Clinical Examples: Thenar Flaps

A key issue is orienting the base of the flap so that the flap comes to lie perpendicular to the recipient site. This is best planned in reverse using a template. This is helpful to also plan the orientation change resulting from donor site closure.

In this design, The donor defect is closed as a transposition flap, making best use of transverse skin laxity in this area. This rotates the final flap orientation.

Click on the image below to view the animation of the repositioning effect of donor site closure:

The goal is to position the flap against the recipient bed without tension or torsion. In addition to proper alignment, two key points are: ¤ Adduct the thumb basal joint to bring the flap to the finger to reduce flap tension. ¤ Flex the finger MCP joint to reduce PIP flexion.

Four corner sutures may be all that is required. ¤ Strong (2-0 or 3-0) sutures should be used to secure these anchoring points. ¤ Avoid multiple sutures or tight closure. ¤ Avoid sutures in the base or tip of the flap - only suture the sides. ¤ The palmar finger skin edge should come to rest against the deep surface of the flap. Flap division is simpler if the palmar finger heals to the flap rather than to the donor site skin edge abutting the base of the flap.

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Case 1. 65 year old woman sustained a palmar oblique amputation of the middle fingertip in a closing garage door  10 days earlier; failure of composite tip replacement as a graft.

Flap elevation and donor site closure.

Flap inset, bringing the thumb to the finger.

Ideally, the flap protrudes beyond the tip, providing extra skin which will recontour to a rounded tip.

Six weeks later, one month after flap division.

Result at one year.

Donor defect.

Excellent contour and new fingerprints.

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Case 2. Palmar oblique meat cutting injury, loss of entire middle finger distal phalanx pulp and over half of the distal phalanx. The amputated part had been replaced as a composite graft by the emergency physician, but was lost to infection.

Because of the length required, a proximally based flap was planned as a trapezoidal flap, allowing Limberg flap style closure.

Closure.

One month after flap division.

The final result was compromised by bone loss. The initial bone loss was severe enough to warrant bone graft, but this was contraindicated by the recent infection.

Over time, loss of this structural support led to shortening and a hook nail deformity.

Result at one year.

Despite this, an excellent resurfacing of the large defect has been achieved.

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Case 3. This gentleman sustained partial amputations of all fingers in an industrial press. His index finger was the only digit with a potentially salvageable fingertip.

Distal phalanx fracture stabilization. Pins were placed to protrude proximally in anticipation of flap cover.

Flap design.

Esmach bandage was used as a template to plan a flap of optimum size and position .

Inset.

One month after flap division and hardware removal.

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Case 4. A dog bit off this young man's index fingertip. Although the PA Xray looks as though the bone was kept, additional views show an amputation through the tuft.

The defect.

Flap design.

Inset, using Gelfilm® (no financial interest) as a nail bed dressing.

Immediately prior to flap division.

Result at six weeks. The bulbous flap "biscuit deformity" due to scar contracture at the flap junction, which was corrected later with small Z-plasties.

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Case 5. Case of Robert Beasley MD showing details of postop immobilization. This gentleman was left with tender, tight unstable skin cover and tender neuromas on the radial tip of his middle finger following a crush-abrasion injury. Thenar flap was chosen as a resurfacing option because of its excellent padding and durability.

An ulnarly based flap was used.

Trapezoidal donor site closure on the proximal radial aspect of the flap.

Excision of the scarred skin and neuromas in continuity.

Flap inset.

Two layers of immobilization were used. First, tape is placed without tension to secure the thumb to the recipient finger.

This was further immobilized in a two piece plaster cast. The base cast supported the thumb in adduction, but left the dorsal view of the surgery exposed. This exposed area was covered with a free strip of plaster held on with tape to create a removable protecting cover.

In a cooperative patient with an adequate bandage, such rigid immobilization is not needed.

Result at three months.

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Case 6. This 72 year old man sustained a crush amputation of his right middle fingertip with exposed bone.

Flap design.

Fingertip defect. Note the skin graft on the dorsum of the middle phalanx: donor site for a cross finger flap to an index fingertip amputation years before by another surgeon.

Result six months postop.

Result ten years postop.

Transfer of fingerprints depends on whether or not the donor area has any. In this case, not.

Donor defect.

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Final caveats and take home points: Plan the flap with a template to avoid tension and torsion. Use a transposition flap approach to close the donor defect primarily. Identify the skin direction having the most laxity: if you can pinch a fold of skin, you should be able to close a defect that size. Use the template to plan the final flap orientation after donor site closure: the flap must face the defect. Adduct the thumb basal joint to bring the thumb to the finger. Flex the finger MCP to minimize PIP flexion. Optionally, inject the PIP joint with a few milligrams of depot steroid at the time of surgery to prevent immobilization stiffness. Only suture the sides of the flap. Tape the finger to the thumb. Divide the flap at 10-14 days. Don't suture anything at the time of flap division. Formal flap inset is usually unneccessary, but if done, delay inset at least two days to avoid suture related flap ischemia. If you need bone graft, this is your best opportunity - do it at the same setting.

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