Free Gluteal Perforator Flap Breast Reconstruction

Introduction

The advent of gluteal artery perforator (GAP) flaps has served to increase the surgeon's armamentarium in autologous breast reconstruction. In 1993, Koshima et al. originally described local-regional GAP flaps for repair of sacral pressure sores. Later in 1995, Allen and Tucker described the utility of the free superior gluteal artery perforator (SGAP) flap in breast reconstruction. Even in thin patients, GAP flaps offer an excellent source of autologous tissue. GAP flaps render soft tissue with a high fat-to-skin ratio, which can be favorable in selected patients. Furthermore, abdominally based flaps may be unavailable due to prior surgery or inadequate volume. Hence, GAP flaps have been championed as an alternative to abdominally based free flaps.

In 2004, Allen et al. further refined the inferior gluteal artery perforator (IGAP) flap to be included into the infragluteal crease, resulting in a more cosmetically acceptable surgical footprint. As with any other perforator flap, muscle is spared which decreases the donor-site morbidity leading to a faster recovery. Additionally, the muscle functionality is preserved. Typical pedicle lengths are 7–10 cm in an IGAP and 5–8 cm in an SGAP. Despite the fact that thigh flaps have essentially replaced buttock flaps as the second choice for perforator flap breast reconstruction, reliability of the tissue quality, abundance of volume, and a reasonable pedicle length of GAP flaps make these operations an essential part of a microsurgeon's armamentarium.

In this chapter, the authors describe the indications and contraindications of GAP flaps for breast reconstruction with emphasis on patient selection, operative techniques, postoperative care, and management of complications.

Indications and Contraindications

Gluteal artery perforator flaps can be considered in women who have undergone mastectomies and desire autologous tissue reconstruction. Other indications include hypomastia, Poland syndrome, anterior thoracic hypoplasia, and correction of breast asymmetry. Ultimately, it is the patient's decision as to where she wants the donor-site scar burden to be located. Women who have had surgery that precludes abdominally based reconstruction or have insufficient abdominal tissue are candidates for GAP flap reconstruction. Prior abdominoplasty and extensive liposuction of the abdomen may render the abdomen unusable for perforator flap–based reconstruction. GAP flaps are a logical alternative. Sometimes a patient does not want a long scar that she can see on her lower abdomen, and would prefer a hidden scar in the back ( Fig. 5.1 ).

Liposuction of the buttocks or is a relative contraindication to GAP flap reconstruction. If the area of liposuction was confined to only a portion of the buttock, sometimes a gluteal flap can be designed on a vessel in the non-operated area.

Preoperative Evaluation

As with any surgical procedure, preoperative patient optimization is paramount. It is equally important to manage patient expectations prior to surgery and discuss goals of the surgery, scar burden, possibility of flap complications, and the need for further revisional surgery. A full review in detail of the past surgical history and patient medication list is indispensable as these can potentially preclude surgery.

Magnetic resonance angiograms (MRA) are a mainstay of our patients’ preoperative work-up ( Fig. 5.2 ). The angiograms allow a qualitative evaluation of perforator location, course, and caliber. Hence, they are integral to the presurgical planning. Our radiologists use a coordinate system with reference points such as the midine and the gluteal fold to describe the perforators’ location as they exit the muscle. Each perforator coordinate is measured in its vertical and horizontal position with respect to these landmarks. Perforator selection is multifactorial, which is why each case must be tailored according to the imaging and patient body habitus. A large vessel diameter, pedicle of sufficient length for insetting, central location of the vessel on the flap, or a pattern of arborization that suggests perfusion of the tissue to be transferred are all considered favorable for the choice of the pedicle to be used. Use of the angiogram in conjunction with a pencil Doppler facilitates the most accurate identification of the perforators prior to the surgery. This method is particularly helpful in designing the skin paddle that will capture the perforators.

Surgical Techniques

Relevant Anatomy of the Gluteal Region

The gluteus maximus muscle measures approximately 24 × 24 cm. It originates from the posterior superior iliac spine, the coccyx, and the lateral aspect of the sacrum. The muscle inserts into the greater trochanter and the iliotibial tract of the fascia lata.

The superior gluteal artery arises from the internal iliac artery and exits through the greater sciatic foramen, above the piriformis muscle perforating the gluteus maximus muscle to supply the overlying skin and fat. The exit point corresponds anatomically to 6 cm below the posterior superior iliac spine and 4.5 cm lateral to the midline of the sacrum. The inferior gluteal artery also arises from the internal iliac artery and along with the sciatic nerve and emerges below the piriformis muscle ( Fig. 5.3 ).