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Laparoscopic intracorporeal square-to-slip knot
SURGEON’S WORKSHOP
LAPAROSCOPIC INTRACORPOREAL SQUARE-TO-SLIP KNOT MAXWELL V. MENG
AND
MARSHALL L. STOLLER
ABSTRACT We review a laparoscopic, intracorporeal technique of securing the square knot. It is useful when a surgeon’s knot is insufficient to maintain tissue approximation. Advantages include the use of standard tying methods, lack of extracorporeal knot creation or need for a pushing device, and ability to secure the knot in difficult locations. UROLOGY 59: 932–933, 2002. © 2002, Elsevier Science Inc.
I
ntracorporeal suturing and knot tying remain some of the most challenging tasks in laparoscopic procedures. Technologic advances have resulted in the development of staplers and suturing devices to aid in these aspects of laparoscopy.1 In addition, a variety of extracorporeal methods have been devised to assist in fashioning the knot.1–3 Nevertheless, there is no substitute for traditional intracorporeal knots. We describe a simple technique of securing the intracorporeal square knot, which has been useful in our experience. MATERIAL AND METHODS The suture length depends on whether an interrupted or running suture is used. Typically 5 to 6 in. and 9 in. are used for interrupted and running sutures, respectively. After the needle has passed through the tissue, the needle end is pulled to produce a tail end of approximately 1.5 in. The first overhand throw is created using a needle driver and flamingo forceps such that the knot will lay flat (Fig. 1A). An opposite throw is created using the instruments and the knot is approximated but not tightened (Fig. 1B). The needle end of the suture and the ipsilateral loop (where the needle exited the tissue) are gently pulled in opposite directions (Fig. 1B, arrows), converting the square knot into a slip knot (Fig. 1C). An atraumatic grasper is then used to push the knot down to secure the tissue (Fig. 1C, arrow) while the needle end is held taut. The two ends of the suture are subsequently pulled in opposite directions (Fig. 1D, arrows) to convert the slip knot back into a square knot (Fig. 1E). Additional instrument throws are placed to secure the initial square knot. The square-to-slip knot has been used and tested in laparoscopic trainers, laparoscopic animal models, and in actual laparoscopic procedures at the University of California, San Francisco and by others.4
From the Department of Urology, University of California, San Francisco, School of Medicine, San Francisco, California Reprint requests: Maxwell V. Meng, M.D., Department of Urology, U-575, University of California, San Francisco, School of Medicine, 533 Parnassus Avenue, San Francisco, CA 94143-0738 Submitted: November 8, 2001, accepted (with revisions): December 21, 2001
932
© 2002, ELSEVIER SCIENCE INC. ALL RIGHTS RESERVED
RESULTS We have routinely used this intracorporeal technique to advance and secure square knots. Although an initial surgeon’s knot can be used in many situations, the square-to-slip knot has several advantages. First, the surgeon’s knot is occasionally insufficient to maintain tissue approximation while the second throw is fashioned. The initial creation of the square knot allows the tie to be secured with a single motion, preventing suture slippage. Second, surgeons are familiar with the traditional instrument-tie motions used. Third, the technique is performed completely within the body. Extracorporeal knots are often more complex and time consuming, require the use of a knot pusher, and decrease the ability to gauge the appropriate tension. The technique can be used with a variety of suture materials. We primarily use Vicryl sutures in laparoscopic reconstructive procedures such as pyeloplasty and ureteral anastomosis. The slip knot slides easily if the throws are not tightened. When using a synthetic monofilament suture (eg, Monocryl for vesicourethral anastomosis), this technique is especially useful. Surgeon’s knots tend to slip because of the decreased suture friction, but the square-to-slip knot slides and secures without difficulty. Problems with this method can be encountered while using silk sutures because of the increased friction and pliability. Thus, coated braided and synthetic monofilament sutures may be most appropriate for the square-to-slip knot. COMMENT Suturing and knot tying are basic skills necessary for tissue approximation during open surgery. These fundamental requirements are no different in laparoscopic operations; however, the hand-eye 0090-4295/02/$22.00 PII S0090-4295(02)01517-0
FIGURE 1. Creation of intracorporeal square-to-slip knot. (A) Formation of first flat throw using traditional laparoscopic instruments. (B) Creation of square knot with an opposite throw that is not tightened, but is approximated, and then converted to a sliding knot by pulling in the directions of the arrows. (C) Advancement of the slip knot to the tissue (arrow) with an atraumatic grasper while holding the needle end taut. (D) Conversion of the slip knot back to a square knot by pulling the ends of the suture in opposite directions (arrows). (E) Final square knot after tissue approximation. Note, applies to a forehand suture from right side.
can be used in a similar fashion. It has been reported that the sliding square knot is not significantly different from intracorporeal flat square knots with respect to strength.5 We find that the extracorporeal sliding square knot requires more time and that manipulation of the knot with the pusher can be cumbersome and less reliable. Many laparoscopic surgeons use slip knots because they can be performed quickly and more easily than square knots. Several extracorporeal variations have been described such as the Roeder, Weston, and Duncan knots; however, all slip knots are significantly weaker than properly formed square knots.6 Similarly, an intracorporeal slip knot may be formed by two throws in the same direction and secured by sliding the “granny” knot to the tissue. Not only is this slip knot weaker than the square-to-slip knot, but the tension required to slide the knot is variable and control of the knot placement is poor. This may lead to knots that do not approximate the tissue (insufficient tension) or tissue damage from suture pull-through (excessive tension). In our experience, the square-to-slip knot can be placed carefully and precisely down to the tissue. Directly guiding the knot rather than pulling on the ends of the suture in opposite directions accomplishes this. CONCLUSIONS
dissociation, poor tactile feedback, and reduction from three dimensions to two make the task more demanding. Many methods and techniques are available to improve these shortcomings, including extracorporeal hand and preformed knots, automatic staplers, and intracorporeal suturing devices. However, the knowledge and ability to tie intracorporeal knots with standard instruments are essential for the laparoscopist. We discuss the square-to-slip knot as a tool to facilitate pure intracorporeal square-knot creation. The flat square knot remains the most familiar and generally reliable knot in laparoscopy.1,2,5 When properly formed, it has comparable strength to conventional open square knots.5,6 Often the first throw is a surgeon’s knot followed by three single-hitches. The initial double-hitch can slip and loosen in situations in which there is tension or the suture lacks sufficient friction to hold. In these cases, we find the square-to-slip knot especially helpful.4 The intracorporeally formed knot can be cinched and converted to a square knot quickly while the tissue remains approximated. In addition, the square-to-slip knot can be manipulated in smaller spaces, such as the pelvis in anastomosis during laparoscopic radical prostatectomy. Alternatively, an extracorporeal sliding square knot
UROLOGY 59 (6), 2002
Laparoscopy in urology is expanding to include complex reconstructive procedures that often require intensive suturing. Knowledge of a variety of techniques is necessary to complete these operations successfully and efficiently. The intracorporeal square-to-slip knot is an important addition to the armamentarium of tricks that should be familiar to the laparoscopist. Ultimately, there is no replacement for practice dedicated to enhancing laparoscopic tying skills and the experience to choose the appropriate knot for a particular situation. REFERENCES 1. Soper NJ, and Hunter JG: Suturing and knot tying in laparoscopy. Surg Clin North Am 72: 1139 –1152, 1992. 2. Szabo Z: Suturing, in Way LW (Ed): Fundamentals of Laparoscopic Surgery. New York, Churchill Livingstone, 1995, pp 137–154. 3. Pun˜ al Rodrı`guez JA: Reliable double-component knots for laparoscopic surgery. Br J Surg 85: 19, 1998. 4. Szabo Z, Stellini L, Rose EH, et al: Slip-knot suspension technique: a fail-safe microanastomosis technique for small caliber vessels. Microsurgery 13: 100 –102, 1992. 5. Dorsey JH, Sharp HT, Chovan JD, et al: Laparoscopic knot strength: a comparison with conventional knots. Obstet Gynecol 86: 536 –540, 1995. 6. Sharp HT, Dorsey JH, Chovan JD, et al: The effect of knot geometry on the strength of laparoscopic slip knots. Obstet Gynecol 88: 408 – 411, 1996.
933
LAPAROSCOPIC INTRACORPOREAL SQUARE-TO-SLIP KNOT MAXWELL V. MENG
AND
MARSHALL L. STOLLER
ABSTRACT We review a laparoscopic, intracorporeal technique of securing the square knot. It is useful when a surgeon’s knot is insufficient to maintain tissue approximation. Advantages include the use of standard tying methods, lack of extracorporeal knot creation or need for a pushing device, and ability to secure the knot in difficult locations. UROLOGY 59: 932–933, 2002. © 2002, Elsevier Science Inc.
I
ntracorporeal suturing and knot tying remain some of the most challenging tasks in laparoscopic procedures. Technologic advances have resulted in the development of staplers and suturing devices to aid in these aspects of laparoscopy.1 In addition, a variety of extracorporeal methods have been devised to assist in fashioning the knot.1–3 Nevertheless, there is no substitute for traditional intracorporeal knots. We describe a simple technique of securing the intracorporeal square knot, which has been useful in our experience. MATERIAL AND METHODS The suture length depends on whether an interrupted or running suture is used. Typically 5 to 6 in. and 9 in. are used for interrupted and running sutures, respectively. After the needle has passed through the tissue, the needle end is pulled to produce a tail end of approximately 1.5 in. The first overhand throw is created using a needle driver and flamingo forceps such that the knot will lay flat (Fig. 1A). An opposite throw is created using the instruments and the knot is approximated but not tightened (Fig. 1B). The needle end of the suture and the ipsilateral loop (where the needle exited the tissue) are gently pulled in opposite directions (Fig. 1B, arrows), converting the square knot into a slip knot (Fig. 1C). An atraumatic grasper is then used to push the knot down to secure the tissue (Fig. 1C, arrow) while the needle end is held taut. The two ends of the suture are subsequently pulled in opposite directions (Fig. 1D, arrows) to convert the slip knot back into a square knot (Fig. 1E). Additional instrument throws are placed to secure the initial square knot. The square-to-slip knot has been used and tested in laparoscopic trainers, laparoscopic animal models, and in actual laparoscopic procedures at the University of California, San Francisco and by others.4
From the Department of Urology, University of California, San Francisco, School of Medicine, San Francisco, California Reprint requests: Maxwell V. Meng, M.D., Department of Urology, U-575, University of California, San Francisco, School of Medicine, 533 Parnassus Avenue, San Francisco, CA 94143-0738 Submitted: November 8, 2001, accepted (with revisions): December 21, 2001
932
© 2002, ELSEVIER SCIENCE INC. ALL RIGHTS RESERVED
RESULTS We have routinely used this intracorporeal technique to advance and secure square knots. Although an initial surgeon’s knot can be used in many situations, the square-to-slip knot has several advantages. First, the surgeon’s knot is occasionally insufficient to maintain tissue approximation while the second throw is fashioned. The initial creation of the square knot allows the tie to be secured with a single motion, preventing suture slippage. Second, surgeons are familiar with the traditional instrument-tie motions used. Third, the technique is performed completely within the body. Extracorporeal knots are often more complex and time consuming, require the use of a knot pusher, and decrease the ability to gauge the appropriate tension. The technique can be used with a variety of suture materials. We primarily use Vicryl sutures in laparoscopic reconstructive procedures such as pyeloplasty and ureteral anastomosis. The slip knot slides easily if the throws are not tightened. When using a synthetic monofilament suture (eg, Monocryl for vesicourethral anastomosis), this technique is especially useful. Surgeon’s knots tend to slip because of the decreased suture friction, but the square-to-slip knot slides and secures without difficulty. Problems with this method can be encountered while using silk sutures because of the increased friction and pliability. Thus, coated braided and synthetic monofilament sutures may be most appropriate for the square-to-slip knot. COMMENT Suturing and knot tying are basic skills necessary for tissue approximation during open surgery. These fundamental requirements are no different in laparoscopic operations; however, the hand-eye 0090-4295/02/$22.00 PII S0090-4295(02)01517-0
FIGURE 1. Creation of intracorporeal square-to-slip knot. (A) Formation of first flat throw using traditional laparoscopic instruments. (B) Creation of square knot with an opposite throw that is not tightened, but is approximated, and then converted to a sliding knot by pulling in the directions of the arrows. (C) Advancement of the slip knot to the tissue (arrow) with an atraumatic grasper while holding the needle end taut. (D) Conversion of the slip knot back to a square knot by pulling the ends of the suture in opposite directions (arrows). (E) Final square knot after tissue approximation. Note, applies to a forehand suture from right side.
can be used in a similar fashion. It has been reported that the sliding square knot is not significantly different from intracorporeal flat square knots with respect to strength.5 We find that the extracorporeal sliding square knot requires more time and that manipulation of the knot with the pusher can be cumbersome and less reliable. Many laparoscopic surgeons use slip knots because they can be performed quickly and more easily than square knots. Several extracorporeal variations have been described such as the Roeder, Weston, and Duncan knots; however, all slip knots are significantly weaker than properly formed square knots.6 Similarly, an intracorporeal slip knot may be formed by two throws in the same direction and secured by sliding the “granny” knot to the tissue. Not only is this slip knot weaker than the square-to-slip knot, but the tension required to slide the knot is variable and control of the knot placement is poor. This may lead to knots that do not approximate the tissue (insufficient tension) or tissue damage from suture pull-through (excessive tension). In our experience, the square-to-slip knot can be placed carefully and precisely down to the tissue. Directly guiding the knot rather than pulling on the ends of the suture in opposite directions accomplishes this. CONCLUSIONS
dissociation, poor tactile feedback, and reduction from three dimensions to two make the task more demanding. Many methods and techniques are available to improve these shortcomings, including extracorporeal hand and preformed knots, automatic staplers, and intracorporeal suturing devices. However, the knowledge and ability to tie intracorporeal knots with standard instruments are essential for the laparoscopist. We discuss the square-to-slip knot as a tool to facilitate pure intracorporeal square-knot creation. The flat square knot remains the most familiar and generally reliable knot in laparoscopy.1,2,5 When properly formed, it has comparable strength to conventional open square knots.5,6 Often the first throw is a surgeon’s knot followed by three single-hitches. The initial double-hitch can slip and loosen in situations in which there is tension or the suture lacks sufficient friction to hold. In these cases, we find the square-to-slip knot especially helpful.4 The intracorporeally formed knot can be cinched and converted to a square knot quickly while the tissue remains approximated. In addition, the square-to-slip knot can be manipulated in smaller spaces, such as the pelvis in anastomosis during laparoscopic radical prostatectomy. Alternatively, an extracorporeal sliding square knot
UROLOGY 59 (6), 2002
Laparoscopy in urology is expanding to include complex reconstructive procedures that often require intensive suturing. Knowledge of a variety of techniques is necessary to complete these operations successfully and efficiently. The intracorporeal square-to-slip knot is an important addition to the armamentarium of tricks that should be familiar to the laparoscopist. Ultimately, there is no replacement for practice dedicated to enhancing laparoscopic tying skills and the experience to choose the appropriate knot for a particular situation. REFERENCES 1. Soper NJ, and Hunter JG: Suturing and knot tying in laparoscopy. Surg Clin North Am 72: 1139 –1152, 1992. 2. Szabo Z: Suturing, in Way LW (Ed): Fundamentals of Laparoscopic Surgery. New York, Churchill Livingstone, 1995, pp 137–154. 3. Pun˜ al Rodrı`guez JA: Reliable double-component knots for laparoscopic surgery. Br J Surg 85: 19, 1998. 4. Szabo Z, Stellini L, Rose EH, et al: Slip-knot suspension technique: a fail-safe microanastomosis technique for small caliber vessels. Microsurgery 13: 100 –102, 1992. 5. Dorsey JH, Sharp HT, Chovan JD, et al: Laparoscopic knot strength: a comparison with conventional knots. Obstet Gynecol 86: 536 –540, 1995. 6. Sharp HT, Dorsey JH, Chovan JD, et al: The effect of knot geometry on the strength of laparoscopic slip knots. Obstet Gynecol 88: 408 – 411, 1996.
933