A surgical knife, also called a scalpel, is a small bladed instrument used to make incisions during medical or scientific procedures such as surgeries, biopsies, and dissections. Variations of such knives are also used by craftsmen and artists because they are highly effective for precision cuts on or through many different surfaces. The blade of a surgical knife must be incredibly sharp because such knives need to slice through skin and other tissues with a high degree of precision. Surgical knives are usually made of high-quality tempered steel, though more expensive, higher-quality materials are also used on occasion.
Just as there are many different uses for the surgical knife, there are many different kinds of surgical knives. Many have reusable handles and replaceable blades so that one does not need to replace the whole knife when the blade gets dull. There are also many different designs for the blade of a surgical knife. The most common surgical knives, standard scalpels, have one curved cutting surface that is good for cutting through skin and muscle. Other surgical knives may have double-edged blades, chisel-shaped blades, triangular blades, or many other different kinds of blades based on the specific task for which they are needed.
When a surgical knife is actually used for surgery, sterility is a significant concern. In general, a single blade on any bladed instrument used in surgery will only be used once before it is recycled and sterilized. This is true even if the blade is only used for a single, tiny incision. If a blade that is not sterile is used, there is a considerable risk of infection to the individual being cut by the knife. Sterile knives are an essential part of safe and effective surgery.
Sometimes, steel surgical knives are unsuitable for surgery. For example, when surgery is is being performed based on an MRI, or magnetic resonance imaging system, the magnets in the MRI would magnetically attract the blade, making surgery difficult or impossible. For this reason, blades made out of nonmagnetic substances are sometimes used in surgery. Alternatively, surgeries can sometimes be conducted through the use of alternate techniques such as electrocautery or laser incision.
There are generally two main ways in which a surgeon holds a surgical knife. The palamar grip, which is similar to the way one holds a dinner knife, is effective for long, large cuts. The pencil grip, which is similar to the way most people hold writing instruments, is more effective for small, precise incisions.