SLR - July 2021 - Jeanne Mirbey

After Incision, the Skin Knife Blade is no More Contaminated than a Fresh Knife Blade

Reference: Smith EB, Russo KA, Maltenfort MG, Sharkey PF, Rihn J. After Incision, the Skin Knife Blade is no More Contaminated than a Fresh Knife Blade. J Am Acad Orthop Surg. 2021 Jan 15;29(2)

Level of Evidence: Level II, Prospective Observational Study

Scientific Literature Review

Reviewed By: Jeanne Mirbey, DPM
Residency Program: Emory University School of Medicine, Emory Decatur Hospital – Decatur, GA

Podiatric Relevance: The reasoning behind discarding the skin knife blade after the initial skin incision is to prevent bacteria on the skin, hair follicles or sweat glands from being carried into deeper layers of the surgical wound. The aim of this study is to compare cultures obtained from the skin knife blade with a control unused blade, testing each blade at identical times. The authors hypothesize that no difference will be noted in contamination rates between the skin knife blades and fresh unused blades. 

Methods: Two specimens from 344 orthopedic cases (TKA, THA, Spine) were obtained. Two knife blades were opened at the beginning of each surgical case. One of the blades was used by the surgeon to make the skin incision and handed off to the back table and cultured by pressing both sides of the blade into a Replicate Organism Detection and Counting plate. At the same time, the control culture was taken in a similar fashion from the other open unused knife blade. The specimens were sent directly to the microbiology department at the end of the case and evaluated for bacterial growth. All the cases were done in the same institute; the surgeries were performed in four different operating rooms by three different surgeons. All patients underwent the same skin preparation preoperatively and they all received similar preoperative antibiotics. All the surgical sites were prepped with either Duraprep or Chloraprep depending on the surgeon’s preference. 

Results: Overall, 5.1 percent of all the combined specimens resulted in positive cultures, with 17 positive skin blade cultures and 18 positive control cultures. The authors noted no statistically significant difference between the rate of positive cultures for skin blades and control blades. They also noted no statistically significant difference in the rate of positive cultures based on the type of surgical case. There was no difference based on the pre-operative antibiotics, the use of Duraprep versus Chloraprep, the order of the case performed that day, the turnover time or the in-room to incision time. 

Conclusions: The authors conclude that a small rate of contamination of the knife blade exists, but this affects both the skin blade and the control unused blade equally. There seems to be a small amount of contamination in the operating room that is likely based on other factors such as length of surgery, air turbulence, number of personnel in the operating room and door openings. Therefore, a knife blade can be discarded at the discretion of the surgeon for any reason however contamination after cutting through the skin does not seem to be a necessary reason. And so, changing the knife blade after making the skin incision is not an effective way to reduce contamination in the operating room. 

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