Surgical Skills:Creating a Leak-Proof Ligature with ConfidencePart 2: Step-by-Step Approach to Surgical Binding Knots
Daniel D. Smeak, DVM, Diplomate ACVS, and Kurtis M. Hazenfield, DVM, MS Colorado State University
Certain binding knots are highly useful in achieving consistently secure ligations. Very little information is available in the human and veterinary literature describing indications and contraindications for use of binding knots for ligation, and we could find no published, wellillustrated instructions on how to tie these knots. There is also considerable confusion regarding the descriptions on tying, and correct names for, these knots.1
In this article series, Part 1—Overview of Ligation & Surgical Binding Knots (January/February 2015 issue)— discussed suture selection and security and types of binding knots. This article provides step-by-step instructions on how to create the following knots:
- Double reverse half hitch (DRHH)
- Miller’s knot
- Strangle knot: A new (to the surgery realm), highly effective, and easy-to-tie binding knot.
QUALITIES OF BINDING KNOTS
Ideal qualities of the first throw of a binding knot include the ability to:
- Cinch down tightly and completely without prematurely locking, allowing the surgeon to “feel” when the knot does not cinch down any further during tensioning, which signals when the first throw is tightly applied
- Resist loosening once placed, allowing time for additional throws to be performed for a permanent secure knot.1,2
Binding knots commonly employed in veterinary surgery can be classified by how many passes areplaced around the pedicle:
- 1-pass binding knot: Chosen by some surgeons as it is easier to apply, requiring only 1 pass of the suture around the pedicle or vessel (eg, DRHH).
- 2-pass binding knot: Takes more effort to pass twice around the pedicle; however, first throw very effectively resists loosening (eg, miller’s knot and strangle knot).3,4
Binding knots can be applied with either hand ties or instrument ties.We describe only hand ties in this article because, in general, complete tightening of each throw is less consistent with instrument ties—as the surgeon receives less tactile feedback—compared with hand ties.1
KEYPOINT: It is important to note that the binding knots described are considered the first throw; they are made permanently secure by adding 4 square throws stacked on top of the binding knot.
Indications and specific comments about each type of knot are provided in the Table.
Hand-Tied Suture Knot Indications & Comments
|Double Reverse Half Hitch|
HAND & STRAND SETUP
A standard hand and strand setup (Figure shown for right-handed surgeons) is used for each of the knots described in this article:
- Position the knot tying board with tubing horizontal, or perpendicular to your line of vision.
- Loop a 14- to 16- inch, unfixed or free, strand behind and underneath the tubing, held toward your body with your right hand.
- Grasp the fixed strand—the strand that will have a needle or instrument attached (in image, this is white strand with knot on end)—with the left hand and hold it in a “gun” shape: palm facing toward you; index finger extended; fixed strand held with left middle, ring, and little fingers; and left thumb held in neutral position.
- Drape and hold the fixed strand over the left palm, facing your body.
Depending on the surgeon’s preference, this technique can be performed with either the fi ngers of the left hand or right hand forming the knot. Most righthanded surgeons choose the left hand manipulation technique in which the fi ngers of the right hand only deliver and tension the free strand while the left hand does the actual tying; however, if unsure, view the images in a mirror to see how the technique works holding the fi xed strand in your right hand, transferring the suture with your left.
DOUBLE REVERSE HALF HITCH (HAND TIE TECHNIQUE)
STEP 1. Begin with the standard hand and strand setup (Figure): On top of your extended left index finger, cross the free strand in your right hand over the fixed strand in your left hand by moving the right hand away from your body at an angle to the left.
STEP 2. Pinch your left thumb and index finger inside the crossed suture loop you have created over your index finger; then turn your left hand and pinched thumb and index finger outward by pronation, allowing the cross in the suture loop to slip onto the left thumb.
STEP 3. Continue to hold these pinched fingers in place with your thumb tip through the crossed suture loop. Keeping these fingers in position, slightly open the pinch between your thumb and index finger of your left hand. With your right hand, deliver the free strand to the slightly opened thumb and index finger of the left hand.
STEP 4. As you pinch the free strand with your left thumb and index finger, release the free strand from the right hand. Keep pinching the free strand with your left hand and rotate the pinched set of thumb and index finger as you supinate the left hand. Drag the free strand through the crossed loop and deliver the strand to be regrasped by the right hand.
STEP 5. With the right hand loosely holding the free strand, lightly pull the fixed strand up toward you with the left hand, which shifts the first throw into a half hitch. Note: This step differs from the standard 2-hand square knot technique (where the throw conformation is kept flat and even tension is applied to both strands).
STEP 6. While holding the fixed strand with the left middle, ring, and little fingers, swing the left thumb under the fixed (white) strand and, with your right hand, cross the free strand toward you over the top of the fixed strand on top of the thumb; the thumb is now inside the crossed loop.
STEP 7. Pinch the left thumb and left index finger and supinate the left hand, drawing the pinched thumb and finger through the crossed loop. Slightly open the pinched thumb and finger, allowing them to receive the free strand from your right hand. Release the free strand from the right hand as the left index finger and thumb grasp it.
STEP 8. Draw the free strand held by the pinched left thumb and index finger through the loop by pronating the left hand.
STEP 9. As you release the free strand from your left hand, pick up this strand with your right hand. Again, with your left hand, purposely pull up slightly on the fixed strand, while keeping the free strand in your right hand loose, creating a double half hitch.
STEP 10. Simultaneously, while pulling the fixed strand up slowly with your left hand toward you (holding the free strand with your right middle finger and thumb), push the loose knot down with your right index finger toward the intended final knot location. Do NOT tighten this hitch knot with your right hand; just help push it down the relatively taut left strand.
Once the structures you are tying are held firmly in position (or the ligature is tightly bound around a pedicle), and you are pleased with your knot placement, snug both strands equally and firmly to bind the knot in place.
Finally, while holding tension on both strands, firmly pull the strands 90° clockwise to the suture loop axis, and again snug the knot tightly. This maneuver converts this double hitch binding knot into a more stable knot that resists slippage as you stack at least 4 square throws over it.
MILLER’S KNOT (HAND TIE TECHNIQUE)
STEP 1. Begin with the standard hand and strand setup (Figure): Cross the free strand held in your right hand over the extended left index finger by moving the right hand away from your body. Keep your left index finger extended inside the loop of suture created; then pinch the crossed suture.
STEP 2. Begin to bring the free end around the backside of the pedicle to the left of the first loop.
STEP 3. Continue to hold the fixed strand with your left middle, ring, and little fingers, and keep your left palm held toward you. Bring the free strand fully around the pedicle, up, over, and to the left of the original pinched cross. Hold both crossed strands with your left thumb and index finger. The fixed strand in your left hand should be to the left of the second pass looped around the pedicle. The second pass loop is to the left of the first pass loop.
STEP 4. With the right hand, move the free strand over the second loop and then under and between the first and second loops and pull the free strand away from you.
STEP 5. Pull the free end away from you with the right hand and the longer fixed strand toward you with the left hand. Final miller’s knot appearance is shown.
STRANGLE KNOT (HAND TIE TECHNIQUE)
STEPS 1–3. Follow Steps 1 through 3 for the miller’s knot.
STEP 4. After you bring the free strand completely around the pedicle, up and over to the left of the original pinched cross, release your thumb on top of the crossed strands, and pinch the tips of your left index finger and thumb together inside the double pass loops.
STEP 5. Rotate your pinched thumb and index finger through the passes from right to left by pronating your left hand, and grasp the free strand. Now your left thumb is within the loops of the 2 passes.
STEP 6. With the pinched left index finger and thumb, draw the free strand under both passes to exit on the right of the 2 crossed strands. Pull the free strand away from you with the right hand, and pull the fixed strand toward you with the left hand.
STEP 7. When this knot is configured correctly, the 2 loops are crossed in the middle, the fixed strand extends under and to the left of the 2 loops, and the free strand is under and to the right.
MODIFIED MILLER’S KNOT: CAUTION — NOT RECOMMENDED
A modified miller’s knot is demonstrated below to show the difference in appearance and mechanics between this knot and the recommended ones demonstrated in this article.1,5 When placed under expansile force, particularly on larger pedicles, this knot does not consistently resist loosening to the degree of the traditional miller’s or strangle knots; therefore, we do NOT recommend its use.
In the miller’s knot, the strands are crossed on the first pass, and the second pass is to the left of the first formed loop.
In the modified version:
- The first pass is wrapped around the pedicle but, instead of crossing the free strand over to the left as in the other 2-pass binding knots, the second pass remains to the right of the fixed strand.
- The free end is then brought over the top of the 2 passes (A) and fed through the dual loops from left to right (B).
Ideally, a tightly placed binding knot will remain taut around a pedicle until subsequent square throws are completed, permanently binding the tight ligature knot in place and safely maintaining hemostasis.
DRHH = double reverse half hitch
- Toombs JP, Clarke KM. Basic operative techniques. In Slatter D (ed): Textbook of Small Animal Surgery, 3rd ed. Philadelphia: Saunders, 2003, pp 208-212.
- Knecht CD, Allen AR, Williams DJ, Johnson JH. Suture materials. Fundamental Techniques in Veterinary Surgery, 3rd ed. Philadelphia: Saunders, 1987, pp 28-49.
- Ashley CW. The Ashley Book of Knots. New York: Doubleday, 1944, pp 11-20, 219, 597-599.
- Hazenfield K, Smeak DD. In vitro holding security of six friction knots used as a first throw in the creation of a vascular ligation. JAVMA 2014; 245(5):571-577.
- Hardie RJ. Surgery STAT: Don’t forget the miller’s knot; available at veterinarynews.dvm360.com/surgery-stat-dont-forget-millers-knot.