FDMA flap

First described by – Kuhn & Holvetich

Neurovascular pedicle was described by – Foucher and Brown ( a/k/a- Foucher flap)

Lister described  axial flap on 2nd DMA

Earley  described – 2nd DMA flap

Maruyama & Quaba – Reverse 2nd DMA flap

Anatomy –

FDMA based on branch to dorso-radial aspect of index proximal phalanx

FDMA courses – within the fascial layer overlying the FDI. Runs parallel to index metacarpal

Anomaly –

in ~10% cases runs deep within the substance of FDI index head.

In some cases it becomes deep at head of 2nd metacarpal

Both these anomaly precludes raising the FDMA flap

Second DMA-

More consistent anatomy than FDMA

Also generally larger than FDMA

Passes below extensor tendon and then runs in fascia over 2nd dorsal interosseoi muscle.

Approx 1cm proximal to head of 2nd metacarpal it gives off branch to skin and then ramify at the web.

FDMA flap –

Skin territory – dorsum of proximal phalanx. Proximal limit is – MP joint. Distal limit is – PIP joint. Laterally – mid-lateral lines

Blood supply – type A, fasciocutaneous

Nerve supply – dorsal sensory branch of radial and ulnar nerve

Dominant pedicle – FDMA. Regional sourse – dorsal carpal arch and radial a

Raising the flap –

Mark the course of FDMA using hand help pencil Doppler.

Mark the flap over dorsum of proximal phalanx – tailor made to defect or full size within the limits

Mark the proximal incision over 1st web space – either S-shaped or tear drop

Dissection proceeds from distal to proximal and ulnar to radial side.

Flap is elevated in the loose areolar plane above the extensor paratenon.

FDMA enters the flap at the radial border of MP joint – extreme care must be taken while elevating the flap here.

Proximal dissection over 1st web space –

After skin incision, skin flap is elevated in plane superficial to the adipose tissue.

After completely raising the skin flap, the pedicle is dissected by incising the fascia overlying the FDI (first dorsal interosseoi). The fascia is incised at radial edge of muscle and over 2nd metacarpal periosteum at the ulnar edge (so as to include all of the fascia overlying the FDI, and hence elevating all of the structures passing through it – vein, artery, nerve)

Periosteum over 2nd metacarpal is elevated and dissection proceeds radially and deep to muscle fascia.

Dorsal vein and superficial branch of radial sensory nerve enter the flap at ulnar border of MP joint and is included in the pedicle.

The pedicle is dissected proximally till the pivot point, which is juncture of 1st and 2nd metacarpal.

Tourniquet is then released and vascularity of the flap is assessed.

Flap can then be tunneled through subcutaneous tunnel to the defect or through open incision.

Donor site over index finger dorsum is covered with FTG.

Motion of thumb is permitted on day 10.

Fully dissected FDMA flap

Second DMA flap –

Skin flap can be raised in two ways –

Second web space raised with skin extension over index and middle finger proximal phalanx or

Skin on the dorsum of index or middle finger proximal phalanx with adjacent web skin.

Pedicle is dissected to the point where it arises deep to extensor tendon

Fascia overlying the dorsum of 2nd interosseoi is included in the pedicle.

Second DMA with retrograde flow (Maruyama pattern) –

Skin island is elevated over the intermetacarpal space and is elevated in continuity with the underlying SDMA. SDMA is divided at its proximal end beneath the index tendon.

Dissection of vascular pedicle is continued distally to the web space. Connections between the SDMA and digital arteries are preserved

Distally based dorsal hand flap (Quaba pattern) –

Skin over the dorsum of hand is elevated without the dorsal metacarpal artery.

Flap is based distally on the branches given to skin approximately 1 cm proximal to the metacarpal head.

Skin is supplied by the anastomosing branches of adjacent metacarpal arteries.

Venous drainage of the flap is ensured by preserving cuff of tissue around the arterial pedicle.

Proximal limit of the flap is – wrist joint.

Flap can reach – just distal to PIP joint.

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