Absorption of suture material can be either hydrolytic (which is more common and results in less tissue inflammation) or proteolytic. There is variation in the rate of suture absorption depending on material type (see Table 3.1), but Vicryl sutures will take 2–3 weeks for their strength to decrease to 50%. Most absorbable sutures lose half their strength within the first 4 weeks and will eventually be completely absorbed. The rate of absorption is proportional to the degree of polymerization and is quite predictable for any given suture. Some sutures such as Vicryl Rapide and Caprosyn (Polyglytone 6211) should be avoided in areas that require longer support as they lose half their strength in the first week. Proteolytic absorption is enzyme mediated and is associated with natural sutures such as those derived from beef or sheep intestine, which are often referred to as cat gut. Synthetic sutures such as polydiaxone (PDS) and polyglactin (Vicryl) absorb by the process of hydrolysis where water from tissues is absorbed into the suture material resulting in disruption of cross-links within the polymeric structure.1 Table 3.1 Qualities of Absorbable Sutures Composition (Proprietary Name) Time to 50% Strength Configuration Reactivity Memory Gut Fast Plain Chromic Unpredictable 5-7 days 7-10 days 10-14 days Monofilament Monofilament Monofilament High High High Low Low Low Polyglytone 6211 (Caprosyn*) 5-7 days Monofilament Low Medium Poliglecaprone 25 (Monocryl†) 7-10 days Monofilament Low Medium Glycomer 631 (Biosyn†) 2-3 weeks Monofilament Low Medium Glycolide/lactide copolymer Low molecular weight (Vicryl Rapide*) Regular (Polysorb†, Vicryl*) 5 days 2-3 weeks Braided Braided Low Low Low Low Polyglycolic acid (Dexon S†) 2-3 weeks Monofilament or braided Low Low Polyglyconate (Maxon†) 4 weeks Monofilament Low High Polydioxanone (PDS II*) 4 weeks Monofilament Low High *Ethicon †Covidien
Elasticity is the tendency of a suture to return to its original length after stretching and can be helpful in wounds where postoperative swelling is anticipated by ensuring that the suture retains sufficiently tight closure after the swelling reduces. Memory refers to the tendency of a suture to return to its original shape and sutures with more memory are usually less pliable, more difficult to handle, and have less knot security. For example, PDS has greater memory than Monocryl or Dexon. Knot security refers to the force required to cause a knot to slip and will be increased with braided sutures such as Vicryl or Ethibond, compared with monofilament sutures such as Monocryl. Fluid absorption is the amount of fluid retained by a suture and capillarity refers to the movement of fluid along the suture. Sutures with greater capillarity (for example, braided subtypes) are more likely to become colonized with bacteria, potentially leading to wound infection. The braided nature of these sutures also provides a greater surface area and recesses for organisms to adhere. For these reasons, sutures such as nylon are less likely to harbor infection when compared with a braided alternative such as Vicryl.
It is a common misconception that the #-0 rating refers to the diameter of a suture. However, the rating for sutures refers to the United States Pharmacopeia (USP) breaking strength rating, rather than suture diameter.1 Therefore, two different types of 3-0 suture can have different diameters but share the same breaking strength. As #-0 rating increases for any given suture, the diameter and breaking strength will both decrease.
There are five main types of needles: conventional cutting, reverse cutting, side cutting, taper point, and blunt tip. Each has a particular use/indication (Fig. 3.1). A standard cutting needle has its cutting surface or point on the inner curve and is at risk of tearing through the tissues causing cheese wiring when closing wounds under tension. In contrast, a reverse cutting needle has its Standard cutting needle Shape of Needle Skin Type of Needle Indication for Use Reverse cutting needle Skin Oral/Nasal mucosa Ophthalmic surgery Fascia Tendon/Ligament repair Pharynx Cartilage Side-cutting (spatula) needle Skin Cornea Microsurgery Taper point needle Abdominal organs Myocardium Peritoneum Dura Fascia, hernia repair Subcutaneous tissues Microsurgery Gynecologic surgery Blunt tip needle Liver Kidney Gynecologic surgery Obstetric surgery High-risk patients point body point body point body point body point body Fig. 3.1 Needle shapes and their indications in surgery. cutting edge on the outer curve and is therefore less likely to cause cheese wiring. Side cutting needles have two cutting surfaces or points and can be used in skin closure to reduce cheese wiring. Taper point or round bodied needles do not have a cutting surface on the needle beyond the sharp tip and are the standard choice for tendon repair to prevent cutting through the tendon fibers and previously placed suture passes/knots. Blunt tip needles are used for intra-abdominal surgery and some high-risk patients.
Fig. 3.2 shows the key components of a curved needle. A needle has a point or tip at the leading edge and a swage at the other end where the thread is attached. Needle length is the distance from the swage to the needle point along the length of the needle body. Chord length is the direct or shortest distance between the swage and the needle point. It is therefore shorter than needle length in a curved needle. The curvature of a needle refers to the amount of a full circle involved and ranges from one-fourth to five-eighths, with three-eighths being most common in plastic surgery applications. Chord length will differ according to needle curvature and will be greatest with the half-circle needle. Needle diameter refers to the thickness of the needle itself and is determined by the balance between providing sufficient material strength yet maintaining the smallest diameter possible for the required size suture.
versions? Dexon is an absorbable suture made from polyglycolic acid. It is unusual in that it is available in either braided or monofilament versions, where most sutures are generally one or the other. It shares similar characteristics, and hence uses, to Vicryl in that it has a low reactivity, with low memory, and loses 50% strength in 2–3 weeks. It is useful in skin closure for dermal and subcuticular situations. Vicryl is a braided suture made from Polyglactin 910 that is popular for use in the skin and closure of the oral lining, muscle, and tying off blood vessels. Vicryl Rapide is a similar braided suture to Vicryl but has a lower molecular weight and therefore loses its strength in just 5 days rather than 2–3 weeks. This suture is often used as an external skin suture in infants and younger children. Caprosyn is made from Polyglytone 6211 and shares some characteristics with Vicryl Rapide in that it has a rapid rate of absorption giving it a time to 50% strength for 5–7 days. It is a monofilament with low reactivity and medium memory. Monocryl is another monofilament and is made from poliglecaprone. It is a popular choice for buried skin closure in plastic surgery as it handles well and has a low reactivity. Biosyn (Glycomer 631) is similar to Monocryl but retains its strength for 1–2 weeks longer.1,2
Polyester sutures may be uncoated such as Mersilene (Ethicon) or coated such as Ethibond (Ethicon), Surgidac (Covidien), and Ticron (Covidien). Coating involves the process of adding a lubricant to improve suture passage and handling. Polyester sutures may be used for tendon or ligament repair and some surgeons use them for securing the superficial musculoaponeurotic system (SMAS) during face lifts. PDS is polydiaxone and this is a monofilament suture that has low reactivity and maintains 50% strength until 4 weeks. For this reason, it is often useful in closure of deep wounds such as closing Scarpa’s fascia during Fig. 3.2 Characteristics of a curved needle. Swage Needle radius CHORD LENGTH Diameter Point Body NEEDLE LENGTH abdominoplasty. Gut is an absorbable suture available in different subtypes. Plain gut loses half its strength in 1 week and chromic gut loses half its strength in 2 weeks. Silk is a nonabsorbable braided suture that will still lose its strength over time and is often used for vessel ties and marker sutures (see Tables 3.1 and 3.2). Nylon is a permanent suture, which is most often a monofilament (Ethilon) but is sometimes braided (Nurolon). It is commonly used for external wound closure in plastic surgery for the head and neck regions. It may also be used for deep permanent sutures as an alternative to polypropylene (Proline). It has a low reactivity and memory differs depending on whether it is a monofilament or braided product. Table 3.1 Qualities of Absorbable Sutures Composition (proprietary name) Time to 50% Strength Configuration Reactivity Memory Gut Fast Plain Chromic Unpredictable 5-7 days 7-10 days 10-14 days Monofilament Monofilament Monofilament High High High Low Low Low Polyglytone 6211 (Caprosyn*) 5-7 days Monofilament Low Medium Poliglecaprone 25 (Monocryl†) 7-10 days Monofilament Low Medium Glycomer 631 (Biosyn†) 2-3 weeks Monofilament Low Medium Glycolide/lactide copolymer Low molecular weight (Vicryl Rapide*) Regular (Polysorb†, Vicryl*) 5 days 2-3 weeks Braided Braided Low Low Low Low Polyglycolic acid (Dexon S†) 2-3 weeks Monofilament or braided Low Low Polyglyconate (Maxon†) 4 weeks Monofilament Low High Polydioxanone (PDS II*) 4 weeks Monofilament Low High *Ethicon †U.S. Surgical Corporation
Stainless steel clips have a number of advantages over sutures for wound closure. Closure is faster and they cause less local tissue ischemia. Some surgeons feel that there is little or no difference in the cosmetic outcome when comparing skin staples to sutures and they certainly can be useful in certain situations such as closure of scalp wounds where they also have a useful hemostatic effect. When using staples on the trunk or limbs, it is important to ensure that a deep layer of sutures is still present if the staples are to be removed sufficiently early (5–7 days) in order to avoid permanent staple marks.1 Table 3.2 Qualities of Nonabsorbable Sutures Composition (Proprietary Name) Tensile Strength Configuration Reactivity Memory/ Handling Silk Lost in 1 year Braided High −/Good Nylon Monofilament (Ethilon*, Monosof-Dermalon†) Braided (Nurolon*, Surgilon†) 81% at 1 year, 72% at 2 years, 66% at 11 years Monofilament Braided Low Low +/Fair −/Good Polypropylene (Prolene*, Surgipro†) Indefinite Monofilament Low + +/Poor Polybutester Uncoated (Novafil†) Coated (Vascufil†) Indefinite Indefinite Monofilament Monofilament Low Low +/Fair −/Good Polyester Uncoated (Mersilene*) Coated (Ethibond*, Surgidac†, Ticron†) Indefinite Indefinite Braided Braided Moderate Moderate −/Good −/Good Surgical steel Indefinite Monofilament or braided Low + +/Poor *Ethicon †Covidien In general, monofilament sutures are a better choice than braided alternatives for closing wounds that have a high risk of developing postoperative infection (e.g., debrided bite wounds) because bacteria may be less adherent to them (as discussed in question 2). Infection in a wound will accelerate the process of suture absorption. In the rat model, as described by Levenson et al,2 skin strength can be expected to regain 5% of its original strength in 1 week, 50% by 4 weeks, and 80% by 6 weeks. In this model, wound strength at 1 year is thought to reach only 80% of original strength. PDS will have retained 50% of its original strength at 4 weeks and will remain in the wound for longer than 12 weeks. It will therefore support a wound until at least 60–70% of its original strength has been regained (see Fig. 3.4, Essentials of Plastic Surgery, third edition). One downside to staples is that they are rigid and thus provide no ability to give or expand to accommodate postoperative soft tissue swelling. Hence, there may be an increased risk of pressure damage to the skin surface which is associated with development of the parallel row component of “railroad scars.”
component occurs because of re-epithelialization around the suture which causes a cylindrical cuff leading to a permanent suture tract. Early suture removal may help avoid this process. The parallel rows result from pressure necrosis on the skin and subcutaneous tissues and are exacerbated by over-tightening of sutures and delayed suture removal (Fig. 3.3). Fig. 3.3 Appearance of a railroad scar following delayed suture removal.
correct? Handling characteristics are largely similar between different microsuture materials, although differences can occur between needles depending on their size, shape, and needle point. The choice of suture size depends on the vessel or structure size. For example, repair of the radial artery is satisfactorily achieved with an 8-0 nylon (Ethilon). A 10-0 is usually unnecessarily small and is more appropriate for repair of an adult digital vessel. Suture materials in microsurgery are monofilament permanent materials like nylon and polypropylene (Prolene and Surgipro). Polyglytone is an absorbable suture material used for wound closure (Caprosyn). It has a rapid absorption similar to Vicryl Rapide and would therefore not be well suited for use in microvascular anastomoses nor microsurgical nerve repair. Moving from a 9-0 to a 10-0 does not necessarily mean the needle will be smaller so needle size should always be confirmed before opening the suture material.
Barbed sutures have been designed with the intention of reducing the total internal suture volume and decreasing surgical operating time, by reducing the number of internal knots tied. They have one-way barbs along the length of the suture placed evenly and may help distribute and maintain tension across or along a wound. A caveat with this type of suture is that the surgeon is unable to backtrack and remove or revise suture placement and also the tightness of the suture pull through cannot be adjusted once tightened antegrade in a way that a traditional subcuticular monofilament suture can be. Most of the major suture manufacturers have a barbed suture in their range and their use for skin closure is driven by surgeon’s preference.1 The use of a mesh suture has been described for high tension internal abdominal wall closures/repairs, as well as patients with an abdominal ventral wall hernia.2 It also has intended uses within orthopedic surgery. The principle of using polypropylene mesh as a suture tie technique has been described by Lanier et al.2 In this study, strips of polypropylene mesh were passed through the abdominal wall without an integrated swaged needle. The Duramesh suture is a device made from macroporous polypropylene with an integrated swaged needle. Using this device reduces suture pull through by redistributing forces over a broader surface area. Once tied, the knots maintain porosity and should allow improved tissue incorporation. Souza et al3 neatly illustrated use of this suture in an animal model displaying improved resistance to suture pull through compared with traditional polypropylene sutures. This device is intended for deep suture repair but not the skin. Embrace (Neodyne Biosciences Inc, Menlo Park, Ca) is a silicone elastomeric dressing that is used following wound closure. It is applied to the incision site and is changed on a weekly basis for 60 days. The dressing is intended to contract and offload the skin’s natural tension. In one multicenter randomized controlled trial (RCT), scar quality was improved when using this device.4,5 The suture bridge device is currently an experimental device used to lift sutures away from the skin in order to disperse pressure from the skin and ideally reduce both pressure effects and epidermal inflammation. In animal studies, it has been shown to increase tensile strength in the early days following tissue injury and repair.6
There are a number of manufacturers offering antibacterial sutures. Ethicon’s range of Monocryl, Vicryl, and PDS are all available in antibacterial versions, each designated as “Plus.” The antibacterial component is triclosan, which is an antibacterial and antifungal, that blocks fatty acid synthesis. There have been many studies assessing the benefits of using such sutures to reduce the risk of surgical site infections (SSIs), and in general it is thought that there is an advantage to using this type of sutures (level I evidence). However, the benefits will depend on factors such as the site and type of wounds being closed.1,2 Flucloxacillin and Augmentin are both systemic antibiotics given either orally or intravenously. Each is potentially useful in reducing surgical site infections. Augmentin is generally the selected antibiotic of choice in human bite wounds such as in this case. Chlorhexidine is a useful skin preparation with antiseptic and disinfectant qualities rather than antibacterial qualities. Cleaning the wound with this can be a useful adjunct in management of a human bite injury prior to debridement and closure. Bacitracin is an antibacterial that can be used topically in preparations as a single agent or combined with polymyxin B in Polyfax ointment. This may be useful postoperatively in such cases. As appropriate debridement has already been performed, there is probably little real indication in this case for their use.