When During Total Knee Arthroplasty Is the Risk of Bacterial Contamination the Greatest? A Prospective Study

Infection is a leading cause of primary total knee arthroplasty failure. Numerous strategies for infection prevention have been devised; however, the vast number of variables has made it difficult to isolate impactful factors. This study aims to narrow the scope by parsing the surgical procedure into stages to determine when the contamination risk is elevated. Twenty-six primary knee arthroplasties were divided into six stages: draping, skin incision, bone cuts, trial placement/balancing, implanting of components, and wound closure. Samples were taken at the end of each stage by swabbing surgical instruments and blotting the surgeon's fingertips. An active particle counter was also in operation during the procedure. A viable contaminant was detected during at least one surgical stage in 54% of the cases. The balancing (19%) and implanting (23%) stages tended to have the most occurrences. Of the contaminated cases, 42% had positive cultures transferred from the surgeon's gloves and 12% from the overhead light handle. A positive correlation was seen between the number of staff present and the occurrence of contamination (<i>p</i> = 0.008). The level of airborne particles 10 μm and larger also correlated with the number of staff present (<i>p</i> = 0.025). Limiting the number of personnel being trained per case and changing the surgical team's gloves after balancing may help to reduce the risk of contamination.