The inferior gluteal free flap in breast reconstruction

THE INFERIOR GLUTEAL FREE FLAP IN BREAST RECONSTRUCTION FELMONT F. EAVES III, MD, MARK A. CODNER, MD, and FOAD NAHAl, MD

The gluteal region is an excellent secondary source of autologous tissue for breast reconstruction when lower abdominal tissue is not available. Although transfer of the buttocks tissue can be based on either of the codominant vessels to the gluteus maximus, we prefer using the inferior gluteal artery and vein. Results are improved by the judicious use of vein grafts to improve flap survival. In addition, careful closure of the donor site helps to reduce donor site morbidity. KEY WORDS: breast reconstruction, gluteal flap, inferior gluteal vessels

For autologous reconstruction of the breast, the TRAM flap remains our tissue of choice. In some patients, however, the TRAM flap may not be suitable because of either previous abdominal operative procedures or the lack of adequate lower abdominal tissue. In this situation, the free gluteus maximus myocutaneous flap becomes our donor tissue of choice, because ample skin and subcutaneous tissues are both supplied. Although donor site complications include frequent early seromas, the ultimate defect is quite acceptable. The gluteus maximus has a codominant (type III) blood supply, with the superior gluteal artery supplying the upper half of the muscle and the inferior gluteal artery supplying the lower half.? Although either vessel is suitable for free transfer of buttock tissue,2-s we favor elevating the gluteal flap based on the inferior gluteal artery and vein(s). The advantages of this inferior gluteal free flap over the superiorly-based flap include a lon~er pedicle and a greater volume of available skin and fat. 9 If necessary, the skin and subcutaneous tissue of the posterior upper thigh can be included for additional volume. The donor defect with the inferiorly-based flap is less conspicuous and is preferred by our patients. The gluteal flap is not without disadvantages. The fat of the buttock region is denser than that of the preferred lower abdominal tissue and, as such, is more difficult to shape after transfer." Elevation of the gluteal flap is tedious and requires careful positioning on the operative table to allow simultaneous dissection of the flap and recipient vessels. Early donor-site morbidity is high. 6 , 8 Despite these drawbacks, careful flap elevation, the use of meticulous microvascular technique with vein grafts as necessary, and careful donor-site closure can lead to successful and extremely satisfying reconstruction results. From the Division of Plastic, Reconstructive, and Maxillofacial Surgery, the Department of Surgery, The Emory Clinic, Atlanta, GA. Address reprint requests to Foad Nahai, MD, Division of Plastic, Reconstructive, and Maxillofacial Surgery, The Emory Clinic, 1327 Clifton Rd, NE, Atlanta, GA 30322. Copyright © 1994 by W. B. Saunders Company 1071-0949/94/0101·0009$05.00/0

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Bilateral reconstructions can be accomplished using gluteal free flaps but require staging of the reconstruction over a 3 to 6 month period.

ANATOMY The anatomy of the gluteal region is shown in Fig 1. The superior gluteal artery is the terminal branch of the posterior division of the internal iliac artery, and it exits the pelvis through the upper part of the greater sciatic foramen above the piriformis muscle. The inferior gluteal artery is the larger of the two terminal branches of the anterior division of the internal iliac artery (the other is the pudendal artery). It also courses through the sciatic foramen but exits just below the piriformis muscle, where it is accompanied by the internal pudendal vessels, greater sciatic nerve, posterior cutaneous nerve of the thigh, and the pudendal nerve. After supplying the lower portion of the gluteus maximus muscle, the inferior gluteal artery continues as a descending cutaneous branch. This branch accompanies the posterior femoral cutaneous nerve and, with this nerve, serves as a critical landmark in gluteal flap elevation.

PREOPERATIVE PREPARATION The patients are admitted on the morning of operation. When the reconstruction is delayed, one or preferably two units of autologous blood are collected from the patient before surgery. When immediate reconstruction is performed, at least one autologous unit can still be obtained between the time of diagnosis and extirpation of the breast. Patients are instructed to abstain from smoking before surgery. Angiographic studies are not required for the donor vessels and are required only rarely for recipient vessels.

MARKINGS The flap is harvested from the same side as the reconstruction to facilitate simultaneous donor and recipient area dissection. The skin and volume requirements are

Operative Techniques in Plastic and Reconstructive Surgery, Vol 1, No 1 (May), 1994: pp 58·65

.~(",\:,~~HH---SUp.

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gluteal a.

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A

maximusm.

gluteal a.

Descending cutaneous branch of inr. gluteal a.

Gluteus medius m.

Fig 1. (A) Anatomy of the buttock region showing the relationship of the superior and inferior gluteal vessels to the pIriformis muscle. (8) Structures deep to the gluteus maximus muscle.

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estimated on the size and configuration of the opposite breast. The horizontally oriented flap is centered 3 to 4 em above the inferior gluteal crease. The area of skin harvest is marked along with any areas for additional fat harvest. Because the central posterior fat and skin of the thigh are reliably supplied by the continuance of the inferior gluteal artery, this area can be included in the flap design, if necessary, to meet additional skin or volume requirements (Fig 2).

POSITIONING During induction of anesthesia and patient positioning, care should be taken to minimize body heat loss. General anesthesia via endotracheal intubation is necessary. Knee-high compression garments are placed on both legs, and their pump system is activated. The patient is carefully positioned, as shown, to allow simultaneous harvest of the gluteal flap along with recreation of the

59

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Fig 2. (A) Outline of the standard Inferior gluteal flap. (8) If additional skin and/or volume requirements mandate additional tissue harvest, this tissue can be obtained from the posterior thigh.

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----------. Subcutaneous fat

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mastectomy defect and dissection of the recipient vessels (Fig 3). The pelvis and lower extremity are in a true lateral position, whereas the upper body is in a semilateral position. Prepping and draping the ipsilateral upper extremity into the operative field allows manipulation of the arm to improve exposure of the axillary vessels and allows easy harvest _of upper extremity vein grafts, should these be necessary. Including the neck in the field allows access to the external jugular vessels, if necessary. The ipsilateral thigh is similarly circumferentially prepped. This, along with circumferential draping of the knee-high compression garment, allows manipulation of the lower extremity, thus facilitating flap dissection and donor-site closure. Positioning includes avoidance of arm hyperextension, of head rotation away from

the side of reconstruction, and of neck flexion to minimize the risk of brachial plexopathy.'?

FLAP ELEVATION Step 1: Identification of Landmarks The first step in elevation of the gluteal flap is identification of the posterior femoral cutaneous nerve and of the accompanying vessels. These structures serve as the key landmarks for safe flap elevation. The initial incision is limited to the inferior skin marking and extends from the ischium approximately 5 em laterally. After the skin is divided, the dissection is directed inferiorly to in-

Stockinet on elevated arm

Fig 3. The patient Is positioned to allow simultaneous harvest of the Inferior gluteal flap and recreation of the mastectomy defect. The Ipsolateral arm Is left free within the field to allow position alteration to Improve aXillary vessel exposure.

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Posterior cutaneous n. and descending cutaneous branch of info gluteal a" V.

Fig 4. The posterior cutaneous nerve and accompanying vessels are Identified at the Inferior margin of the inferior gluteal flap.

corporate additional fat within the flap. The incision is continued through the deep fascia. This exposes the posterior cutaneous nerve and vessels that are then identified and ligated under loupe magnification (Fig 4).

Step 2: Isolation of the Skin and Fat Island Once the key landmarks have been identified, the remainder of the skin and fat incision is safely and rapidly completed. Again, the fat is divided in a beveled manner away from the center of the flap to provide maximum volume. This dissection is completed with exposure of the gluteal muscles superiorly and of the posterior thigh muscles inferiorly (Fig 5).

Step 3: Lateral Flap Elevation While retracting on the lateral corner of the flap, elevation of the skin and fat proceeds from lateral to medial. The fat is rapidly and safely separated from the tendinous insertion of the gluteus maximus, laterally. As this ele-

Fig 5. With the posterior cutaneous nerve and accompanyIng vessels as a reference the remainder of the skin and flap Incisions are completed.

vation proceeds medially, the fat is elevated off the muscle itself. The location of the ligated posterior cutaneous nerve and vessels is constantly reaffirmed. As the dissection approaches these structures, gentle retraction under the inferior edge of the gluteus maximus muscle exposes the inferior gluteal vessels. This initial, rapid, lateral flap elevation stops several centimeters short of these vessels (Fig 6).

Step 4: Muscle Elevation With the inferior gluteal vessels directly visualized, the muscular portion of the flap may now be elevated. The muscle is divided from its free inferior edge lateral to the gluteal vessels for a distance of 5 to 8 cm superiorly. At least two sets of vascular branches from the main inferior gluteal trunk are seen entering the muscle segment. The muscle is then divided medial to the gluteal vessels, starting at the inferior border. The superior border is divided last, although several fibers are preserved laterally to protect the vascular pedicle from tension as the

Fig 6. Lateral flap elevation exposing the gluteus maxim us muscle stopping short of the level of landmark structures.

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Biceps femoris m.

Fig 7. Elevation of the gluteus maxlmus muscle.

Ligated in!. gluteal a., v.

dissection is completed. As the muscle is divided, the sciatic nerve comes into view (Fig 7).

the time of flap transfer, the flap is immobilized with temporary skin staples (Fig 8).

Step 5: Vascular Pedicle Dissection

Step 6: Preparation of Recipient Vessels

The inferior gluteal vessels are now clearly visualized, because they course adjacent to the sciatic and posterior femoral cutaneous nerves. Dissection of the pedicle is now addressed using loupe magnification. The posterior femoral cutaneous nerve is divided a second time at the superior aspect of the gluteal island. The vascular pedicle is carefully dissected superiorly to the level of the piriformis. In this manner, a pedicle of 8 to 10 cm can be consistently dissected. The pedicle will consist of the inferior gluteal artery -and one or two accompanying veins, all measuring at least 2 to 3 mm in diameter, although the veins may be as large as 5 mm. The pedicle is not divided until the recipient vessels are dissected, microclarnps are applied, and the microscope is positioned. Rather, the remaining gluteal fibers are divided at this time, leaving the flap connected to the donor site only by the vascular pedicle. To protect the pedicle until

In delayed reconstructions, the mastectomy scar is excised, and the defect recreated is recreated by mobilizing the skin flaps. The dissection is extended into the axilla to allow exposure of the thoracodorsal and subscapular vessels that are our recipient vessels of choice. In cases of immediate reconstruction, this step has already been completed by the general surgeon. The vessels of the subscapular axis are acceptable for microvascular anastomosis in the vast majority of cases, and the axillary vessels themselves may be utilized if necessaryr' The vessels are dissected free of to allow easy placement of microvascular clamps on both the artery and vein. If these vessels are not suitable, vein grafts are harvested to allow anastomosis to the axillary vessels. We prefer the cephalic or external jugular veins for grafting and avoid the saphenous system. The internal mammary vessels may also be used and

Sciatic n.

Fig 8. Dissection of the vascular pedicle. Firm retraction of the gluteus maximus allows the development of an 8to 1o-cm pedicle.

Post. femoral cutaneous n. Inf. gluteal a" v.

62

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Fig 9. The gluteal flap Is transferred to the chest wall without rotations.

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have the advantage of easier microscope positioning. However, the internal mammary veins are fre1uently unsuitable for anastomosis to the gluteal vein. 1 We reserve this option for those cases that are complicated by severe axillary scarring secondary to irradiation.

Step .7: Flap Transfer to the Chest Wall The inferior gluteal vessels are individually divided and the proximal ends are ligated. The open vessel ends are then irrigated with heparinized saline. The flap is transferred to the chest with the pedicle in a superiolateral position; therefore, the lateral flap becomes the medial aspect of the reconstructed breast (Fig 9). It is important that the flap be correctly positioned and the muscle temporarily secured to the chest wall; this allows evaluation of pedicle length and course and for the potential need for vein grafting. It is critical to position the new breast mound appropriately before proceeding with microvascular anastomosis, using vein grafts as necessary.

Step 8: Microvascular Anastomosis The anastomosis is created only after satisfactory positioning of both the flap and pedicle is obtained. If the pedicle will be under any tension, then vein grafts should be used. Vein grafts may also be necessary to overcome diameter discrepancy or to allow anastomosis to the axillary vessels when the subscapular axis is inadequate. The use of vein grafts should not be seen as a compromise. Rather the liberal yet judicious use of vein grafts will allow optimization of flap positioning and recipient vessel selection, ultimately leading to a superior and more reliable reconstruction. In our experience, vein grafts have been used in 17.4% of inferior gluteal reconstructions." The anastomosis is performed in the usual manner with 9-0 Prolene suture under microscopic visualization (Fig 10). Before release of the clamps, 30 mL of low molecular weight dextran is administered as an intravenous bolus. The dextran infusion is then continued at 30mLIh intravenous drip for 5 days. The clamps are re-

Fig 10. Generally, an end-to-side arterial anastomosis is completed to the thoracodorsal artery. The venous anastomosis (not shown) Is constructed end-to-end.

END TO SIDE ANASTOMOSIS TO THORACODORSALVESSELS -+----~,.,.."...--Subscapulara.

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63

Closing gluteus maximus m. with interrupted sutures

Fig 11. Initial donor site closure. Careful approximation of the divided gluteus maxlmus allows protection of the underlying sciatic nerve to decrease postoperative nerve symptoms.

leased, and the pedicles are reinspected. If there appears to be either redundancy or deficiency of pedicle length, even if minimal, then this should be corrected. Skin staples are placed to secure the flap during donorsite closure.

Step 9: Donor-Site Closure Meticulous closure of the donor site is important to minimize complications (Fig 11). The closure should be completed with the hip in extension. The remaining gluteus maximus is mobilized to cover the sciatic nerve. The proximal end of the posterior cutaneous nerve of the thigh is buried within the muscle to minimize neuroma formation that may cause postoperative pain. A closed suction drain is positioned over the muscle, and the fatty layer is closed with interrupted 2-0 absorbable sutures. Skin flaps are mobilized superiorly and inferiorly to reduce tension across the wound. Absorbable, interrupted, deep dermal sutures and a running, absorbable, intracuticular suture complete the closure. The drain is secured with 3-0 suture. The wound is dressed, and then the patient is turned and placed in a supine position with the upper extremities extended. The chest area (including both breasts), the neck, and ipsilateral upper extremity are included in the prepared field.

Step 10: Flap Shaping and Inset With the patient repositioned, the ipsilateral arm may be abducted and adducted while the pedicle is observed. This important step may further identify any kinking or twisting of the pedicle or the presence of undue tension on the anastomosis secondary to arm movement. If present, these must be corrected. The muscle may now be definitively secured to the chest wall. The patient is then placed in an upright position for shaping. Tailortaking staples are placed until symmetry with the opposite breast is achieved. The flap is marked and deepithelized. The breast is drained with a 7-mm or IO-mm soft-suction drain, and the axilla/anastomotic area is drained with a small closed drainage system. Final closure is performed with 3-0 absorbable, interrupted, deep dermal sutures and with a running 4-0 absorbable, intercuticular suture.

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POSTOPERATIVE MANAGEMENT The dextran infusion, begun intraoperatively, is kept at 30 mUh continuously. After extubation in the operating room, the patient is transferred directly to her own bed with a low air-loss mattress. Monitoring of the flap during the postoperative period is accomplished by frequent clinical examination. The patient's hips are kept in extension at all times in the early postoperative period and upper extremity mobility is minimized. On the fourth postoperative day, the dextran infusion is tapered to 15 to 20 mUh, and 325 mg aspirin is administered orally. After 5 full days of therapy, the dextran is subsequently discontinued. After the dextran infusion is stopped, the breast drains can usually be discontinued, and the patient discharged home with instructions to take aspirin every other day. The gluteal drain will be removed after 2 to 3 weeks.

SUMMARY Although the TRAM flap remains our first choice for autologous reconstruction of the postmastectomy defect, the inferiorly-based gluteal flap is an excellent option when the lower abdominal tissue is inadequate or unavailable. Careful harvest technique with meticulous closure of the donor site will minimize donor-site morbidity. With judicious use of vein grafts, careful microvascular technique, and careful pedicle adjustment, the inferior gluteal free flap is a reliable and satisfying technique for breast reconstruction.

REFERENCES 1. Mathes 5J, Nahai F: Classification of the vascular anatomy of muscles: Experimental and clinical correlation. Plast Reconstr 5urg 67: 177-187, 1981 2. Fujino T, Harashina T, Aoyagi F: Reconstruction for aplasia of the breast and pectoral region by microvascular transfer of a free flap from the buttock. Plast Reconstr 5urg 56:178-181, 1975 3. Lee Quang C: Two new free flaps developed from aesthetic surgery. II. The inferior gluteal flap. Aesthetic Plast Surg 4:159-168, 1980 4. Paletta CE, Bostwick J III, Nahai F: The inferior gluteal free flap in breast reconstruction. Plast Reconstr Surg 89:875-883, 1989

5. Shaw WW: Breast reconstruction by superior gluteal microvascular free flaps without silicone implants. Plast Reconstr Surg 72:490501/1983 6. Nahai F, Bostwick J III: Microsurgical techniques, in Bostwick J III (ed): Plastic and Reconstructive Breast Surgery. St Louis, MO, Quality Medical, 1990, pp 883-961 7. Nahai F: Inferior gluteus maximus musculocutaneous flap for breast reconstruction. Perspect Plast Surg 6:65-77/ 1992

s. Codner MA, Nahai F: The gluteal free flap breast reconstructionMaking it work. Clin Plast Surg 21:289-296/ 1994 9. Paletta CE, Bostwick J/ Nahai F: The inferior gluteal free flap in breast reconstruction. Plast Reconstr Surg 89:875-883, 1989 10. Core GB, Grotting JC: Peripheral nerve injury in the free TRAM procedure. Perspect Plast Surg 7:49-57, 1993 11. Shaw WW/ Ahn CY: Microvascular free flaps in breast reconstruction. Clin Plast Surg 19:917-926, 1992

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