Author: Edward Bollen, Final-year medical student at Basildon University Hospital
Skin suturing comes at the beginning and the end; the career begins with suturing, and the operation ends with it. This article outlines the key principles of suturing to achieve a cosmetic, functional scar. The following are discussed:
- Relaxed skin tension lines
- The basic structure of the skin
- Suture depth
- Skin eversion
- Skin instrumentation
- Complications of skin suturing
Relaxed Skin Tension Lines
Also known as Langer’s lines, relaxed skin tension lines map the orientation of the skin’s collagen fibres. They represent an important guide in skin suturing; one must align the orientation of wound closure with them in order to minimise tension and the likelihood of an unsightly scar(1). A wound which is misaligned with these lines is placed under greater tension and is therefore at greater risk of complications including dehiscence and hypertrophic scarring.
Interestingly, these lines show where the wrinkles of ageing skin appear. For example, one can visualise forehead lines, crow’s feet and nasolabial folds in the diagram below.
The part of the skin responsible for creating relaxed skin tension lines is the dermis, the middle of the three main layers of the skin.
Basic Structure of the Skin
While the structure of the skin is very complex, for one who is suturing it may be summarised as comprising three layers(2):
- The epidermis: the most superficial layer, the epidermis provides protection from trauma, sunlight and the entry and exit of fluids.
- The dermis: composed mainly of connective tissue, the dermis gives the skin its elasticity and flexibility, and plays a key role in wound healing(3).
- The hypodermis: also referred to as the subcutaneous fat, this layer helps to contain heat and protect underlying tissues from trauma.
Recognising these three layers is important in determining the depth to which to suture.
It is essential that sutures include at least the full thickness of the dermis. Failure to do so risks creating dead space: a cavity between the two wound edges in which a haematoma or seroma may develop. This in turn may lead to infection.
As already mentioned, the dermis, the source of the skin’s fibroblasts and collagen, plays a key role in wound healing. Sutures which do not include the entire thickness of the dermis do not maximise its potential to drive wound healing.
As well as placing deep bites, everting the wound edges helps to ensure full apposition of the dermal edges.
This is the process of manipulating the wound edges in an ‘up and out’ fashion while approximating them. The benefit of doing so is twofold. Firstly, eversion helps to bring together the two edges of the dermis. Secondly, contraction of the healing wound leads to a degree of inversion which may lead to a less cosmetic scar. Eversion counterbalances this process.
The best way to evert the wound edges involves using the correct instruments.
The fibrous structure of the skin makes it amenable to gentle handling with relatively sharp instruments. In contrast to non-toothed forceps, toothed forceps and skin hooks allow one to delicately grip the skin while applying minimal force, thereby avoiding crush injury to the wound and subsequent scarring(4). This principle also applies to other fibrous tissues including tendons, ligaments and fascia. Unfortunately, even with the best suturing technique, complications may occur.
The following are some notable complications of skin suturing:
- Infection: the commonest complication, this may be prevented by the use of a sterile field, wound debridement and cleaning as necessary, and the maintenance of good hygiene postoperatively(5).
- Haematoma and seroma: a collection of blood or serous fluid, often forming in dead space, which may lead to infection.
- Dehiscence: a wound may pull open which, untreated, ultimately yields a wide depressed scar. Wound dehiscence can be caused by infection, excessive tension postoperatively (e.g. in highly mobile areas), or by placing sutures too loosely.
- Hypertrophic scar: sutures placed too tightly incur more growth in the healing wound and a bigger scar. The hypertrophic scar does not grow beyond the wound.
- Keloid: unlike the hypertrophic scar, the keloid extends beyond the wound. It occurs as a result of deranged collagen production, and is known to be more common in certain parts of the body and in certain demographics.
1. Son D, Harijan A. Overview of surgical scar prevention and management. J Korean Med Sci. 2014 Jun; 29(6):751-7.
2. Fore J. A review of skin and the effects of aging on skin structure and function. Ostomy Wound Manage. 2006 Sep; 52(9):24-35.
3. Rippa AL, Kalabusheva EP, Vorotelyak EA. Regeneration of Dermis: Scarring and Cells Involved. Cells. 2019 Jun; 8(6):607.
4. Janis JE, Kwon RK, Lalonde DH. A practical guide to wound healing. Plast Reconstr Surg. 2010 Jun; 125(6):230e-244e
5. Adigbli G, Alshomer F, Maksimcuka J, Ghali S. Principles of Plastic Surgery, Wound Healing, Skin Grafts and Flaps in: Kalaskar D., Butler P., Ghali S. Textbook of Plastic and Reconstructive Surgery. 1st ed. London: UCL Press; 2016. pp 3-37.