Square knot
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The Square Knot is the recommended knot for tying most sutures (ie. silk, gut, cotton, some monofilament plastics, as well as stainless steel). In the diagrams below, adapted from the Ethicon guide, one "half" of the suture has been colored purple to make the instructions more clear -- a good way to practise is with a shoelace that you've colored to match this. Care must be taken not to tie a granny knot by accident (that's what you'll get if you mess up the crossing). It's a little confusing, but once you get the hang of it, it's like riding a bike and becomes almost reflex:
- White half is placed over the extended index finger of your left hand (acting as bridge), and held in palm. The purple half is held in your right hand.
- The purple half is brought between left thumb and index finger.
- Rotate your left hand inward and swing your thumb under the white half to form the first loop.
- The purple half is crossed over the white half and held between your left thumb and index finger.
- Releases the purple half from your right hand. Rotate your left hand and, with your thumb and index finger still holding the purple half, bring the purple half through the white loop. Regrasp the purple half with your right hand.
- Release the purple half from your left hand. Apply horizontal tension by moving your left hand toward your and right hand away from you, completing the first half hitch.
- Release your left index finger from the white half and raotate your left hand to loop the white half over your left thumb. Angle the purple half slightly to the left.
- Bring the purple half toward the you with the your right hand and cross it over the white strand.
- Rotate your left hand further and slide the white half onto your left index finger, forming a loop as you grasp the purple half with your left index finger and thumb.
- Rotate your left hand inward with your thumb carrying the purple half through the white loop. Grasp the purple half with your right hand.
- Apply horizontal tension by moving your left hand away from you and your right hand toward you.
- The final tension should be horizontal.