A proximally based dorsal rectangular flap for web reconstruction, along with interdigitating flaps, is used.

The proximally based dorsal rectangular flap is designed by marking the metacarpal heads and a point on each digit at the midpoint of the proximal phalanx. The points are connected to form a proximally based flap with its base at the level of the metacarpal heads (Fig. 36-8).

The interdigitating flaps are designed as two Zs, one on the dorsum and the other on the palmar surface, such that they form mirror images. The dorsal Z is designed first and connects the following four points sequentially (Fig. 36-9):

For the flaps to interdigitate, the tips of the palmar and dorsal Zs must oppose each other. A 25-gauge needle is inserted through the skin from the dorsum to the palmar surface at the same level as the tip of the proximal dorsal flap (point B), and a palmar flap is designed such that the tip is on the other finger (Fig. 36-10A). The remainder of the mirror palmar incision is then designed (Fig. 36-10B).

The incisions are made, and the designed skin flaps are elevated.

The distal fingertip with nail plate is divided sharply with tenotomy scissors (Fig. 36-13).

The longitudinal neurovascular structures are identified and protected (Fig. 36-14).

Tenotomy scissors are used to spread between the digits in a transverse direction as the fused digits are retracted laterally. The transverse fascial bands are identified and divided sharply. This dissection is begun distally and continued proximally until the digits are completely released at the level of the transverse intermetacarpal ligament, which is spared (Fig. 36-15).

The dorsal skin flap is advanced into the new web space and secured with 4-0 absorbable (chromic) suture. The skin flap should easily advance into the new web space without tension (Fig. 36-16).

The interdigitating flaps are inset across the digits (Figs. 36-17 and 36-18).

Areas that are not covered with these skin flaps are grafted with a full-thickness skin graft harvested from the groin (Fig. 36-19). An elliptical incision is made along the groin crease, and the skin and dermis are incised with a no. 15 scalpel.

The skin and dermis are elevated sharply using a scalpel or tenotomy scissors. Any additional subcutaneous fat that is taken with the graft is removed sharply with tenotomy scissors.

The skin graft is then cut to fill any additional defects not covered by the interdigitating flaps. It is preferable to leave fewer, larger gaps to be filled by a skin graft, rather than multiple small areas, because these will make it technically easier to contour the skin graft to the defect.

The skin graft donor site is closed using a few dermal sutures with absorbable suture, and the skin is approximated with chromic suture.

The dorsal pentagonal island flap is based on a constant cutaneous perforator of the dorsal metacarpal artery that arises in the intermetacarpal space at the level of the neck of the metacarpal (Fig. 36-21). This flap design is useful in patients who have a relatively lax simple syndactyly or an incomplete simple syndactyly, where it is felt that a skin graft may not be required for coverage of the digital raw areas. In such cases, the dorsal pentagonal flap is better than the standard proximally based dorsal rectangular flap because (1) a larger flap can be designed on the dorsum of the hand to resurface the web space and sides of the finger simultaneously, (2) the island design allows the flap to advance further than the standard proximally based flap, and (3) the lax dorsal skin permits primary closure of the flap donor site. However, the senior author does not use this flap design if a skin graft is required for coverage of the digit (e.g., tight syndactyly, complex syndactyly) because the time saved by doing this flap is negated by use of skin grafts. Additionally, a prominent dorsal scar is created.

The flap is designed by marking the metacarpal heads and outlining a pentagonal flap to incorporate the perforating vessel that arises at the level of the metacarpal neck. This perforating vessel is not visualized in the flap elevation. The V-shaped portion of the flap is designed proximally for primary closure, and a curved incision is made 2 mm distal to the head of the metacarpals to match the curved incision over the volar web space (Fig. 36-22).

This flap is combined with interdigitating flaps as described previously (Fig. 36-23).

The pentagonal flap is incised, and scissors are used to separate the flap from the adhering septa so that the flap can be more mobile (Fig. 36-24).

The flap is mobilized in a plane superficial to the paratenon.

The digits are separated as described previously (Fig. 36-25).

The flap is advanced and sutured to the volar web skin (Fig. 36-26).

The interdigitating flaps are inset across the digits (Fig. 36-27).