Skin Transposition Flap
Source
Surgeon:
Hannu Kuokkanen
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Summary
Focus: Excision of a skin lesion or scar and closure of the resulting defect with a rhomboid or Limberg transposition flap.
Key elements: Careful flap planning, preservation of vascular supply, tension-free closure, wound dressing, aftercare, and recognition of flap-related complications.
Indications and Clinical Context
Medical expert: Hannu Kuokkanen, plastic surgeon
Names of procedure: Excision of skin lesion and transposition flap, rhombic flap, rhomboid flap, Limberg flap
Goal of Operation
To cover a wound or defect with healthy tissue, ensuring its precise fit to optimize healing and minimize scarring, especially in areas where primary closure is not possible.
Problem
A skin defect or wound, often due to surgical removal of skin malignancy, trauma, or chronic non-healing wounds, particularly in areas where there is limited surrounding tissue for primary closure.
Diagnosis
Other and unspecified skin changes (ICD-10: R23.8)
Short Pathophysiological Description
Skin defects can occur due to various reasons, such as surgical excision of skin malignancies, trauma, or chronic wounds. In particular, the removal of skin malignancies with adequate margins often results in significant skin defects that cannot be closed primarily due to insufficient surrounding tissue. In the facial area specifically, a rhomboid flap should be designed to align with and respect the natural lines and contours of the face, thereby leading to an improved aesthetic outcome.
In this content, we are using a rhomboid-shaped flap, the Limberg flap, consisting of healthy skin and underlying tissue from an adjacent area to cover the defect. This usually leads to an aesthetically pleasing wound closure result, maintaining vascular supply and skin function, thereby restoring skin integrity and minimizing potential complications.
Key Anatomy and Landmarks
Epidermis
Dermis
Subcutis
Muscle fascia
Subcutaneous nerves in the surgical field, for example:
Facial area: the temporal branch and the marginal mandibular branch of the facial nerve
Upper limb: antebrachial cutaneous nerve of the forearm, superficial radial branch
Lower limb: lateral cutaneous nerve of the thigh, saphenous nerve, superficial fibular nerve, sural nerve
Step-by-Step Technique
Preparations
The surgical field will be prepped with a gentle but diligent surgical wash.
Sterile adhesive drapes are used to designate the sterile operating field.
In the facial area, the entire face should remain exposed. Three sterile drapes are used: one placed under the head, the second enclosing the hair in a hood, and the third sterile drape over the thorax. This will allow the patient to breathe easily and leave the skin crease lines visible. The eyes should be covered with sterile gauze to guard against glare.
Planning the Skin Flap
The aim is to design a flap with enough healthy skin and subcutaneous tissue to cover the defect without excessive tension while preserving the flap's vascular supply for optimal healing. The donor site should match the Langer lines, the lines of minimal tension, for less visible scarring.
A classic rhomboid flap, the Limberg flap, has four sides with opposite sides being equal in length and angles of 60 and 120 degrees. This offers flexibility in the flap with minimal tension.
Using a sterile soft marker, first trace the excision site of the lesion with adequate margins.
Draw the defect as a rhomboid shape on the skin with 120 and 60 degree angles.
Then, mark the rhomboid flap adjacent to the defect. The flap should be of the same size and shape as the defect.
The tip of the flap is the same width as the width of the middle part of the skin excision site.
The outer side of the flap is aligned with the side of the skin excision.Four potential flap locations exist, one on each side of the rhomboid. Choose the site that allows for minimal tension during flap movement and has the best vascular supply to ensure the viability of the flap.
Local Anaesthesia
The most commonly used local anaesthetic is 1% lidocaine with adrenaline.
Use a small needle and inject the local anesthetic gently whilst advancing the needle through the numbed area. Administer more anesthetic on withdrawal of the needle to avoid too much pressure within the tissue.
Using a syringe with a threaded hub, for example Luer Lock, prevents the needle from coming off on withdrawal.Wait for at least 5 minutes after administering the anesthetic and make sure that the whole surgical field has been fully anesthetized before proceeding. If necessary, use more anesthetic.
Removal of the Skin Lesion/Re-excision of the Scar
The aim is to completely excise the lesion along with adequate margins to ensure all pathological tissue is removed, which is then confirmed by histopathological analysis.
Follow the planned outlines and advance perpendicular through the skin, simultaneously stretching the skin in all directions. Advance down to the desired depth.
Take hold of the specimen with forceps and detach it sharply at the fascia level.
Before detaching the specimen completely, use sutures to define the orientation of it for the pathologist, for example: short tail for superior and long tail for lateral border.
Use bipolar cauterization thoroughly. This helps to avoid unwanted hemorrhage in the operating area as well as post-operative bleeding.
Preparing the Flap
The goal is to carefully incise and elevate the flap while preserving its blood supply, ensuring that the base of the flap, which contains the primary blood vessels, maintains adequate thickness and is not damaged.
When removing a potentially malignant skin lesion, it is recommended to take off your sterile gloves and put on a new pair once you have completed the excision of the lesion. Furthermore, continue with a new set of surgical instruments to avoid potential tumor cell spreading.
The flap edges are incised along the planned line perpendicular through the skin, again stretching the skin in all directions simultaneously.
Advance down to the subcutaneous fat and harvest a flap that is of the same thickness as the excised skin lesion. Make sure to preserve the flap thickness especially at the base of the pedicle to avoid compromising the flap's blood supply.
The tip of the flap can be a bit thinner than the base to allow for better aesthetic integration with surrounding tissue, increased flexibility, and reduced tension upon suturing.Mobilize and turn the flap to test that there’s enough room for closure.
If there is too much tension, undermine the wound edges beneath the subcutaneous layer.Start the closure after careful hemostasis.
Transposition and Closure
The goal is to move the flap into the defect area with minimal tension and suture the flap into place. This involves suturing the graft without excessive tension and maintaining close contact with the wound bed for revascularization. The thread size will be chosen based on the site: 5-0 for the face, 4-0 for the trunk and upper limbs, and 3-0 for the lower limbs.
First close the flap donor site, which facilitates transposition of the flap to the target site.
The first sutures will be inserted subcutaneously by taking an absorbable monofilament suture, e.g. Monocryl/Biosyn, deeply through the dermis without coming through the epidermis so that the knot will be buried deep, as an inverted suture. This helps avoid suture fistula formation as the absorbable suture knot is not next to the epidermis.Close all corners with the same absorbable dermal suture to make sure that wound closure is possible. Dermal sutures are mainly responsible for holding the skin edges together.
Once the dermal sutures help bring the wound edges within reach of each other, close the superficial skin layer using interrupted non-absorbable nylon stitches or a continuous suture.
Cover the sutures with sterile non-woven tape and protect the entire area with gauze with adhesive edges. On the limbs it’s suitable to use non-woven swabs and spiral bandage on top.
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Piftalls and Complications
Pitfalls
Inadequate Planning
If the base of the flap is too narrow or left too thin, it can compromise the blood supply, potentially leading to flap necrosis. Furthermore, the flap should be designed and mobilized to avoid excessive tension on the wound edges, as too much tension can lead to wound dehiscence, poor scarring, and further risk of flap necrosis.
If the flap does not respect the skin tension lines, specifically in the facial area, the esthetic outcome might be poor.
Careless Tissue Handling
Tissue should be handled carefully both when excising the lesion and when detaching the flap, whenever possible grasping the specimen without touching the skin lesion.
Inadequate skin mobilisation may result in tightness at the skin edges. This is associated with the risk of wound edge or flap edge necrosis, infection, and wound dehiscence.
Inadequate Hemostasis
Pay attention to adequate hemostasis. Wound hematoma may be susceptible to infection, slow healing, or cause wound dehiscence.
Wound Closure Problems
Make sure to match dermis to dermis and epidermis to epidermis. If the skin edges do not match and instead fold downward, the wound will not heal but there will be dehiscence.
Negligence in Wound Dressing
Use of wound tape will prevent wound dehiscence and keep the skin edges correctly aligned. The tape also prevents scar formation up to 6 weeks. In the beginning stages of wound healing, a bandage with light pressure can be considered. It can help with hemostasis but also eliminate the dead space, immobilise the wound, relieve pain, and prevent wound dehiscence.
Complications
Flap Necrosis
Sometimes a part of the flap or the whole flap is lost due to infection, hematoma, or inadequate blood circulation to the flap. If the tissue is clearly necrotic, it needs to be removed and the wound left open for a while. Eventually, wound closure can be re-assessed, either with a new flap or with a full thickness skin graft. In some cases, a small wound can heal through a process of granulation.
Wound Edge Necrosis
If the wound edge skin is very thin, e.g. in the elderly, and there is a lot of tension on the skin edges, it may cause skin necrosis. This is prevented by facilitating wound closure through adequate skin mobilisation. Closure of the wound in two layers so that the greatest tension is in the dermal sutures will also reduce the risk of wound edge necrosis.
Hematoma
Wound hematoma may be susceptible to infection, slow the healing, or cause wound dehiscence.
If the wound continues to bleed at home or a large hematoma swelling develops, the patient should be advised to contact the surgical unit or the ER. Hemorrhaging can be persistent, particularly in patients on anticoagulants.
Infection
All operations are associated with the risk and possibility of infection. Mild infections can typically be managed locally, and may also require antibiotics. If there is a deep suppurative infection, the sutures should be removed, the wound left open, and appropriate infection treatment initiated.
A new flap can be considered once the infection has cleared.
Scar Hypertrophy
Some patients may have a strong tendency to scar hypertrophy and keloid formation. This should be asked about beforehand. After the wound has healed, if there is itching, pain, erythema, and swelling of the scar, the patient may have scar hypertrophy. Scar hypertrophy should be treated actively and proactively. A prophylactic mindset is of utmost importance.
Nerve Injury
Sensory loss around the wound may be due to skin nerve trauma caused by stretching or severing a nerve. Loss of sensation in a minor area is usually harmless but severing a sensory nerve serving a larger area should be referred to a specialist, such as a hand surgeon or plastic surgeon.
If there is loss of function in the facial area, e.g. forehead muscle paresis and dropping of the eyebrow, a plastic surgeon should be consulted.
Aftercare
General Guidelines
The non-woven tape should be kept in place until stitch removal. The patient can take a shower 24 hours post-operation. The wound should not be hit with direct water pressure. The tape can be replaced if it comes off.
Based on the wound location, the stitches can be removed 7-14 days postoperatively.
The scar should be covered with wound tape after stitch removal and left in place for 2-6 weeks to prevent scar formation.
FAQ
What is the goal of a skin transposition flap?
The goal is to cover a wound or defect with healthy tissue, ensuring its precise fit to optimize healing and minimize scarring, especially in areas where primary closure is not possible.
What flap type is described in this article?
This article describes a rhomboid-shaped flap, the Limberg flap, consisting of healthy skin and underlying tissue from an adjacent area to cover the defect.
How is the flap planned?
The defect is drawn as a rhomboid shape with 120 and 60 degree angles, and the adjacent rhomboid flap is marked to be the same size and shape as the defect.
When can the patient shower after the operation?
The patient can take a shower 24 hours post-operation, but the wound should not be hit with direct water pressure.
When are stitches removed?
Based on the wound location, the stitches can be removed 7-14 days postoperatively.
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