Is Your Surgical Helmet System Compromising the Sterile Field? A Systematic Review of Contamination Risks and Preventive Measures in Total Joint Arthroplasty
Authors: Porto Joshua R. , Lavu Monish S. , Hecht Christian J. , Kamath Atul F. 
Published: February 2025

Background
Surgical helmet systems remain widely used in total joint arthroplasty (TJA) despite evidence to suggest that they may increase infection risk via contamination of sterile equipment and operating room air. However, the challenging nature of conducting high-quality clinical trials to study outcomes with low incidence, such as prosthetic joint infection (PJI), has made drawing definitive conclusions from the available experimental studies difficult. Therefore, a comprehensive analysis of the best available evidence is needed to clarify the association between surgical helmet system use and contamination and infection risk and to provide clinical recommendations for use in TJA.

Questions/purposes
This systematic review aimed to address the following questions: (1) What is the level of sterility of surgical helmet systems and concomitantly used personal protective equipment (PPE)? (2) Is there an association between surgical helmet systems and air contamination within the operating room? (3) Does the use of a surgical helmet system affect wound contamination and/or infection?

Methods
PubMed, Medline, EBSCOhost, and Google Scholar were queried on July 31, 2024, to identify studies published from inception to July 2024 that have evaluated the impact of surgical helmet system use in TJA on sterile field contamination (operating room air, PPE, sterile equipment), wound contamination and infection, or practices that may impact related outcomes. Inclusion criteria were that the study evaluate the sterility, donning, or intraoperative use (including mock TJA) of a surgical helmet system in association with contamination or infection. The following articles were excluded: case reports, case series, reviews, commentaries, editorials, duplicate studies among databases, gray literature, studies specific to a procedure other than TJA, and studies unavailable as a full-text English manuscript. After screening 536 articles, 21 were included. The 13 studies that evaluated the sterility of surgical helmet systems and concomitantly used PPE comprised 126 gowning simulations, 445 mock TJA procedures, and 191 patients who had undergone TJA. The seven studies that evaluated contamination of operating room air comprised 38 gowning simulations, 82 mock TJA procedures, and 96 patients who had undergone TJA. Three studies directly evaluated wound contamination or infection, comprising 83,888 patients who had undergone TJA. Risk of bias was determined via the Methodological Index for Nonrandomized Studies (MINORS) tool, with a mean ± SD score of 20 ± 1.4 (of 24) for comparative studies and 14 ± 0.8 (of 16) for noncomparative studies, indicating good study quality. Notably, the quality of evidence was limited by the inclusion of experimental study designs that did not directly measure infection; however, the inclusion of such studies is necessitated by the infeasibly large study population required to directly evaluate the association between surgical helmet systems and infection prospectively. Heterogeneity among studies precluded meta-analysis, and a qualitative synthesis was instead conducted.

Results
The best available evidence suggests that surgical helmet systems frequently harbor microbes known to be common causes of SSI and PJI, and that their improper donning and use (for example, activation of the exhaust fan before fully gowned) can lead to the contamination of gowns and sterile gloves worn by surgical personnel. Furthermore, several studies suggest that the exhaust from surgical helmet systems presents a potential source of operating room air contamination, although there were mixed findings based on the location of air sampling and whether or not a toga was used and the gown-glove interface was sealed (both of which were shown to mitigate airborne contaminants). However, whether there is a direct association between surgical helmet system use and wound infection remains understudied and unclear, with one retrospective comparative analysis demonstrating no difference in odds of infection when comparing surgical helmet systems used to a standard gown during TJA, and another reporting reduced odds of revision for deep infection with a 12-month follow-up time when a surgical helmet system was used (adjusted OR 0.55).

Conclusion
Although the best available evidence suggests that the use of surgical helmet systems in TJA can increase the likelihood of sterile field contamination, including sterile surgical attire and equipment, as well as operating room air, that finding derives largely from experimental studies with effect sizes (based on endpoints like colony counts) that are difficult or impossible to convert to real-world infection risk. Robust investigations into the association between surgical helmet systems and infection are limited by the need for infeasibly large study populations to conduct sufficiently powered clinical trials, with no evidence found by this review to directly implicate surgical helmet systems in increased infection risk. Still, because the risk for contamination has been shown to be driven substantially by donning technique and the type of gown used, we recommend waiting to activate the surgical helmet system fan until fully gowned, taping the gown cuff at the inner glove, utilizing a toga system set up, and implementing sterilization protocols for reusable helmets.

Clinical Relevance
When used appropriately, there is insufficient high-quality evidence to suggest that surgical helmet systems pose meaningful harm to patient safety. However, the persistent lack of evidence to demonstrate their effectiveness in achieving the initial purpose of reducing infection warrants careful evaluation of their utility in TJA. Ample consideration must be given to their role as personal protection systems for surgical personnel, as studies have demonstrated superior protection from surgical debris and splatter compared with conventional surgical attire. While the added cost of surgical helmet systems may therefore be justified, surgeons wishing to continue utilizing surgical helmet systems in their practice should do so while taking proper precautionary measures to mitigate contamination risks.