A scalpel, or lancet, is a small and extremely sharp bladed instrument used for surgery, anatomical dissection, and also for various arts and crafts (called a hobby knife). Scalpels may be single-use disposable or re-usable, and recently Safety Scalpels are the norm in the Operating Rooms. Re-usable scalpels can have permanently attached blades that can be sharpened or, more commonly, removable single-use blades. Disposable scalpels usually have a plastic handle with an extensible blade (like a utility knife) and are used once, then the entire instrument is discarded. Scalpel blades are usually individually packed in sterile pouches but are also offered non-sterile. Double-edged scalpels are referred to as “lancets”.
Scalpel blades are usually made of hardened and tempered steel, stainless steel, or high carbon steel; in addition, titanium, ceramic, diamond and even obsidian knives are not uncommon. For example, when performing surgery under MRI guidance, steel blades are unusable (the blades would be drawn to the magnets, or may cause image artifacts). Historically, the preferred material for surgical scalpels was silver, on account of its antimicrobial properties (although the mechanics were not understood at the time). Scalpel blades are also offered by select manufacturers with a zirconium nitride-coated edge to improve sharpness and edge retention. Others manufacture blades that are polymer-coated to enhance lubricity during a cut. Alternatives to scalpels in surgical applications include electrocautery and lasers.
Reusable handle (top) and disposable scalpels (bottom):
Surgical scalpels consist of two parts, a blade and a handle. The handles are often reusable, with the blades being replaceable. In medical applications, each blade is only used once (even if just for a single, small cut).
History and Use of Scalpels in Surgery
The Harmonic scalpel is a surgical instrument used to simultaneously cut and cauterize tissue. Unlike Electrosurgery, the harmonic uses ultrasonic vibrations instead of electric current to cut and cauterize tissue.
The harmonic is superior to a Bovie in that it can cut through thicker tissue, creates less toxic surgical smoke, and may offer greater precision. The harmonic scalpel is not as easily maneuverable as the Bovie, and takes longer to cut and coagulate tissue. Additionally, while a Bovie can be used to coagulate bleeding tissue at any time, the Harmonic scalpel only coagulates as it cuts.
A Harmonic scalpel cuts via vibration. The scalpel surface itself cuts through tissue by vibrating in the range of 55,500 Hz. The high frequency vibration of tissue molecules generates stress and friction in tissue, which generates heat and causes protein denaturation. This technique causes minimal energy transfer to surrounding tissue, potentially limiting collateral damage. However, incidents have been reported where the active jaw has caused bowel perforation.