Keywords
complex sacrococcygeal defect - rectal cancer - gracilis myocutaneous flap
Two patients underwent pelvic exenteration including resection of sacrum for rectal
malignancies. One a locally recurrent rectal cancer and the other a primary case,
rendering a large defect which was reconstructed with bilateral and unilateral pedicled,
gracilis myocutaneous flap, respectively. Postoperatively the patient was nursed in
the prone/lateral position for 2 weeks.
Case 1
Our first patient was a 55-year-old man who presented with a large locally recurrent
disease involving the sacrum following an abdominoperineal resection and radiation
therapy for a primary rectal cancer, after a disease-free interval of 8 years. The
patient underwent an extended pelvic exenteration involving removal of sacrum with
an end colostomy and an ileal urinary conduit, rendering a complex three-dimensional
(3D) defect bounded anteriorly by pubic bone and pelvic side wall laterally measuring
18 cm in length, 10 cm in width, and 15 cm in depth. The defect was reconstructed
using a bilateral gracilis myocutaneous flap; the first flap was de-epithelized and
used to fill the pelvic cavity and the second flap was stacked over it as skin cover.
The superficial flap suffered partial pressure injury due to nonadherence to nursing
care in prone position and necessitated subsequent debridement and skin closure ([Fig. 1]).
Fig. 1 (a–c) Defect post abdominosacral resection. (d) Bilateral gracilis myocutaneous flap harvested in supine on the major pedicle. (e) In prone position, abdominal cavity protected with mesh and muscle flaps tunneled
and placed one over the other after de-epithelization. (f) Immediate postoperative status. (g) 3 months postoperative status.
Case 2
Our second patient was a 58-year-old man who had a locally advanced rectal cancer
invading the sacral fascia and perianal tissue. Patient was treated with neoadjuvant
chemoradiation followed by extra-levator ani abdominoperineal excision along with
overlying sacrum. The 3D surgical defect was bounded anteriorly by bladder and laterally
by pelvic side walls measuring 16 cm in length, 8 cm in width, and 10 cm in depth.
A unilateral gracilis myocutaneous flap was used for reconstruction ([Fig. 2]).
Fig. 2 (a–c) A case of rectal cancer invading the sacral fascia, pelvic and soft tissue in the
perianal region status post radiation therapy. (d) Unilateral gracilis myocutaneous flap harvested in supine, pedicled, tunneled, and
sutured into the defect post resection in prone position after placing a mesh to protect
the abdominal cavity. (e,f) Immediate postoperative status. (g) 2 months postoperative status.
Surgical Technique
Reconstruction was done following pelvic exenteration, ostomy creation, and abdominal
closure. Omental flap was mobilized and placed in pelvis followed by mesh placement
to prevent herniation of abdominal contents. In the first case, bilateral gracilis
myocutaneous flap was planned with a broad skin paddle that was centered over the
muscle. It extended upto distal third of thigh with a maximum width of 12 cm proximally
and tapering distally for a length of 18 cm. In the second patient, skin paddle was
taken with a maximum width of 10 cm proximally and tapering distally for a length
of 16 cm. With the patient in supine position and legs abducted, incision was made
posterior to adductor longus to expose gracilis muscle belly, without separating the
cutaneous portion from the proximal portion of muscle. Dissection was done from the
distal to proximal direction in the avascular plane between adductor longus and gracilis
muscles sacrificing distal minor pedicles and retaining the dominant proximal pedicle.
Proximal elevation of skin paddle was done in continuity with gracilis and temporarily
sutured to muscle to prevent disruption of perforating blood vessels. The flap was
mobilized by proximal pedicle dissection upto the entry of major pedicle into the
gracilis muscle, pivoted at that point and tunneled in subcutaneous plane. After repositioning
the patient into prone position, flap was inset into the defect. Reach of the flap
posteriorly till L4–L5 level achieved. Postoperative care continued in prone position
to prevent pressure injury to the flap.
Discussion
Rectal cancer is increasingly being managed with multimodal treatment to improve survival.
But surgical resection remains the cornerstone of treatment. In patients with locally
advanced disease, radical surgical resections are being performed increasingly leaving
complex challenging surgical defects to the reconstructive surgeons. Recurrent rectal
cancers are more aggressively resected with the curative intent, further adding to
the complexity of the issue. Use of radiation therapy in the preoperative setting
for carcinoma of rectum increases the chance of impaired wound healing following reconstruction.
Size of the defect combined with rigid bony pelvis favors fluid accumulation which
may interfere with wound healing.[1] Ours is one such experience where large 3D surgical defects was given to us for
reconstruction.
Options available to us were the gracilis flap (gracilis muscle flap, gracilis myocutaneous
flap), rectus abdominis flap (vertical rectus abdominis myocutaneous [VRAM] flap,
oblique or transverse rectus abdominis myocutaneous flap). The rectus abdominis flap
often has been favorably described in literature.[2]
[3]
VRAM flap reconstruction based on deep inferior epigastric artery, is an established
standard and remains the workhorse flap for the large complex perineal defects since
decades.[4] The robust well-vascularized skin paddle and muscle bulk provided by this flap along
with the ease of surgical technique are distinct advantages that make this flap to
be preferred over other flaps by most reconstructive surgeons.[5] However, this flap has its own limitations like abdominal wall weakness and tendency
to herniate and cosmetically poorly placed scar. In patients who are more likely to
have dual ostomies, placement of ostomies becomes technically more challenging. Even
though anterolateral thigh flap provides the adequate muscle bulk it comes at the
cost of significant functional disability.[6]
The gracilis myocutaneous flap was first described by Bartholdson and Hulten. [7] Gracilis is the superficial most adductor muscle of thigh supplied predominantly
by medial femoral circumflex artery with additional minor perforators from the obturator
artery. Although pedicled gracilis flap is principally used in perineal reconstruction,
its use extends to defects involving groin, thigh, external genitalia, and gluteal
region. The distinct advantages of this unique flap include lack of donor site morbidity
and adequate skin paddle with a constant neurovascular pedicle. It provides the option
of harvesting bilateral flaps for larger defects. The added advantages of gracilis
flap when used for perineal reconstruction include donor site from an area away from
irradiated site, noninterference with the ostomy site.[8] It does not compromise on abdominal wall tension or lower limb function unlike other
flaps.
The use of gracilis flap for small perineal defects is well established and is commonly
performed.[9] But in our study we used gracilis flap for two patients who had a large 3D defect.
Gracilis becomes an option if the VRAM flap is technically not available due to previous
abdominal surgeries. In our patient gracilis myocutaneous flap provided sufficient
vascularized tissue to reconstruct the large complex defect following pelvic exenteration
for rectal cancers. With gracilis myocutaneous flap, abdominal wall integrity and
possibility of herniation risk due to harvest of VRAM is technically avoided.
In series from Chong et al, the gracilis flap has been used for recontruction of large
perineal and pelvic defects including complex perineal reconstruction following abdomino
perineal resection (APR) and pelvic exenterations.[6]
Sharma et al recommends gracilis myocutaneous flaps as a viable option to provide
the bulk and skin resurfacing for large perineal defects.[1]
Disadvantages
Since bulk offered by a single flap is less, need for bilateral flap for obliterating
dead space exists. Vascularity of skin paddle over distal third of muscle is less
reliable. This necessitates postoperative nursing care in prone position to prevent
pressure injury, shearing, and necrosis of flap. Unfortunately it does not provide
a stable interface to prevent herniation. A strong fascial component is missing unlike
tensor fascia-lata flap or the anterolateral thigh flap.
Conclusion
With advancement in the treatment options for rectal cancer patients, the survival
rates are increasing. This forces reconstructive surgeons not only to think about
reconstruction but to choose an option that has minimal morbidity to the patient without
interfering with quality of life. Gracilis myocutaneous flap has its own place with
unique advantage adding to the armamentarium of reconstructive options for complex
perineal defects, thereby avoiding the morbidity associated with VRAM flap. It stands
as a reliable alternative in patients where VRAM cannot be used, obviating the need
for microsurgery.
