44: Dorsal Metacarpal Artery Perforator Flap

Procedure 44 Dorsal Metacarpal Artery Perforator Flap



Sandeep J. Sebastin, Kevin C. Chung


imageSee Video 36: Dorsal Metacarpal Artery Perforator Flap



Indications




image Dorsal and lateral finger soft tissue defect proximal to the distal interphalangeal (DIP) joint (Fig. 44-1)


image Palmar finger soft tissue defect proximal to the DIP joint in patients with injuries to multiple fingers that make it difficult to use local flaps from adjacent digits


image Palmar or dorsal soft tissue defects proximal to the DIP joint in more than one finger


image

FIGURE 44-1



Examination/Imaging



Clinical Examination




image Defect: The flap should be used 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.


image Perforator: There should be no injury in the vicinity of the selected perforator. Injuries that may disturb the perforator include metacarpal neck fractures, lacerations extending into the web space, contusion on the dorsum of the hand, and previous injection of local anesthetic agent. The perforator artery may be intact, but the tenuous venae comitantes are easily injured and can result in flap failure owing to venous congestion.


image Morbidity: This flap requires division of some dorsal sensory branches during flap elevation. This will result in loss of sensation in the territory of the nerve and, rarely, a painful neuroma. Closure of the flap donor site will result in a visible scar on the dorsum of the hand. Patients should be informed about these problems preoperatively.



Imaging




image A radiograph of the hand is useful in patients with a posttraumatic defect to rule out any associated metacarpal neck fractures.


image A preoperative Doppler assessment of the perforator is not required. It is difficult to separate the Doppler signals of the perforator from the dorsal metacarpal artery (DMA). In our experience, the perforator is always present, and, if the DMA is absent, the perforator should arise directly from one of the branches of the deep palmar arch.



Surgical Anatomy




image Vascular basis: The flap is based on the distal cutaneous perforator of the DMA that arises at the level of the metacarpal neck in the second to fourth intermetacarpal spaces. In addition to the DMA, this flap is also nourished by the palmar arterial system through a dorsopalmar anastomosis. This anastomosis is formed by the dorsal perforating branch of the palmar metacarpal artery (arising from the deep palmar arch) and the DMA at the neck of the metacarpal (Fig. 44-2).


image Limits of the flap: We limit our flaps between the distal edge of the extensor retinaculum, the metacarpophalangeal (MCP) joint, and the outer borders of the adjoining metacarpals (Fig. 44-3A and B).


image

FIGURE 44-2


image

FIGURE 44-3



Positioning




image The procedure is performed under tourniquet control.


image The patient is positioned supine with the affected extremity on a hand table.



Exposures




image Flap design: The DMA perforator closest to the defect is marked at the level of the metacarpal neck in the intermetacarpal space. The location of the perforator represents the pivot point 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.


image The flap may be designed as wholly cutaneous, cutaneous with a dermoadiposal bridge segment, or wholly adiposal.


image Flaps with a dermoadiposal bridge segment can reach the defect by passing the bridge under a skin tunnel or by laying open the intervening skin segment (Fig. 44-4).

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Mar 5, 2016 | Posted by in Hand surgery | Comments Off on 44: Dorsal Metacarpal Artery Perforator Flap

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