Medical Students Training Program - Square Knot

Training Program
MEDICAL STUDENTS

Square Knot

Two Hand Technique
The two-hand square knot is the easiest and most reliable for tying most suture materials. It may be used to tie surgical gut, virgin silk, surgical cotton, and surgical stainless steel.

Standard technique of flat and square ties with the additional throws if indicated by the surgical circumstances and the experience of the operator should be used to tie BIOSYN (poliglecaprone 25) suture, Coated POLYSORB (polyglactin 910), TICTON polyester suture, SOFSILK silk suture, and SURGIPRO polypropylene suture.

Suture Names
Biosyn = Monocryl Monosof = Ethilon	Polysorb = Vicryl Sofsilk = Perma-Hand Surgidac = Mersilene	Surgipro = Prolene Ticton = Ethibond


White strand placed over extended index finger of left hand acting as bridge, and held in palm of left hand. Purple strand held in right hand.
Purple strand held in right hand brought between left thumb and index finger.
Left hand turned inward by pronation, and thumb swung under white strand to form the first loop.
Purple strand crossed over white and held between thumb and index finger of left hand.
Right hand releases purple strand. Then left hand supinated, with thumb and index finger still grasping purple strand, to bring purple strand through the white loop. Regrasp purple strand with right hand.
Purple strand released by left hand and grasped by right. Horizontal tension is applied with left hand toward and right hand away from operator. This completes first half hitch.
Left index finger released from white strand and left hand again supinated to loop white strand over left thumb. Purple strand held in right hand is angled slightly to the left.
Purple strand brought toward the operator with the right hand and placed between left thumb and index finger. Purple strand crosses over whit strand.
By further supinating left hand, white strand slides onto left index finger to form a loop as purple strand is grasped between left index finger and thumb.
Left hand rotated inward by pronation with thumb carrying purple strand through loop of white strand. Purple strand is grasped between right thumb and index finger.
Horizontal tension applied with left hand away from and right hand toward the operator. This completes the second half hitch.
The final tension on the final throw should be as nearly horizontal as possible.

Square Knot

One-Hand Technique
Wherever possible, the square knot is tied using the two-hand technique. On some occasion it will be necessary to use one hand, either the left or right, to tie a square knot. These illustrations employ the left-handed technique.

The sequence of throws illustrated is most commonly used for tying single suture strands. The sequence may be reversed should the surgeon be holding a reel of suture material in the right hand and placing a series of ligatures. In either case, it cannot be too strongly emphasized that the directions the hands travel must be reversed proceeding from one throw to the next to ensure that the knot formed lands flat and square. Half hitches result if this precaution is not taken.


White strand held between thumb and index finger of left hand with loop over extended index finger. Purple strand held between thumb and index finger of right hand.
Purple strand brought over white strand on left index finger by moving right hand away from operator.
With purple strand supported in right hand, the distal phalanx of left index finger passes under the white strand to place it over tip of left index finger. Then the white strand is pulled through loop in preparation for applying tension.
The first half hitch is completed by advancing tension in the horizontal plane with ht left hand drawn toward and right hand away from the operator.
White strand looped around three fingers of left hand with distal end held between thumb and index finger.
Purple strand held in right hand brought toward the operator to cross over the white strand. Continue hand motion by flexing distal phalanx of left middle finger to bring it beneath white strand.
As the middle finger is extended and the left hand pronated, the white strand is brought beneath the purple strand.
Horizontal tension applied with the left hand away and right hand toward the operator. This completes the second half hitch of the square knot. Final tension should be as nearly horizontal as possible.

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