Simple Interrupted Stitch
Simple Interrupted Suture
Wayne W. LaMorte, M.D., Ph.D., M.P.H.
Photography by Michael J. LaMorte
Small toothed forceps, such as the Addison forceps shown here, should be used to grasp the skin edges during suturing. Forceps with teeth provide a secure grasp with minimal pressure, thereby avoiding crushing of the skin edge. The forceps should be held in the first three fingers as one would hold a pen, using the first three fingers.
The needle holder should be held in a way that is comfortable and affords maximum control. Most surgeons grasp the needle holder by partially inserting the thumb and ring finger into the loops of the handle. Note that the index finger provides additional control and stability.
This illustrates the same grasp, but with the hand pronated. Supination and pronation are required to manipulate the curved needles used in surgery.
As a rule, the needle should be grasped at its center or perhaps 50-60% back from the pointed end. The needle should be grasped 1-2 mm from the tip of the needle holder.
(Drawing from Ethicon website: http://www.ethiconinc.com/wound_management/procedure/wound/ )
One should avoid grasping the suture material or the distal end of the needle with the needle holder, since this will damage the suture.
Placement of the 1st suture is begun by grasping and slightly everting the skin edge. The right hand is rotated into pronation so that the needle will pierce the skin at a 90o angle.
Note that the trailing suture is placed away from the surgeon to avoid tangling.
The needle is driven through the full thickness of the skin by rotating the needle holder (supinating). By keeping the shaft of the needle perpendicular to the skin surface at all times, one takes advantage of the needle’s curvature in traversing the skin as atraumatically as possible.
The needle has been released and is about to be regrasped. Note that the forceps maintain their grasp, thereby preventing the needle from retracting. The right hand has been fully pronated in preparation for regrasping the needle.
Pronation in the previous step makes it possible to complete passage of the needle with a smooth, natural supination which rotates the needle upwards and away from the surgeon. Again, this minimizes trauma to the tissues.
Here the needle is being regrasped in preparation for passage through the opposite skin edge. This was traditionally done by grasping the needle with the non-dominant hand. However, given the risks of HIV and hepatitis, it is probably advisable to train yourself to use the forceps for this instead of fingers.
The skin edge closest to the surgeon has been grasped and everted slightly, while the right hand is pronated to “cock” the needle and position it for passage through the skin.
Again, the right hand is supinated in order to rotate the needle through the full thickness of the skin, keeping the shaft at a right angle to the skin surface.
After releasing the needle, the right hand is pronated before the needle is regrasped…
… and the right hand is then supinated in order to rotate the needle through the skin atraumatically.
The suture material is drawn through the skin, leaving 2-3 cm. protruding from the far skin surface. The forceps are then dropped or “palmed” so the left hand can grasp the long end in preparation for an instrument tie. Note that the needle holder is positioned between the strands over the wound.
The long strand is being wrapped around the needle holder to form the loop for the first throw of a square knot.
The needle holder is then rotated away from the surgeon to grasp the short end of the suture.
The short end is grasped and drawn back through the loop toward the surgeon.
The throw is tightened…
… creating a flat throw which will be tightened just enough to approximate the skin edges. Remember: approximate; do not strangulate.
The second throw of the square knot is initiated with the needle holder pointed to the left as the long strand is wrapped around it by bringing the long strand toward the surgeon.
The needle holder is then rotated toward the surgeon to retrieve the short end, …
… and the short end is drawn through the loop that has been created, pulling it away from the surgeon.
The second throw is then brought down and tightened securely against the first throw.
With a braided material, such as silk, a third throw (replicating the first) would be placed to secure the knot. If a slippery monofilament material, such as nylon, were being used, one would place 5 or 6 throws of alternating construction in order to minimize the likelihood of knot slippage.
The suture will then be cut leaving 3-4 mm tails. The next suture will then be placed about 4 mm away from the first one. The distance between stitches will depend on how easily the wound edges can be approximated and how much tension or motion is likely to be exerted across the wound during healing. For example, a wound on a flexion surface, such as a knuckle, might require closer sutures than a wound in the scalp.