Did You Know?
Sutures and ligatures were used by the Egyptians and Syrians as early as 2,000 BCE.
In simple terms, a suture is a type of thread used by surgeons to stitch tissues together. It can be used for bringing together tissues in case of an injury or incisions made during a surgical procedure. It can also be used for tying blood vessels. Several types of materials are used for suturing subcutaneous tissues, fascia, or deep structures.
The composition, thickness, or texture of sutures might vary. The suture material is chosen on the basis of the location and nature of the wound. In case of deep structures, the deep sutures below the surface allow the wound to heal faster, preventing the scar from becoming wider.
The sutures on the surface close the edges on the epidermis, speeding up healing to provide a good cosmetic outcome. It is extremely important to use the right type of suture material, as that could impact the healing process. The United States Pharmacopoeia (USP) recommends that suture boxes must provide complete information about the type and size of the suture materials, along with the type of needles to be used.
Characteristics and Uses of Sutures
All sutures produce an inflammatory response in the skin, as these are considered as a foreign body by the immune system. The inflammatory response peaks between the second and the seventh day. While suturing an incision/wound, the surgeons need to ensure that the wound or incision is closed in such a way that there's no dead space in the subcutaneous tissue. However, it should not be so tight that it affects the blood supply or leads to tissue death. Wound tension should be minimized. There are certain characteristics that should be present in suture materials. The suture material should be non-allergenic. It should have adequate tensile strength. It must be strong and easy to handle. It should allow for knot security, and provide support to the margins of the tissue till the tissue heals completely. It should not harbor bacteria or pathogens. It should not cut through the tissues or cause any reaction. Be it any kind of material, the objective is to ensure quick healing. Over the years, several types of suture materials have been used for this purpose. These materials are classified on the basis of their characteristics.
Natural and Synthetic Sutures
Some of the materials are natural, while others are synthetic. Natural sutures are derived from naturally-occurring substances. The examples of natural sutures include:➠
Plain/Chromic catgut (connective tissue or purified collagen fibers from the intestine of healthy sheep or cows)
Plain and chromic/coated catgut sutures get absorbed due to the process of proteolytic enzymatic degradation. Since these sutures are made from multiple fibers, they remain extremely strong in the first few days of healing. Thereafter, they lose their strength rapidly, within a couple of weeks. These can be used for muscle injuries, as muscles usually heal faster and they need strong sutures in the initial healing period. The popularity of catgut has waned with the advent of stronger, synthetic sutures and the likelihood of uneven absorption in case of manufacturing defects.
Synthetic sutures are made from polymers such as polyamide, polyolefins, polyesters, and absorbable polymers that are derived from polyglycolic acid. Synthetic absorbable sutures are broken down non-enzymatically by hydrolysis, wherein water enters the filaments and breaks down the polymer chain. Due to this, these are not associated with intense inflammatory reaction that occurs in case of catgut. The synthetic absorbable suture material tend to cause milder tissue reaction than plain/chromic gut. The examples of synthetic suture materials include:➠
Vicryl (Polylactic acid)➠
Dexon (Polyglycolic acid)➠
Prolene (Polypropylene)Caution: The following section contains images that are graphic in nature and may seem disturbing to some readers.
Absorbable and Non-absorbable Sutures
Sutures can be absorbable or non-absorbable. The terms 'absorbable' and 'non-absorbable' are self-explanatory. Basically, absorbable sutures are the ones that dissolve or get absorbed into the tissue. The time taken for such sutures to get absorbed will depend on the type of material, size of the suture, condition and the location of the injured tissue, and the overall health of the patient. The examples of absorbable sutures include:➠
More often than not, the absorbable gut sutures are used for closing tissue that heals quickly and needs less support. It can be used for mucosal layer of the oral cavity or procedures involving the superficial blood vessels. Coated vicryl sutures get absorbed between 56 and 70 days, whereas monocryl sutures get absorbed between 91 and 119 days.
Vicryl sutures are often used for closing muscles, fatty tissue, or dermis/subcutaneous tissue in the skin. Polydioxanone (PDS) is often considered for closing fascia and muscles. Monocryl sutures are considered for closing soft tissue and skin incisions. Monocryl and macron can be used as absorbable subcuticular suture, wherein stitches are made at the meeting point of the outer layer of the skin and the underlying dermis, so that the wound or incision is completely closed. Absorbable sutures are mostly used under the skin, as they are likely to leave behind a pronounced scar.
On the other hand, most non-absorbable sutures remain intact. Some of the sutures that are permanent don't get dissolved or absorbed into the tissue. Silk is also considered to be non-absorbable, as it deteriorates at a very slow rate. These are used for internal tissues that need a long time to heal properly. These are used for approximating internal fibrous tissues that do not have a rich blood supply. The non-absorbable sutures are made from:➠
While prolene sutures are used for approximating muscles, blood vessels, or fascia, silk sutures are mainly considered while tying segments of intestine or blood vessels. Nylon sutures could be used for closing skin wounds or incisions.
Monofilament and Multifilament Sutures
Monofilament sutures are single strand sutures, whereas multifilament sutures are braided sutures that are made up of several strands. Though a monofilament suture requires more knots, tying knots is easier and there's less likelihood of trauma to the tissues. It resists the growth of pathogens due to its structure. Its examples include:➠
Nylon (Available as monofilament and multifilament)
Multifilament suture, as the name suggests, are fibers that are twisted or braided together. These are stronger, as well as easier to handle and tie. Due to their structure, these require fewer knots. However, braided sutures have a greater potential for infection due to the presence of small spaces within the suture material. These spaces can become a breeding ground for bacteria. The examples include:➠
Chromic gut (twisted)➠
On a concluding note, the choice of suture material plays an important role in wound care. Besides using the right size and type of material, it is essential to use the right instruments (needle and needle holder) and the right suturing technique to minimize tension and scarring. Different types of suture patterns that might be used for wound closure include simple interrupted, simple continuous, vertical mattress, horizontal mattress, subcutaneous pattern, subcuticular pattern, etc. In order to ensure proper healing, there should be proper blood supply to the wound. Seek medical assistance at the earliest, if the suture opens and edges of the wound are pulling away from each other. Inform the doctor, if you notice redness or swelling around the wound, or blood/pus oozes out of the edges of the wound.