Surgical staples are medical devices used to close incisions and wounds, often faster and more consistently than traditional suturing. They hold tissue edges together, whether on the surface of the skin or deep inside the body, to allow for healing. The use of staples over stitches can sometimes reduce the local inflammatory response and the time required to complete the closure of a defect following a procedure.
Appearance of External Skin Staples
Skin staples, used to close external incisions, are what most people picture when they hear the term. These staples look like small, rectangular metal wire bridges across the incision line. They are typically made of stainless steel, which is strong and non-reactive, though some are made from titanium. A standard skin staple generally spans between 6 to 10 millimeters wide, with a wire diameter of approximately 0.5 millimeters and a leg length around 3.5 millimeters.
When a staple is deployed, the two ends of the wire penetrate the skin and are bent into a box or rectangular shape by the stapling device’s anvil. This holds the tissue firmly together, pulling the skin edges slightly outward, a technique known as eversion, which is beneficial for proper wound healing. The resulting line of staples resembles a small, evenly spaced metal zipper running along the surgical cut. Once the wound has healed (usually within five to ten days), a specialized removal tool deforms the staple back into an “M” shape, allowing it to be lifted cleanly out of the skin. Their quick application provides a strong, reliable closure for wounds following major surgery, such as on the scalp or after a Cesarean section.
Forms and Functions of Internal Staples
Staples used inside the body look dramatically different from their external counterparts, as their shape is dictated by their specific function. While external staples are designed for simple edge-to-edge closure, internal staples are engineered to connect, divide, or seal internal organs and vessels. After being fired from a stapling instrument, internal staples primarily form a distinct “B” shape. This “B” shape ensures that the tissue within the staple remains compressed but not completely crushed, allowing small blood vessels to pass through the openings and keeping the tissue viable near the cut edge.
These internal staples are often deployed in multiple, staggered rows to create a secure, leak-proof closure, especially when connecting two hollow organs, a process called anastomosis. Linear staplers create a straight line of these “B”-shaped staples, often with an integrated blade that cuts the tissue between the rows simultaneously, separating the organ while sealing the new edges. Circular staplers are used to connect tubular structures like the intestines, creating a ring of staples that forms a new connection after a diseased section has been removed. The resulting configuration is a closed tube secured by two interlocking circular rows of staples, often leaving a small ring of excised tissue as a byproduct.
Materials and Absorption Properties
The composition of surgical staples is chosen based on where they will be used in the body and whether they are intended to be permanent or temporary. For internal use, the most common material is titanium, which is favored due to its high biocompatibility, meaning it causes minimal reaction with the body’s immune system. Titanium is also non-ferrous, which means it does not significantly interfere with magnetic resonance imaging (MRI) scanners, an important consideration for a permanent implant. Stainless steel is also used, particularly for some external skin staples, but titanium is the preferred choice for fixtures that remain inside the body long-term, such as those used to seal blood vessels or connect sections of the gastrointestinal tract.
A growing category of internal and even some external staples are made from synthetic absorbable polymers, such as copolymers of polylactide and polyglycolic acid. These materials offer temporary support, gradually breaking down through a process called bio-absorption over a period of months. This temporary nature is useful when the tissue needs to be held together only until it is strong enough to support itself. The staples slowly hydrolyze, or break down chemically by reacting with water, and the resulting non-toxic products are metabolized and safely cleared by the body.