9: Selection of Suture Materials, Suture Patterns, and Drains for Wound Closure

Selection of Suture Materials, Suture Patterns, and Drains for Wound Closure

Christophe Celeste, DrVet, PhD, Diplomate ECVS, Diplomate CVS


Sutures play an important role in wound repair by supporting healing tissues. Understanding the various characteristics of suture materials enables appropriate selection. However, no single suture material is ideal, and compromises must be made. Proper suture placement, using specific patterns, generally ensures a predictable progression of wound healing and of scar formation. Drains, when properly applied, may help to prevent or at least lessen complications during healing. Sutures and drains are not substitutes for proper wound management because they cannot compensate for poor cleansing, debridement, and wound irrigation. Moreover, inappropriate use of sutures and drains may delay healing and may lead to scarring.


Sutures serve important functions in wound repair, namely holding tissues in apposition and counteracting physiologic forces until healing progresses to the point that the tissue can take over this function. Sutures also provide hemostasis and obliterate dead space, thereby minimizing the risk of infection and promoting repair.

A broad range of suture materials is available. A sound knowledge of the properties of various suture materials, an accurate assessment of the wound’s condition, an appreciation of the wound’s location, as well as a good understanding of the healing process of the particular tissues involved in the wound, ensure selection of the most appropriate suture material by the surgeon, and thereby enhance the healing process.

Although selection of the appropriate suture material is important, so is the surgical technique used to close the wound. Good surgical technique is mandatory because it significantly affects outcome. Proper placement of sutures allows precise approximation of the wound’s edges, which helps minimize and distribute tensional forces on skin. Proper application of a drain facilitates elimination of dead space by evacuating accumulations of fluid and gas, thereby minimizing the risk of infection. Satisfactory results are best achieved when the surgeon uses the appropriate suture material and optimal suture pattern for wound closure, as well as the most suitable system of drainage.

The aim of this chapter is to review the various suture materials and patterns used to close wounds and to discuss the proper use of drains in wound management.

Suture material and selection

Optimal material

The optimal suture material should:

  • be easy to handle and comfortable for the surgeon to use;
  • have first‐throw holding strength and good knot security;
  • stimulate minimal tissue reaction to avoid creating an environment favorable to bacterial growth;
  • retain adequate tensile strength until its purpose is achieved and then be absorbed without inducing complications;
  • resist infection and have good elasticity to accommodate for swelling of the wound;
  • be non‐electrolytic, non‐capillary, non‐allergenic, non‐carcinogenic, non‐ferromagnetic, non‐corrosive, and non‐toxic;
  • be inexpensive, readily available, and easily sterilized without altering its properties.

Although some of the newly available suture materials have many of these characteristics, none possess all of them; consequently, compromises must be made.1–3

Suture material characteristics

Suture materials are described and compared on the basis of their composition, morphology, and biologic and biomechanic properties. A sound understanding of the main characteristics of all suture materials is mandatory so that the appropriate suture is selected.


Sutures are made from naturally occurring substances, synthetic polymers, or metallic fibers. Natural materials, such as cotton and silk, tend to elicit a substantial inflammatory reaction and have mostly been replaced by synthetic materials.


Sutures can be broadly classified as monofilament or multifilament. Sutures constructed of one filament (i.e. single‐stranded) are referred to as monofilament, whereas those constructed of multiple filaments (i.e. multi‐stranded) that are either braided or twisted together are referred to as multifilament. Multifilament sutures have greater strength and pliability than monofilament sutures of the same material and thus are easier to handle and manipulate for tying knots and are less susceptible to catastrophic damage from crushing or nicking. Moreover, less tension is required to ensure good apposition of tissues when using multifilament sutures, because they have a higher coefficient of friction than monofilament sutures; this characteristic also improves knot security. Multifilament sutures, however, have greater tissue drag and thereby injure tissue further when inserted and removed. Multifilament sutures have interstices between fibers, making them more capillary than monofilament sutures, which in turn, makes them more likely to absorb and retain fluid and bacteria.1,2,4,5 Recent studies reported that biofilms show a preference for growing in the braid grooves formed between filaments; thus, multifilament sutures might be a predisposing factor for the formation of biofilms.6,7

Suture materials, especially multifilament sutures, can be coated with a variety of compounds, broadly characterized as water soluble or insoluble, including antibiotics, to increase pliability, reduce capillarity, decrease tissue drag, improve tying characteristics, facilitate knot formation, and lessen the likelihood of surgical site infection (SSI). Nevertheless, coatings, especially water‐insoluble ones, tend to reduce knot security compared with similar uncoated suture.

Antibiotic coatings are now available on a number of sutures. The most common antibiotic coating contains triclosan (Coated Vicryl Plus Antibacterial; Monocryl Plus Antibacterial; Polydioxanone Plus Antibacterial – Ethicon, Johnson & Johnson Company, Inc.), a bacteriostatic drug that has been shown to inhibit the in vitro growth of both wild‐type and methicillin‐resistant Staphylococcus aureus and Staphylococcus epidermidis 8 and to reduce the incidence of SSI after clean, clean–contaminated, and contaminated surgery9 without affecting tissue reaction, healing response, or the absorption profile of coated sutures.10 The use of triclosan in many consumer products including soaps, toothpastes, shower gels, deodorants, etc., over the years has, however, led to the emergence of strains of bacteria that are triclosan resistant. A new synthetic antimicrobial suture coating, poly[(aminoethyl methacrylate)‐co‐(butyl methacrylate)] (PAMBM), inspired by natural antimicrobial peptides (AMPs), has been shown to provide bactericidal activity against both wild‐type and methicillin‐resistant S. aureus compared with the bacteriostatic property of triclosan in vitro. Because of their simple physical mechanism of action, AMPs display broad‐spectrum activity against Gram‐positive and Gram‐negative bacteria, and it appears difficult for bacteria to develop resistance against them.11 Such products have not yet been tested in vivo and are, therefore, not available commercially.

A variant in the morphology of suture material is the presence of surface barbs, created by placing linear nicks along the suture material. Self‐anchoring, barbed monofilament sutures have been developed (V‐LocTM 90, 180 or PBT Wound Closure Device, Covidien, Medtronic; QuillTM PDO Knotless Tissue‐Closure Device, Angiotech, Surgical Specialties Corporation, Inc.) in an attempt to eliminate knots, thus providing increased tensile strength and a stronger repair, and shortening surgical times. Knots are known to be the weakest portion of a suture line. Indeed, implanting, tying, and especially knotting of suture decrease its strength by up to 40%.4 Knot‐tying techniques are described later in this chapter, and the influence of various suture materials on security of the knot and suture line is summarized in Table 9.3. Contrary to expectations, studies report that knotless absorbable barbed suture devices yielded wound strength and tissue reaction scores that were comparable to traditional non‐barbed sutures secured with knots.12,13 According to Rosen,14 barbed sutures have, however, revolutionized the approach of plastic surgeons not only by shortening surgical times but also by enhancing their ability to quilt and powerfully lift tissue and to eliminate surgical drains. Although little is yet known about the use of barbed sutures in the management of wounds of horses, the security and utility provided by this suture look promising.

Degradation behavior

Absorbable sutures degrade and lose tensile strength, usually within 60–90 days after implantation, either by hydrolysis, enzymatic digestion, or phagocytosis.4 Their rate of absorption varies depending on their composition, coating, size, biologic environment, and species into which they were implanted. The environment surrounding the suture material is a major determinant of the rate at which the material is absorbed. Thus, although general times for absorption are offered as guidelines for clinical use, considerable variations in the rate of absorption and residual strength are noted. As an example, exposure to bodily fluids, such as urine, especially infected urine,15 or gastric secretions, substantially accelerates the rates of degradation and absorption.

Non‐absorbable sutures retain tensile strength for longer than 90 days, and, consequently, they are mainly used when extended support of the wound is required. Non‐absorbable sutures are not degraded substantially after implantation and are usually encapsulated or walled off by fibrous tissue.

It is widely accepted that synthetic absorbable and non‐absorbable suture materials are superior to the natural suture materials because the latter elicit more reaction, including inflammation; thus, the use of synthetic suture materials should be favored. The most important characteristics of commonly used absorbable and non‐absorbable, natural and synthetic, monofilament and multifilament suture materials are summarized in Table 9.1 and Figure 9.1.

Table 9.1 Characteristics of the most commonly used non‐absorbable and absorbable suture materials.

Source: Adapted from Celeste,1 Kümmerle,3 Schmiedt,4 McPhail,5 Toombs,16 Blackford.17,18

Generic name Trade name Suture
Reduction in tensile strength * Complete absorption (days) Relative knot security Handling Tissue reaction Comments
Polypropylene PROLENEa
Biologically inert
No reduction after implantation

+++ – (slippage) Higher knot security than all monofilament non‐metallic synthetic suture materials
Stable in contaminated wound environment
Best suture available for skin
Polybutester NOVAFILb Non‐absorbable
Biologically inert
No reduction after implantation

++ ++ Non‐reactive in tissues
Provides prolonged support for slow‐healing tissues
Silk SILKa, d, e
Uncoated or coated
30% at 14 days
50% at 1 year

+++ +++ +++ Rapid loss of tensile strength
Incites tissue reaction
May potentiate infection
Surgical stainless steel FLEXONb
Monofilament or multifilament
Biologically inert
No reduction after implantation

+++ Greatest tensile strength of all sutures
Inflexible ends can cause inflammation and tissue necrosis, leading to localized skin infection
Tends to cut tissue
Polymerized caprolactam SUPRAMID f
Retains no tensile strength after 6 months
++ ++ (if coating breaks) Superior tensile strength compared to nylon
Should not be buried since it absorbs up to 10% of its weight in fluid
Elicits moderate to severe tissue reaction, swelling, and sinus tract formation
Monofilament or multifilament
30% at 2 years (monofilament)
75% at 180 days (multifilament)

+ + Incidence of infection very low, even in contaminated wounds (similar to stainless steel)
Degradation products have antibacterial properties
Polyester/polybutester MERSILENE a
Monofilament or Multifilament
Uncoated or coated
Biologically inert
No reduction after implantation

++ + ++ (when there is no coating or if coating breaks) One of the strongest non‐metallic suture materials available
Provides prolonged support for slow‐healing tissues
Non‐coated form has a high coefficient of friction
Coating reduces friction and knot security
Causes the most tissue reaction of the synthetic non‐absorbable suture materials
Should not be used in contaminated wounds
Surgical gut CATGUT Absorbable
33% at 7 days
100% at 2–3 weeks
70 days
– wet + +++ Rarely used
Induces inflammatory reaction
Rapid loss of tensile strength
Polyglactin 910 VICRYL a
VICRYL Rapide a
25% at 14 days
50% at 21 days
100% at 35 days
50% at 5 days
100% at 21 days
56–70 days
42 days
++ +++ + Minimal tissue reaction, excellent handling properties, stable in contaminated wounds
Polyglycolic acid DEXON b Absorbable
Can be coated
35% at 14 days
65% at 21 days
60–90 days
++ ++ + Degradation products have some antibacterial effects Prematurely absorbed in the oral cavity and urine
Tends to drag through tissues
Lactomer POLYSORB b Absorbable
20% at 14 days
70% at 21 days
56–70 days
++ +++ Biomechanically superior to Polyglactin 910
High initial tensile strength
Polydioxanone PDS II a Absorbable
25% at 14 days
30% at 28 days
50% at 42 days
180 days
++ ++ + Maintains tensile strength over a prolonged period of time
Polyglyconate MAXON b Absorbable
25% at 14 days
50% at 28 days
75% at 42 days
180 days
+++ ++ + Best effective postimplantation strength and best knot security of all absorbable suture materials
Poliglicaprone 25 MONOCRYL a Absorbable
40–50% at 7 days
70–80% at 14 days
90–120 days
++ +++ + Very low tissue drag, minimal tissue reaction
Glycomer 631 BIOSYN b Absorbable
25% at 14 days
60% at 21 days
90–110 days
++ +++ + Minimal memory and excellent handling properties
Polyglytone 6211 CAPROSYN b Absorbable
40–50% at 7 days
70–80% at 14 days
56 days
+++ +++ + Provides short‐term tensile strength combined with very rapid absorption

* Values are approximate. Actual loss of tensile strength may vary

a Ethicon, Johnson & Johnson company, Inc.

b Covidien, Medtronic

c Mallinckrodt Veterinary, Schering Plough, Merck & Co

d Merck & Co

e C.P. Medical

f S. Jackson, Inc.

g Jorgensen Laboratories

h United States Surgical

Tree diagram presenting the characteristics of sutures most commonly used in veterinary medicine.

Figure 9.1 Characteristics of sutures most commonly used in veterinary medicine. TS, tensile strength.

Source: Adapted from McPhail 2013.5 Reproduced with permission of Elsevier.

Suture size

Suture size is standardized to U.S. Pharmacopeia (USP) standards. The USP size (expressed with zeroes, with 12‐0 being the smallest and 7 the largest) indicates a specific diameter necessary to produce a predetermined tensile strength, which varies among the different categories of suture material. The tensile strength of a suture material is the maximal stress that the suture can withstand before breaking. Tensile strength varies among suture materials and is correlated to suture diameter. The smaller the suture size, the less tensile strength the suture has. Sutures should be as strong as the tissue through which they are placed.2 The tensile strength of the selected suture material, however, need not exceed that of the tissue it secures, and the rate at which the suture material loses tensile strength and that at which the wound gains strength should concord as much as possible to avoid dehiscence.2 Consequently, the smallest‐diameter suture that adequately apposes and holds the wound’s edges during healing should always be preferred.1,19

Using an unsuitably large suture introduces more foreign material into the wound than is necessary, interferes with the blood supply, and may cause excessive inflammation, all of which alter the tissue’s architecture and ability to resist infection.1 Excessive tension on sutures leads to tissue necrosis, which favors wound dehiscence by interfering with local blood supply and increasing edema of the wound and surrounding tissues.20–23 Most suture materials are recognized by the body as foreign and, therefore, can potentiate the risk of wound infection when used in excess (i.e., too much suture, too large a diameter, or too many knots).1,24

If suturing alone cannot reduce the tissue tension to an optimal level, other tension‐relieving techniques to mobilize the wound’s edges should be used before closing the wound.1,19,25 The reader is referred to Chapter 10 for more information about mobilizing skin to reduce tension upon closure.

Suture selection

The goal of suturing a wound is to provide secure partial or complete closure while minimizing morbidity. A sound knowledge of the suture material’s properties, an accurate assessment of a wound’s location and condition, and a good understanding of the process of repair of the particular tissues involved in the wound ensure selection of the most appropriate suture material by the surgeon, thereby optimizing healing. The following biomechanical principles should be considered in order to select the most suitable suture material and size:

  • synthetic sutures elicit a weaker tissue reaction than do natural ones;
  • suture material should be as strong as the intact tissue through which it is placed;
  • temporal loss of tensile strength of the suture material and gain in strength of the wound tissues should concord;
  • selecting inappropriately large suture material and exerting undue tension result in excessive tissue reaction;
  • increasing the number of sutures apposing the wound edges and/or using tension‐relieving techniques is preferable to increasing the size of suture material in wounds sutured under tension;
  • the strength of a wound is more dependent on the injured tissue’s ability to retain suture materials and the trauma created at the time of surgical repair than on the strength of the suture material itself;
  • environmental variables, such as tissue pH, temperature, infection, or exposure to bodily fluids (digestive secretions, blood, milk, urine, etc.), can dramatically alter the performance of suture materials and should be considered when choosing the optimal suture for a given application.1,15,16,25

Guidelines for selecting the type and size of suture material for use in large‐animal surgery have not been officially established. Table 9.2 reflects the author’s preferences for suturing wounds of horses.

Table 9.2 Guidelines for suture material selection in equine wound management.

Source: Adapted from Boothe,2 Blackford,17,1 8 MacKay,26 Miller,27 Millichamp,28,2 9 Nasisse.30

Tissue type Suture size (USP) Suture type
Skin – appositional suture 2–0 to 0 Non‐absorbable monofilament (polypropylene, nylon, polybutester)
Skin – tension suture 0 to 2 Non‐absorbable monofilament (polypropylene, nylon)
Subcutis 3–0 to 2–0 Absorbable monofilament (poliglecaprone 25, glycomer 631) or multifilament (polyglactin 910, polyglycolic acid)
Fascia 0 to 3 Slow absorbable monofilament (polyglyconate, polydioxanone) or multifilament (polyglactin 910)
Muscle 2–0 to 2 Absorbable monofilament (polyglyconate, polydioxanone) or multifilament (polyglactin 910)
Tendon 2 Slow absorbable monofilament (polydioxanone, polyglyconate)
Vessel (ligatures) 3–0 to 0 Absorbable monofilament (poliglecaprone 25) or multifilament (polyglycolic acid, polyglactin 910)
Vessel (sutures) 6–0 to 5–0 Non‐absorbable monofilament (polypropylene, nylon)
Nerve 10–0 to 7–0 Non‐absorbable monofilament (polypropylene, nylon) or multifilament (silk)
Eye – eyelid 6–0 to 4–0 Non‐absorbable monofilament (nylon) or multifilament (silk)
Eye – sclera 8–0 to 6–0 Non‐absorbable monofilament (nylon)
Eye – conjunctiva and cornea 9–0 to 7–0 Absorbable monofilament (polydioxanone) or multifilament (polyglactin 910, polyglycolic acid)

Surgical needles

Suture needles are manufactured from surgical steel and are usually described by the geometric shape of the body and point, the taper ratios associated with the point section, and the method by which the suture is attached to the needle.

Surgical needle characteristics

Surgical needles can be straight, half‐curved, or curved into a 1/4‐, 3/8‐, 1/2‐, or 5/8‐circle configuration (Figure 9.2). The type of tissue and the wound’s depth, size, and accessibility for suturing are factors that guide the selection of a needle’s shape.1,4 Straight and half‐curved needles are most often used for suturing close to the surface of the body and are used almost exclusively to suture skin, whereas 5/8‐curved needles are preferred for suturing in confined, deep locations. In most situations, the 3/8‐ or 1/2‐circle needle is used because it is easier to handle within tissues than are the straight, half‐curved, and 5/8‐circle needles. The needle should be long enough to penetrate both edges of the wound in one bite. Its diameter should be the smallest that allows it to penetrate tissue without buckling or bending; the length‐to‐diameter ratio should be less than 8:1 to limit tissue trauma.31

Schematic of the various shapes of surgical suture needles such as straight, half curved or curved with 1/4, 1/2, and 3/8 circle configuration.

Figure 9.2 Various shapes of surgical suture needles.

The shape of the needle’s point and body determines the needle’s ability to penetrate tissue (Figure 9.3). Non‐cutting (i.e., taper‐point) needles have a sharp point and cylindrical body; they should be used whenever possible to minimize tissue trauma and inadvertent damage to vessels and nerves. Cutting needles are designed to penetrate dense connective tissues. The following types of cutting needles are available: (1) the conventional curved cutting needle, the cutting edge of which lies on the needle’s concave surface; (2) the reverse curved cutting needle, the cutting edge of which lies on the needle’s convex surface so that the suture lies within the hole created by the needle and is less likely to cut through tissue; (3) the tapered cutting needle, which combines a round shaft with a reverse cutting point to make the needle useful for suturing delicate yet dense tissue (e.g., fascia, periosteum, tendons).31,32

Schematics of different surgical suture needles with various point and body designs such as conventional cutting, taper point, reverse cut, taper cut, and special k needles.

Figure 9.3 Various point and body designs of surgical suture needles.

Suture needles can be classified as non‐swaged (i.e., eyed) and swaged (i.e., eyeless). Non‐swaged needles have a closed eye or a ridged slit to hold suture as the needle is passed through tissue, whereas a swaged needle is attached to the suture by a crimp so that the needle and suture form a single, continuous unit. Non‐swaged needles, which are reusable, are more traumatic to tissues than are swaged needles, because when using a non‐swaged needle, a double strand of suture is pulled through tissues, whereas when using a swaged needle only one strand is pulled through tissue. In addition, non‐swaged needles become dull with reuse and repeated cleaning and sterilization. Swaged needles are used more commonly because they are less traumatic to tissue, easier to handle, for single use only (and thus always sharp), and make surgery quicker, since threading the suture on to the needle is obviated.

Selecting the surgical needle

Selecting an appropriate suture needle is important for optimal healing of sutured wounds. Factors to be considered when selecting a surgical needle include: (1) characteristics of the tissue to be sutured; (2) configuration of the wound; and (3) size of the suture material.1

The needle should meet the following specific requirements: (1) the hole made by the needle should be just large enough to permit the passage of the suture material; (2) the design and diameter of the needle should minimize tissue damage (i.e. the sutured tissue should not be weakened by passage of the needle); and (3) the needle should have the appropriate design to permit rapid, accurate, and precise suturing.32

Suturing techniques

Because the blood supply at the margin of the wound is inversely proportional to the tension on the closed wound, sutures must be placed accurately and without tension to maximize blood flow to the edges of the wound, which in turn optimizes healing and minimizes the likelihood of scarring.

Suture placement

The choice of where the suture is placed in relation to the wound is often influenced by the configuration and biomechanical properties of the wound. A common recommendation is to place sutures at a distance from the wound’s edge equal to the thickness of the wound’s edge. Factors, such as tension on the edges of the wound and the thickness and stiffness of the lacerated tissues, however, must also be considered. Inflammation and lysis of collagen by collagenases occur during the early phases of wound healing and remain high within 0.5 cm of a skin incision. These processes weaken the suture‐holding power of a wound, so sutures should be placed at least 0.5 cm from the wound’s edge for improved security.33 Because new epithelium lacks holding power, sutures should be placed well back from the wound’s edge to ensure optimal holding strength when repair is to be achieved by delayed secondary closure.

For both human and veterinary patients, placing interrupted sutures 0.5 cm apart generally ensures good apposition of tissue, minimal tension on individual sutures, and maximum holding strength.1,3,33,34 Placing interrupted sutures closer together than this may result, in some instances, in delayed healing, because of excessive reaction by the tissue to the suture and interference to the blood supply of the wound’s edges.1 Spacing between sutures can be increased in thick‐skinned regions and regions where incisions or lacerations are parallel to the skin’s lines of tension. The opposite is true in thin‐skinned regions and regions where incisions or lacerations are perpendicular to the lines of tension.1

Drawing of the skin with simple interrupted suture pattern.

Figure 9.4 Simple interrupted suture pattern. Knots should be offset so they do not rest upon the apposed skin margins. Sutures should be placed close enough to prevent gaping. a = distance from the wound edge the suture should be placed to ensure optimal holding strength (>0.5 cm). b = minimal distance between two consecutive suture bites (±0.5 cm).

Suture knots

Sutures are most commonly tied in a square knot because this knot is among the most secure. When the first throw of a square knot does not accurately appose the wound’s edges, the knot can be modified into a surgeon’s knot (Figure 9.5a). The surgeon’s knot, however, places more suture material within the wound, thus potentiating the likelihood of infection. Moreover, use of a surgeon’s knot with some suture materials (e.g., chromic catgut) may decrease the structural stiffness of the knot; therefore, the surgeon’s knot should be used only when needed to achieve accurate apposition of the wound’s edges. The influence of knot‐tying techniques and the characteristics of suture materials on the security of the knot and suture line are summarized in Table 9.3. The three techniques of knot‐tying, the one‐handed tie, the two‐handed tie, and the instrument tie, are discussed in depth elsewhere (ETHICON Knot‐Tying Manual – freely available online) and, therefore, are not discussed here.

Schematic of the surgeon’s knot (left) and square knot (right).

Figure 9.5 Surgical knots. (a) Surgeon’s. (b) Square.

Table 9.3 Minimal number of throws required (including the first) for a secure square knot in interrupted suture patterns and continuous suture patterns. abs, absorbable; non‐abs, non‐absorbable; mono, monofilament; multi, multifilament.

Source: Adapted from Rosin 1998.35

Suture type Interrupted suture pattern Beginning continuous suture pattern Ending continuous suture pattern
abs, mono
4 4 7
abs, multi
3 4 5–6
Polyglycolic acid
abs, multi
3 3 5–6
Polyglactin 910
abs, multi
3 3 5–6
non‐abs, mono
3 3 5–6
non‐abs, multi/mono
4 4 6–7

Knots, when placed in subcutaneous or intradermal tissue, must be buried (Figure 9.5b and Figure 9.6) to reduce irritation caused by rubbing of the knot against superficial tissue and to prevent extrusion of the suture. To decrease the likelihood of extrusion of buried suture, the volume of suture material should be kept to a minimum, useless throws should be avoided (Table 9.3), the knots should be as flat as possible and positioned perpendicular to the suture line, and the suture end length should not exceed 3 mm, which is the minimum recommended length to optimize knot integrity.1,3,36 The use of inappropriately large suture material increases the size of knots buried immediately beneath or within the skin. These knots can cause excessive pressure on overlying skin leading to local skin necrosis, extrusion of the suture, infection of the wound, and a poor cosmetic outcome.

Drawing illustrating suture placement for a subcutaneous continuous or running suture pattern on the skin, with initial knot being buried in the subcutaneous tissues (displayed in inset).

Figure 9.6 Suture placement for a subcutaneous continuous or running suture pattern. The initial knot is buried in the subcutaneous tissues.

Suture patterns

A wide variety of suture patterns has been described for use in animals and people. The patterns are classified as interrupted or continuous by the way in which they appose tissue, or as appositional, everting, inverting, or tension‐relieving by the way they overcome tension that may disrupt accurate approximation. Inverting sutures are rarely used in wound management and, therefore, are not discussed in this chapter. Sutures can further be classified according to the tissues they appose (e.g., muscular or subcutaneous).

In wounds characterized by no loss of tissue, such as most surgical wounds, an appositional suture pattern provides superior approximation of the edges of the wound, leading to secure closure and good cosmetic results. Wounds with large defects or loss of tissue, such as most accidental wounds in horses, are much more difficult to close without creating tension on the suture line. Tension sutures redistribute tension across the edges of the wound, minimizing interruption of blood flow and necrosis. Everting sutures are sometimes useful to close skin because skin edges apposed with appositional sutures tend to invert during healing.1

The reader is referred to Table 9.4 and Table 9.5 for the general features and the common uses of appositional (Figures 9.7, 9.8, 9.9, 9.10, 9.11, 9.12, 9.13, 9.14, 9.15, and 9.16), everting (Figures 9.10a and 9.12a), and tension sutures (Figures 9.17, 9.18, 9.19, 9.20, 9.21, 9.22, and 9.23).

Table 9.4 Appositional suture patterns for wound management.

Source: Adapted from Celeste,1 Toombs,16 Blackford,17 Provost.1 9

Suture type Advantages Disadvantages Common uses
Simple interrupted (SI)
(Figure 9.7)
Easily and quickly applied
Precise suture tension possible
Minimally alters the skin architecture
Provides secure, anatomic closure
Concurrent closure of skin, subcutis, and underlying fascia may reduce dead space
Minimal alteration in blood supply
Requires increased time for placement
Excessive tension causes inversion of skin margins
Skin, subcutis, fascia, blood vessels, nerves
Interrupted intradermal (II) or subcuticular
(Figure 9.8)
Similar to SI (upsidedown SI suture placed in dermis and subcutis) Requires increased time for placement compared to SI and continuous suture patterns Intradermal skin closure
Rarely used
Interrupted cruciate or cross mattress
(Figure 9.9)
Easiest of all mattress sutures to apply, more rapidly applied than SI
No alteration of blood supply even when placed under tension
Provides stronger closure than SI
Resists tension
Prevents eversion of wound edges at fascia level
Excessive tension causes inversion of skin margins
Skin margins tend to gap between sutures
Fascia (occasionally skin)
Interrupted vertical mattress (IVM)
(Figure 9.10)
Provides precise wound edge‐to‐edge apposition with slight eversion when tied
Minimal alteration in skin blood supply
A single layer can be used for concurrent closure of skin and subcutis to eliminate dead space
Takes longer to apply and creates slightly more inflammation because suture passes through tissue four times Skin, subcutis, fascia
Can be alternated with SI sutures to prevent inversion and gaping
Allgöwer corium vertical mattress
(Figure 9.11)
Minimal trauma (through dermis only)
Perfect alignment of skin margins without inversion and with minimal or no eversion
Cosmetically superior closure
Interrupted horizontal mattress (IHM)
(Figures 9.12)
Appositional to everting suture, depending on suture tension and whether suture penetrates tissue full or split thickness
Requires less suture material than IVM
Tends to reduce skin blood supply
Potential for tissue strangulation (can be reduced with stents)
Excessive scar formation when used alone because of skin eversion and gaping
Skin, subcutis, fascia, muscle, tendon
Simple continuous (SC)
(Figure 9.13)
Saves time
Promotes suture economy
Provides good apposition of wound edges or skin margins
Provides airtight or watertight seal
Good only for layers under low tension
Provides less strength than SI
Gain in wound tensile strength delayed compared to SI
Excessive tension causes puckering and strangulation of skin
Skin, subcutis, fascia, blood vessels
Continuous intradermal or subcuticular
(Figure 9.14)
Similar to II
Saves time
Promotes suture economy
Provides less strength than skin closure Intradermal skin closure
Continuous mattress; horizontal (Figure 9.15a) and vertical (Figure 9.15b) Horizontal: appositional to everting suture, depending on suture tension; facilitates rapid closure
Vertical: minimal alteration in blood supply; precise edge‐to‐edge contact
Horizontal: can cause skin eversion/gaping
Vertical: difficult to apply; rarely used
Skin, subcutis, fascia
Continuous lock or Ford interlocking
(Figure 9.16)
Similar to SC
Provides greater security than SC if broken
Similar to SC
Requires large amount of suture
Time consuming to apply
May cause pressure necrosis and become buried when placed under tension

Table 9.5 Tension suture patterns for wound management.

Source: Adapted from Celeste,1 Toombs,16 Blackford,17 Provost.19

Suture type Advantages Disadvantages Common Uses
Interrupted vertical mattress (IVM)
(Figure 9.17)
Minimal alteration to cutaneous blood supply
Adding more, widely placed rows of IVM suture reduces tension on appositional primary suture line
Stronger than IHM in tissues under tension
Occasionally suture will cut out when placed under excessive tension Undermined skin under tension
Used with supports (bandage, buttons, stents)
Interrupted horizontal mattress (IHM)
(Figure 9.18)
Placed widely, IHM suture reduces tension on appositional primary suture line
Less suture material than IVM
Tends to compromise skin blood supply
Does not reduce tension as effectively as IVM
Potential for tissue strangulation (can be reduced with stents)
Skin, subcutis, fascia, muscle, tendon
Supports are added to reduce cutting out of sutures in regions that cannot be bandaged
Quilled or stented
(Figure 9.19)
Similar to IVM (variation of IVM that loops over a stent on either side of incision)
Very effective in reducing tension on appositional primary suture line
Everting mainly
Can also be a variation of the IHM
Skin necrosis underneath the quilled/stented sutures can occur if too much suture tension
Should not be used under a cast
Combined with appositional suture for skin in areas of extreme tension where bandage cannot be applied
Near and far (or far and near)
(Figure 9.20)
Combines tension suture (far portion) and appositional suture (near portion)
Higher tensile strength than either SI or mattress pattern
Provides necessary tension for wound edge approximation without applying tension to wound edge itself
Excessive tightening can cause inversion
Leaves large amount of suture material in wound
Skin, subcutis, fascia
Looking loop (LL)
(Figure 9.21)
Provides good apposition compared with other tendon sutures, with equal holding strength May compromise intrathecal blood supply Tendons
Three loop pulley
(Figure 9.22)
Has slightly higher tension strength compared to LL
Minimal alteration to blood supply
More suture is exposed compared to LL Tendons
(Figure 9.23)
Centrally placed neurorrhaphy suture anchored externally with silicone buttons N/A Nerve
Drawing of the skin with simple interrupted suture pattern. Each suture is located in the irregularly shaped areas.

Figure 9.7 Simple interrupted suture pattern. The independent nature of each suture allows for mobility and use in irregularly shaped areas.

Drawing of the skin displaying interrupted intradermal suture, depicted by dashed circle located at the dermis region.

Figure 9.8 Interrupted intradermal suture.

2 Drawings of the skin with cruciate mattress suture pattern (left) and inverted cruciate mattress suture pattern (right).

Figure 9.9 (a) Cruciate mattress suture pattern. (b) Inverted cruciate mattress suture pattern.

3 Drawings of the skin, with interrupted vertical mattress suture pattern (a, b) and alternating vertical mattress and simple interrupted suture patterns (c).

Figure 9.10 (a) Interrupted vertical mattress suture pattern. These sutures provide precise edge‐to‐edge skin apposition with slight eversion after they are tied. They also minimally compromise skin vasculature. (b) Interrupted vertical mattress suture pattern used to decrease dead space. (c) Alternating vertical mattress and simple interrupted suture patterns to prevent skin inversion. Note: There is no biomechanical advantage over a simple interrupted suture pattern when placed as described. The alternating vertical mattress suture pattern can however be placed widely to reduce tension on the primary suture line or associated with rubber “stents” or buttons.

Drawing of the skin with Allgöwer corium vertical mattress suture pattern.

Figure 9.11 The Allgöwer corium vertical mattress suture pattern. This minimally traumatic suture pattern provides good apposition of skin margins with minimal or no eversion of the skin edges.

2 Drawings of the skin with horizontal suture pattern, displaying slight aversion and gaping of wound (left) and swelling of tissues due to tight tying of sutures (right).

Figure 9.12 (a) Horizontal mattress suture pattern. Slight eversion and some gaping of the wound edges occur after they are tied. (b) If the sutures are tied too tightly or if tissues swell excessively after placement, reduction of the skin blood supply occurs (elevated tissue and dashed lines within the suture pattern) and can impair wound healing.

Drawing of the skin illustrating suture placement through all skin layers in a simple continuous suture pattern.

Figure 9.13 Suture placement through all skin layers in a simple continuous suture pattern.

Drawing of the skin with continuous intradermal suture pattern, displaying sutures passing through the dermis, with suture bites in equivalent depth.

Figure 9.14 Continuous intradermal suture pattern. The suture should pass through the dermis perpendicular to the long axis of the wound. Suture bites in the dermis should be of equivalent depth. Spacing between bites should also be regular.

2 Drawings of the skin displaying continuous mattress suture pattern, with (left) horizontal mattress and (right) vertical mattress.

Figure 9.15 Continuous mattress suture pattern. (a) Horizontal mattress. (b) Vertical mattress.

2 Drawings of the skin with continuous locking or Ford interlocking suture pattern, illustrating the (left) passage of the suture and (right) tying of the suture after completion.

Figure 9.16 Continuous locking or Ford interlocking suture pattern. (a) Passage of the suture. (b) Tying the suture after completion.

3 Drawings of the skin with vertical mattress sutures (a) preplaced and skin edges apposed with towel clamps, (b) in two, and (c) three rows, with interrupted vertical mattress sutures (a, b) in “echelon” pattern.

Figure 9.17 (a) Vertical mattress sutures are preplaced and the skin edges apposed with towel clamps. (b) Two rows of vertical mattress sutures are used to reduce the tension at the site of primary closure. (c) Three rows of vertical mattress suture are used to reduce the tension at the site of primary closure. In both b and c, placement of interrupted vertical mattress sutures is in an “echelon” pattern.

Drawing of the skin illustrating a widely placed interrupted horizontal mattress and simple interrupted sutures for tension reduction on the primary repair site and prevention from eversion of skin edges.

Figure 9.18 Widely placed interrupted horizontal mattress and simple interrupted sutures reduce tension on the primary repair site and prevent eversion of the skin edges.

Drawing of the skin illustrating the quilled or stented tension sutures augmented by supports such as rubber stents or buttons.

Figure 9.19 Quilled or stented tension sutures augmented by supports (rubber stents or buttons).

Drawing of the skin with far–near near–far suture pattern. The far component reduces tension while the near component holds the tissue edges in apposition.

Figure 9.20 A far–near near–far suture pattern. The far component reduces tension while the near component holds the tissue edges in apposition.

Illustrations of single modified locking loop suture pattern (top) and double modified locking loop suture pattern (bottom).

Figure 9.21 (a) Single modified locking loop suture pattern. (b) Double modified locking loop suture pattern.

Schematics illustrating three‐loop pulley suture pattern on skin, with (a) 1st loop in near‐far suture pattern, (b) 2nd  loop equidistant from the transected ends of tendon, and (c, d) 3rd loop in far–near pattern.

Figure 9.22 The three‐loop pulley suture pattern. Each loop is oriented 120 degrees relative to the others. The first loop is in a near‐far suture pattern (a), the second loop is equidistant from the transected ends of the tendon (b), and the third loop is placed in a far–near pattern (c, d).

Schematic of the skin with intraneural suture pattern.

Figure 9.23 Intraneural suture pattern.

Interrupted versus continuous suture patterns

The choice of an interrupted over a continuous suture pattern is somewhat contentious because both types of patterns have advantages and disadvantages. The major advantages of using an interrupted suture pattern are the ability of interrupted sutures to precisely control tension at each point along the wound, the possibility of making adjustments to improve alignment of the edges of an irregularly shaped laceration, and the minimal interference of the suture pattern with the skin’s blood supply.1,19 Disadvantages of using an interrupted suture pattern include increased surgical time (to tie multiple knots and cut the suture ends), increased volume of foreign material within the wound when the sutures are buried, increased risk of wound dehiscence,37 and poor economic use of suture material.16

In contrast, a continuous suture pattern is quickly placed, thus reducing surgical time; distributes tension evenly along the entire length of the wound; uses less suture material, thus reducing cost; and minimizes the number of knots, thus reducing the amount of foreign material within the wound (Figure 9.13).16 A continuous pattern also forms a better seal against fluid and air.38 On the downside, the tension on a continuous suture line cannot be varied to the same degree as can tension on an interrupted suture pattern, and failure of the knot or suture material can have a disastrous effect on the closure. Suture used in a continuous pattern, therefore, must be handled carefully. Instrument‐induced trauma to the suture should be avoided (e.g., grasping the suture with needle holders or thumb forceps), throws of the knots should be applied correctly, and the knots should be secure. Because of their design, continuous suture patterns tend to compromise the microvascular supply to the edges of the wound.39 If the compromise is marked, it may lead to the formation of edema that, in turn, can prolong the inflammatory phase of wound healing and delay the wound’s gain in tensile strength. The Ford interlocking suture pattern represents a compromise between interrupted and continuous suture patterns (Figure 9.16).

Inverting versus everting suture patterns

Disrupted tissue may be apposed using a suture pattern that inverts or everts tissues, depending on the wound’s location. Inversion is usually desirable only to close hollow viscera to prevent leakage, but excessive inversion reduces luminal diameter. Slight eversion to counter the tendency of edges of a cutaneous wound to invert during healing is desirable because slight eversion leads to the most cosmetic outcome after sutures are removed.1

Tension sutures

Wounds suffering from a substantial loss of tissue are difficult to close without creating tension on the suture line. Some suture patterns offer mechanical advantages over others, by requiring less force to close the wound.40 Although clinical experience suggests that a moderate amount of tension is acceptable in sutured wounds of horses,19 when the forces exerted by individual sutures increase to the point where sutures cut through tissue and restrict blood flow, tension sutures should be used. Tension sutures draw the wound edges together while minimizing the risk of vascular damage, which leads to necrosis and dehiscence.

Tension sutures, which are usually everting sutures (Figures 9.10a, 9.12a), placed well away from the wound edges to avoid strangulation of tissue, can be used either alone (Figure 9.20) or in combination with an appositional suture pattern (Figures 9.17, 9.18, 9.19). Tension sutures are usually preplaced. Skin edges are brought into apposition with the aid of towel clamps, and the preplaced tension sutures are tied. The edges of the laceration or incision are apposed using an appositional suture pattern (Figures 9.17b,c, 9.18, 9.19).1

Walking sutures (Figure 9.24) are buried tension sutures that: (1) move skin progressively toward the center of the wound or the opposite margin of the wound; (2) distribute tension; and (3) obliterate subcutaneous dead space, thereby preventing the formation of a serum pocket.3

Sep 15, 2017 | Posted by in GENERAL | Comments Off on 9: Selection of Suture Materials, Suture Patterns, and Drains for Wound Closure

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