BACKGROUND

 

 

The anterior flap hemipelvectomy is a modified version of the classic posterior flap hemipelvectomy. Instead of using the traditional posterior skin flap of the gluteal region, a myocutaneous flap from the anterior thigh is used to close the peritoneum after amputation through the sacroiliac joint and the pubic symphysis. This modification has permitted the treatment of difficult buttock and pelvic tumors where the posterior flap was involved or contaminated by tumor.

 

Patients with extensive soft tissue sarcomas of the buttock or bone sarcomas of the pelvis that extend posteriorly, once thought to be incurable by standard posterior flap hemipelvectomy, can often be treated with an anterior flap hemipelvectomy.

 

The procedure, which originally entailed use of an anterior skin flap raised off a portion of the superficial femoral vessels,1 was modified to include a full-thickness myocutaneous flap raised from the anterior thigh.2,7

 

The major advantage of anterior flap hemipelvectomy is the creation of a large vascularized myocutaneous flap that is ideal for closure of significant posterior defects (FIG 1). As much of the anterior thigh compartment may be saved as needed, depending on the size of the defect being closed. As always, careful patient selection is critical in ensuring that an acceptable outcome is achieved. For example, elderly patients and diabetics with silent atherosclerotic disease of femoral vessels must be carefully evaluated with preoperative angiography.

 

The hemipelvectomy procedures described in the previous chapter require a flap of buttock skin to cover the surgical defect. Anterior flap hemipelvectomy allows sacrifice of the entire buttock and all the overlying skin and soft tissue to the midline. Even patients who have a tumor-contaminated buttock to the midline may have

a potentially curative procedure.11,12

 

If possible, tumors in this area, especially those of low histologic grade, should be treated with an excision of the gluteus maximus muscle (buttockectomy). However, if tumor extends through the gluteus maximus muscle to involve the gluteus medius or minimus, if tumor encases the sciatic nerve, or if tumor is directly adjacent to the pelvic bones, a radical amputation using an anterior myocutaneous flap is indicated.

 

ANATOMY

 

The surgeon must be familiar with the pelvic anatomy as well as the thigh musculature and femoral vessels. The anatomic key to this procedure is the major vascular pedicle of the pelvis and extremity. Oncologic considerations for tumor involvement of the bone or soft tissues in the pelvis are identical to those discussed in the chapter on posterior flap hemipelvectomy.

 

The external iliac vessels leave the pelvis and cross through the femoral triangle where they become the common femoral vessels. A single branch supplying the iliac crest may be encountered along the medial aspect of the external iliac vessel just below the inguinal ligament. The superficial femoral vessels travel underneath the sartorius muscle along most of the length of the thigh; they pass through the adductor hiatus and become the popliteal vessels behind the knee. The major branch in the femoral triangle is the profunda

femoris, which arises from the posterior aspect of the superficial femoral vessel and passes deep to the posterior surface of the femur. Ligation of the profunda femoris is required to elevate the anterior flap. The common femoral and superficial femoral vessels are preserved.

 

The (four) quadriceps muscles, the adductor muscles, and the sartorius muscle all have a vascular supply that arises from pedicles off the superficial femoral artery. Perforating branches from the profundus are present in the vastus lateralis and may be encountered as they pass through the intramuscular septum.

 

The entire anterior and medial compartments can be elevated off the femur by dividing the quadriceps tendon

above the patella and peeling the full-thickness myocutaneous flap off the anterior femoral periosteum.3,4,6 To prevent hemorrhage, care must be taken to properly ligate all perforating vessels, as well as the superficial femoral vessels, at the level of the adductor hiatus.

 

Division of the skin at the inguinal canal and skeletonization of the external iliac vessels permit the entire flap to be rotated as necessary to cover the defect created by the amputation.

 

Use of this flap for closure results in improved cosmesis and facilitates fitting of a prosthesis for an improved functional result.9,10,11 In addition, this flap permits radiation therapy to the remaining pelvis without any wound complications. The nature of the flap available for closure permits greater posterior resection than that

possible during a traditional posterior flap hemipelvectomy.

 

The entire buttock compartment (ie, the gluteal muscles, sciatic nerve, sacrospinous ligaments, and sacral alar) can be safely removed.

 

The anterior myocutaneous flap consists of a portion of or the entire quadriceps muscle group on its vascular

pedicle, the superficial femoral artery.4 This flap covers the entire peritoneal surface and generally heals with minimal problems.

 

IMAGING AND OTHER STAGING STUDIES

 

In addition to the routine radiographic evaluation of the pelvis (radiography, computed tomography [CT] and magnetic resonance imaging [MRI], and bone scanning) necessary

 

P.251

to determine the patient's suitability for a hemipelvectomy, angiography of the femoral vessels is essential for patients undergoing anterior flap hemipelvectomy.

 

 

 

FIG 1 • Clinical photograph showing a sarcoma recurrence in the posterior thigh with local tumor fungation after surgery and radiation therapy. The old posterior incision is visible (arrow). This is a classic indication for an anterior flap hemipelvectomy, which is used instead of the classic posterior flap hemipelvectomy. (Courtesy of Martin M. Malawer.)

 

 

The variable nature of the profunda femoris, as well as the frequent presence of silent atherosclerosis of the superficial femoral artery in elderly patients or in patients with a history of smoking, can greatly affect the outcome of this procedure. In addition, visualization of the pelvic vessels can help to ensure that they are not involved with the tumor.

 

CT and MRI are required to determine whether the tumor involves the sacrum or the vertebra. Spinal involvement is a contraindication to this procedure (FIG 2).

 

INDICATIONS

Anterior flap hemipelvectomy is indicated for tumors involving the buttock that cannot be resected with a less radical procedure. Patients who have failed to respond to prior attempts at limb-sparing surgery, with or without radiation, or who have tumors that primarily involve the posterior thigh and sciatic nerve are also candidates for this procedure.

This procedure may also be indicated after failed attempts at limb-sparing surgery5 as well as for patients

with nononcologic indications for amputation8 (eg, uncontrollable sepsis from sacral or trochanteric osteomyelitis).

 

 

 

 

FIG 2 • CT scan showing a large extraosseous chondrosarcoma of the buttock (Tu) with a thin rim of gluteus maximus muscle remaining (G). There is early intrapelvic extension through the sciatic notch (arrow). (Courtesy of Martin M. Malawer.)

 

 

 

FIG 3 • A. Clinical photograph of anterior flap drawn before surgery. The anterior myocutaneous flap consists of a large portion of the anterior thigh skin, subcutaneous tissue, and underlying quadriceps muscle. This flap is based on the common femoral and superficial femoral artery. The profundus artery is ligated when raising this flap. The incision extends along the medial aspect of the thigh below the sartorius so that the superficial femoral artery can be identified and ligated distally to preserve adequate vascularity to the quadriceps. The transverse incision is performed several inches above the knee. B. The posterior incision outlined extends from the anterior flap and follows the sacroiliac joint down to the gluteal crease. It then travels transverse posteriorly to meet the anterior flap. This incision avoids any contamination of the posterior incision. This procedure was developed by Dr. Paul H. Sugarbaker at the National Cancer Institute during the 1980s. C. Intraoperative photograph showing a large myocutaneous quadriceps flap elevated off the femur as the first operative stage during an anterior flap hemipelvectomy. The profundus femoris artery is ligated so that the flap can be raised above the inguinal ligament and the retroperitoneal approach of the hemipelvectomy can proceed. (Courtesy of Martin M. Malawer.)

 

 

Nononcologic indications include selected paraplegics with uncontrollable chronic osteomyelitis of the pelvis or hip joint.

SURGICAL MANAGEMENT

Preoperative Planning

 

Careful presurgical planning is necessary to achieve optimal results. The planned surgical incision is drawn before any cutting to visualize the separate components of the anterior flap hemipelvectomy incisions (FIG 3).

 

Preoperative preparations include correction of blood deficits and a complete bowel preparation. In females, the vagina is also prepared. Venous and arterial lines are secured, and a drainage catheter is placed in the bladder.

 

Positioning

 

After being placed supine on the operating table, the patient is rolled into the lateral position, with the iliac crest at the flexion point of the table (FIG 4). As the patient is positioned, a cushion is placed beneath the iliac crest and greater trochanter to prevent pressure necrosis of the skin. Padding beneath the axilla is used to allow full excursion of the chest wall and to prevent injury to the brachial plexus.

 

 

P.252

 

The arm is placed on a Krasky arm rest. An elastic wrapping or a support stocking is used to prevent blood from pooling in the contralateral lower extremity.

 

 

The operating room table is flexed to open the angle between the crest of the ilium and the lumbar vertebrae. The anus is sutured shut.

 

The lower extremity is prepared and draped free, with the skin exposed circumferentially from the knee to the iliac crest.

 

 

 

 

FIG 4 • Positioning the patient. (Courtesy of Martin M. Malawer.)

 

TECHNIQUES

• Anterior and Posterior Skin Incisions

Before the operation, the surgeon must ensure that the myocutaneous flap created from the tissue

 

overlying the quadriceps muscle will cover the operative defect created in the buttock. The location of the proposed incision is mapped out with a marking pen and the width and length of the flap are compared with the anticipated defect in the buttock. Once it is ascertained that the flap is adequate to cover the defect, the remainder of the incision is determined (TECH FIG 1).

 

First, the location of the incision is drawn medially to the tumor at or near the midline posteriorly above the anus. Superiorly and laterally, the incision should parallel the wing of the ilium to the anterior superior iliac spine. It then continues distally along the midpoint of the lateral aspect of the thigh to the junction of the lower and middle thirds of the thigh.

 

The medial incision courses 2 to 3 cm lateral to the anus, then anteriorly in the gluteal crease toward the pubic tubercle. It continues along the midpoint of the thigh to the junction of the lower and middle thirds of the thigh.

 

The two longitudinal incisions extending along the lateral and medial aspects of the thigh are connected by a transverse incision over the anterior aspect of the thigh. The location of this transverse incision determines the length of the myocutaneous flap. Hence, the transverse incision is positioned so the tip of the flap will extend to the level of the iliac crest.

 

 

 

TECH FIG 1 • Incision. (Courtesy of Martin M. Malawer.)

• Posterior Dissection in the Ischiorectal Space

   

  In excision of buttock tumors, the medial margin of the tumor is usually the closest one to the line of excision. Therefore, the dissection should commence medial to the tumor to allow the surgeon to assess operability before completion of the amputation is required (TECH FIG 2).

   

  The initial incision is made superficial to the sacrum in the midline through fascia to the midsacral spines. A cuff of skin 2 to 3 cm long is preserved around the anus.

   

  The sacral attachments of the gluteus maximus and erector spinae muscles are divided from their origins between the midsacral spines and the dorsal sacral foramina. Biopsies from the medial margin of resection are secured. By removing the outer table from the sacrum, biopsies from sacral nerves may also be obtained if indicated. If by cryostat sectioning and histologic examination these biopsies are negative, the amputation may proceed.

   

   

   

  TECH FIG 2 • Posterior incision to determine operability. (Courtesy of Martin M. Malawer.)

   

   

  P.253

• Lateral Incision of the Myocutaneous Flap

   

  Abdominal and back muscles that arise on the sacrum and the iliac crest are incised in the plane of

  attachment of muscle to bone to minimize blood loss. Muscles to be cut include the external oblique, erector spinae, latissimus dorsi, and quadratus lumborum (TECH FIG 3).

   

   

   

  TECH FIG 3 • Release of the back muscles of the iliac crest. (Courtesy of Martin M. Malawer.)

• Transection of the Superficial Femoral Artery

   

  The extremity is flexed at the hip to place the tissues in the area of the gluteal crease under tension. The perianal incision is extended toward the pubic tubercle along the gluteal crease. The deep dissection is continued lateral to the rectum into the ischiorectal fossa. The remaining origins of the gluteus maximus muscle are now severed from the coccyx and sacrotuberous ligament (TECH FIG 4).

   

   

   

  TECH FIG 4 • Posterior dissection in the ischiorectal space. (Courtesy of Martin M. Malawer.)

• Release of the Vastus Lateralis

   

  The surgeon now moves from the posterior to the anterior aspect of the patient. The anterior incision at the junction of the middle and lower thirds of the thigh is made and continued down to the femur, transecting the entire quadriceps muscle (TECH FIG 5).

   

  Laterally, this incision is continued superiorly toward the greater trochanter to the anterior superior iliac spine. The tensor fascia lata muscle is separated from its investing fascia so that it is included with the specimen.

   

   

   

  TECH FIG 5 • Lateral incision of the myocutaneous flap. (Courtesy of Martin M. Malawer.)

   

   

   

• Transection of the Superficial Femoral Artery

  P.254

   

  The fascial covering of the vastus lateralis of the quadriceps femoris muscle is dissected free of the flexor muscles and traced to its insertion on the femur. Then, the vastus lateralis is severed from the femur using electrocautery. In performing the dissection from this point on, care must be taken not to separate muscle bundles of the myocutaneous flap from the overlying skin and subcutaneous tissue (TECH FIG 6).

   

   

   

  TECH FIG 6 • Release of the vastus lateralis from the femur. (Courtesy of Martin M. Malawer.)

• Release of the Quadriceps Muscle from the Femur

   

  The medial skin incision is from the area of Hunter canal to the pubic tubercle. The superficial femoral vessels are located at their point of entry into the abductor muscles and are ligated and divided at this level. These vessels course along the deep margin of the myocutaneous flap, and, in the subsequent dissection, they are traced superiorly to the inguinal ligament. Multiple small branches from the superficial femoral vessels to the abductor muscles must be clamped, divided, and ligated (TECH FIG 7).

   

   

   

  TECH FIG 7 • Transection of superficial femoral artery. (Courtesy of Martin M. Malawer.)

• Release of the Myocutaneous Flap from the Femur

   

  Vigorous upward traction on the myocutaneous flap allows the origins of the vastus intermedius and the vastus medialis to be severed from the femur. As the release of the myocutaneous flap continues up toward the pelvis, the profunda femoris vessels are identified. These vessels are ligated and divided at their origin from the common femoral artery (TECH FIG 8).

   

  The myocutaneous flap is freed from its pelvic attachments by the following procedure. The abdominal muscles and fascia are severed from the iliac crest. The sartorius muscle is transected at its origin on the anterior superior iliac spine. The rectus femoris is transected at its origin on the anterior inferior iliac spine. The femoral sheath overlying the hip joint is divided. The left rectus abdominis muscle is released from the pubic bone.

   

  By retracting the myocutaneous flap medially, full access to the pelvis is achieved. Blunt dissection along the femoral nerve allows rapid dissection into the pelvis to expose the vessels and nerves to be transected in the subsequent phases of the procedure.

   

  P.255

   

   

   

  TECH FIG 8 • A. Release of the quadriceps muscle from the femur. B. Release of the myocutaneous flap from the pelvis. (Courtesy of Martin M. Malawer.)

• Division of the Symphysis Pubis

   

  To divide the symphysis pubis, the bladder and urethra are protected and a scalpel is used to locate and divide the cartilaginous joint (TECH FIG 9).

   

   

   

  TECH FIG 9 • Division of the symphysis pubis. (Courtesy of Martin M. Malawer.)

• Transection of the Iliac Vessels

   

  The internal iliac artery and vein are divided at their point of origin from the common iliac vessels. Multiple visceral branches of the internal iliac vessels are divided in their course superficial to the sacral nerve roots. Strong medial traction on the viscera will help expose these vessels. When this phase of the dissection is completed, the nerve roots should be clearly visualized throughout their course in the pelvis (TECH FIG 10).

   

  The common iliac lymph nodes remain with the patient in this procedure, in contrast to a standard hemipelvectomy in which they are removed.

   

   

   

  TECH FIG 10 • Transection of internal iliac vessels and branches. (Courtesy of Martin M. Malawer.)

   

   

   

• Division of the Psoas Muscles and Nerve Roots

  P.256

   

  The psoas muscle is divided near its junction with the iliacus muscle. The obturator nerve deep to the muscle is also divided. Care is taken to preserve the femoral nerve coursing into the myocutaneous flap. The lumbosacral and sacral nerve roots are ligated and divided close to the ventral sacral foramina (TECH FIG 11).

   

   

   

  TECH FIG 11 • Division of the psoas muscle and nerve roots. (Courtesy of Martin M. Malawer.)

• Division of the Pelvic Diaphragm and Sacrum

   

  The leg is elevated to place under tension the individual muscles that constitute the pelvic diaphragm. Care is taken to protect the urethra, bladder, and rectum. The urogenital diaphragm, levator, and piriformis muscles are divided. These muscles are transected near their pelvic attachments (TECH FIG 12).

   

  The surgeon should again change orientation and move back to the posterior aspect of the patient. Using an osteotome and commencing at the tip of the coccyx, the coccyx and sacrum are divided in a plane that bisects the sacral foramina.

   

   

   

  TECH FIG 12 • A. Division of the pelvic diaphragm. B. Division of the sacrum. (Courtesy of Martin M. Malawer.)

   

   

  Initially, the course of the osteotome should parallel the midsacral spines. The surgeon, being posterior to

  the patient, reaches around the coccyx with the left hand to locate the S5 neural foramina from within the sacrum. This is at the junction of the sacrum and the coccyx. By holding the osteotome with the right hand, the direction for bone transection can be precisely determined. The assistant drives the osteotome through the bone with the mallet.

   

   

  At the upper portion of the sacrum, care must be taken not to fracture inadvertently through the bone. The lumbosacral ligament is divided to release the specimen.

   

• Closure

P.257

 

The operative site and myocutaneous flap are copiously irrigated and bleeding points are secured. The myocutaneous flap is folded posteriorly into the operative defect over two sets of suction drains. The fascia of the quadriceps femoris is sutured to the musculature of the anterior abdominal wall, to the back muscle, to the sacrum, and to the muscles of the pelvic diaphragm. The skin is closed with interrupted sutures (TECH FIG 13).

 

 

 

TECH FIG 13 • Closure. (Courtesy of Martin M. Malawer.)

 

 

PEARLS AND PITFALLS

Closure

• Sugarbaker5,8 and others1,2,4,9 have shown the use of a myocutaneous pedicle flap based on the femoral vessels and anterior compartment of the thigh for closure of the wound in patients with tumors involving the posterior buttock structures.

• The primary advantage of this procedure is that the anterior flap raised from the thigh can be used to reconstruct an enormous posterior defect with little risk of flap necrosis. Patients who are expected to require substantial doses of radiation postoperatively should be considered for this procedure whenever possible because the well-vascularized myocutaneous flap tolerates radiation well.

• Great care must be taken not to dissect or shear the subcutaneous tissue and skin overlying the quadriceps during the creation of the flap because this will compromise the cutaneous circulation.

• Occasionally, tumor tissue or heavily irradiated skin overlying the superficial femoral artery may require sacrifice of the skin pedicle. In this instance, the island myocutaneous flap should be used.

 

POSTOPERATIVE CARE

The patient should understand that phantom limb sensations are to be expected and that he or she can be treated with analgesics. The discomfort will lessen over time.

Although successful rehabilitation depends to a great extent on the patient's attitude, the physiatrist can help tremendously in these efforts. A positive attitude toward functional recovery augmented by early postoperative ambulation may move the patient rapidly to his or her goals. A positive approach is amplified by contact with other patients who have met some of the rehabilitation challenges. This can provide an immeasurable psychological boost to the patient. The oncologist, rehabilitation therapist, and others involved in the postoperative care must coordinate their efforts carefully.

 

OUTCOMES

The potential for rehabilitation with this procedure is excellent. Patients who are free of disease use a prosthesis regularly. Patients walk with the prosthesis without the use of crutches or a cane.

Because of the vascular nature of this flap, the surgical wound heals rapidly in the vast majority of patients. Accordingly, the 10% to 30% risk of ischemic necrosis associated with posterior flap hemipelvectomy is not seen with an anterior flap procedure. Likewise, the risk of infection in the postoperative period is markedly reduced. However, some studies have shown that the design of the flap

is not a factor with statistical significance in the number of wound infections or flap necrosis.8

Rehabilitative considerations and the risk of phantom pain are similar to those associated with other types of hemipelvectomies. Because of the rapid healing seen with this type of flap, prosthetic fitting may be performed earlier.

 

 

COMPLICATIONS

Lengthy and extensive operations have shown association with the development of wound infection and flap necrosis.

Early postoperative complications with this procedure have not occurred to date. The serious problem of skin flap ischemia seen in nearly 25% of patients undergoing a standard posterior flap hemipelvectomy, especially with the ligation of the common iliac vessels, has not been observed.

The most bothersome long-term postoperative problem with this procedure (as with a standard hemipelvectomy) is phantom limb pain. Approximately 20% of patients currently surviving have severe phantom limb pain requiring narcotic analgesics on a daily basis. However, this incidence of phantom limb pain is not noticeably different from that seen with standard hemipelvectomy.

 

 

P.258

REFERENCES

1. Bowden L, Booher RJ. Surgical considerations in the treatment of sarcoma of the buttock. Cancer 1953;6:89-99.

    

2. Frey C, Matthews LS, Benjamin H, et al. A new technique for hemipelvectomy. Surg Gynecol Obstet

    

   1976;143:753-756.

    

    

3. Gebhart M, Collignon A, Lejeune F. Modified hemipelvectomy: conservation of the upper iliac wing and an anterior musculocutaneous flap. Eur J Surg Oncol 1988;14:399-404.

    

    

4. Larson DL, Liang MD. The quadriceps musculocutaneous flap: a reliable, sensate flap for the hemipelvectomy defect. Plast Reconstr Surg 1983;72:347-354.

    

    

5. Lotze MT, Sugarbaker PH. Femoral artery based myocutaneous flap for hemipelvectomy closure: amputation after failed limb-sparing surgery and radiotherapy. Am J Surg 1985;150:625-630.

    

    

6. Luna-Perez P, Herrera L. Medial thigh myocutaneous flap for covering extended hemipelvectomy. Eur J Surg Oncol 1995;21:623-626.

    

    

7. Mnaymneh W, Temple W. Modified hemipelvectomy utilizing a long vascular myocutaneous thigh flap. J Bone Joint Surg Am 1980;62A: 1013-1015.

    

    

8. Senchenkov A, Moran SL, Petty PM, et al. Predictors of complications and outcomes of external hemipelvectomy wounds: account of 160 consecutive cases. Ann Surg Oncol 2008;15(1):355-363.

    

    

9. Sugarbaker PH, Chretien PA. Hemipelvectomy for buttock tumors utilizing an anterior myocutaneous flap of quadriceps femoris muscle. Ann Surg 1983;197:106-115.

    

    

10. Temple WJ, Mnaymneh W, Ketcham AS. The total thigh and rectus abdominis myocutaneous flap for closure of extensive hemipelvectomy defects. Cancer 1982;50:2524-2528.

     

     

11. Workman ML, Bailey DF, Cunningham BL. Popliteal-based filleted lower leg musculocutaneous free-flap coverage of a hemipelvectomy defect. Plast Reconstr Surg 1992;89:326-329.

     

     

12. Yamamoto Y, Minakawa H, Takeda N. Pelvic reconstruction with a free fillet lower leg flap. Plast Reconstr Surg 1997;99:143.