The Foucher Flap (Kite Flap): Covering Thumb Defects with an Island Flap from the Index Finger

Soft tissue defects on the thumb have particularly serious consequences for hand function: the thumb needs durable, well-vascularised and, as far as possible, sensate skin cover. The Foucher flap – also called the “kite flap” because of its shape – has for decades been one of the standard procedures in hand surgery for covering such defects.

Background

In 1979, the French hand surgeon Guy Foucher, together with Jean-Bernard Braun, described the flap in the journal Plastic and Reconstructive Surgery as a “new island flap transfer from the dorsum of the index to the thumb”. In their first twelve cases there was no flap necrosis. As advantages over the Moberg-Littler neurovascular island flap, which was widely used at the time, they cited better venous drainage and a donor site on the dorsal side instead of on the tactile surface of a finger. In addition, the defect can be covered with sensate skin in a single operation.

Anatomy

The first dorsal metacarpal artery arises from the radial artery just before it passes between the two heads of the first dorsal interosseous muscle into the palm, and runs in the first intermetacarpal space on or within the fascia of the first dorsal interosseous muscle. It supplies the skin over the proximal phalanx of the index finger. Accompanying veins and terminal branches of the superficial branch of the radial nerve run with it. Because the course of the artery can vary, Doppler ultrasound mapping before surgery is recommended.

Indications

• skin and soft tissue defects on the thumb, particularly dorsally and over the proximal phalanx, with exposed tendons, bone or joints,
• defects of the thumb tip, if the pedicle length is sufficient and sensate replacement is desired,
• defects of the first web space, for example after release of contractures,
• defects on the radial dorsum of the hand.

A prerequisite is that the defect can neither be closed directly nor reliably covered with a free skin graft – for example because tendons without paratenon or bone are exposed.

Contraindications

• injuries or previous surgery in the area of the first dorsal metacarpal artery or the dorsal carpal arch,
• injuries to the skin over the proximal phalanx of the index finger (donor site),
• acute infections in the operative field,
• relative: marked circulatory disorders, heavy smoking.

Surgical technique

The following description reflects the typical procedure; in individual cases it is adapted to the defect and anatomy.

1. Planning: Doppler mapping of the artery, marking of the skin island (usually about 2 × 4 cm) over the dorsum of the proximal phalanx of the index finger and of the course of the pedicle. A thread or swab is used to check whether the pedicle length reaches the defect.
2. Approach: longitudinal or curved incision along the radial border of the second metacarpal up to the skin island.
3. Pedicle dissection: the fascia of the first dorsal interosseous muscle is incised next to the extensor tendon of the index finger and raised as a strip about 1 cm wide with the artery, accompanying veins and nerve branches. The vascular pedicle is not dissected free individually, so as not to damage the fine vessels.
4. Raising the skin island: the skin island is detached above the gliding tissue of the extensor tendon (paratenon) so that the donor site can later accept a graft.
5. Transfer: the flap is rotated to the defect through a subcutaneous tunnel or an open skin incision. The pedicle length is usually several centimetres. Kinking and compression of the pedicle must be avoided.
6. Closure of the donor site: usually with a full-thickness skin graft.

Aftercare

• immobilisation in a splint for about one week, elevation of the hand,
• close monitoring of flap perfusion in the first few days,
• start of hand therapy after the end of immobilisation,
• removal of sutures after about 14 days.

Complications

• Venous congestion – the most common early complication; usually temporary.
• Partial or total necrosis of the flap, rare.
• Failure of the skin graft to take at the donor site.
• Altered sensation in the territory of the superficial radial nerve.
• Misperception: touch on the flap is initially felt on the index finger. Many patients learn over time to attribute it to the thumb (“cortical reorientation”); in some, double perception persists.

Alternatives

Depending on the size and location of the defect, other procedures may be considered: the Moberg palmar advancement flap for tip defects, the cross-finger flap, the Littler heterodigital neurovascular island flap, radially pedicled flaps from the forearm or, for large defects, free flaps. A recent systematic review of innervated local flaps on the fingers emphasises that the choice depends on the defect, the desired sensibility and the surgeon’s experience.

Frequently asked questions

Will the thumb have sensation again after a Foucher flap?

Yes, the flap brings its own nerve branches and is therefore usually sensate. However, the quality of sensation does not reach that of an original fingertip.

Will there be a scar on the index finger?

Yes. The donor site is usually closed with a skin graft and remains permanently visible, but it lies on the dorsal side and generally does not impair function.

Note: This article is for professional information only and does not replace medical advice. Last updated: October 2026.

Sources and further information

• Foucher G, Braun JB: A new island flap transfer from the dorsum of the index to the thumb. Plastic and Reconstructive Surgery 1979;63(3):344–349
• Wilhelm K, Putz R, Hierner R: Lappenplastiken in der Handchirurgie. Urban & Fischer
• Considerations in Flap Selection for Soft Tissue Coverage of the Hand and Digits (PMC)
• Innervated Local Flap Reconstruction for Digital Soft Tissue Defects: A Systematic Review (PMC)