Uneven wounds, dog ears
An ideal wound would lie precisely in a natural wrinkle line and would follow the contour of the adjacent skin. In fact a compromise has to be made because the removal of a piece of skin and underlying fat inevitably leads to some distortion when the edges are drawn together. The problems are:
• unequal length of wound edges
• different skin thickness of wound edges
• failure of the sutured wound to follow the curvature of the area, e.g. on a forearm
Unequal Length (Halving Method) -
Some excisions result in a wound with sides of different lengths. If suturing is begun at one end and progresses to the other it will leave a dog ear at the end (see dog ear repairs). It is often possible to 'lose' a small inequality by using the halving method. First place a suture half way along the wound, and then half way between the first sutures and the wound end, etc. This is called the rule of halves and gives a curved wound.
If you cut out a triangle from the longer side before suturing the result is a straight line.
NB: The longer side is often higher than the shorter side and a combination of closure by halves and high on the high (longer) side and lower on the low (shorter) side.
Uneven Heights -
Skin thickness varies considerably according to anatomical site. After removing a skin lesion it is not uncommon to find that the two edges to be sutured are different heights. This may be more marked if one edge is under tension. The unevenness can be corrected by taking a more superficial bite on the edge, which is higher, and a deeper bite on the lower edge. You can create uneven edges on the pig's trotter by placing an uneven subcutaneous suture.
Dog Ear Repairs
Dog ears are redundant tissue at the end of an excision line.
They are common in the following situations:-
sides of excision are unequal lengths
broad ellipse or circular defect
altered skin elasticity
convex surface, e.g. forearm
Dog ears can often be avoided but you should not worry if one forms - they are easy to deal with. Experience shows that some dog ears can be left and will settle spontaneously; this is often the case on the forehead. If the formation of a dog ear is inevitable sutures should be placed so that the dog ear is created in the least conspicuous part of the wound or placed so that it may be excised in a wrinkle.
The dog ear may be excised as a straight line continuation of the wound or in a curve. The redundant tissue is tented with a skin hook and either
• divided along the roof into 2 triangles which are then excised
- pulled to one side and the base divided on one side and then the other
Wound Healing by Secondary Intention
There are three phases to wound healing, which affects both primary closures and those allowed to heal by secondary intention. During the first forty-eight hours there is an inflammatory phase. This is characterised by an initial fibrin net being infiltrated by polymorphonuclear leucocytes and macrophages. These cells release mediators that initiate the second phase. After forty-eight hours the second phase, that of collagen synthesis, begins. Here fibroblasts spread throughout the wound and begin to produce collagen. This phase lasts for about six weeks and is followed by the remodelling phase, when scar shrinkage takes place and lasts eighteen months to two years.
• Avoids need for reconstruction
• Low complication rate
• Recurrences of tumours not buried under flaps or grafts
• Usually good cosmetic results
• Wounds take longer to heal • Increased incidence of hypertrophic scarring
• May cause retraction at free edges, e.g. lips and eyelids
• Haemostasis must be good
• Guiding sutures may be used
• Daily dressings with water or saline followed by topical antiseptic/antibacterial e.g. Bacitracin, Mupirocin, Silver Sulphadiazine, Chlorhexidine etc.
• Non stick dressing e.g. paraffin gauze and absorbent gauze.
The cosmetic result of wounds healed by secondary intention varies according to anatomic site. Healed wounds are often imperceptible in NEET areas (concave surfaces of the nose, eye, ear, and temple). In NOCH areas (convex surfaces of the nose, oral lips, cheeks and chin, and helix of the ear) superficial wounds heal with an acceptable appearance, but deep wounds heal with depressed or hypertrophic scars acceptable only to some patients. Wounds healed in FAIR areas (forehead, antihelix, eyelids [i], and remainder of the nose, lips, and cheeks) result in flat hypo-pigmented scars acceptable to many patients.