The Superior Gluteal Artery Preforator Flap
in Plastic Surgery
Robert J. Allen, MD, FACS
As breast reconstruction becomes more of an expected
rather than merely accepted addition to cancer therapy,
the number of options available to the surgeon increases.
In the case of autogenous tissue reconstruction, the
most common donor site used today is the lower abdomen.!'
4, 6 Occasionally, patients in whom the lower abdomen
is not available as a donor site present desiring autogenous
tissue reconstruction. Reasons for the unavailability
of this tissue vary from thinness and nulliparity to
the presence of scars from previous abdominal operations
and resulting uncertainty of vessel location. In such
cases, an-other choice for the donor site is the gluteal
region. Although myocutaneous free flaps using this
area have been described, their use has been complicated
by the short vascular pedicle that they provide, the
problems arising from exposure of the sciatic nerve,
and the recipient vessel size discrepancy that has been
Another option that makes use of this do-nor region
involves the harvest of free flaps based on dissection
of the myocutaneous perforators using microsurgical
technique. This allows the use of overlying skin and
fat alone, which are ideal for breast reconstruction,
and avoids any muscle sacrifice and resultant functional
deficits. The authors used the superior gluteal artery
perforator (S-GAP) free flap for autogenous breast reconstruction
in patients without adequate lower abdominal tissue.2
This flap provides a long pedicle based upon the superior
gluteal artery. Ad-vantages of GAP flap reconstruction
Avoids exposure and retraction of the sciatic nerve
Ample amount of skin and fat Natural permanent result
Avoids muscle loss
Long vascular pedicle
Easily concealed donor scar Brief hospitalization
No fat necrosis
Indications for GAP flap reconstruction include:
Lower abdomen not suitable
Patient refuses muscle loss
Patient refuses implants
Failure of other methods
The blood supply to the gluteal region has been described
in detail. The superior gluteal artery and the inferior
gluteal artery, both branches of the internal iliac
artery, are the dominant pedicle of the gluteus maximus
muscle. The first perforator of the profunda femoris
artery and intermuscular branches of the lateral circumflex
femoral artery are minor pedicles of this muscle. Twenty
to 25 cutaneous perforators, the larger of which originate
from the superior and inferior gluteal arteries, supply
the skin and fat overlying the muscle. Koshima7 notes
that larger perforators vary from 3 cm to 8 cm in length
and 1.0 mm to 1.5 mm in diameter. Superior gluteal artery
perforators reach the superolateral region of the buttock,
whereas the inferior gluteal artery sends perforators
to the inferomedial and inferolateral regions. The fourth
lumbar artery, the lateral sacral arteries, and the
internal pudendal arteries also provide cutaneous perforators
to the parasacral area.
The author's own cadaver studies identified multiple
perforators in each buttock with at least three main
perforators originating from the superior gluteal artery.
These perforators averaged 8 cm in length when dissected
down to their origins at the superior gluteal vessels.
Average superior gluteal artery diameter was 3.5 mm,
and its two vena comitantes typically were found to
be 2 mm to 4 mm in diameter.
Preparation and Preoperative Marking
The patient is placed in the lateral decubitus position,
allowing a two-team approach. Pneumatic compression
ankle devices are used for deep venous thrombosis prophylaxis.
The location of the superior gluteal vessels is marked
based on known anatomic landmarks. Specifically, this
vessel often can be found one third down a line drawn
from the posterior superior iliac spine to the greater
trochanter. Once this is done, a Doppler probe is used
to identify the vessel's cutaneous perforators, and
their positions are marked.l2 With these landmarks in
mind, a skin island is drawn over the perforators in
an elliptical fashion. With proper planning, the resultant
scar can be hidden easily in a swimsuit (Fig. 1A).
Once the skin island has been incised through the skin
and subcutaneous tissue down to the muscle, dissection
is begun from the lateral to the medial aspect using
loupe magnification and careful technique. It is
helpful to dissect below the fascia because this allows
quicker identification of perforators. When very small
perforators are encountered, they should be coagulated
with the bipolar. Larger perforators on which the flap
will be based should be located in the vicinity of the
Doppler-guided preoperative markings. Because selected
perforators travel within single muscle fiber planes,
complete muscle sparing is possible. As the muscle is
divided in the direction of its fibers to facilitate
further dissection of the perforators, any small branches
of the vessels are ligated or clipped as they are encountered
(Fig. 1B). The advantage of this meticulous technique
is that it creates an almost bloodless field. Just above
the pyriformis muscle, multiple perforating branches
of the superior gluteal artery must be identified to
avoid ligating the pedicle. Upon reaching the superior
gluteal vessels, the dissection is complete, and the
pedicle length should measure approximately 8 cm in
length, with an arterial diameter of 3 mm to 4 mm. One
or two veins accompany the artery; these should be separated
before ligation of the flap. Once this has been completed,
the flap is removed and weighed (Fig. 2A).
Recipient Vessel Dissection
While the first team harvests the S-GAP flap, the second
team prepares the recipient vessels. The internal mammary
artery is an excellent recipient vessel, with a diameter
of approximately 3 mm.3 Isolation of this vessel starts
with identification of the third costar cartilage. This
is followed by dissection of the pectoralis major muscle
from the sternocostal margin, exposing the third rib
cartilage, which is then removed. One artery and one
or two veins are found at this level. The larger vein
diameter varies from 2 mm to 4 mm and is always adequate.
These are dissected for a distance of approximately
3 cm to 4 cm under loupe magnification and prepared
for anastomosis. Once dissection is completed, the wound
is closed with staples and a clear, occlusive dressing
is placed before repositioning the patient.
Donor Site Closure
Before microvascular anastomosis is begun, the donor
site is closed. Once homeostasis is ascertained, a drain
is placed. If necessary, undermining is performed to
facilitate wound closure in two layers. Deep layer closure
using 2-0 absorbable is followed by subcuticular skin
closure with 3-0 absorbable (Fig. 1C). Once sterile
dressing has been applied, the patient is returned to
the supine position, and a compression garment is applied.
Figure 1. Skin island location of the S-GAP flap (A).
The superior gluteal vessel courses through the divided
gluteus maximus muscle (B). Postoperative view (C).
Figure 2. Once freed, the S-GAP flap typically has
a lengthy pedicle (A). The S-GAP flap inset with anastomosis
between the internal mammary artery and the superior
gluteal artery (shaded) (B).
Figure 3. A 34-year-old patient post modified radical
mastectomy (A), and 2 years postoperatively after GAP-flap
reconstruction (B). Donor site marked preoperatively
with patient in lateral decubitus position (C), and
donor site at 2 years follow-up (D).
Figure 4. A 55-year-old patient 27 years post augmentation
mammoplasty with severe capsular contractures (A). Donor
site marked within swimwear line for bilateral autogenous
augmentation with S-GAP flaps; Perforators marked using
Doppler (B). Calcified capsule with ruptured silicone
gel prosthesis (C).
Figure 4 (Continued). One year postoperative follow-up
of autogenous augmentation (D), oblique view (E), and
donor site with improved contour and buttock lift (F).
With the patient in the supine position, the chest
wall dressing is removed and prepped with betadine.
The flap is transferred to the chest and sutured to
the skin for stability during microvascular anastomosis.
The above preparations result in an easily tolerable
flap ischemia time of approximately 40 minutes. Pharmacologic
agents routinely are not needed for control of vessel
spasm or anticoagulation. The gluteal perforators usually
match quite well with the internal mammary vessels.
Breast Mound Creation
Once the microvascular anastomosis is complete, the
patient may be placed in a more suitable position for
flap insetting and con-touring. Intraoperative Doppler
scanning identifies the locations of the perforators
relative to the skin surface. Marking these locations
on the skin facilitates postoperative flap monitoring
by the nursing staff. The previously elevated pectoral
flap is brought down to cover the anastomosis to prevent
a palpable defect in the chest wall. The flap is first
contoured and then sutured to the pectoral fascia or
inframammary fold. One drain is placed under the flap
and in the axilla. Next, the skin is closed with a running,
subcuticular, absorbable suture (Fig. 2B). A temperature
strip is placed centrally on the flap, and a control
strip is placed over the sternal skin. A clear, occlusive
dressing is applied.
The S-GAP flap is an ubiquitous autogenous tissue flap
that should be considered if the lower abdomen is not
available. The amount of tissue in the superior gluteal
region has proven a good match with the amount needed
for reconstruction because patients with larger breasts
tend to have more
tissue in this area and vice versa. As an added benefit
to the patient, the scar is easily concealed by a swimsuit.
In the author's series of 70 S-GAP flaps, no flap loss
was experienced and reconstruction for a variety of
indications was performed (Table 1). On four occasions,
bilateral, simultaneous S-GAP flap reconstruction were
performed. In addition, 12 staged bilateral breast reconstructions
using two S-GAP flaps were done. The inferior gluteal
artery perforator (I-GAP) flap was used for six reconstructions.
Donor site morbidity has proven minimal. Patients are
ambulatory on the first postoperative day and are discharged
on the second or third postoperative day.
Skin island size has varied from 8 x 22 cm to 12 x
32 cm. The vast majority of flaps have been elevated
based on one perforator, the rest on two. Because the
flap provides a long vascular pedicle with vessel diameters
compatible with that of the internal mammary vessels,
there has been no need for vein grafts. In addition,
the use of the internal mammary vessels allows for medial
placement of the flap, avoiding excessive lateral fullness.
In very thin patients, the costar cartilage defect may
be palpable; however, the pectoralis muscle has been
used, as described previously, to obliterate this space.
The gluteus muscle is a powerful extensor and lateral
rotator of the thigh. It is important for running, climbing,
and jumping. Al-though previous studies have reported
no loss of function if half of the gluteus muscle remains
intact, use of the S-GAP flap avoids the possibility
of any functional loss by taking no muscle. Also important
is that no major nerves are exposed during the procedure.
Early in the author's series, donor site seroma was
a common complication. By using compression garments,
the incidence of this unwanted occurrence was greatly
decreased. No significant fat necrosis has occurred
in any of the flaps. Flap tissue has been adequate in
all patients, and there has been no need for implants
to provide additional volume.
GAP FLAP INDICATIONS IN A SERIES OF 70 PATIENTS
Figure 5. An 18-year-old patient with pectus excavatum
and right breast hypoplasia (A). Donor site marked within
swimwear line (B). Lateral view of hypoplastic breast
preoperatively (C), and reconstructed breast postoperatively
(D). Oblique view postoperatively of S-GAP flap beneath
right breast (E). Normal buttock contour, 7 months postoperatively
Figure 6. A 25-year-old patient with Poland's syndrome
has absent left breast tissue and partially absent pectoralis
major muscle (A). B. Donor site left buttock. C, Note
thickness of buttock fat. Initial flap weight was 467
9. Plaster mold of normal right breast was 350 cc. Final
flap weight was 394 9. Three years postoperatively after
left S-GAP flap breast reconstruction (D), oblique view
(E), and donor site left buttock (F).
As many as 25% of patients do not have adequate lower
abdominal tissue available for autogenous breast reconstruction.
In such cases, the gluteal artery perforator flap should
be considered a reliable and worthy substitute. Figures
3 through 6 present a series of case studies illustrating
the use of the S-GAP flap for autogenous breast reconstruction.
The author wishes to thank Ksenija Gagic for preparation
of the manuscript.
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