Sutures, or stitches, are a way to close an open wound to speed healing and usually to ensure the least possible amount of scarring. There are many different types of sutures, with the most commonly used one called the interrupted suture. Among many others, additional types of sutures include running sutures and mattress sutures. The different types of sutures have their advantages as well as disadvantages, and usage of a specific type depends on the kind of wound that warrants the sutures in the first place.
The interrupted suture is versatile. The needle enters the outer layer of the skin as well as the layer beneath it on one side of the wound and exits on the other side of the wound. There should be symmetry in the depth and width of each side of the suture. In addition, the entire suture should exhibit a wider base on the layer beneath the skin, forming the shape of a flask. Each stitch that makes up the interrupted suture ties separately; that is, each stitch is tied and cut, then the next stitch begins.
Unlike the interrupted suture, the running suture uses one unbroken length of material, meaning it is uninterrupted. The first stitch is tied in a knot but not cut, and the remaining stitches are not tied or cut at all until the last line. A running suture can be locked or unlocked, meaning each stitch is locked with the previous through a loop. While the running suture is faster to execute than the interrupted suture, it does not allow for better approximation of wound edges.
The mattress suture has many variations, from vertical to horizontal and half-buried to far-near near-far. Essentially, the mattress suture is made with two parallel stitches to the wound edge, with the first stitch deeper than the second, more superficial one. The double stitching helps make the suture strong as each stitch passes through both sides of the wound two times. The pulley suture is a variation of the mattress suture in which the vertical mattress stitch is left untied and instead, looped through another loop at one side of the wound, pulling tension away from other strands.
These three types of sutures are not the only kinds that can be used to close a wound. There are many other types of sutures, such as continuous locking sutures and purse string sutures. In general though, a great many of other sutures are simply different variations of others, such as the pulley suture being a variation of the mattress suture. The point of having so many variations is that one type of suture can be more beneficial than others for closing a specific type of wound.