Procedure 45 Dorsal Ulnar Artery Perforator Flap
Indications
Examination/Imaging
Clinical Examination
Defect: The flap should be selected for defects that are free of infection. This is determined by looking at the wound bed and the surrounding skin for edema and erythema. This is a low-flow flap that is easily compromised by any residual infection. (Figure 45-3 shows predébridement appearance of the patient in Fig. 45-1.)
Imaging
A preoperative Doppler assessment of the perforator is essential to identify the location of the perforator. The Doppler probe is moved from distal to proximal along the ulnar border of the forearm beginning at the pisiform and staying ulnar to the flexor carpi ulnaris (FCU). The perforator is located 2 to 6 cm proximal to the pisiform.
Surgical Anatomy
Vascular basis: The flap is based on a perforator of the ulnar artery that arises 2 to 6 cm proximal to the pisiform. This vessel passes from palmar to dorsal under the FCU tendon and divides into an ascending branch (directed proximally toward the forearm) and a descending branch (directed distally toward the hand). This flap is based on the ascending branch of the dorsal ulnar artery (DUA) (Fig. 45-4). In addition to the ulnar artery perforator, this flap is also nourished by the dorsal carpal arch through its communications with the descending branch.
Limits of the flap: We limit the proximal extent of the flap to the mid-forearm. This results in a 10- to 15-cm long flap, depending on the exact location of the perforator. Selective dye injection studies in cadavers have shown that the staining is limited to the distal third of the forearm skin. The maximum width of the flap is limited to 6 cm because this permits linear closure of the flap donor site. The arc of coverage of the flap is therefore limited to defects within 10 to 15 cm of the perforator (Fig. 45-5).
Exposures
Flap design: The location of the DUA perforator is determined by Doppler and marked preoperatively. The location of the perforator represents the pivot point of the flap. A line drawn between the pisiform and the medial epicondyle represents the axis of the flap. The distance between the perforator and the proximal edge of the defect represents the bridge segment of the flap. Based on the size of the soft tissue defect, a flap is designed proximal to the perforator at a distance that equals the bridge segment. The flap may be designed as wholly fasciocutaneous, fasciocutaneous with an adipofascial bridge segment, or wholly adipofascial.
