46: Pedicled Groin Flap

Published on 21/04/2015 by admin

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Last modified 21/04/2015

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Procedure 46 Pedicled Groin Flap

Sandeep J. Sebastin, Kevin C. Chung

The groin flap used to be the workhorse flap for hand reconstruction, but it has been supplanted by the use of regional flaps (radial forearm and posterior interosseous artery) and free skin flaps (lateral arm and anterolateral thigh). However, it continues to be a safe and reliable alternative for primary coverage of wounds on the hand, particularly when secondary reconstruction is contemplated, such as to add soft tissue for subsequent toe transfer or tendon reconstruction. We use the groin flap as the first choice for dorsal hand coverage, unless there are specific needs to initiate early active motion after fracture fixation and tendon reconstruction. In these select situations, we will cover the wound with a free flap. When the groin flap is used, patients can expect to require several operations after flap division to debulk the flap and to perform tissue rearrangement for contouring the circular flap appearance on the hand.

Indications

Dorsal or palmar soft tissue defect of the hand (Fig. 46-1)

In preparation for a toe-to-thumb transfer following traumatic thumb or finger loss

Dorsal or palmar soft tissue defects involving multiple fingers

Circumferential thumb soft tissue defect

First stage of an osteoplastic thumb reconstruction

FIGURE 46-1

Examination/Imaging

Clinical Examination

Patients should be examined for signs of previous surgery in the groin, including hernia repair, lymph node biopsy, or vein stripping. A higher incidence of thromboembolic and other general complications has been reported in patients older than 50 years with a pedicled groin flap, and an alternative method of coverage may be more suitable in older patients (e.g., a radial forearm flap), provided that the palmar arch is intact and there is no peripheral vascular disease affecting the circulation in the hand.

The amount of skin required for thumb reconstruction is often underestimated, and the thickness of the flap increases the requirements when circumferential coverage is needed. A rough guideline with regard to the skin requirements in an adult male is as follows:

• Thumb (circumferential)

♦ Distal to the metacarpophalangeal (MCP) joint: 9 × 8 cm

♦ Distal to the thenar crease: 13 × 12 cm

• Palmar hand: 12 × 10 cm

• Dorsal hand: 12 × 10 cm

• Finger (circumferential): 7 × 10 cm

Morbidity: This flap requires attachment of the hand to the groin for 3 to 4 weeks, which restricts movements at all joints of the involved upper limb. Patients typically are able to shrug the shoulder, move the elbow minimally, and move the wrist and hand to a greater degree. This period of immobilization will result in stiffness, especially in older patients. In addition, patients will have the use of only one hand and may require help to manage toileting and other activities of daily living. There is a risk for injury to the lateral femoral cutaneous nerve with resultant loss of sensation in the lateral aspect of the thigh and, rarely, a painful neuroma. Patients need a minimum of two surgical procedures (one for inset and another for flap division) and occasionally may need more procedures (for flap delay and flap thinning). Patients must be informed about these issues before surgery.

Surgical Anatomy

Vascular basis: The flap is based on the superficial circumflex iliac artery (SCIA). The SCIA is the smallest branch of the femoral artery and arises about 1 inch below the inguinal ligament. It arises directly from the femoral artery in about 70% of cases; in the remainder, a common trunk is shared with the superficial epigastric artery. The SCIA travels obliquely toward the anterior superior iliac spine (ASIS), becoming progressively superficial as it travels from medial to lateral (Fig. 46-2A and B). At the medial border of the sartorius, the SCIA divides into a deep branch (which remains below the deep fascia and enters the sartorius) and a superficial branch (which pierces the deep fascia, becomes superficial, and supplies the overlying skin on its way to the ASIS). The femoral artery can be palpated immediately below the inguinal ligament at the midinguinal point (midway between pubic symphysis and ASIS). A point is marked 1 inch (2 fingerbreadths) below the inguinal ligament along the femoral artery. This represents the origin of the SCIA. A line drawn from this point to the ASIS represents the course of the SCIA and the vascular axis of the flap. Because of the obliquity of the vascular axis, about two thirds of the flap is designed superior to this axis and one third below this axis.

FIGURE 46-2

Beyond the ASIS, the superficial branch divides into three branches that anastomose with the branches of the superior gluteal, deep circumflex iliac, and ascending lateral femoral circumflex arteries. The venous drainage of the flap is by a dual pathway: the superficial circumflex iliac vein (SCIV) representing the superficial venous system, and the venae comitantes of the SCIA representing the deep system. Both of these may drain directly into the femoral vein or indirectly through the saphenous vein.

Limits of the flap

• Medial limit: Although the origin of the SCIA at the femoral artery represents the theoretical medial limit of the flap, it is safer to limit dissection to about 3 to 4 cm lateral to the femoral artery. This is usually 2 to 3 cm medial to the medial border of the sartorius.

• Superior and inferior limits: The maximum width of a groin flap that can be closed primarily is about 10 to 12 cm (about 4 inches). The superior margin is made 4 fingerbreadths above the vascular axis and the inferior margin 2 fingerbreadths below the axis.

• Lateral limit: The portion of the groin flap beyond the ASIS has random pattern vascularization, and it is better to design this portion of the flap with a 1 : 1 length-to-width ratio. Given that the maximum width of the flap that can be closed primarily is 10 cm, a point 10 cm from the ASIS represents the lateral limit of the flap.

Flap size: The maximum size of a groin flap is about 13 × 10 cm. This is adequate to resurface most soft tissue defects of the hand and thumb. However, this will not allow tubing of the flap in most cases without further medial dissection (Fig. 46-3).

FIGURE 46-3

Positioning

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