Suture techniques

(Survival manual/6. Medical/e) Skin/Suture techniques

 A.   Introduction
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As a method for closing cutaneous wounds, the technique of suturing is thousands of years old. Although suture materials and aspects of the technique have changed, the goals remain the same: closing dead space, supporting and strengthening wounds until healing increases their tensile strength, approximating skin edges for an aesthetically pleasing and functional result, and minimizing the risks of bleeding and infection.

Proper suturing technique is needed to ensure good results in dermatologic surgery. The postoperative appearance of a beautifully designed closure or flap can be compromised if an incorrect suture technique is chosen or if the execution is poor. Conversely, meticulous suturing technique cannot fully compensate for improper surgical technique. Poor incision placement with respect to relaxed skin tension lines, excessive removal of tissue, or inadequate undermining may limit the surgeon’s options in wound closure and suture placement. Gentle handling of the tissue is also important to optimize wound healing.

The choice of suture technique depends on the type and anatomic location of the wound, the thickness of the skin, the degree of tension, and the desired cosmetic result. The proper placement of sutures enhances the precise approximation of the wound edges, which helps minimize and redistribute skin tension. Wound eversion is essential to maximize the likelihood of good epidermal approximation. Eversion is desirable to minimize the risk of scar depression secondary to tissue contraction during healing. Usually, inversion is not desirable, and it probably does not decrease the risk of hypertrophic scarring in an individual with a propensity for hypertrophic scars. The elimination of dead space, the restoration of natural anatomic contours, and the minimization of suture marks are also important to optimize the cosmetic and functional results.

In this article, the suture techniques used in cutaneous surgery are reviewed. The techniques of suture placement for each type of stitch are described, the rationale for choosing one suture technique over another are reviewed, and the advantages and disadvantages of each suture technique are discussed. Frequently, more than one suture technique is needed for optimal closure of a wound. After reading this article, the reader should have an understanding of how and why particular sutures are chosen and an appreciation of the basic methods of placing each type of suture.1,2

B.  Basic suturing principles
Many varieties of suture material and needles are available to the cutaneous surgeon. 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.

1.  Needle construction
•  The needle has 3 sections. The point is the sharpest portion and is used to penetrate the tissue. The body represents the mid portion of the needle. The swage is the thickest portion of the needle and the portion to which the suture material is attached.
•  In cutaneous surgery, 2 main types of needles are used: cutting and reverse cutting. Both needles have a triangular body. A cutting needle has a sharp edge on the inner curve of the needle that is directed toward the wound edge. A reverse cutting needle has a sharp edge on the outer curve of the needle that is directed away from the wound edge, which reduces the risk of the suture pulling through the tissue. For this reason, the reverse cutting needle is used more often than the cutting needle in cutaneous surgery.

2.  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.

[Left: The needle holder is held through the loops between the thumb and the fourth finger, and the index finger rests on the fulcrum of the instrument.]

•  Incorrect placement of the needle in the needle holder may result in a bent needle, difficult penetration of the skin, and/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 by placing the index finger on the fulcrum of the needle holder to provide stability (see first image below). Alternatively, the needle holder may be held in the palm to increase dexterity (see second image below).

•  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 gently grasp the tissue. 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. Prior to removing 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.
[Above: Using forceps to stabilize the tissue while the suture is placed.]

•  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 2 sides of the suture should become mirror images, and the needle should also exit the skin perpendicular to the skin surface.

3.  Knot tying
•  Once the suture is satisfactorily placed, it must be secured with a knot. 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 material for 2 complete turns. 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, such that the 2 ends of the suture material are situated 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 grasped with the needle holder tip, and the short end is pulled through the loop again.

•  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, 1-2 additional throws may be added.

•  Properly squaring successive ties is important. That is, 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 (see image below).

 4.  Placement
Sutures are placed by mounting a needle with attached suture into a needle holder. The needle point is pressed into the flesh, advanced along the trajectory of the needle’s curve until it emerges, and pulled through. The trailing thread is then tied into a knot, usually a square knot or surgeon’s knot. Sutures should bring together the wound edges, but should not cause indenting or blanching of the skin, since the blood supply may be impeded and thus increase infection and scarring. Sutured skin should roll slightly outward from the wound (eversion), and the depth and width of the sutured flesh should be roughly equal. Placement varies based on the location, but the distance between each suture generally should be equal to the distance from the suture to the wound edge.

Many different techniques exist. The most common is the simple interrupted stitch; it is indeed the simplest to perform and is called “interrupted” because the suture thread is cut between each individual stitch. The vertical and horizontal mattress stitch are also interrupted but are more complex and specialized for everting the skin and distributing tension. The running or continuous stitch is quicker but risks failing if the suture is cut in just one place; the continuous locking stitch is in some ways a more secure version. The chest drain stitch and corner stitch are variations of the horizontal mattress. Other stitches include the Figure 8 stitch and subcuticular stitch.

 5.  Removal
•  While some sutures are intended to be permanent, and others in specialized cases may be kept in place for an extended period of many weeks, as a rule sutures are a short term device to allow healing of a trauma or wound.
•  “Different parts of the body heal at different speed. Common time to remove stitches will vary: facial wounds 3–5 days; scalp wound 7–10 days; limbs 10–14 days; joints 14 days; trunk of the body 7–10 days.
•  “Not all stitches must be removed. If a small area remains unhealed, notify the health care practitioner. Then if ordered, remove sutures from the healed area only.”


C.  Tissue adhesives
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In recent years, topical cyanoacrylate adhesives (“liquid stitches”), a.k.a super glue, have been used in combination with, or as an alternative to, sutures in wound closure. The adhesive remains liquid until exposed to water or water-containing substances/tissue, after which it cures (polymerizes) and forms a flexible film that bonds to the underlying surface. The tissue adhesive has been shown to act as a barrier to microbial penetration as long as the adhesive film remains intact. Limitations of tissue adhesives include contraindications to use near the eyes and a mild learning curve on correct usage.

Cyanoacrylate is the generic name for cyanoacrylate based fast-acting glues such as methyl-2-cyanoacrylate, ethyl-2-cyanoacrylate (commonly sold under trade names like Superglue and Krazy Glue) and n-butyl-cyanoacrylate. Skin glues like Indermil and Histoacryl were the first medical grade tissue adhesives to be used, and these are composed of n-butyl cyanoacrylate. These worked well but had the disadvantage of having to be stored in the refrigerator, were exothermic so they stung the patient, and the bond was brittle. Nowadays, the longer chain polymer, 2-octyl cyanoacrylate, is the preferred medical grade glue. It is available under various trade names, such as LiquiBand, SurgiSeal, FloraSeal, and Dermabond. These have the advantages of being more flexible, making a stronger bond, and being easier to use. The longer side chain types, for example octyl and butyl forms, also reduce tissue reaction.


 D.  Adventure Medical Kits Suture/Syringe Kit, ~$64.99
Product Features
•  Also used for injecting medications or anesthetics
•  And for starting or delivering IV’s
VA hospital quality field surgical kit for closing wounds

 Suture/Syringe Kit:
Suture/Syringe Supplies, 1 – Angiocatheter, 18G x11/4, 1 – Bandage, Conforming Gauze, Sterile, 3, 1 – Catheter, 18 Gauge, Plastic Tip, 1 – Gloves, Surgical Sterile, Size7.5 (pair), 1 – Gloves, Surgical Sterile, Size8 (pair), 1 – IV Start Kit, Sterile, 1 – Mayo Heger Needle Holder, 5, 1 – Packaging, Suture/Syringe Medic, 1 – Povidone Iodine Solution, 3/4 oz, 1 – Scalpel, Sterile, Disposable, with #11 Blade, 1 – Scissors, Stainless Steel, 5, 1 – Suture, Nylon, 3-0, 1 – Suture, Nylon, 5-0, 1 – Syringe, Irrigation, 20 cc with18 Gauge Tip, 1 – Syringe, Luer Lok, Sterile, 5 ml, 1 – Tape, 1/2 x10 Yards, Box/24, 1 – Thumb Tissue Forceps, Mouse-Tooth, 4.5, 1 – Towel Drape, Sterile, 1 – Wound Closure Strips, 1/4 x4, Pkg./10, 2 – Dressing, Gauze, Sterile, 4 x4, Pkg./2, 2 – Dressing, Non-Adherent, Sterile, 3 x4, 2 – Needle, Disposable, Sterile, 18G x11/2, 2 – Needle, Disposable, Sterile, 21G x11/2, 2 – Needle, Disposable, Sterile, 25G x5/8, 2 – Syringe, Luer Lok, Sterile, 3 ml, 2 – Tincture of Benzoin Topical Skin Adhesive, Swab, 2 – Trauma Pad, 5 x9, 4 – Triple Antibiotic Ointment, Net Wt. 0.9 g, , 5 – After Cuts & Scrapes Anesthetic/Antiseptic Wipe,

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