Historically, the original Tranquilli-Leali or Atasoy-Kleinert flap has been described to cover partial amputation defects of the distal phalanx; however, these flaps do not work well on the thumb because of the inflexibility of the subcutaneous soft tissues. Laterally based single pedicle flaps, vascularized in the same way by the small vessels beyond the trifurcations of the digital arteries, also move poorly. The neurovascular Tranquilli-Leali or Atasoy-Kleinert flap is designed to be much larger and is islanded on both neurovascular pedicles bilaterally (Fig. 24-2). The flap is designed to extend to, or across, the IP joint crease proximally. This flap works well for minor transverse or oblique injuries of the distal phalanx with exposure of bone.

This flap can be used for stump reconstruction of any length of amputated thumb and is more useful than the original Tranquilli-Leali flap; however, it moves less freely than on a finger, partly because of the fibrous nature of the subcutaneous tissues of the thumb and partly because of what has been described as the “vertical dimension” of the thumb, that is its palmar-dorsal width at the tip (1). On fingers, it can be used to reconstruct defects with a palmar slope of up to 30 degrees; on the thumb it can only reconstruct defects with bone exposure which are dorsally facing, transverse, or palmar facing with less than 10 degrees of slope (Fig. 24-3).

The incisions of the V cross the interphalangeal joint crease at an angle and thus do not cause contractures (see Figs. 24-2 and 24-3). When designing the flap, one takes the V incisions out almost to the lateral nail folds distally. Having made the flap wide, the leading edge of the flap after advancement is wider than the original thumb tip. Unless the lateral corners of the flap are excised, this results in a spatulate end to the digit. Cutting off the lateral corners and allowing the resulting raw edges and tip to epithelialize not only narrows the digital tip but also rounds it to achieve a good appearance. The flap is designed as a “V” at its proximal extremity and was conceived to close proximally as a “Y” after the flap has moved distally. Mostly, the proximal donor defect is left open to close under dressings as primary closure of the vertical limb of the “Y” tightens

the thumb too much proximally over the vascular pedicles of the flaps and compromises vascular inflow into the flap.

With greater losses of palmar thumb tissue, more sloping palmar oblique injuries, and when the whole distal pulp of the thumb has been avulsed, the neurovascular Tranquilli-Leali flap is too small and cannot advance sufficiently. For larger thumb defects confined to the distal phalanx we favor the use of a modified Moberg flap. The Moberg flap, as described by Moberg in 1964, is an advancement flap based on both neurovascular bundles of the thumb (2). The advantages of this flap are that it returns sensation and glabrous skin to the defect site. The downside to the original flap design was the IP joint flexion contracture necessary to achieve suture of the flap distally to the nail. Our preferred modification of the Moberg flap avoids the IP joint flexion necessary with the original to advance the flap to the tip of the digit. This is, essentially, O’Brien’s modification of the Moberg flap, but uses a “V” tail proximally instead of a skin graft at the base of the thumb (Fig. 24-4) (3). This V-Y Moberg flap achieves the same excellent results as the original Moberg flap in terms of sensibility of the thumb tip, but without the restrictions of interphalangeal joint movement associated with the original flap or the need for skin graft of the O’Brien modification.

There is no danger of dorsal skin loss in raising Moberg-type flaps on the thumb, as the dorsal skin of the thumb has a separate blood supply. Because of the safety of the V-Y Moberg flap, the speed and ease with which it can be dissected, and the excellent sensibility of the thumb tip which can be achieved with it, this technique remains our favorite thumb tip reconstruction if the defect is limited to the distal phalangeal segment of the thumb.

The flap is created laterally along the mid-lateral lines on each side of the thumb and with the tip of the proximal “V” well back on the thenar eminence, at least as far proximally as a line drawn proximally from the ulnar border of the middle finger. This creates a large flap which incorporates the more lax subcutaneous tissues of the thenar eminence. Smaller flaps with the proximal “V” at the base of the thumb move less easily and less far distally. The wider and longer flap avoids any need for addition of techniques to accommodate tightness at the base of the thumb. The use of this flap is considerably extended in reconstructing palmar oblique defects if the pulp distally which is denuded of skin cover remains as the leading edge of the flap, with suture of subcutaneous tissue, not skin, to the nail distally then epithelialization under dressings (Fig. 24-4).