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Transposition flap in the hand

    Overview

    Learn the Transposition flap in the hand surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Transposition flap in the hand surgical procedure.
    Local skin flaps are used to cover small to medium sized defects in the hand of which there are several geometric designs including advancement flaps, pivot flaps and interpolation flaps.
    With an Advancement flap the skin advances in a single plane and is based on a single pedicle(uni-pedicled flaps), two pedicles(bi-pedicled) or V-Y advancement (a technique wherein a V-shaped defect is converted to a Y). These flaps are useful for fingertip defects where more dorsal skin is lost. The advancement is done from the volar side.
    Pivot flaps implies a side to side movement of the flap. This can be done as a rotational flap where there is no secondary defect or as a transposition flap where there is a secondary defect which has to be either closed directly or resurfaced with a skin graft.
    Interpolation flaps move over intact skin to reach the defect. This leaves a pedicle which has to divided in two to three weeks. Cross finger flaps are an example of these. Cross finger flaps are usually taken from the dorsal skin of the middle phalanx and used to cover finger tips. These are most useful for covering pulp defects where there is more loss from the palmar side.
    The case demonstrated is a soft tissue defect following an open fracture, itself treated with a primary fusion of the PIP joint using plate and screws. The wound broke down three weeks following the operation, exposing the metal work, and leading to a significant infection risk. Check X-Rays showed that there was little bony union and therefore the metal work could not be removed.
    A local transposition flap was used to cover the defect with the secondary defect closed using a split skin graft taken from the same forearm.
    The skin in this finger was indurated and tight secondary to the recent trauma and wound breakdown, leaving no slack for the use of a rotation flap, which allows direct closure of the donor site. Though there is the need for a split skin graft to cover the secondary defect produced by a transposition flap its design allows enough movement to cover the entire defect with healthy and immediately vascular flap tissue.

    Indications

    INDICATIONS
    Small to medium-sized wounds in the hand which cannot be closed directly can be covered with a split skin graft. Examples of such wounds are: Traumatic defects, defects following excision of a skin lesion, defects following excision of a subcutaneous lesion(eg. mucous cyst) which has caused skin necrosis
    Defects in the hand where a skin graft is not an option:The pre-requisite for using a split skin graft is a wound bed which has vascularity. A split skin graft does not have its own blood supply and takes blood supply from the wound bed. Exposed bare bone, bare tendon, bare cartilage or metalwork are all contraindications for a skin graft.
    SYMPTOMS & EXAMINATION
    This patient presented with a wound break down following the initial operation which was done to fuse the PIP joint following a circular saw injury. There was persistent discharge from the wound which was also painful.
    IMAGING
    X-rays were done to check the position of the plate, look for evidence of union and also for any evidence of osteomyelitis.
    The position of the plate and screws were satisfactory, there was little evidence of bone healing and no evidence of osteomyelitis.
    ALTERNATIVE OPERATIVE TREATMENT
    The potential alternative surgical options in this case are are:
    Rotation flap: This would be possible if there was enough loose skin which will allow a closure of the donor site.
    Reversed Cross-finger flap: This involves taking a fascial flap from the middle finger and leaving the two fingers attached for three weeks. The flap would need division at three weeks. As well as being inconvenient this will leave a skin grafted area on the middle finger and has a risk of causing stiffness to the middle finger.
    Other flaps to be aware of are:
    An Advancement flap: the skin advances in a single plane and is based on a single pedicle(uni-pedicled flaps), two pedicles(bi-pedicled) or V-Y advancement, a technique wherein a V-shaped defect is converted to a Y). These flaps are useful for fingertip defects where more dorsal skin is lost. The advancement is done from the volar side.
    A Pivot flap: implies a side to side movement of the flap. This can be done as a rotational flap where there is no secondary defect or as a transposition flap where there is a secondary defect which has to be either closed directly or resurfaced with a skin graft.
    An Interpolation flap: moves over intact skin to reach the defect. This leaves a pedicle which has to divided in two to three weeks. Cross finger flaps are an example of these. Cross finger flaps are usually taken from the dorsal skin of the middle phalanx and used to cover finger tips. These are most useful for covering pulp defects where there is more loss from the palmar side.
    NON-OPERATIVE MANAGEMENT
    Continuing with dressings in the hope that a wound heals is an option if there is healthy bed for granulation tissue to develop on. The course is likely to be more protracted and onerous.
    CONTRAINDICATIONS
    The main contra-indication to a local flap such as this would be a trauma to the local tissue being considered for the flap. Relative contraindications include heavy smokers, patients with vascular disorders such as diabetic arteriopathy and previous trauma to the area with significant scarring.

    Setup

    Surgery can be done under Regional anaesthetic with an upper arm tourniquet.
    A single dose of intraveous antibiotic is administered prior to inflating the tourniquet.
    Patient is is supine with the arm on a hand table.

    Operation – 1

    The location and size of the defect is assessed. It is also important to assess the surrounding skin where the flap is planned.
    If there are pre-existing scars in the area of the planned flaps, it can compromise the viability of the flap.
    The wound should already be relatively clean with no pus or necrotic tissue prior to closure with a flap.

    The arm is prepped and draped and positioned on a hand table. Hand is placed on a Lead hand and a rolled up cotton towel is used under the hand.

    An X-ray of the finger is taken using the Mini C-arm to check the position of the plate and screws. The X-Ray shows that the fusion has not united. Therefore it is not possible to take the plate and screws out at this stage.

    The margins of the wound are marked out for debridementIt is important that the wound edges are debrided prior to doing a flap cover. This gives a healthy wound edge to suture the flap.

    Excising the edges neatly can be tricky. A No.15 blade on a Barron handle(rounded handle) is useful for this.

    The wound is debrided, down to bone if needs be and a local flap can still be used for wound cover.The debrided wound can be seen. It appears clean with no slough or pus in the base.
    The depth of debridement depends on the extent of necrotic tissue.

    Chronic wounds are usually colonised by bacteria. It is important to irrigate the wound with copious normal saline to clean it.

    The transposition flap is plannedAt this stage the transposition flap is planned. The design for the flap is a rectangle in this instance. The length to breadth ratio is 1:2.

    The flap design is completed.

    There are geometric principles which are used to help in designing these flaps. However, small transposition flaps are often drawn free hand after making a visual assessment of the defect.
    The principles of designing a transposition flap are:
    a) Convert the defect into an isosceles triangle
    b) Draw a rectangular flap with almost the same width as the base of the triangle
    c) Make sure that the flap is longer than the triangle. How much longer to draw the flap is a matter of judgment. Making a template of the flap and using it for planning helps to design it.

    A diagrammatic representation of how the transposition flap is moved to cover the primary defect and the secondary defect that results.

    A diagrammatic representation of how the transposition flap is moved to cover the primary defect and the secondary defect that results.

    The flap is raised using a No.15 blade.The incision is made all around the margins of the flap.

    The flap is raised whilst being careful to preserve the underlying paratenon covering the tendon.The paratenon is vascular layer has to be preserved over the extensor tendon while raising the flap. This is important because the secondary defect is covered with a split skin graft. Skin graft will only take over tissues that have good vascularity. Paratenon will suffice as a bed for the graft but bare tendon will not.

    Once the flap is lifted off the extensor tendon, it is transposed to cover the defect.This will create a skin fold called a ‘dog ear’ which can be seen.

    The flap is sutured to the wound edge using 4-0 vicryl rapide sutures.

    With the flap transposed and sutured the secondary defect can be seen.The cosmetic appearance will not be good at this stage due to the dog ear.

    Saline irrigation is used to keep the wound moist. It is important as the split skin graft will be applied over the secondary defect and keeping these tissues as viable as possible will help a successful graft “take”.

    Once sutured into place check the vascularity of the flap and also ensure that the bleeding from the secondary defect is controlled.The small blood vessels over the wound are cauterised using bipolar cautery. If the wound continues to bleed under the skin graft the haematoma which forms can lift the graft.

    The sutured flap and the wound can be seen. The flap looks pink and healthy. The secondary defect is clean.

    The dimensions of the secondary defect are measured using a ruler to plan for an appropriately sized split skin graft which is harvested from the forearm.

    The approximate dimensions of the split skin graft are marked out over the forearm.

    The skin over the skin graft donor site is shaved using a No.15 scalpel.
    I prefer to do the skin shaving just before taking the skin graft using a scalpel. Skin is shaved to make graft harvesting easy. The split skin graft is taken through the mid-dermis, above the plane of the hair follicles. Therefore the risk of hair growing on the split skin graft is minimised.

    Split skin graft can be harvested using a power-driven Dermatome or using a handheld knife.
    As it is a small skin graft, I have chosen a Weck blade for harvesting the skin graft.
    The Weck blade is usually used for debriding burn wounds. It comes with three guards, 8, 10 and 12. In this case I have chosen a No.10 guard which gives a graft of intermediate thickness.

    The forearm skin is distracted and placed under tension.
    The Weck blade is kept at an angle of about 30 degrees to the forearm and a “too and fro” motion is used to take the graft.

    Operation – 2

    As the harvest progresses it is important to look at the donor defect.
    Punctate bleeding suggests that the plane is through superfical/mid dermis which is correct.
    Blotchy bleeding suggests that the plane is through deep dermis or into subcutaneous fat, which is too deep. If this happens it is best to put the skin back and suture it.

    The harvested skin graft is placed over the defect to check its size.

    The split skin graft is spread over a kidney dish with the shiny undersurface facing up.

    Fenestrations are made on the skin graft using No.15 blade.This is to allow any blood or serous exudate to come through these fenestrations. This helps to keep the graft adherent to the defect.

    The wound is irrigated once more prior to application of the graft.

    The graft is spread over the defect as shown.

    The corners of the graft are sutured using 4.0 Vicryl Rapide.

    Excess graft is trimmed using a tenotomy scissors.

    Suturing is continued by using 4.0 Vicryl Rapide sutures.

    The sutured graft can be seen. The dog-ear(A) of the transposition flap is conspicuous and makes it aesthetically unpleasing. However the temptation to trim it at this stage should be resisted as it can compromise the circulation of the flap. The tip of the flap looks slightly congested but this should settle down.

    The wound is dressed in layers. Mepitel is used as the first layer.

    Betadine soaked gauze is used as the next later.

    Dressings gauze is added on top of the betadine soaked gauze.

    Kaltostat is applied over the skin graft donor site. This helps to get haemostasis over the donor site.

    Gauze is applied over the Kaltostat.

    Velband is applied over the gauze.

    A small POP backslab is applied to support the finger and stop movements. This is important to ensure that the skin graft takes on the wound. Bandage is applied as a final layer.

    The completed dressings and cast.

    Post Operative

    Post-operatively hand is elevated in a Bradford sling for 48 hours. The patient is discharged home the same day on analgesics.
    The dressings is changed at 5 days to check the flap and graft. A healthy flap should have pink colour with normal capillary refill. The skin graft should look well stuck the wound with no collection underneath. The skin graft donor site is left undisturbed at this stage. The wound is redressed with Mepitel, gauze and bandage. The wound is further checked at one week. This time the donor site of the skin graft is also checked and the Kaltostat should life off revealing a healed donor site. If it is not fully healed, further dressings can be applied using Mepitel.
    At this stage usually, the wound can be left open. Patients can wash the hand as normal and gently start moisturising the graft. Hand therapy is started to mobilise all the fingers. As this finger had fusion of the PIP joint, MCP joint mobilistaion is started again.
    At 6 weeks a further check X-Ray is done to see if the fusion has united. The dog ear has usually settled by then. If not a revision surgery can be done to make it cosmetically better.

    Recommended Reading


    Venkatramani H, Varadharajan V. Adipofascial, Transposition, and Rotation Flaps. Hand Clin. 2020 Feb;36(1):9-18.
    Soft tissue loss over the dorsum of the finger could potentially expose critical structures like extensor tendon, bone, and joint. These exposed structures often require flap coverage. Local flap is one of the available options to cover most small-sized defects on the dorsum of fingers. One of the primary requisites for any flap used on the dorsum of the finger, especially over a joint, is to enable the full range of motion of the finger. Even though skin over the dorsum of the fingers can be pinched easily in extension, with full flexion such suppleness is not demonstrated.

    Lister G.The theory of the transposition flap and its practical application in the hand. Clin Plast Surg. 1981 Jan;8(1):115-27.
    The author describes the geometry and practical steps of raising a transposition flap and how it can be used for covering defects in the hand.

    Hojo J, Omokawa S, Shigematsu K, Onishi T, Murata K, Tanaka Y.
    Patient-based outcomes following surgical debridement and flap coverage of digital mucous cysts. J Plast Surg Hand Surg. 2016;50(2):111-4.
    The purpose of this prospective cohort study was to evaluate patient-based outcomes and complications following excision of mucous cysts, joint debridement, and closure with one of three types of local flaps.
    From 2000-2011, 35 consecutive patients with 37 digital mucous cysts were treated surgically. The surgical procedure included excision of the cyst together with the attenuated skin, joint debridement on the affected side including capsulectomy, and removal of osteophytes. Depending on the size and location of the cyst, the skin defect was covered by a transposition flap (31 ), an advancement flap (2), or a rotation flap (4).
    At an average follow-up time of over 4 years there was no wound infection, flap necrosis, or joint stiffness. Preoperative nail ridging resolved in seven of nine fingers, and no nail deformities developed after surgery. One cyst, treated with a transposition flap, recurred 10 months after surgery. The average satisfaction score for the affected finger significantly improved and the average pain score decreased significantly.

    Reference

    • orthoracle.com

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