Introduction Large wounds often require inventive surgical reconstruction techniques to limit the amount of tension that is placed on the wound edges. Tension is one of the most common reasons for skin reconstructions to fail and the even distribution of tension or, better, the elimination of tension from the wound edges will improve wound healing and flap survival. The most common and relatively easy techniques of flap reconstruction will be discussed in this abstract.

Pedicle, skin or local flap

Definition

A partially detached segment of skin and subcutaneous tissue, with viability based on circulation maintained by its base and the subsequent subdermal plexus.

Use

The idea behind this technique is that local skin located in an area with relative abundance or elasticity is used to close the primary wound. The created secondary wound can be closed relatively tension free.

Positive aspects

Pedicle flaps are often easy and economical to perform and often substitute the appearance of the original hair coat well.

Negative aspects

Pedicle flaps can not be performed in areas with movement or variable tension. The vascularity of the pedicle often limits the length of the flap. A flap with a direct cutaneous artery included has a better survival that flaps without. Increasing the length of the flap or failing to include sufficient vascularity to the flap will increase the chance of dehiscence of the tip of the flap. The wider the base, the more chance that a direct cutaneous branch is included in the flap, thus improving viability.

Tips

 Try to create flaps that are a little wider than long. Shorter is better. Sometimes it is better to use two small flaps instead of one big one.

 Prevent tension.

 Always use a diligent and atraumatic technique.

 The use of sterile skin markers improve the general overview.

Examples

 Advancement flap

 Rotation flap

 Transposition flap

Advancement flap (French flap)

Definition

An advancement flap is a skin flap that is mobilised by undermining and advancing the skin in the direction of the pedicle-wound axis.

Indications

 Relatively square wounds

 Tension free skin in the direct vicinity of the wound

Surgical technique

Two skin incisions are made in the donor skin parallel to the wound edges. One edge of the wound is thus used as the leading edge of the flap. The skin is undermined and elevated preserving the panniculus muscle attachment, if present. The flexibility of the skin allows stretching of the skin to cover the wound bed. The panniculus muscle or the subcutaneous tissue is sutured to the wound edges using monofilament absorbable material; the skin is closed with nonabsorbable monofilament suture material or skin staples.

Tips

 Slightly divergent incisions will broaden the pedicle base

 The incision should a least be as long as the width of the defect Bilateral French flaps will create the famous H-flap, decrease tension and improve viability.

 Try to save direct cutaneous vessels

 Lengthening the flap is also possible

 Dog ears at the base are a aesthetic nuisance but rarely need fixing

 Walking sutures are dangerous and should be avoided. Large covered defects demand drainage!

Positive aspects

Simple, fast.

Negative aspects

 Tension is created in an area where tension often should be avoided

 H-flaps are rarely anatomically applicable, and may undermine the vascularity of the wound edges.

Rotation flap

Definition

A rotation flap is a flap that has a semicircular form and the flap is rotated into the defect around a pivot point.

Indications

 Relatively triangular wounds

 Tension free skin in the direct vicinity of the wound

Surgical technique

A semilunar incision is made extending from the outer edge of the wound. The baseline of the wound is also the baseline of the rotational flap and is preserved. The arc of incision is supposed to be 4 times the length required to rotate the flap into the defect. The incision is made in a stepwise fashion until it fully covers the defect without tension. The panniculus muscle of subcutaneous tissue is sutured to the wound edges using monofilament absorbable material; The skin is closed with nonabsorbable monofilament suture material or skin staples.

Tips

 The use of a sterile marking pen is advised

 The incision should be performed in a stepwise fashion

 Try to save direct cutaneous vessels

 Two rotation flaps on each side are also possible

 A short back cut at the end of the incision may allow more flexibility of the flap.

 The use of a drain is advisable.

Positive aspects

Simple, fast.

Negative aspects

 You may create tension in an area where tension should be avoided

 Adjacent to the flap skin may be redundant and result in a dog ear; even distribution of the tension will avoid this problem in most cases.

 The back cut may impede the vascularity of the base of the flap.

Transposition flap

Definition

A transposition flap is a rectangular skin flap that is rotated into the defect around a pivot point. The defect is most commonly located at a 90 degree angle to the axis of the flap. The flap is called an interpolation flap if the flap does not border the defect and has to cover intact skin between the donor and recipient site.

Indications

 Relatively square wounds

 Tension free skin perpendicular to the wound axis

Surgical technique

The width of the flap equals the width of the wound. A line is drawn from the pivot point to the most distant point of the defect. This distance determines the length of the flap. Two incisions are made, one along the border of the wound edge perpendicular on the base of the flap and one parallel to this starting at the pivot point. At the desired length these two incisions are connected. The skin is undermined and elevated preserving the panniculus muscle attachment, if present. The flexibility of the skin allows rotation of the skin to cover the wound bed. The panniculus muscle of subcutaneous tissue is sutured to the wound edges using monofilament absorbable material; the skin is closed with nonabsorbable monofilament suture material or skin staples. The donor bed is closed routinely.

Tips

 The flap is also possible with a 45 degree angle

 Rounding off the sharp edges will prevent ischemic skin necrosis

 Always add a little bit of length because rotating the flap will decrease its size

 Drawing the flap before incision or using a drape to measure the flap length can be useful

 Try to save direct cutaneous vessels

 Dog ears can always be removed at a later stage

 A large dead space will need drainage!

Positive aspects

Additional skin is transposed to the area of tension Very versatile

Negative aspects

 Tension is created if the flap length is too short; accurate preoperative planning is necessary.

 The 45 degree flap creates more tension because the skin is elevated closer to the wound

Axial pattern flap

Definition

An axial pattern flap is a skin flap in which a direct cutaneous artery is incorporated. These arteries supply the subdermal plexus and guarantee a sufficient blood supply to the flap. The vascularity is thus better than the earlier described subdermal plexus flaps. Most commonly used axial pattern flaps are listed in Table 1.

Table 1. Common axial pattern skin flaps

 Omocervical axial pattern flap

 Thoracodorsal axial pattern flap

 Caudal superficial epigastric axial pattern flap

 Cranial superficial epigastric axial pattern flap

 Superficial brachial axial pattern flap

 Deep circumflex iliac axial pattern flap

Indications

Any wound, located on areas with limited surrounding skin

Surgical technique (Ex. caudal superficial epigastric axial pattern flap)

A midline incision is made through the skin starting a couple of centimeters cranial of the vulva. The incision is extended as far as needed with a maximum of 4 mammary glands. In between the two cranial mammary glands the incision is drawn laterally and continued on the lateral side parallel to the median incision. After careful haemostasis the incision is deepened towards the abdominal fascia and upon reaching this level the skin including the mammary glands are carefully dissected from the attachment to the fascia in a craniocaudal direction. Cranially the superficial pectoral muscle can be elevated with the flap to ensure the viability of the subdermal plexus. Careful preparation is necessary in the area of the inguinal canal. Preservation of the caudal epigastric artery and vein is essential. The flap can be rotated into the defect and sutured in three layers. The mammary fascia is sutured with a 2-0 or 3-0 monofilament absorbable material; the subcutis with a 4-0 monofilament absorbable material and the skin is closed with staples.

Tips

 Drainage is important

 Ovariectomy is recommended

 The flap can be easily converted to an island flap. The cutaneous pedicle is divided in an island flap, but vascularity is ensured by the direct cutaneous artery.

 Dividing the cutaneous pedicle increases the versatility of the flap.

Positive aspects

 Additional skin is transposed to the area of tension

 Very versatile

 Blood supply is ensured

Negative aspects

 More labour intensive

 Careful dissection is necessary

References

1.  Swaim SF, Henderson RA. Small Animal Wound Management. 2nd ed. Chapter 7. Various wounds. Williams and Wilkins, Baltimore 1997, pp. 235-274.

2.  Pavletic M.M. Atlas of Small Animal Reconstructive Surgery. 2nd ed. W.B. Saunders, Philadelphia 1999, pp. 191-275.