A scalpel is a very sharp knife used for surgery, anatomical dissection, and various arts and crafts. Scalpels may be disposable or re-usable. Re-usable scalpels can have attached, resharpenable blades or, more commonly, non-attached, replaceable blades. Disposable scalpels usually have a plastic handle with an extensible blade (like a utility knife) and are used once, then the entire instrument discarded.
Scalpel blades are usually of hardened and tempered steel. Medical blades are made of high carbon steel, while craft blades are made of stainless steel, but titanium, ceramic, diamond and even obsidian are not unknown. For example, when performing surgery under MRI guidance, metallic blades are unusable (the steel blades would be drawn to the magnets) or may cause image artifacts. Alternatives to scalpels in surgical applications include electrocautery and lasers.
Surgical scalpels consist of two parts, a blade and a handle. The handles are reusable, with the blades being replaceable. In medical applications, each blade is only used once, (even if just for a single, small cut). Medical scalpel handles come in two basic types. The first is a flat handle used in the #3 and #4 handles. The #7 handle is more like a long writing pen, rounded at the front and flat at the back. A #4 handle is larger than a #3, and while some blades fit both others are too large or small and can only fit one or the other. The following table of blades is incomplete and some blades listed may work with handles not specified here.
|Blade No.||Compatible Handles||Blade Description||Uses|
|#10||1, 3, 7||Curved cutting edge with flat back||For cutting skin and muscle in surgery, and for general carving and stencil making|
|#10a||4||This blade is a small disk, sharpened all the way around, except where it attaches to the handle|
|#11||1, 3, 4, 7||Triangular blade with sharp point, flat cutting edge parallel to the handle and flat back||For precision cutting, stripping, and sharp angle cuts|
|#12a||3, 7||A small, pointed, crescent-shaped blade sharpened on the inside edge of the curve|
|#12b||3, 7||A small, pointed, crescent-shaped blade sharpened on both sides of the curve|
|#15||3, 7||A smaller version of the #10||For the same general uses as the #10 blade|
|#15c||3, 7||The #15 with a downward angle, flatter and thinner than the #15|
|#16||1, 3||A narrow chisel-like blade with flat, angled cutting edge, positioned higher than the axis of the handle||For cutting stencils, scoring and etching|
|#17||1, 3||A flat face 1.6 mm chisel blade||For narrow cuts|
|#18||2, 5, 6||A 12.7 mm chisel blade||For deep cuts and scraping|
|#19||4||A similar blade to the #15|
|#22||2, 5, 6||A larger version of the #10||For general use, shaping, whittling and trimming|
|#24||2, 5, 6||A wide, flat, angled cutting edge||For corner cuts, trimming, stripping, and cutting mats and gaskets|
|#25||4||A triangular blade similar to the #11, with the flat back edge taking a downwards angle|
|#60||4||A long blade resembling the #10 with a long cutting edge, rounded tip and flat back.|
Gripping a medical scalpel
- Palmar grip
- Also called the "dinner knife" grip. The handle is held with the second through fourth fingers and secured along the base of the thumb, with the index finger extended along the top rear of the blade and the thumb along the side of the handle. This grip is best for initial incisions and larger cuts.
- Pencil grip
- Best used for more precise cuts with smaller blades (e.g. #15) and the #7 handle. The scalpel is held with the tips of the first and second fingers and the tip of the thumb with the handle resting on the "anatomical snuff box," at the fleshy base of the index finger and thumb. Care should be taken not to allow the handle to rest too far along the index finger as this promotes an unstable grip and cramped fingers. This is widely considered the non standard grip by the medical professionals, despite its more practical usage.
In the last decade, a rising awareness of the dangers of sharps in a medical environment has led to the development of various methods of protecting healthcare workers from accidental cuts and puncture wounds. According to the CDC (the Centers for Disease Control and Prevention) as many as 1,000 people each day are subject to accidental needle sticks and lacerations while providing medical care . Companies like Bard-Parker and Shippert Medical Technologies offer lines of retractible-blade scalpels which protect users by covering the blade when not in use. Some such scalpels are disposable and others feature replaceable blades on re-usable metal handles.
Graphic design and arts and crafts blades
Graphical and model-making scalpels tend to have round handles, with textured grips (either knurled metal or soft plastic). These are often called by the name of the most well-known manufacturer of graphic arts blades, X-Acto knives. The blade is usually flat and straight, allowing it to be run easily against a straightedge to produce straight cuts.
There are many kinds of graphic arts blades, the most common around the graphic design studio is the #11 blade which is very similar to a #11 surgical blade (q.v.). Other blade shapes are used for wood carving, cutting leather and heavy fabric, etc.