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Foucher Flap to reconstruct volar thumb soft tissue defect

    Overview

    Learn the Foucher Flap to reconstruct volar thumb soft tissue defect surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Foucher Flap to reconstruct volar thumb soft tissue defect surgical procedure.
    Thumb contributes to almost half of the hand function. Reconstruction of thumb defects are therefore of a high priority and complex reconstructions are often undertaken to maintain the length and sensations. Pulp of the thumb is a specialised area where the texture of skin and sensations are important. Where possible, local flaps from the thumb tissue is used to reconstruct pulp defects. However when the defects are more substantial, reconstructions become more challenging.
    Pulp loss can results from trauma, infection or resection of tumours. Traumatic loss can involve the skin alone, skin and deeper soft tissues or a composite loss involving soft tissues and bone.
    There are several reconstructive options for a thumb pulp loss involving the whole of the thumb distal phalanx. These range from skin grafting, cross finger flap from the index finger dorsum, Foucher flap(flap taken from the dorsum of the index finger metacarpal based on the first dorsal metacarpal artery or a free tissue transfer from the great toe pulp based on the dorsalis pedis artery. The reconstructive method is often chosen based on the patient’s functional demands and co-morbidities.
    This case illustrates reconstruction of the thumb defect using a Foucher flap. Foucher flap is an eponymous flap based on the first dorsal metacarpal artery and was first described by the French Hand surgeon Guy Foucher.
    The radial artery enters the palm between the two heads of the first dorsal interosseus muscle. At this point it gives off a branch called the first dorsal metacarpal artery which divides into smaller branches and supplies a fascia over the first dorsal interosseus muscle and the skin over the dorsum of the index finger. The skin overlying the index finger proximal phalanx can therefore be harvested based on this arterial plexus if the fascia, the overlying superficial radial nerve branches and the superficial veins are harvested. This provides a good quality skin over the thumb which is sensate, though the sensations are referred to the index finger till the brain re-learns it. The donor defect over the index finger will need reconstruction and this is done using a full thickness skin graft taken from a suitable donor site.


    Indications

    INDICATIONS
    The main indication for this flap is reconstruction of a thumb defect. It is classically described for pulp defects but it can also be used for dorsal defects. The defects requiring reconstructions of this nature can be from trauma such as avulsions or ragged flap lacerations, infections causing pulp necrosis or following resection of tumours.

    SYMPTOMS & EXAMINATION
    The defect and the patient has to be assessed before making a definite treatment plan for reconstruction. The size, shape and depth of the defect has to be assessed. Defects which are not exposing the bone can sometimes be reconstructed using a skin graft though the resulting surface does not have sensations. In the case of infected wounds it is important that the wound is clear of infection and the edges healthy.
    it is also important to assess patient factors such as age, occupation, handedness, hobbies and co-morbidities. Patient’s preference for a particular reconstructive method should also be taken into account.
    The principles in choosing a method for reconstruction runs along the concept of ‘reconstructive triangle'(Mathes and Nahai). The three limbs of the triangle are form, function and safety. For example in a young fit patient a complex reconstruction such as a free toe pulp transfer is often chosen for better form and function. Likewise in an elderly patient with multiple co-morbidities, a skin graft may be chosen over other complex methods to make it a safe method.
    IMAGING
    X-rays are important in the setting of trauma to rule out fractures. In infections X-Rays are useful to make sure that there is no bony infection.
    ALTERNATIVE OPERATIVE TREATMENT
    There are several surgical options for thumb pulp reconstruction. For a moderate defect such as the one in this case the options are:
    Skin graft: This can be a split skin graft or a full thickness skin graft. Full thickness skin graft gives some sensory recovery but there is a greater risk of graft loss.
    Cross finger flap: This is a flap taken from the dorsum of the index finger. The flap is raised superficial to the paratenon and and sutures to the defect. The thumb and the index finger are left attached together for two weeks before the flap is detached. The defect over the index finger is reconstructed with a full thickness skin graft.
    Littler flap: This is a flap taken from the radial side of the pulp of the ring finger islanded on the digital artery, venae comitantes and digital nerve. The defect on the ring finger is reconstructed with a full thickness skin graft. This flap however is not very popular due to the donor site morbidity and is hardly used.
    Toe hemipulp transfer: A free tissue flap is harvested from the fibular side of the great toe including the glabrous skin, dorsalis pedis artery. dorsal veins and plantar nerves. This flap is transferred to the thumb and vascular anastamoses and nerve anatastamoses done. The dorsalis pedis is anastamosed to the radial artery in the anatomical snuff box and veins to the dorsal veins in the hand. The plantar nerves are anastamosed to the digital nerve stumps of the thumb. This however is a long and complex procedure and there is a risk of vascular thrombosis resulting in flap failure.
    NON-OPERATIVE MANAGEMENT
    Conservative management with dressing can be used for small defects not exposing bone or tendon. For larger defects if conservative management is to be used due to patient factors, VAC therapy or Topical Negative Pressure therapy can be used which will provide a faster healing.

    CONTRAINDICATIONS
    The main contraindications to the use of this flap are patients who have damage to skin over the dorsum of index finger and patients with injury to the radial artery.
    Relative contraindications include heavy smokers or patients with microvascular disease.

    Setup

    Operation – 1

    The photograph shows the thumb with necrotic tissue over the pulp. The necrosis extends from the thumb tip to the middle of the proximal phalanx. A previous incision used to washout the thumb tip can be seen.

    The dorsum of the thumb can be seen. Though there is some redness of the skin this is more of an inflammatory response than infection. Rest of the dorsal skin appears normal.

    A close up of the thumb pulp can be seen. There is evidence of ongoing infection in the surrounding skin.

    The excision marking for debridement is marked.

    Debridement is done using a No.15 blade. Resection is done down to healthy tissues. In this case it is down to the bone.

    The resultant defect following resection can be seen. There is no bleeding from the wound bed as the tourniquet is inflated.

    The resected tissue can be seen.

    A pattern of the defect is made using an absorbent paper. The underlay of the instrument tray is quite useful for this.

    The pattern of the defect is drawn using a marking pen.

    The pattern is cut out using scissors.

    Using the template, the flap is marked on the dorsum of the index finger.

    A lazy ‘S’ extension is drawn from the flap down to the apex between the thumb and index metacarpals.

    The incision is made on the dorsum of the hand. The skin is lifted as a very thin flap leaving the dorsal cutaneous veins and nerves behind. It is important not to make the skin flap too thin in which case it may button-hole and can lead to skin necrosis. This plane of dissection os only on the lazy ‘S’ part of the incision.

    The plane of dissection can be seen here. The dorsal veins are preserved on the hand.

    Now the incision is made of the rectangular part of the skin flap. The plane of dissection here is different. It is through the level of the paratenon over the extensor tendon. The easiest way to identify this plane is to go just deep to the dorsal veins. This dual plane of dissection is important in a successful flap raising.

    The subcutaneous pedicle of the flap is marked using a marking pen. It is taken about 3-4cm wide including at least wto dorsal veins and the dorsal sensory nerve branches of the radial nerve.

    The flap is now raised from distal to proximal. As you can see the plane over the proximal phalanx is through the paratenon. This is important as the defect over the proximal phalanx will be covered with a skin graft.

    The incisions marked on the dorsum of the hand are made and this allows one to raise the subcutaneous pedicle of the flap. This pedicle includes the dorsal veins, the cutaneous nerves and the fascia over the tendons as well as the deep fascia over the first dorsal interosseus muscle. It is futile to look for an artery in the flap pedicle. The blood supply to this flap is through the dorsal branch of the radial artery which divides into small branches and supply the fascia. The fascial plexus made up of the small vessels is the blood supply to the skin flap.

    The flap is being raised superficial to the extensor tendons. The photograph shows the deep fascia over the first dorsal interosseous being raised.

    The mobility of the flap is checked to see if it reaches the tip of the thumb. If the mobility is not sufficient, further dissection of the pedicle is carried out.

    The flap needs to be tunnelled subcutaneously to inset it to the defect. A tunnel is created through the skin bridge between the thumb defect and the flap pedicle base.

    Using an artery forceps, the flap is delivered to the defect as shown.

    The flap is delivered to the defect.

    At this point it is felt that the skin bridge is tight. There will be swelling during the post-operative period and therefore a decision is made to release the skin bridge.

    The skin bridge has been divided.

    Operation – 2

    The wounds are now closed using interrupted 4-0 Nylon. The flap is sutured to the wound defect and the donor site is closed.

    Suturing the flap to the defect is shown.

    Wound closure has been completed. The defect over the proximal phalanx where the skin flap has been harvested will need reconstruction using a full thickness skin graft.

    This shows another view of the flap insetted on the defect. Insetting is the technical word used for suturing a flap to a defect.

    The skin defect on the proximal phalanx is measured and marked on the forearm. An area without tattoos is chosen.

    A full thickness skin graft is harvested using a No.15 blade. The plane of harvesting is just below the dermis.

    The harvested skin graft can be seen.

    The skin graft usually has areas of fat which have to be excised. The easiest way to do it is to spread the graft on the finger and to trim it using a tenotomy scissors.

    The donor site of the skin graft can be seen.

    The skin graft donor site is closed in layers. A deep layer of 3-0 Monocryl is used first followed by interrupted 4-0 Nylon on the skin.

    The closed forearm wound can be seen.

    The skin graft is placed over the defect on the proximal phalanx and sutured using running 5-0 vicryl rapide sutures.

    Once the graft is sutured in place, about eight long 4-0 nylon sutures are placed on the edges of the wound and left long.

    A doubled up jelonet dressing is used as the first layer.

    Cotton wool soaked in proflavine solution is placed over the jelonet. Proflavine is an antiseptic and has properties which help to absorb exudate.

    The long Nylon sutures are tied over the jelonet and proflavine wool. This provides compression of the graft and avoids the risk of haematoma under the graft.

    The final result with the ti-over in place can be seen.

    The wound is dressed using jelonet and gauze.

    Cotton wool is used as the next layer.

    A bandage is applied. The flap is not exposed in this case. Flap monitoring is usually not necessary.

    Post Operative

    Patient is advised to keep the hand elevated for 24 hours. Patients can be discharged the same day if otherwise fit. No post-operative antibiotics are necessary. Analgesics such as paracetamol and codeine are prescribed.
    Post-operative wound check is done at five days when the dressings and tie-over dressing over the skin graft are removed. A successful graft take is indicated by adherence of graft to the bed with normal skin colour. With full thickness skin grafts sometimes blistering of the epidermis can be seen. This usually heals within a few days. Light dressings are applied after the first wound check.
    The next wound check is done at two weeks when the sutures are removed. At this stage the patient is referred to the hand therapist for mobilisation exercises. Patients are advised to apply moisturising cream on the
    If the wounds heal satisfactorily, patients can get back to driving by four weeks and light work around the same time. Manual work usually takes eight weeks when the skin graft is mature and can withstand shearing.
    Swelling of the flap can be present for upto three months. Gentle massage helps to resolve this.

    Recommended Reading

    Reference

    • orthoracle.com

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