2 Boel A. Fransson and John C. Huhn In the early years of minimally invasive surgery (MIS), controversy existed regarding the need for suturing skills. Many practicing surgeons thought that laparoscopic suturing was too difficult to ever be considered a realistic requirement.1 However, in the early 1990s, a consensus was built: laparoscopic surgeons had to learn and apply basic suturing skills unless the development of laparoscopic surgery was to be impeded.2 Soon it was recognized that these complex skills had to be practiced with other methods than the classical “see one, do one, teach one” paradigm of conventional residency training. As a result, simulation training became a requirement. Currently, veterinary medicine is facing the same dilemma. The introduction of MIS into small animal surgery has resulted in MIS technology being available at most specialized and many nonspecialized practices. For progressive evolution of small animal MIS, we need to embrace suturing techniques. Because of the challenge of suturing, many replacement devices have been introduced, but most are expensive and not always as versatile or secure as desired. With suturing skills, many open surgical techniques can be replaced with minimally invasive counterparts for the benefit of our patients. Having suturing skills also increases the surgeon’s confidence to deal with emergent situations during a surgical procedure without the need for conversion to open surgery. This chapter is intended to give novice laparoscopic surgeons a foundation, enabling them to start practicing suturing in a simulator in preparation for clinical application. With suturing skills developed in the simulator, we have found that the step to intracorporeal clinical suturing is small for most trainees. Conventional laparoscopic needle holders differ from most other laparoscopic instruments in that they do not rotate around the axis of the instruments in order to provide stability. Articulating and rotating needle drivers have been introduced but have been criticized for creating imprecision in needle exit and for being more difficult to learn to use than conventional needle drivers.3 The handles are often of a straight axial design, placing the needle in line with the surgeon’s hands to allow greater maneuverability and more natural motion of the wrist when suturing. The jaws are often single action and are usually operated by means of an ergonomic spring-loaded palm grip on the handle. Several handle types are available, and the efficacies of four of them were compared.4 It was found that a pistol grip (Figure 2.1) was superior for experienced operators but not for novices, who preferred a palmed straight grip. Neither experienced or novice users performed well nor preferred a thumb–ring finger grip (Figure 2.2).4 Figure 2.1 Pistol grip laparoscopic needle driver. (© 2014 Photo courtesy of KARL STORZ GmbH & Co. KG.) Figure 2.2 Needle driver with handle designed for thumb–ring finger grip. These did not perform as well as other designs.4 (© 2014 Photo courtesy of KARL STORZ GmbH & Co. KG.) For novice laparoscopic surgeons, we recommend a needle driver that is sturdy, with straight handle, a ribbed grip, and a conveniently located needle release button on the grip (Figure 2.3). Hand size differs among surgeons; therefore, the preferred position of the release button may differ. When the release button is placed in the axis of the instrument, it can be used with either hand. Figure 2.3 For novice laparoscopic surgeons, we recommend needle drivers that are sturdy, with straight handles, ribbed grips, and conveniently located needle release buttons on the grips. (© 2014 Photo courtesy of KARL STORZ GmbH & Co. KG.) Needle driver jaws may be straight, curved left, or curved right (Figure 2.4). They can also be self-righting. Straight jaws are this author’s (BAF) preference because they can be used in both left and right positions. The jaws are designed for a particular range of needle sizes, which is important to note before purchase. Self-righting needle drivers force the needle into a fixed position, usually at 90-degree angle to the instrument shaft. The limitations of self-righting needle drivers is that they should not be used to grasp the suture because they may damage or weaken the material. In addition, they reduce the surgeon’s freedom to position the needle in different angles. Figure 2.4 Different configurations of needle driver jaws. From top to bottom: “parrot jaw” curved left, “flamingo jaw” curved right for a 6-mm cannula, and “flamingo jaw” curved right for an 11-mm cannula. (© 2014 Photo courtesy of KARL STORZ GmbH & Co. KG.) Conventional suture materials are routinely used in MIS (Table 2.1). Braided synthetic absorbable sutures are often favored over monofilament synthetic absorbable sutures for intracorporeal suturing. The primary reason for this preference is the ease of handling that follows from the decreased memory of braided versus monofilament sutures. Furthermore, braided sutures are more resistant to instrument-induced damage during the knotting process. As knots are formed, there is significant interstrand friction, commonly known as chatter. This friction can induce significant damage to suture materials, particularly monofilaments. Braided materials are less vulnerable to this damage because their strength is distributed over many fibers similar to the cables of a suspension bridge. Braided materials are not without their downside, however. They have considerably more tissue drag than monofilament sutures, and they can harbor and potentiate bacterial infections. To minimize these effects, suture manufacturers have devised two solutions. First, application of coating agents, such as silicone, wax, polytetrafluoroethylene (PTFE), caprolactone, and calcium stearate, fills in the gaps in the interstices of the braid and decreases friction during tissue passage. Second, some manufacturers use antimicrobial coatings on their materials to preemptively address suture-potentiated infections. Table 2.1 Conventional Sutures Used in Minimally Invasive Surgery Knot security is a function of suture interstrand friction. Braided suture materials have a higher coefficient of friction than monofilament sutures. As such, braided sutures can form secure knots with fewer throws than monofilament sutures. In general, whereas braided sutures require three or four throws to form a secure knot, monofilament sutures require four or five throws.5 Coated braided materials have less interstrand friction than their uncoated counterparts but still require fewer throws than monofilaments for stable knot formation. Conventional 1/2 and 3/8 suture needles are commonly used in MIS. Specialized half-curved (“ski”) needles can be advantageous when operative space is limited. The J needle may be beneficial when closing port incisions. Straight needles can be used in special circumstances, but limited access precludes their general usage (Figure 2.5). Figure 2.5 Numerous needle configurations can be used for intracorporeal suturing. In general, whereas shorter needle arcs allow easier needle retrieval, longer needle arcs facilitate working where access is limited. It is helpful to use needles that are flattened along their bodies to allow stable grasping with an endoscopic needle holder. Taper or tapercut points are best. Reverse cutting needles may be used, but one must be conscious of the cutting edge on the convex surface. Inadvertent cutting of vascular structures is possible because of poor visualization of the back side of the reverse cutting needle. Usage of cutting needles should be avoided because the sharp concave edge cuts through tissue during needle passage. This can lead to suture “pull-through” as well as increased hemorrhage. Suture needles used in MIS should be strong enough to resist the increased forces placed on them during intracorporeal suturing. Suture needles are made of stainless steel alloys containing chromium and nickel. Chromium confers corrosion resistance, and nickel imparts strength to the needle. With the optimal component ratios, suture needles demonstrate the ability to deform without fracture, a property known as ductility.6 Major suture manufacturers commonly produce standard and premium grade suture needles as part of their suture line. There is a premium to be paid for higher quality suture needles, which can be custom manufactured in combination with any suture material. Proprietary coatings are applied to suture needles to facilitate their tissue passage. Two of the most difficult aspects of intracorporeal suturing are square knot formation and maintaining suture tension during continuous pattern suturing. The incorporation of barbed suture technology into MIS has made a significant impact in alleviating these difficulties. In 2007, absorbable and nonabsorbable bidirectional barbed sutures (Quill SRS; Angiotech Pharmaceuticals, Vancouver, British Columbia, Canada) received U.S. Food and Drug Administration (FDA) clearance for use in approximating soft tissues.7 These materials were cut from poliglecaprone and polydioxanone for absorbable sutures and polypropylene and nylon for nonabsorbable sutures. Quill SRS sutures feature a helically barbed strand with bidirectional barbs (10 barbs/cm) emanating from a central unbarbed segment. The strand itself is double armed and is meant to be applied so that the suturing process commences at the midpoint of the surgical incision. Suturing proceeds with each arm proceeding 180 degrees away from the center toward the opposite edges of the incision. At the end of the incision, the respective suture needles are directed 90 degrees laterally to the sutured line and cut flush with the tissue. With Quill sutures, the suture size naming convention is such that the size of the suture is a function of the parent strand from which it was barbed. For example, a 3/0 Quill suture is derived from a 3/0 parent strand. However, the strength of this suture more closely approximates a 4/0 USP suture.8 This is important for the surgeon to bear in mind when using these products. In 2009, absorbable unidirectional barbed sutures (V-Loc 90/180, Covidien, Mansfield, MA) were FDA approved for soft tissue approximation. These materials were produced from absorbable glycolide–dioxanone–trimethylene carbonate polyester (V-Loc 90) and absorbable polyglyconate (V-Loc 180). More recently, a nonabsorbable polybutester (V-Loc PBT) has become available. V-Loc sutures feature a single-armed strand with unidirectional helical barbs (20 barbs/cm) that proceed from the swage toward the terminal end of the strand, which is welded into a loop. V-Loc suturing begins with advancement of the suture needle through the tissue on one side of the incision until the base of the terminal loop is reached. The suture needle is then passed through the tissue on the opposite side of the incision, leaving the terminal loop on the contralateral side. Before taking a third tissue bite, the suture needle tip is advanced through the terminal loop. The following suture bites may be performed in either a vertical or horizontal pattern to affect a simple continuous or mattress closure respectively. The suture size naming convention used with V-Loc sutures is such that the suture size is a function of USP tensile strength.8 As such, 3/0 V-Loc suture has a tensile strength that is close to that of a conventional monofilament 3/0 suture. This eliminates the “mental gymnastics” that the surgeon might encounter when deciding an appropriate suture size for the tissue application. V-Loc sutures are available in sizes 0 to 4/0 and in 6-, 9-, 12-, 18-, and 24-inch strand lengths (Figure 2.6). Figure 2.6 V-Loc 90 (A) and Quill Monoderm (B) barbed suture materials. V-Loc 180 sutures feature unidirectional dual-angle barbs with a suture needle on one end and a terminal welded loop on the other. Quill Monoderm sutures are double armed and feature bidirectional, helical, single-angle barbs that emanate from the center of the strand. (Reproduced with permission from J. Zaruby.) Barbed sutures can greatly simplify intracorporeal suturing. A notable example is in laparoscopic gastropexy. Maintaining suture tension during stomach suspension is greatly facilitated with barbed sutures.9 Another example is in intrapelvic herniorrhaphy, in which suture approximation is difficult because of space limitations.10 Other uses for barbed suture remain to be determined but are developing with MIS implementation in veterinary surgery. Please note that most descriptions in this section refer to right-handed surgeons, preparing to take a right to left suture bite, for the purpose of increased readability. The instruments involved usually consist of a needle driver in the dominant hand (right in the examples here) and either a good-quality grasper or a second needle driver in the nondominant (left) hand. A fundamental difference between laparoscopic and open suturing is the restricted instrument mobility. The surgeon is confined by the cannula placement to a single arc of rotation perpendicular to the axis of the instrument. The cannula placement has to be as ideal as possible to make suturing easier. An intercannula distance of at least 5 cm is desirable for the needle driver and accessory instrument. The working tips of these instruments should meet at oblique angles with each other at a relatively wide angle of 60 degrees or more. If possible, the cannula for the right needle driver should be parallel to the suture line. The distance between cannula entrance and operative field should be approximately half of the length of the instrument (e.g., for 30-cm instruments, the cannula should be placed 15 cm [∼6 in] from the target field).2 The instruments and camera need to be directed in the same axis as the surgeon’s view toward the screen to avoid mirrored vision. The needle introduction method used depends on the type and size of needle, the size of the cannulas used, and the animal’s size in relation to needle size. If the body wall thickness and needle size allow, the needle can simply be passed transcutaneously into the abdominal cavity anywhere in the surgically prepared area and be grasped intracorporeally with the needle driver. If so, the needle is ideally passed perpendicular to the dominant hand instrument axis so the needle can simply be grasped at the midpoint, and suturing ensues. Often the needle and suture need to be passed through the cannula or the cannula site. If the needle size is compatible with cannula size, which usually requires a 10- to 12-mm cannula, the easiest introduction for a right-handed surgeon is to grasp the suture 2 to 3 cm from the swaged on end of the needle with the left instrument and pass it through the cannula. The suture is grasped with the needle tip pointing toward the left (Figure 2.7) and thus is ready to be grasped with the right hand instrument. If the needle position is not good, it can easily be corrected by applying gentle traction to the suture material (Figure 2.8). An alternative is to backload the needle and introduce through the cannula, and when intracorporeal, reposition the needle as described in detail later (Figures 2.9 and 2.10).11 The cannula valve may need to be released when introducing to avoid disrupting the needle position or damaging the valve. Figure 2.7 Needle introduction through a cannula. A.
Minimally Invasive Suturing Techniques
Introduction to Laparoscopic Suturing
Needle Holders for Laparoscopic Suturing
Suture Materials for Minimally Invasive Suturing
Conventional Sutures
Tensile Strength
Memory
Absorption Profile22,23
Throws Required5
Braided
Polysorb
++++
–
3–4
Vicryl
++++
–
3–4
Monofilament
Monocryl
++
–
3–4
Biosyn
+++
—
90–110 d
4–5
Polydioxanone (PDS)
++
–
3–4
Maxon
+++
—-
180 d
4–5
Suture Needles
Barbed Suture
Intracorporeal Suturing Technique
Cannula Placement
Needle Introduction
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