ABSTRACT
BACKGROUND: Airborne biologic particles (ABPs) can be measured intraoperatively to evaluate operating room (OR) sterility. Particulate matter (PM) up to 2.5 microns can contain microbial species which may increase infection risk. Our study examines the differences in air quality and ABP count in primary total knee arthroplasty (TKA) and revision TKA (rTKA). METHODS: We analyzed primary and rTKAs in a single OR at an academic institution from January 2020 to December 2020. Procedures from March 15, 2020, to May 4, 2020, were excluded to avoid COVID-related confounding. Temperature, humidity, and ABP count per minute were recorded with a particle counter intraoperatively and cross-referenced with surgical data from the electronic health records using procedure start and end times. Descriptive statistics were used to evaluate the differences in variables. P values were calculated using t-test and chi-square test. RESULTS: A total of 107 TKA cases were included: 79 (73.8%) primary TKAs and 28 (26.2%) rTKAs. Time spent in an OR was significantly higher for rTKAs (primary: 176 ± 46.7 minutes vs revision: 220 ± 47.1 minutes, P < .0001). Compared to primary TKAs, rTKAs had significant percent increases in ABP rates for particles measuring 0.3 µm (+70.4%, P < .001), 0.5 µm (+97.2%, P < .0001), 1.0 µm (+53.2%, P = .001), and 2.5 µm (+30.3%, P = .017) and for PM 2.5 (+108.3%, P < .001) and PM 5.0 (+105.6%, P < .001). CONCLUSION: rTKAs had significantly longer time spent in an OR and significant percent increases in ABP rates for particles measuring 0.3 µm, 0.5 µm, and 1.0 µm compared to primary TKAs. Measurements of PM 2.5 and 5.0 (which can contain large numbers of microbes) were also significantly greater in rTKAs. Further research is needed to determine whether the size and quantity of ABPs translate to higher infection rates after rTKA.