJA cases in high air turnover rooms were included. 13 of the 23 (57%) cases demonstrated culture positive bacterial growth on at least one time point. Of the 109 independent swabs collected, 19 (17%) had bacterial growth. The most common bacterial species isolated was Staphylococcus epidermidis. There were no statistically significant associations between time (p= 0.35), operating room (OR) temperature (p = 0.99), and OR humidity (p = 0.07) and with bacterial growth. Conclusion: In spite of isolating an organism in 57% of cases, we could not identify a time-dependent increase in bacterial contamination throughout our operative cases. We were unable to associate OR environmental temperature and humidity to bacterial growth. Level of Evidence: II.