Small composite defects of the hand and fingers require careful consideration to select the optimal reconstructive strategy. Although the area of tissue loss is often small, the tissues are unique in both form and function, and a diverse combination of highly specialized structures can be involved in even the smallest defects. The author presents his experience over a two-year period with a free flap from the volar wrist to resurface hand and finger composite defects. The nine flaps were based on the palmar branch of the radial artery at the wrist, with arterial diameters of 0.8-1.2 mm. Either one or two parallel venae comitans were used for drainage. Two of the flaps used sections of the palmar cutaneous branch of the median nerve at the wrist to supply flap sensation. One flap used a section of palmaris longus tendon to reconstruct an injured segment of the extensor tendon mechanism. The flap is located at the distal flexion crease on the volar wrist, with one edge of the flap placed in the crease to conceal the donor scar as much as possible. The flap is oriented transversely across the volar wrist. Anastomosis of the palmar branch of the radial artery was to branches of digital or metacarpal arteries in the vicinity of the defect. The nine flaps were used to treat defects from trauma and infection. All nine survived, with one flap demonstrating partial necrosis at the ulnar border. In the two innervated flaps, moving 2-point discrimination was reported at 4 and 5 mm. In fingertip injuries covered with non-innervated flaps, moving 2-point discrimination was reported at 9 and 11 mm. Both of the patients with palmar cutaneous nerves included in the flap complained of localized hypesthesia in the proximal palm.
This report of a variation of the thenar free flap offers another viable option in the growing list of local tissue transfers for defects of the hand and fingers. It provides thin, pliable skin and subcutaneous tissue, can be harvested as an innervated flap, and can incorporate the palmaris longus tendon for use as a tendon graft. As such, it is perhaps best considered as a solution to the problem of vessel size mismatch when the radial forearm free flap is used for very distal lesions in the hand. The flap does not require sacrifice of a major axial source artery. The donor site can be closed primarily without skin grafts. However, a number of drawbacks that must be carefully considered before selecting this flap over a dorsal metacarpal artery flap, a heterotopic digital island flap, or a distant flap such as a dorsalis pedis free flap. The vessels are very small, and technical problems with the anastomoses will be very difficult to correct. The skin is of a very different type than glabrous digital skin when the flap is considered for palmar fingertip injuries, as illustrated in the photographs from the manuscript. Lymphatic edema and venous congestion can detract from the quality of the overall result. The inclusion of the palmar cutaneous branch of the median nerve is problematic, in that injury to this nerve in the vicinity of the flap at the distal wrist is well known to cause unacceptable loss of sensation and painful neuromas in a high percentage of individuals. Lastly, the donor scar, although easily closed, can present a very unsightly and socially conspicuous scar at the distal aspect of the wrist, as longstanding experience with similar patterns for harvesting full-thickness skin grafts suggests. Overall, therefore, this flap presents a number of problems that may make it a relatively less useful option in all but a very few selected defects. Nonetheless, it is another flap to keep in the growing list of available solutions to problems of composite tissue losses in the hand and fingers.
Plastic & Reconstructive Surgery