Ultraclean air systems and the claim that laminar airflow systems fail to prevent deep infections after total joint arthroplasty.

The World Health Organization published guidelines in 2016 for preventing surgical site infections. The guidelines contained a conditional recommendation that laminar airflow (LAF) ventilation systems should not be used to reduce the risk of infection after total joint arthroplasty (TJA). This recommendation was largely based on a systematic review and meta-analysis of information from hospital infection surveillance registries. The recommendation contradicts information published in earlier major studies carried out by Charnley and the UK Medical Research Council (MRC). The first aim of this article is to revisit and explain the MRC study, and reply to criticisms of it. The second aim is to suggest reasons why some recent studies have failed to demonstrate that ultraclean air (UCA) systems reduce deep joint infection after TJA. It demonstrates that if a UCA system establishes average airborne concentrations of microbe-carrying particles (MCPs) <10/m3, and preferably <1/m3, then deep joint infection after TJA will be lower than in conventionally ventilated operating theatres.