Dropped implants in OR: A hidden contamination threat

The “five-second rule” doesn’t hold in the operating room, where even brief contact with the floor contaminates implants and challenges surgeons’ real-time responses. 

Study: The “five-second” rule for dropped food: does it apply to dropped medical objects in the operating room? A randomized study of disinfection approaches for contaminated arthroplasty implants. Image credit: Yulai Studio/Shutterstock.com

A recent randomized bench study published in Infection Control & Hospital Epidemiology evaluated whether immersion in sterile chlorhexidine-alcohol (CHG) or povidone-iodine (PI) could effectively reduce the bioburden of polyethylene liners accidentally dropped onto operating room (OR) floors, compared with ethanol immersion or no intervention.

Implant Drops in the OR: An Overlooked Clinical Risk

Contrary to common assumptions, a briefly dropped implant in the OR is not free of contamination and results in measurable microbial contamination. Accidental implant drops occur more frequently than anticipated, with a notable proportion occurring during emergency procedures when operative conditions are most demanding. Despite the clinical significance of this event, no standardized guidelines currently exist to direct surgeons in managing a dropped implant intraoperatively.

OR floors, like most surfaces in clinical environments, are regularly colonized by harmful pathogens. Therefore, any item that comes into contact with the floor, especially surgical implants, poses a real contamination risk. A previous study examined expert responses to the use of dropped polyethylene (PE) implants in the OR. This study found that the majority of experienced orthopedic surgeons prefer replacement to contaminated implants. Some surgeons, however, have described alternative approaches, such as soaking the implant in an antiseptic solution or temporarily placing a provisional implant while a replacement is obtained.

Evaluating Disinfectant Efficacy on Contaminated PE Liners

The current prospective, randomized controlled bench study evaluated the efficacy of disinfectants in decontaminating PE liners dropped on OR floors. This study was conducted across four orthopedic ORs at Duke University Medical Center between June and July 2025. It simulated real-world intraoperative conditions.

PE liners from primary hip or knee arthroplasty cases were placed on the OR floor for 10 seconds at the surgeon’s standing position. Each liner surface was divided into two halves: the left was swabbed pre-intervention, and the right post-intervention. Liners were randomized 1:1:1:1 to control (no disinfection), 2 % chlorhexidine-alcohol (CHG) in 70 % isopropyl alcohol, 10 % povidone-iodine (PI), or 70 % ethanol (EtOH). All disinfectants were sterile.

Floor sponge samples were collected to assess baseline bioburden. Samples were plated on standard microbiological media, colony-forming units (CFUs) were quantified, and organisms were identified by 16S rRNA sequencing.

The primary outcome was total CFU count post-intervention; the secondary outcome was the proportion of liners contaminated with clinically important pathogens. Researchers defined clinically important pathogens as Staphylococcus aureus, Enterococcus species, and Gram-negative bacteria.

Dropped PE Liners Harbor Clinically Relevant Pathogens, Effectively Reduced by CHG and PI Disinfectants

The current study analyzed 213 PE liners (142 hip and 71 knee liners) and randomized them prospectively into a control group (35 hip, 21 knee), an EtOH group (31 hip, 22 knee), a CHG group (38 hip, 16 knee), and a PI group (38 hip, 12 knee). This randomized design allowed for direct comparative assessment of disinfectant efficacy under standardized operative conditions.

To characterize the baseline microbial environment of the OR, nineteen sponge samples were collected from designated floor-drop sites. Analysis indicated a heavily contaminated OR floor environment. The median total CFU count was 2,958, and all 19 samples yielded microbial growth, indicating universal contamination across the sampled sites.

Pathogen-specific analysis identified methicillin-resistant and methicillin-sensitive Staphylococcus aureus (MRSA/MSSA) in 42 % of samples despite a median CFU of 0, Enterococcus spp. in 95 % (median CFU 3,690), and Gram-negative species in 63 % (median CFU 399), confirming a diverse and substantial microbial burden that poses a direct contamination risk to PE liners upon floor contact.

Pre-intervention bioburden across all liners was 10 CFU, confirming measurable microbial contamination of implant surfaces prior to disinfection. Following intervention, the overall median bioburden decreased to 0 CFU, reflecting a statistically significant reduction in surface contamination.

CHG and PI demonstrated comparable efficacy, achieving statistically significant reductions in CFU relative to the untreated control, highlighting their superior antimicrobial performance. However, ethanol failed to achieve a statistically significant reduction compared with control and was significantly less efficacious than both CHG and PI, suggesting its inadequacy as a standalone disinfectant for implant surfaces.

When stratified by implant type, all three disinfectants significantly reduced CFU in knee liners compared with the control. In hip liners, however, only CHG and PI demonstrated statistically significant reductions. Ethanol did not outperform control, highlighting a potential difference in performance that may relate to implant characteristics or sample size rather than a confirmed mechanism.

Clinically important pathogens, organisms with established relevance to periprosthetic joint infection (PJI), were recovered from 34.3 % of PE liners prior to disinfection. Post-intervention, pathogen recovery decreased significantly to 19.2 % of liners.

CHG and PI both significantly reduced clinically important pathogen recovery compared with the control. Ethanol revealed no statistically significant difference from either control or PI, and was significantly less effective than CHG, further reinforcing its limited clinical utility in this context.

S. aureus prevalence declined from 22 % to 12 % post-disinfection, with CHG outperforming both control and ethanol while performing comparably to PI. Enterococcus spp. prevalence fell from 16 % to 8 %, though no significant between-arm differences were observed. Gram-negative prevalence decreased from 12 % to 3 %, with all three disinfectants outperforming control but showing no significant differences among themselves, indicating similar effectiveness rather than a defined class-level mechanism.

By implant type, knee liners showed no significant between-arm differences, while hip liners mirrored overall trends, with CHG and PI outperforming control and ethanol, possibly due to differences in geometry, surface area, or sample size.

Disinfection reduces risk but does not eliminate bacteria

The current study findings establish that OR floors are a significant and underappreciated source of microbial contamination, capable of transferring clinically relevant pathogens to PE liners upon contact. Although CHG and PI reduced bacterial burden, neither reliably achieved sterility, indicating a persistent residual risk that cannot be dismissed. Residual contamination may persist even after disinfection.

Replacement of a dropped PE liner, therefore, remains the recommended course of action. When replacement is not feasible, immersion in CHG or PI represents the most defensible rescue strategy. Patients should be informed of such events and monitored for signs of infection. Going forward, standardized intraoperative rescue protocols are needed to reduce variability in clinical decision-making and improve patient safety outcomes. Importantly, these findings are based on a bench study of contamination and do not directly demonstrate clinical infection outcomes.

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