After Incision, the Skin Knife Blade Is No More Contaminated Than a Fresh Knife Blade

Area of Science:

• Surgical infection prevention
• Microbiology in healthcare settings
• Orthopaedic surgical techniques

Background:

• The practice of changing surgical knife blades after skin incision is debated, aiming to prevent deeper wound contamination by skin bacteria.
• Existing research on the efficacy of this blade-changing protocol is limited and contradictory, necessitating further investigation.

Purpose of the Study:

• To directly compare the bacterial contamination rates of skin knife blades versus control blades immediately after skin incision in orthopaedic surgery.

Main Methods:

• Surface samples were collected from 344 skin knife blades and 344 control blades using Replicate Organism Detection and Counting plates across four orthopaedic procedures.
• Statistical analysis, including bivariate two-sample z-tests, was employed to compare contamination rates between skin and control blades overall and within subgroups.

Main Results:

• Overall contamination rates were similar: 4.9% for skin blades and 5.2% for control blades (35/688 specimens positive).
• No significant differences in contamination rates were observed between skin and control blades across total hip arthroplasty, total knee arthroplasty, and spine surgeries.
• Factors such as skin preparation, room details, and timing did not influence contamination rates.

Conclusions:

• The study found no evidence supporting the routine changing of knife blades after skin incision to prevent bacterial contamination.
• Contamination rates were equivalent for both skin and control blades, indicating the practice may not offer a significant theoretical advantage.