Reverse Digital Artery Flap
The reverse digital artery (RDA) flap described in 1986 by Kojima et al1 is used for one-stage reconstruction of finger pulp defects. Lai et al modified this to include a dorsal sensory nerve branch for reinnervation of the flap.2
Indicated for coverage of acute and chronic fingertip defects of 1 cm2 or more with exposed bone, tendon, or neurovascular structures and the need to maintain the length of the digit
Can be used for fingertip reconstruction to correct a hook nail deformity coverage or large defects of the dorsal aspects of the middle and distal phalanx that cannot be covered with other local digital sensory flaps
Resurfacing of posttraumatic painful neuromas of the fingertip
Following release of volar scar contractures of the fingers
No time limits and no age restrictions, although it may not be required as often in pediatric patients because of their superior wound-healing abilities
The RDA flap cannot be used if there is only one patent digital artery or if there has been an injury to the distal transverse palmar arch.
A preoperative digital Allen test with or without Doppler ultrasound is performed to assess the patency of both digital arteries.
Angiography is not necessary.
The RDA flap is harvested from the dorsolateral skin of the proximal phalanx, which derives its blood supply from the opposite digital artery through abundant communicating branches.
There are three transverse palmar arches connecting the radial and ulnar digital arteries. The proximal and middle arches are always in association with the limbs of the C1 and C3 pulleys ( Fig. 3.1a,b ). The distal arch lies just beyond the insertion of the profundus tendon.
When the proximal digital artery is ligated, the blood crosses over from the opposite digital artery through the middle and distal transverse palmar arches. The blood then flows down the ligated artery in a retrograde fashion ( Fig. 3.2 ).
The RDA flap is designed over the dorsolateral area of the proximal phalanx, which is nourished by a proximal dorsal cutaneous branch. This small branch, 0.3 mm to 0.6 mm in size, arises from the palmar digital artery at the midpoint of the proximal phalanx ( Fig. 3.3 ). It passes through Cleland′s ligament, running close to the bone, and emerges on the dorsal aspect of the finger.
Histologic studies have revealed the presence of venules and capillaries in the perivascular fat tissue that appear to represent adequate channels for venous drainage.
The dorsal sensory nerve branch is harvested with the skin flap ( Fig. 3.4 ). In the border digits, the terminal branches of the superficial radial nerve or dorsal cutaneous branch of the ulnar nerve can also be transferred.
The arc of rotation is around the midpoint of the middle phalanx, which allows the flap to easily reach the fingertip. The digital artery cannot be elevated beyond the middle phalanx for fear of disrupting the distal transverse arch ( Fig. 3.5 ).