All types of suture materials can be divided into two basic groups, those that are classified as absorbable sutures and those that are non-absorbable. The biggest distinction between the two is that the absorbable sutures, as the name implies, will dissolve over time, eliminating the need for suture removal. Non-absorbable sutures may need to be removed, typically within the shortest period of time possible after the wound has closed and healed. Both types of sutures are effective in treatment of surgeries as well as in the closure of wounds that provide enough tissue to allow this type of closure.
The mechanism by which the body dissolves or eliminates absorbable sutures is similar to the way that the body would fight off an infection, bacterial invasion or the presence of any type of foreign object. It is also consistent with the way that protein is digested and used within the body cells. The cells in the body react to the wound and the sutures and the blood flow is increased to that area. This helps the body to fight off infection and also keeps the growing tissues supplied with nutrients and oxygen. The blood also carries specific cells known as phagocytes, literally the attack cells of the body. These highly specialized cells attack the suture itself, dissolving it completely and removing the waste material via the circulatory system.
As the stitches do need the presence of the blood system to allow effective dissolving and absorption into the body, it is recommended that these stitches be used for internal surgical incisions only. When used on the surface of the skin there is a chance that the interior stitches will dissolve while the parts on the exterior of the skin will remain. In time they will simply fall off but they can leave small holes, know as skin tunnels, which remain as small indentations around the edge of the scar. This is particularly problematic for areas of skin that are visible such as those on the hands, face, neck or legs.
There are several different types of materials that are used in the production of absorbable sutures. This can include catgut, which is actually a natural fiber that comes from the intestines of cattle. New types of gut come in a variety of different options including those that are treated with specific solutions such as chromic salt solutions. This type of suture is less inflammatory that standard gut and also has predictable strength and uniform absorption. It is important to note that with this or any other type of absorbable sutures it is impossible to accurately predict the rate of absorption as each individual wound can have a variety of factors that influence this aspect.
There are several different types of synthetic absorbable sutures. These range from monofilament and braided options that are typically made of a polyglycolic acid. There are also those that are made of a plydioxanone synthetic, which is a good option if predictability of tensile strength and absorption is required. These synthetic options are actually absorbed by the body through hydrolysis, which means less chance of skin tunnels or irritation.