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RECONSTRUCTIVE
The Iliacus Muscle Flap: An Anatomical and
Clinical Evaluation
Daniel A. Medalie, M.D.
Ramon Llull, M.D., Ph.D.
Frederick Heckler, M.D.
Cleveland, Ohio; Palma de Mallorca,
Spain; and Pittsburgh, Pa.
Background: The iliacus muscle is proposed as a new solution for coverage of
small to medium defects where either a bulky flap or conspicuous donor sites
are undesirable.
Methods: Dissection and Microfil studies were performed on fresh cadavers to
define the gross and microvascular anatomy of the muscle. Live evaluation of
the muscle was performed in combination with multiple iliac crest free tissue
transfer procedures. The muscle was then used as a free flap in four separate
cases to cover difficult extremity wounds. It was used as a pedicled flap in
conjunction with a free iliac crest in a fifth case to assist with a composite
mandible and facial defect.
Results: The iliacus originates from the inner aspect of the iliac crest and then fuses
with the psoas at the level of the inguinal ligament. Its primary blood supply derives
from a large branch off of the deep circumflex iliac artery. The isolated muscle
resulted in a pancake-like flap measuring approximately 8 ⫻ 8 cm with a 6- to 8-cm
pedicle (deep circumflex iliac artery). The muscle was then used clinically both as
isolated free flaps and as a pedicled flap in conjunction with a free iliac crest. All
flaps survived, resulting in healed wounds without complication.
Conclusions: These results demonstrate that the iliacus is a new muscle that
should be added to the microsurgeon’s choices for free tissue transfer. It is easily
harvested, has a large and well-defined pedicle, and is less prone to donor-site
complications than some other muscles typically used for free tissue
transfer. (Plast. Reconstr. Surg. 127: 1553, 2011.)
M
icrosurgical transfer of muscle is now a
routine procedure for the coverage of difficult wounds. Large wounds can be easily
covered by the latissimus or rectus abdominis.1
Sometimes, however, smaller wounds still require
free tissue transfer. The foot and ankle and the
dorsum of the hand are places where free flaps
might be desired for coverage of exposed bone
and tendons. Intraoral defects with exposed bone
are also candidates for free tissue transfer. Typically, fasciocutaneous flaps such as the radial forearm have been used in these instances because
From Case Western Reserve Medical School and MetroHealth
Medical Center; Stem Center, Clinica Palmaplanas; and
Allegheny General Hospital.
Received for publication September 3, 2010; revised October
26, 2010.
Poster presented at the Annual Meeting of the Plastic Surgery
Research Council, in Pittsburgh, Pennsylvania, May 21
through 25, 1999, and oral presentations given at the Pennsylvania Ivy Society, 1999, and the Spanish Society of Plastic
Surgery, 2001.
Copyright ©2011 by the American Society of Plastic Surgeons
DOI: 10.1097/PRS.0b013e318208d30e
they are less bulky.2 Unfortunately, they leave a
rather conspicuous and sometimes debilitating
donor site. The gracilis muscle is a smaller muscle
with a more hidden donor site but tends to be long
and narrow, with a finer pedicle.3 Temporoparietal fascia is an ideal flap for dorsal hand or distal
ankle and foot coverage but is difficult to dissect
and frequently has small venae comitantes.4 The
purpose of this study is to propose the iliacus muscle as a new flap for microsurgical transfer that can
cover small to medium defects where either a
bulky flap or a conspicuous donor site is undesirable. The flap is based on a previously undescribed
but consistent branch off of the deep circumflex
iliac artery that we have named the “iliacus
branch.” This vessel is distal and posterior to the
well-described ascending branch that feeds the
internal oblique muscle.5,6 In our clinical studies,
the flap has proved to be reliable to date.
Disclosure: The authors have no financial interest
to declare in relation to the content of this article.
www.PRSJournal.com
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Plastic and Reconstructive Surgery • April 2011
MATERIALS AND METHODS
RESULTS
Sixteen iliacus muscles were dissected in eight
fresh cadavers. Careful inspection of each muscle
was performed to determine its anatomy and feeding blood vessels, and in eight of the dissections,
20 cc of Microfil (Flow Tech, Inc., Carver, Mass.)
was injected into the deep circumflex iliac artery
at its origin from the external iliac artery before
the muscle dissection. The muscles were then removed and radiographed to define their microvascular anatomy. All muscles demonstrated excellent staining by the Microfil technique.
Further anatomical analysis was performed in
conjunction with 12 clinical procedures. Eight of
these procedures were free flap procedures using
iliac crest with and without muscle for various
reconstructions. The other four were free flap procedures specifically using the iliacus muscle for
reconstruction of complex wounds. At these operations, the iliacus muscle was identified and evaluated for blood supply and dimensions. A 25-gauge
needle was inserted perpendicular to the muscle
down to iliac crest, and the thickness of the muscle
at resting length at different locations was determined by measuring the penetration of the needle.
Anatomical Observations
The iliacus is a flat muscle originating from the
inner aspect of the iliac crest and then fusing with
the psoas at the level of the inguinal ligament to
form a conjoined muscle (Fig. 1). Its primary
blood supply in seven of eight cadavers studied (14
dissections) derived from a large branch off of the
deep circumflex iliac artery within 2 cm of the
deep circumflex iliac artery crossing posterior to
the anterior superior iliac spine. We have named
this the iliacus branch (Figs. 2 and 3). This is not
to be confused with the ascending branch of the
deep circumflex iliac artery, which supplies the
internal oblique muscle and usually takes off several centimeters proximal to the iliacus branch.5,6
A smaller blood supply, “the psoas branch,” was
consistently observed coming from the external
iliac artery, passing deep to the psoas and entering
the iliacus muscle’s deep posterior aspect (Fig. 3).
In one cadaver on both sides, multiple small
branches were observed off of the deep circumflex
iliac artery feeding into the iliacus distal to the
anterior superior iliac spine. In several other ca-
Fig. 1. The iliacus is a flat muscle originating from the inner aspect of the iliac crest
and then fusing with the psoas at the level of the inguinal ligament (IL) to form a
conjoined muscle. Its primary blood supply is the iliacus branch (IB) derived from a
large branch off of the deep circumflex iliac artery (DCIA) and vein (DCIV) within 2
cm of the deep circumflex iliac artery crossing posterior to the anterior superior iliac
spine (ASIS). The iliacus branch is a separate branch from the previously described
ascending branch (AB) to the internal oblique muscle. Typically, the deep circumflex iliac branches originate from the external iliac vessels just superior to the inguinal ligament as they transition to the common femoral artery (CFA) and vein
(CFV). The vessels travel over the femoral nerve (FN).
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Volume 127, Number 4 • Iliacus Muscle Flap
The average size of muscle that could be harvested
was 8 ⫻ 8 cm, and the thickness of the muscle
ranged from 7 to 13 mm just adjacent to the deep
circumflex iliac artery and 10 to 17 mm at the deeper
portions of the muscle adjacent to the psoas. The
nerve supply to the muscle was found to derive consistently from the femoral nerve as it traveled in the
groove between the psoas and the iliacus.
Fig. 2. The iliacus muscle is approximately 8 ⫻ 8 cm and is supplied by the deep circumflex iliac artery and veins (DCIA-V). Its
main blood supply is the iliacus branch.
Fig. 3. Radiograph of a cadaver iliacus muscle injected with Microfil to demonstrate the deep circumflex iliac vessels (DCIA-V)
and iliacus branch. It is seen to anastomose with a deeper vessel
originating from the external iliac vessels deep to the psoas
(psoas branch).
davers and in clinical subjects, occasional smaller
branches off of the deep circumflex iliac artery
distal to the iliacus branch were also observed. We
believe that this places the muscle in the type II
variant of the Mathes and Nahai classification of
muscular vascular anatomy, namely, one dominant pedicle with several lesser pedicles.7 Variations with the anatomy of the deep circumflex iliac
artery and venae comitantes were consistent with
previously described anatomical studies.8 –10 The
average pedicle length for the iliacus was 6 to 8 cm.
Surgical Technique
The patient is placed supine with a slight
bump under the buttock of the side to be dissected. The incision is planned approximately 2
cm above and parallel to the inguinal ligament
and iliac crest. The initial dissection is designed to
identify the deep circumflex iliac artery at its takeoff from the external iliac vessels. Once the vessel
is identified proximally, it is traced distally toward
the anterior superior iliac spine. The ascending
branch to the internal oblique muscle is identified
and ligated. The external oblique, internal
oblique, and transversus abdominis are incised
just superior to the iliac crest until the iliac crest
is identified. On the inner aspect of the crest is the
iliacus muscle covered by thin iliacus fascia. The
deep circumflex iliac artery penetrates the fascia
and travels superficial to the iliacus muscle. The
muscle with its investing fascia can be bluntly freed
from the preperitoneal fat on top of it until it is
easily visible along with the psoas in the deep
portion of the wound. The femoral nerve lies in
the groove between the psoas and the iliacus, and
the lateral femoral cutaneous nerve travels anterior to the iliacus, heading toward the anterior
superior iliac spine. It can travel under or over the
deep circumflex iliac artery in the region of the
anterior superior iliac spine and can be inadvertently transected unless it is identified. The iliacus
fascia is incised parallel to the deep circumflex
iliac artery and reflected off of the muscle in a
bloodless dissection. This exposes the entirety of
the iliacus muscle and enables the surgeon to visualize the deep circumflex iliac artery, the iliacus
branch, and any other vessels running to the iliacus, including the deep psoas branch. The periosteum of the inner aspect of the iliac crest is then
incised and the muscle is elevated off of the crest in
a subperiosteal plane. This is also a rapid and bloodless dissection. The dimensions of the muscle to be
harvested are decided and the distal end of the deep
circumflex iliac artery is clipped, as is the deep psoas
branch. A scalpel (or Bovie) is then used to incise the
distal and deep portions of the muscle, freeing it
from the iliac crest and from its caudal attachments
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Plastic and Reconstructive Surgery • April 2011
to the psoas. This aspect of the dissection is somewhat bloody but can be performed in under 5 minutes, thus limiting overall blood loss. The isolated
muscle is then allowed to perfuse for 20 minutes
before division of the pedicle. For a more detailed
description of the anatomy of the deep circumflex
iliac artery, the venae comitantes, and the iliac crest
region, the reader is referred to Ramasastry et al.,5
Taylor et al.,9 and Strauch et al.10
The muscle can be harvested in conjunction
with the iliac crest and overlying skin to create a
composite osteomusculocutaneous flap in a fashion very similar to the composite flap using the
internal oblique muscle.5,11,12 In this case, the muscle can be taken with the iliac crest and allowed to
remain attached to the bone to provide an extra
muscular cuff for coverage of adjacent defects in
the recipient site. Such uses for this would be in
mandible reconstruction with an adjacent floor-
of-mouth defect. The muscle can also be incised
below the level of the deep circumflex iliac artery
and isolated as an island on the iliacus branch,
giving it a greater arc of rotation when transferred
as part of a composite flap.
Closure of the isolated muscle flap defect is quite
simple and poses minimal risk for subsequent hernia
formation. The transversus abdominis, internal
oblique, and external oblique are sewn back to the
muscular and periosteal cuff of the iliac crest and the
inguinal incision is repaired in a layered fashion.
Because there is no loss or denervation of muscle of
the anterior abdominal wall, there is no greater risk
of hernia than with any other groin incision.
CASE REPORTS
Case 1
A 19-year-old man sustained an accidental shotgun wound to
the right foot. After several débridements, he had exposed
Fig. 4. Case 1. (Above, left)A shotgun wound to the right foot, with exposed, damaged navicular and cuneiform-navicular joint
space and an 8 ⫻ 5-cm soft-tissue defect. (Above, right) The patient’s right iliacus muscle was harvested in approximately 11⁄2
hours and allowed to perfuse on its pedicle. (Below, left) It was then anastomosed to his dorsalis pedis vessels successfully and
covered by a split-thickness skin graft. (Below, right) Four months later, he demonstrated a completely healed wound with no
contour abnormality.
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Volume 127, Number 4 • Iliacus Muscle Flap
damaged navicular and cuneiform-navicular joint space and an
8 ⫻ 5-cm soft-tissue defect (Fig. 4). It was felt that a free flap
would be the best reconstructive option for him, and he consented to iliacus muscle transfer to the foot. The muscle was
harvested in 1½ hours without complication and anastomosed
to his dorsalis pedis vessels successfully. It was then covered by a
split-thickness skin graft. Four months later, he demonstrated a
completely healed wound with no contour abnormality. He also
demonstrated normal ambulation. His donor site healed uneventfully and the scar was completely hidden by his underwear.
Case 2
A 40-year-old man sustained a distal tibia fracture secondary
to a tractor injury. The wound broke down and the patient was
referred to plastic surgery for soft-tissue coverage (Fig. 5). An
8 ⫻ 6-cm iliacus muscle flap was designed and then transferred
microsurgically to the patient’s ankle wound. The deep circumflex iliac artery was anastomosed end-to-side to the posterior tibial artery. A meshed skin graft was applied to the flap.
Three months later, the patient was walking and demonstrated
a well-healed wound with only a mild contour deformity.
Case 3
A 19-year-old woman sustained a soft-tissue traumatic injury
with exposed patella and patellar tendon (Fig. 6). A 6 ⫻ 6-cm
iliacus muscle flap was harvested and then transferred microsurgically to the patient’s lower knee wound with a meshed skin
graft. The deep circumflex iliac artery was sewn in end-to-side
fashion to the anterior tibial vessel. One year later, the patient
was completely active and demonstrated a well-healed wound
with minimal contour deformity.
Case 4
A 59-year-old woman was diagnosed with an invasive parotid
tumor adjacent to the body of her right mandible. After resection was complete, she had a 6-cm bone defect and an accompanying loss of parotid and overlying skin (Fig. 7). It was decided to use a free iliac crest to reconstruct the bone defect and
then use an accompanying pedicled iliacus muscle and skin
graft to reconstruct the soft-tissue defect. During the operation,
the deep circumflex iliac artery was traced to the iliac crest and
then identified along with the iliacus branch on the surface
of the iliacus muscle. The planned limit of bone resection was
marked and the distal pedicle was then ligated. The iliacus was
then incised laterally and deeply and raised in a subperiosteal
plane from deep to superficial, stopping just beneath the deep
circumflex iliac artery as it traveled over the muscle along the
inner lip of the iliac crest. The bone cuts were completed and
the bone and muscle were completely isolated on the pedicle.
Fig. 5. Case 2. (Above, left) A distal tibia fracture with soft-tissue necrosis. An iliacus muscle was harvested from his right side.
(Above, right) Shown is the deep circumflex iliac artery and vein (white arrows), the lateral femoral cutaneous nerve (black
arrow) traveling near the anterior superior iliac spine (ASIS), and the iliacus muscle in situ. An 8 ⫻ 6-cm piece of iliacus was
harvested (below, left) and then transferred microsurgically to the patient’s ankle wound with a meshed skin graft (not shown).
(Below, right) Three months later, the patient demonstrated a well-healed wound.
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Plastic and Reconstructive Surgery • April 2011
Fig. 6. Case 3. (Above, left) A soft-tissue traumatic injury with exposed patella and patellar tendon. A 6 ⫻ 6-cm
iliacus muscle flap was harvested (above, right) and then transferred microsurgically to the patient’s lower knee
wound with a meshed skin graft (below, left). One year later, the patient was walking and demonstrated a wellhealed wound with minimal contour deformity (below, right).
The deep portion of the muscle was then cut from the bone and
isolated on the iliacus branch so that the majority of the muscle
was freely mobile in relation to the bone. The flap was then
harvested and the flap vessels were anastomosed end-to-side to
the external carotid and internal jugular veins. The iliacus was
used to fill the defect left by the missing parotid and overlying
skin and then covered by a split-thickness skin graft. The
donor site was closed in the fashion recommended for iliac
crest harvest with drill holes placed in the bone to anchor
sutures from the abdominal musculature to the remaining
crest. The patient tolerated the procedure well and recovered uneventfully. The flap survived and the skin graft demonstrated excellent take on the iliacus muscle despite aggressive postoperative irradiation.
DISCUSSION
These anatomical and clinical studies demonstrate that the iliacus muscle is an excellent alternative for the reconstruction of complex small to
medium upper and lower extremity defects. It also
has uses for head and neck and extremity recon-
1558
struction in conjunction with the iliac crest.13 It is
a thin (approximately 1 to 1.5 cm thick), broad
muscle with a consistent blood supply and a welldescribed pedicle (deep circumflex iliac artery
and vein). Because it is the lesser contribution of
musculature to the conjoined iliopsoas muscle, its
loss results in a minimal deficit, and the donor-site
scar remains hidden.
The average size of flap that was evaluated was
roughly 8 ⫻ 8 cm; thus, the flap is ideal for relatively small defects. Although it can, of course, be
tapered down to any size, it is not recommended
for defects larger than the dorsum of the typical
patient’s hand. The iliacus is thinner than most
other described muscle flaps and thus is suited for
reconstructing defects of the hand, foot, or ankle
where excessive bulk can be a significant functional problem for the patient. Wu et al. in 2009
Volume 127, Number 4 • Iliacus Muscle Flap
Fig. 7. Case 4. A patient with a right lateral mandible and parotid and skin defect (above, left) underwent reconstruction with a
composite free iliac crest and iliacus muscle. The deep portion of the muscle was cut from the bone and isolated on the iliacus branch
so that the majority of the muscle was freely mobile in relation to the bone. The flap is shown still attached to its pedicle, with the
bone (#) and the iliacus muscle (*) freely mobile in relation to each other (below). The bone was inset and the muscle transposed on
top to fill in the parotid and skin defect. A skin graft was applied to the muscle and is shown reflected back to reveal the muscle
underneath (above, center). The patient is shown after 6 months of healing and radiation therapy (above, right).
described seven consecutive patients treated with
vascularized iliac osteomuscular free flaps for
bone and soft-tissue defects. They had 100 percent
survival of the flaps with acceptable contour.13 As
demonstrated in our first cases, the flap, like all
muscle flaps, over time loses a great deal of its mass
and flattens out significantly, resulting in an even
contour over the defect.
Another advantage of the flap is that its dissection is routinely started at the takeoff of the
circumflex iliac vessels from the external iliac.
Therefore, a relatively small incision can be used
at first to determine whether the vascular anatomy
of the deep circumflex iliac artery and vein is
normal. If the pedicle cannot be identified, the
incision can be extended medially to enable the
surgeon to harvest rectus abdominis muscle in-
stead. If the pedicle is identified, subsequent incisions to harvest the pedicle and muscle travel
very close to the inguinal ligament and avoid
injuring the iliohypogastric and ilioinguinal
nerves.6 This is in contradistinction to the internal oblique muscle flap, which is based on the
ascending branch of the deep circumflex iliac
artery and vein.5,6 Dissection of the oblique puts
at risk the aforementioned nerves and the lower
thoracic nerves.6
The iliacus muscle is not part of the abdominal
wall musculature; it is a thigh flexor in combination with its larger partner, the psoas. Harvest of
the muscle therefore does not have the theoretical
disadvantage of weakening the abdominal wall as
significantly as harvest of other nearby muscles
such as the rectus or internal oblique.6 It is nev-
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Plastic and Reconstructive Surgery • April 2011
ertheless recognized that any incision through abdominal wall musculature can lead to weakness
and possible herniation. We have not seen this
complication, but our clinical cases are few.
Other potential disadvantages of the flap are
as follows: (1) the anatomy is initially difficult for
surgeons unfamiliar with iliac crest harvest and (2)
the lateral femoral cutaneous nerve runs over or
under the pedicle around the anterior superior
iliac spine and may be damaged by an inexperienced dissector. Injuries to the nerve may result in
paresthesias and chronic pain. We feel that, overall, the dissection can be carried out by an experienced microvascular surgeon by perusing the
multiple texts describing the dissection of the iliac
crest, even if the surgeon has no prior knowledge of
the region. Once the inner aspect of the iliac crest
is exposed, removal of the iliacus becomes a selfevident procedure. The vascular supply is easily visible, as are the important surrounding structures.
CONCLUSIONS
The iliacus muscle based on the iliacus branch
of the deep circumflex iliac artery appears to be an
expendable and readily harvested muscle. Its uses
and advantages are significant and its limitations
minor. A new muscle flap based on a previously
undescribed branch of the deep circumflex iliac
artery is outlined. Fresh cadaver dissections and
live surgery were used to study the flap extensively.
In each clinical use of the iliacus, the muscle demonstrated 100 percent survival. The advantages of
this flap include its thin, flat nature; its consistent
large pedicle; and its hidden donor site. Its disadvantages relate to the relative unfamiliarity of
most surgeons with the region, damage to the
lateral femoral cutaneous nerve, and possible
weakening of the abdominal wall. We therefore
recommend the flap as an excellent alternative for
coverage of small to medium defects in the upper
1560
and lower extremities and in conjunction with iliac
crest for the reconstruction of intraoral defects.
Daniel A. Medalie, M.D.
MetroHealth Medical Center
2500 MetroHealth Drive
Cleveland, Ohio 44109
[email protected]
REFERENCES
1. Asko-Selijavaara S, Lähteenmäki T, Waris T, Sundell B. Comparison of latissimus dorsi and rectus abdominis free flaps.
Br J Plast Surg. 1987;40:620–628.
2. Chang TS, Wang W, Hsu CY. The free forearm flap: A report
of 25 cases. Ann Acad Med Singapore 1982;11:236–240.
3. Heckler FG. Gracilis myocutaneous and muscle flaps. Clin
Plast Surg. 1980;7:27–44.
4. Brent B, Upton J, Acland R, et al. Experience with the temporoparietal fascial free flap. Plast Reconstr Surg. 1985;76:
177–188.
5. Ramasastry SS, Tucker JB, Swartz WM, Hurwitz DJ. The internal oblique muscle flap: An anatomic and clinical study.
Plast Reconstr Surg. 1984;73:721–733.
6. Taylor GI. The internal oblique muscle flap: An anatomic
and clinical study (Discussion). Plast Reconstr Surg. 1984;73:
731–733.
7. Mathes SJ, Nahai F. Classification of the vascular anatomy of
muscles: Experimental and clinical correlation. Plast Reconstr
Surg. 1981;76:177–187.
8. Mathes SJ, Nahai F, Vasconez LO. Myocutaneous free-flap
transfer: Anatomical and experimental considerations. Plast
Reconstr Surg. 1978;62:162–166.
9. Taylor GI, Townsend P, Corlett R. Superiority of the deep
circumflex iliac vessels as the supply for free groin flaps. Plast
Reconstr Surg. 1979;64:595–604.
10. Strauch B, Yu H-L, Chen Z-W, Liebling R. In: Atlas of Microvascular Surgery: Anatomy and Operative Techniques. New York:
Thieme; 1993:142–165.
11. Shenaq SM. Reconstruction of complex cranial and craniofacial defects utilizing iliac crest-internal oblique microsurgical free flap. Microsurgery 1988;9:154–158.
12. Urken ML, Weinberg H, Vickery C, Buchbinder D, Lawson
W, Biller HF. The internal oblique-iliac crest free flap in
composite defects of the oral cavity involving bone, skin, and
mucosa. Laryngoscope 1991;101:257–270.
13. Wu K, Ren D, Hou S, et al. Vascularized iliac osteomuscular
free flaps for composite soft tissue and bone defects of the
lower extremity. Ann Plast Surg. 2009;63:53–58.