Wound closure

See also 'Skills': (Preparation of traumatic wounds)

Current therapy of wounds

Table 1. Current clinical therapies of wounds: pros and cons

Therapy	Advantages	Disadvantages
Sutures	Highest tensile strength Time honoured Ability to achieve meticulous closure Low rate of dehiscence	High tissue reactivity Slowest application rate Need for removal Requires anaesthesia Most expensive
Staples	Quick application Low tissue reactivity Low risk of infection Low cost	Need for removal Requires anaesthesia Reduced quality and thoroughness of closure Possible interference in imaging techniques
Surgical tape	Rapid application Least reactive Painless application Lowest risk of infection Low cost	Lack of tensile strength Fall off frequently Highest rate of dehiscence Cannot use on hairy areas Must be kept dry
Tissue adhesives (2-octylcyano-acrylate)	Rapid rate of application Low level of pain High resistance to bacterial growth (antibacterial effect) Fast repair time Eliminate the risk of needlestick injury No need for removal Low cost	Low tensile strength Dehiscence occurs in areas of high tension Cannot use of hands Area of application must remain completely dry

NOTE: If a wound closes at the epidermal and not the dermal layer, the patient is at risk for infection, tissue breakdown, and circulation problems at the site.

Needles

In modern surgical needles the thread is actually attached to the needle (Fig. 1). This reduces the cross sectional area of the needle, which minimises trauma to tissue (Taylor B, Bayat A, 2003) .

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Fig. 1. Surgical suture unpacked:needle with the thread

Needles come in a variety of shapes and lengths and may be straight or curved:

• Straight needles are currently discouraged because of the risk of needlestick injuries.
• Curved needles' shapes range from a ¼ circle to five eights of a circle, depending on the how confined the operative site is.

Needles have either acutting tip or a round-bodied tip (Taylor B, Bayat A, 2003) , (Raftery AT, Delbridge M, 2006) :

• Cutting needles are usually triangular in cross-section, and have acutting edge to slice through tough tissues - theyare useful for skin, tendon, and breast tissue.
• Round-bodied needles are oval or round in cross-section. They areuseful for GI tract and vascular anastomoses, because the hole they make is entirely filled by the suture, so that leakage is minimal. Also blunt round-bodied needles can be used to pierce fascia, with reduced risk of piercing surgical gloves.
• Tapercut needles combine the penetration of cutting needles with the benefits of a round-bodied needle.

Sutures

Sutures, or stitches, are materials used to close a wound, in an attempt to improve and speed healing process by pulling the edges of a wound together and stitching (Surgical Products Marketplace) . Sutures are used to close cuts from injuries or surgery. They are commonly used on the skin, internal tissues, organs, and blood vessels.

There is a wide range of different suturematerialsthat can be used to close a wound depending upon the type of wound, location and depth in the body.

Types of sutures

The sutures are broadly divided into: a) absorbable and non-absorbable; b) natural and synthetic; c) braided and monofilament (Raftery AT, Delbridge M, 2006) , (Taylor B, Bayat A, 2003) .

Absorbable sutures degrade naturally in the body and do not require removal (a particularly important advantage in children). These sutures include: plain and chromic catgut (natural monofilament); polyglycolic acid (synthetic braided – Dexon); polyglactin (synthetic braided – Vicryl); polydioxanone (PDS – synthetic monofilament), and polyglyconate (Maxon). Catgut degrades by proteolysis and tend to cause an inflammatory tissue reaction. Modern synthetic sutures degrade by hydrolysis. In time, the tensile strength of absorbable sutures declines according to the material, catgut being the quickest to lose strength. (Catgut sutures are no longer available in some countries, including the UK and Germany, because of their theoretical potential for transmitting spongiform encephalopathy and the fact that there are adequate supplies of acceptable alternative synthetic sutures.)

Non-absorbable sutures have to be removed after specified time. They include: silk and linen (natural braided); wire (stainless steel, usually monofilament); nylon (synthetic monofilament – Ethilon); polypropylene (synthetic monofilament – Prolene); expanded polytetrafluoroethylene (ePTFE – expanded monofilament), and others.
Non-absorbable sutures retain their tensile strength almost indefinitely; they also decay, however, but at a slower rate. These sutures are used where strength is needed until repair is completed naturally (e.g. abdominal incisions and hernia repair), and often for skin closure – synthetic monofilament used in subcuticular fashion giving the best cosmetic result.

Natural sutures include catgut, silk, linen, but their use is declining. Catgut is cheap but of variable strength. Silk handles well but, as with linen, it excites a strong inflammatory reaction.

Synthetic sutures include Dexon, Vicryl, PDS, nylon, polypropylene and ePTFE. They are more expensive than natural sutures, but cause little tissue reaction. The degree of strength and absorbability can be controlled in manufacture.

Monofilament sutures are single stranded, smooth and pass easily through tissues and cause less tissue reaction. The disadvantage is that they are stiff, slippery, and difficult to knot. These include catgut, polydioxanone, polyglyconate, polypropylene, nylon, and wire.

Braided (polyfilament) sutures have several strands braided together. They handle well, but may cause tissue drag, and the spaces between filaments can harbour bacteria. Examples include polyglycolic acid, polyglactin, silk, nylon, linen.

Wire is useful for closing the sternum in cardiac procedures and for orthopaedic procedures. It is strong, inert, but subject to breakage and handles poorly.

Properties of sutures

Gauge (sizes of sutures)

Gauge is the calibre of the suture and is expressed in numbers, according to the U.S. Pharmacopoeia; a metric system is also used (Taylor B, Bayat A, 2003) . Originally, the finest gauge was ‘1’ and the heaviest ‘4’ but with the development of thinner sutures a scale of ‘0s’ was developed – the more 0s the finer the suture, e.g. ‘0’, ‘00’ (2/0), ‘000’ (3/0). Today, the scale starts at 3 for the thickest suture, and the finest suture is 12/0, used in ophthalmology (eye surgery) and microsurgery. Generally, the use of sutures smaller than 7/0 requires magnification.
The gauge used depends on the nature of the repair, the strength required, number of sutures, type of suture material being used and cosmetic requirements. Smaller sutures (i.e. 5/0, 6/0) should be used on the face as they cause less tissue trauma and subsequent scarring. They have lower tensile strength, however, and can break more easily (Taylor B, Bayat A, 2003) .

Table 2. Characteristics of surgical sutures

Material/Type	Knot security	Tensile strength	Wound security	Tissue reaction	Ease of working
Absorbable sutures
Surgical (plain) gut	+	++	5-7 days	+++	+
Chromic gut	++	++	10-14 days	+++	++
Polyglycolic acid (Dexon®)	+++	+++	25 days	+	+++
Polyglactin 910 (Vicryl®)	++++	+++	30 days	+	++
Polydioxanone (PDS®)	++	++++	45-60 days	++	++
Polyglyconate (Maxon®)	++	++++	45-60 days	++	++
Non-absorbable sutures
Silk	++++	+	+	+++	++++
Polyester (Mersilene®)	++++	++	+++	+++	++++
Nurolon	+++	++	++	+++	+
Nylon (Ethilon®)	+++	+++	+++	+	+++
Polypropylene (Prolene®)	++	++++	++++	++	++
Ethibond®	+++	++++	++++	++(+)	+++

Legend: (+) poor/minimal; (++) fair/least; (+++) good/most; (++++) best/maximal

Methods of suturing

Suturesmay be interrupted, vertical mattress, horizontal mattress, continuous or subcuticular (Raftery AT, Delbridge M, 2006) , (Oakley E. Wound management. In: Cameron P, Jellinek G, Everitt I, et al. (eds), 2006) . The choice depends on the site,nature of the operation and surgeon's preference:

• Simple interrupted sutures may be used if there is a risk of infection, where some individual sutures may be removed to allow drainage.
• Vertical mattress sutures are useful in regions with minimal subcutaneous tissue where the wound edges are difficult to maintain in eversion.
• Horizontal mattress sutures reinforce the subcutaneous tissue and relieve skin tension, but do not provide wound edge approximation as well as the vertical mattress suture.
• Continuous sutures can be used to close the lacerations. They can be percutaneous or subcutaneous and made with absorbable or non-absorbable suture material.
• Subcuticular sutures may be used to give good cosmetic results, especially when using synthetic monofilament. Synthetic absorbable subcuticular sutures (e.g. Vicryl) may be used in children to avoid the trauma of suture removal.
  

Removal of sutures

The timing is a balance between strength of healing and a good cosmetic result. Some areas are better vascularized, under less tension, and therefore heal quicker than others. The rough guide for the time of removal for different areas is presented below as Tab. 3.

Table 3. Optimal time for suture removal (Capellan O, Hollander J, 2003)

Location	No. days
Face and neck	3-5
Scalp	5-7
Chest, abdomen and extremities	8-10
High tension (joints, hands)	10-14
Back	10-14