There are different types of suture materials and needles. The choice of needles and sutures are determined by lesion location, skin thickness, etc. However, the basic suture practice, including needle driving, needle holding as well as knot placement remains the same.
1. Suture Placement & Knot Tying
The needle is held by a needle holder. The angle and distance from the needle tip vary based on the surgeon’s preference. The needle holder should be tightened, but not excessively to prevent damage to both the holder and needle. The needle is held in a vertical position and it is longitudinally perpendicular to the holder. Incorrect placement of the needle in its holder may cause problems. The problems include difficult skin penetration, bent needle, and improper entry in skin tissue. The tissue has to be sterilized to let suture placement be proper. Based on the preference of the surgeon, skin hooks, forceps can be used to hold the tissue gently. The tissue that is being sutured should not be subjected to excessive stress to diminish the risk of tissue strangulation. Forceps are required for needle grasping when it exits tissue post a pass. Prior to removing the needle holder, holding and stabilizing the needle will be required. This maneuver reduces the risk of losing a needle in the dermis. This is required when small needles are deployed in the back and big needle bites are required for apt tissue approximation. The needle has to penetrate the skin at a 90° angle as it reduces entry wound size and promotes skin edge eversion. This needle has to be inserted 1-3 mm away from the skin edge, but this can vary on skin thickness. The angle and depth of the suture vary on the specific suturing technique. Both sides of the suture should be like mirror images. The needle must exit the skin while being perpendicular to the surface of the skin. After the suture is placed well, it has to be secured with a knot. As it is, the instrument tie is deployed the most in cutaneous surgery and the square knot is typically used. At first, the needle holder tip is rotated clockwise by the suture’s long end for two complete turns. Its tip is deployed to hold the short end of the suture. The suture’s short end is pulled through a loop on its long end by crossing hands. This ensures two ends of suture remain on opposite sides. The needle holder is then rotated once counterclockwise around the suture’s long end. This short end is held with the needle holder tip and then gets pulled through the loop once more. The suture has to be tightened adequately to approximate wound edges minus constricting the tissue. Often leaving a suture loop after its 2nd row is prudent. This reserve loop lets the stitch expand slightly and thwarts tissue strangulation. The surgeon may add one additional row. Using successive ties is necessary. A tie has to be laid down parallel to the one preceding it.
Placement of Various Specific Suture Types
2. Simple Interrupted Suture
The most versatile and commonly done suture is known as a simple interrupted suture. This suture is done by inserting the needle in a perpendicular position to the epidermis, passing through it and dermis, and then exiting perpendicular to epidermis on the wound’s other side. The sides of the stitch have to be symmetrically positioned in terms of width and depth. This suture has a flask-shaped configuration overall. The stitch has to be broader at the base compared to the superficial portion at the epidermal side. If the stitch covers a bigger tissue volume at the base rather than the apex, the compression will press the tissue upward and enable wound edge eversion. This reduces the risk of depressed scar getting created as the wound squeezes while healing is in progress. As a matter of fact, tissue bites need to be evenly placed to ensure wound edges meet at the exactly same level. This brings down the risks of wound-edge height mismatch. The size of the bite derived from wind sides can be kept different by altering the distance of the needle insertion zone from the wound edge, distance of the needle exit zone from the wound edge. The bite depth taken is also a factor here. Using varying sized needle bites on the wound’s each side can rectify preexisting asymmetry in the height and thickness of the edge. Small bites can be deployed to cope with wound edges. Large bites are ideal to diminish wound tension.
3. Simple Buried Suture
This suture is extremely important for distributing wound tension to the dermis rather than the epidermis and also for closing dead space. It provides longer-term support to the healing wound and improves the cosmetic result. The wound edge is everted with a skin hook and then an absorbable suture is introduced at the subcutaneous level and brought back out at dermal level on the same side of the wound.
4. Vertical Mattress Suture
The vertical mattress suture is basically a variant of the simple interrupted suture. It comprises of one simple interrupted stitch which is put deep and wide into wound edge and another superficial interrupted stitch which is positioned closer to the edge of the wound in the opposite direction. The stitch’s width has to be increased proportionately to the wound tension amount. So, if the tension is higher, the stitch has to be broader.
5. Horizontal Mattress Suture
The horizontal mattress suture is made by entering the needle in skin approximately 5mm to 1 cm from the edge of the wound. The suture is made to pass through deep in the dermis to the suture line’s opposite side and then exits the skin at the same distance from the edge of the wound. The needle enters the skin again on the suture line’s side just 1 cm from the exit point. The stitch is then made to pass deep to the wound’s opposite side. Then it exits the skin and the knot is tied.
6. Simple Running Suture
A continuous or simple running suture is basically simple interrupted sutures done in series. It is initiated by making a simple interrupted stitch and it is tied. Then a range of simple sutures is put in succession, but the suture material is not tied or cut post every pass. The sutures have to be evenly spaced so that tension gets distributed evenly along the line of the suture. The stitch line is wrapped up by a tying knot after the final pass at the suture line’s end. The knot gets tied between the suture material’s tail end where it actually exits the wound and last suture’s loop.
7. Simple Running Locking Suture
A simple running suture can either be locked or it can be left unlocked. The first knot of any running locked suture gets tied like a traditional running suture. This may be locked by passing the needle through one loop preceding it as every stitch is positioned. This suture is alternatively named as the baseball stitch since the ultimate appearance of running a locked suture line looks like it.
8. Subcuticular Running Suture
This is an epidermal approximation technique suitable for wounds under minimal to no tension. This technique should almost never be employed in the absence of a deep dermal suture since its strength is in fine-tuning epidermal approximation and it is less effective in the presence of significant tension. Its use is also predicated on the presence of a relatively robust dermis since it is a primarily intradermal technique and therefore does not recruit any strength from the epidermis. Therefore, it should be avoided in the context of atrophic skin or in areas with a very thin dermis, such as the eyelids.