How is the type of closure material chosen?
The purpose of repairing a wound is to provide good cosmetic results. All wounds will eventually heal by themselves; however, bringing the edges together and without tension will allow for a better result. All lacerations will leave a scar, and a good wound closure will minimize the visibility of that scar.
Since there are many layers of skin, there may need to be layers of sutures placed to bring the edges together if the wound is deep and affects more than the superficial dermis and epidermis layers. As well, if the wound is deep and only the skin is closed, empty spaces may be formed beneath the outer skin layer. Fluid may accumulate within these empty spaces, increasing the risk for infection.
For skin sutures, the hope is to cause minimal inflammation so that the scar will form nicely. If deep sutures are placed, the suture material used gradually disintegrates or dissolves as part of the inflammatory response of the body.
The strength of the suture depends upon the thickness of the suture material. Some suture materials used to repair nerves may be so thin that the surgeon needs a microscope to see the suture and be able to sew. Some suture material is as thick as string. The thinner the suture, the less tension it can tolerate and the more stitches need to be placed closer together, to keep the wound from breaking open as it heals.
Different types of needles are used as well, depending upon the situation. The two major kinds are cutting and non-cutting. The cutting needles have a diamond-shaped tip and are designed to "cut" through skin. The non-cutting needle tips are circular and are meant to be used on deep tissues that do not have the resistance of skin. There are different shapes of the needle curve as well to help guide the needle and the attached suture on its path.
Almost all suture material is preloaded on a needle and does not need to be hand-threaded. The care provider will specify the type of suture, the thickness, and the type of needle when planning to repair a laceration.