General Principles Many varieties of suture material and needles are available. The choice of sutures and needles is determined by the location of the lesion, the thickness of the skin in that location, and the amount of tension exerted on the wound. Regardless of the specific suture and needle chosen, the basic techniques of needle holding, needle driving, and knot placement remain the same. Suture placement A needle holder is used to grasp the needle at the distal portion of the body, one half to three quarters of the distance from the tip of the needle, depending on the surgeon’s preference. The needle holder is tightened by squeezing it until the first ratchet catches. The needle holder should not be tightened excessively, because damage to both the needle and the needle holder may result. The needle is held vertically and longitudinally perpendicular to the needle holder (see the image below). Needle is placed vertically and longitudinally perpendicular to needle holder. Incorrect placement of the needle in the needle holder may result in a bent needle, difficult penetration of the skin, or an undesirable angle of entry into the tissue. The needle holder is held by placing the thumb and the fourth finger into the loops and placing the index finger on the fulcrum of the needle holder to provide stability (see the first image below). Alternatively, the needle holder may be held in the palm to increase dexterity (see the second image below). Needle holder is held through loops between thumb and fourth finger, and index finger rests on fulcrum of instrument. Needle holder is held in palm, allowing greater dexterity. The tissue must be stabilized to allow suture placement. Depending on the surgeon’s preference, toothed or untoothed forceps or skin hooks may be used to grasp the tissue gently. Excessive trauma to the tissue being sutured should be avoided to reduce the possibility of tissue strangulation and necrosis. Forceps are necessary for grasping the needle as it exits the tissue after a pass. Before removal of the needle holder, grasping and stabilizing the needle is important. This maneuver decreases the risk of losing the needle in the dermis or subcutaneous fat, and it is especially important if small needles are used in areas such as the back, where large needle bites are necessary for proper tissue approximation. The needle should always penetrate the skin at a 90° angle, which minimizes the size of the entry wound and promotes eversion of the skin edges. The needle should be inserted 1-3 mm from the wound edge, depending on skin thickness. The depth and angle of the suture depends on the particular suturing technique. In general, the two sides of the suture should become mirror images, and the needle should also exit the skin perpendicular to the skin surface. Knot tying Once the suture is satisfactorily placed, it must be secured with a knot. [35] The instrument tie is used most commonly in cutaneous surgery. The square knot is traditionally used. First, the tip of the needle holder is rotated clockwise around the long end of the suture for two complete turns (see the image below). The tip of the needle holder is used to grasp the short end of the suture. The short end of the suture is pulled through the loops of the long end by crossing the hands, so that the two ends of the suture are on opposite sides of the suture line. The needle holder is rotated counterclockwise once around the long end of the suture. The short end is then grasped with the needle holder tip and pulled through the loop again. Knot tying. The suture should be tightened sufficiently to approximate the wound edges without constricting the tissue. Sometimes, leaving a small loop of suture after the second throw is helpful. This reserve loop allows the stitch to expand slightly and is helpful in preventing the strangulation of tissue because the tension exerted on the suture increases with increased wound edema. Depending on the surgeon’s preference, one or two additional throws may be added. Properly squaring successive ties is important. In other words, each tie must be laid down perfectly parallel to the previous tie. This procedure is important in preventing the creation of a granny knot, which tends to slip and is inherently weaker than a properly squared knot. When the desired number of throws is completed, the suture material may be cut (if interrupted stitches are used), or the next suture may be placed. Placement of Specific Suture Types Simple interrupted suture The most commonly used and most versatile suture in cutaneous surgery is the simple interrupted suture. [36] This suture is placed by inserting the needle perpendicular to the epidermis, traversing the epidermis and the full thickness of the dermis, and exiting perpendicular to the epidermis on the opposite side of the wound. The two sides of the stitch should be symmetrically placed in terms of depth and width. In general, the suture should have a flask-shaped configuration, that is, the stitch should be wider at its base (dermal side) than at its superficial portion (epidermal side). If the stitch encompasses a greater volume of tissue at the base than at its apex, the resulting compression at the base forces the tissue upward and promotes eversion of the wound edges (see the image below). This maneuver decreases the likelihood of creating a depressed scar as the wound retracts during healing. Simple interrupted suture placement. Bottom right image shows a flask-shaped stitch, which maximizes eversion. As a rule, tissue bites should be evenly placed so that the wound edges meet at the same level; this minimizes the possibility of mismatched wound-edge heights (ie, stepping). However, the size of the bite taken from the two sides of the wound can be deliberately varied by modifying the distance of the needle insertion site from the wound edge, the distance of the needle exit site from the wound edge, and the depth of the bite taken. The use of differently sized needle bites on each side of the wound can correct preexisting asymmetry in edge thickness or height. Small bites can be used to precisely coapt wound edges. Large bites can be used to reduce wound tension. Proper tension is important to ensure precise wound approximation while preventing tissue strangulation. (See the image below.) Line of interrupted sutures. Simple running suture A simple running (continuous) suture is essentially an uninterrupted series of simple interrupted sutures. The suture is started by placing a simple interrupted stitch, which is tied but not cut. A series of simple sutures are placed in succession, without the suture material being tied or cut after each pass. The sutures should be evenly spaced, and tension should be evenly distributed along the suture line. The line of stitches is completed by tying a knot after the last pass at the end of the suture line. The knot is tied between the tail end of the suture material where it exits the wound and the loop of the last suture placed. (See the image below.) Running suture line. Running locked suture A simple running suture may be either locked or left unlocked. The first knot of a running locked suture is tied as in a traditional running suture and may be locked by passing the needle through the loop preceding it as each stitch is placed (see the image below). This suture is also known as the baseball stitch because of the final appearance of the running locked suture line. Running locked suture. Vertical mattress suture A vertical mattress suture is a variation of a simple interrupted suture. It consists of a simple interrupted stitch placed wide and deep into the wound edge and a second more superficial interrupted stitch placed closer to the wound edge and in the opposite direction (see the image below). The width of the stitch should be increased in proportion to the amount of tension on the wound—that is, the higher the tension, the wider the stitch. Vertical mattress suture. Half-buried vertical mattress suture A half-buried vertical mattress suture is a modification of a vertical mattress suture that eliminates two of the four entry points, thereby reducing scarring. It is placed in the same manner as the vertical mattress suture, except that the needle penetrates the skin to the level of the deep part of the dermis on one side of the wound, takes a bite in the deep part of the dermis on the opposite side without exiting the skin, crosses back to the original side, and finally exits the skin. Entry and exit points thus are kept on one side of the wound. Pulley suture A pulley suture is a modification of a vertical mattress suture. A vertical mattress suture is placed, the knot is left untied, and the suture is looped through the external loop on the other side of the incision and pulled across (see the image below). At this point, the knot is tied. This new loop functions as a pulley, directing tension away from the other strands. Pulley stitch, type 1. Far-near near-far modified vertical mattress sutures Another stitch that serves the same function as a pulley suture is a far-near near-far modified vertical mattress suture. The first loop is placed about 4-6 mm from the wound edge on the far side and about 2 mm from the wound edge on the near side. The suture crosses the suture line and reenters the skin on the original side at 2 mm from the wound edge on the near side. The loop is completed, and the suture exits the skin on the opposite side 4-6 mm away from the wound edge on the far side (see the image below). A pulley effect is thus created. Far-near near-far modification of vertical mattress suture, creating pulley effect. Horizontal mattress suture A horizontal mattress suture is placed by entering the skin 5 mm to 1 cm from the wound edge. The suture is passed deep in the dermis to the opposite side of the suture line and exits the skin equidistant from the wound edge (in effect, a deep simple interrupted stitch). The needle reenters the skin on the same side of the suture line 5 mm to 1 cm lateral of the exit point. The stitch is passed deep to the opposite side of the wound, where it exits the skin; the knot is then tied (see the image below). Horizontal mattress suture. Half-buried horizontal suture A half-buried horizontal suture (also referred to as a tip stitch or three-point corner stitch) begins on the side of the wound on which the flap is to be attached. The suture is passed through the dermis of the wound edge to the dermis of the flap tip. The needle is passed laterally in the same dermal plane of the flap tip, exits the flap tip, and reenters the skin to which the flap is to be attached. The needle is directed perpendicularly and exits the skin; the knot is then tied (see the image below). Half-buried horizontal suture (tip stitch, three-point corner stitch). Dermal-subdermal sutures A dermal-subdermal suture is placed by inserting the needle parallel to the epidermis at the junction of the dermis and the subcutis. The needle curves upward and exits in the papillary dermis, again parallel to the epidermis. The needle is inserted parallel to the epidermis in the papillary dermis on the opposing edge of the wound, curves down through the reticular dermis, and exits at the base of the wound at the interface between the dermis and the subcutis and parallel to the epidermis. The knot is tied at the base of the wound to minimize the possibility of tissue reaction and extrusion of the knot. If the suture is placed more superficially in the dermis at 2-4 mm from the wound edge, eversion is increased. Buried horizontal mattress suture A buried horizontal mattress suture is a purse-string suture. The suture must be placed in the mid-to-deep part of the dermis to prevent the skin from tearing. If tied too tightly, the suture may strangulate the approximated tissue. Running horizontal mattress sutures A simple suture is placed, and the knot is tied but not cut. A continuous series of horizontal mattress sutures is placed, with the final loop tied to the free end of the suture material. [37] Running subcuticular sutures A running subcuticular suture is a buried form of a running horizontal mattress suture. It is placed by taking horizontal bites through the papillary dermis on alternating sides of the wound (see the image below). No suture marks are visible, and the suture may be left in place for several weeks. Subcuticular stitch. Skin surface remains intact along length of suture line. Running subcutaneous suture A running subcutaneous suture begins with a simple interrupted subcutaneous suture, which is tied but not cut. The suture is looped through the subcutaneous tissue by successively passing through the opposite sides of the wound. The knot is tied at the opposite end of the wound by knotting the long end of the suture material to the loop of the last pass that was placed. Running subcutaneous corset plication stitch Before the needle is inserted, forceps are used to pull firmly on at least 1-2 cm of tissue to ensure tissue strength. [14] The corset plication includes at least 1-2 cm of adipose tissue and fascia within each bite. After the first bite is tied, bites are taken on opposite sides of the wound in a running fashion along the defect. The free end is pulled firmly to reduce the size of the defect, and the suture is then tied. Variations of tip (corner) sutures Modified half-buried horizontal mattress suture In a modified half-buried horizontal mattress suture, an additional vertical mattress suture is placed superficial to the half-buried horizontal mattress suture. A small skin hook instead of forceps is used to avoid trauma of the flap.[5] Deep tip stitch A deep tip stitch is essentially a fully buried form of a three-corner stitch. The suture is placed into the deep dermis of the wound edge to which the flap is to be attached, passed through the dermis of the flap tip, and inserted into the deep dermis of the opposite wound edge. [4] Source
