The reason for discarding the skin cutting blade and replacing it with an unused blade for deeper tissue dissection is to avoid bacteria that may be present in the skin, hair follicles or sweat glands from being carried deeper into the wound, thereby increasing the risk of deeper infection.

This practice of blade replacement has been controversial, as there are numerous studies for and against this practice. However, these studies also have some problems that lead to unreliable findings. For example, some scholars have compared the rate of positive bacterial cultures for skin-cutting blades versus deeper blades.

Four common types of orthopedic surgery were selected: total hip arthroplasty, total knee arthroplasty, lumbar spine surgery, and cervical spine surgery, using a total of 344 skin-cutting blades.

The bacteria obtained by culture were mainly staphylococci. Overall, 35 (5.1%) of the 688 samples were positive for bacteria. 344 cutaneous blades were positive for bacteria at a rate of 4.9%; 344 unused blades were positive for bacteria at a rate of 5.2%; no significant difference was seen between the two groups (P>0.05).