Two Hand Tie
Two Hand Square Knot
Wayne W. LaMorte, M.D., Ph.D., M.P.H.
Photography by Michael J. LaMorte
The two hand square knot is the most fundamental knot for the surgeon.
Well-constructed square knots with flat throws have less likelihood of slipping.
1) This shows the beginning of knot construction.
Note that the short end is in the right hand, and the thumb of the left hand is beginning to create a loop by pushing the long strand to the right.
2) The right hand has brought the short end toward the surgeon and across the left hand strand to form a loop. The left thumb protrudes through the loop.
Note that the left forefinger contacts the thumb, so the thumb can guide the index fingert down through the loop.
3) The left index finger has been rotated down into the loop.
4) The short strand is now placed between the thumb and forefinger in order to transport the short end up through the loop.
5) The left hand is now rotated counterclockwise to bring the thumb back up through the loop, pushing the short end up with it.
6) The short end has now emerged completely through the loop and will be re-grasped with the right hand in order to tighten the “throw” that has been created..
7) The surgeon begins to tighten the throw by pushing the long strand away… and pulling the short strand toward himself.
8) The throw is now snugged down.
Note that tension is applied by pulling the two strands in opposite directions at an angle of 180 degrees.
9) The left forefinger now begins to form the loop for the next throw by sliding beneath the long strand and pushing it to the right.
10) The short strand is now brought to the left and beneath the long strand to form the new loop.
11) The left thumb contacts the forefinger and begins to rotateup into the loop.
12) The left thumb has now emerged from the loop, and the short strand will be pinched between the thumb and forefinger of the left hand.
13) The right hand releases the short end, and the left hand is now rotated in the opposite direction to drive the short end through the loop toward the surgeon.
14) The short end is re-grasped by the right hand and pulled away from the surgeon, and the long strand is pulled toward the surgeon.
15) Equal tension is applied to both strands as they are pulled in opposite directions to secure a flat square knot.
16) To secure the knot, a third throw will be added, using the same technique for the first throw.
17) After creating the loop, the left index finger is rotated clockwise into the loop, and the short end is placed between the thumb and index finger of the left hand.
18) The left hand is rotated back in a counterclockwise direction to pass the short end through the loop.
19) Finally, the short end has been re-grasped with the right hand and pulled toward the surgeon as the left hand pushes the long strand away to secure the third throw.
Multifilament or braided materials such as silk can usually be secured with just three throws. The throws are alternated to create successive square knots, so with three alternating throws, one essentially creates a double square knot.
Slippery monofilament suture material, such as nylon or prolene, requires 5 or 6 alternating throws because it has a tendency to slip and untie itself.