BACKGROUND

 

 

Metastatic tumors of the pelvis may cause pain and a major loss of function and weight-bearing capacity. Because of the relatively large size of the pelvic cavity and the elastic nature of the organs it contains and its surrounding muscles, tumors at that site usually reach considerable size before causing symptoms.

 

Although some locations of these metastases within the pelvis have no impact on pelvic stability and function (eg, ilium, pubis), tumors of the posterior ilium may pose a threat to lumbosacral integrity, and tumors of the acetabulum may profoundly impair hip function and the weightbearing capacity of the lower extremity.

 

Both primary sarcomas and metastatic tumors usually present with considerable extension into the soft tissues. Because of their inherent sensitivity to radiation therapy, however, the surgical management of metastatic lesions does not require en bloc resection of overlying muscles, and microscopic residua are treated with adjuvant radiation. The complex anatomy of the pelvic girdle mandates detailed preoperative imaging, planning of exposure and reconstruction technique, and careful and meticulous execution of the surgical procedure.

 

 

 

FIG 1 • Metastatic tumors of the ilium, periacetabular region, pubis, and posterior ilium require types I, II, III, and IV pelvic resections, respectively.

 

 

Pelvic metastases are treated with either curettage and reconstruction with cemented hardware or by wide resections. These procedures are grouped together and termed pelvic resections, the classification of which is attributed to Enneking and is based on the resected region of the innominate bone:

 

Type I—ilium

 

 

Type II—periacetabular region Type III—pubis

 

En bloc resection of the posterior ilium with the sacral ala is classified as an extended type I or type IV resection (FIG 1).1

ANATOMY

Ilium

 

The iliac crest is the attachment site for abdominal wall musculature and quadratus lumborum (FIG 2).

 

The iliacus muscle overlies the inner iliac table and the femoral nerve lies medial to it in the groove between the iliacus and the psoas muscle.

 

Gluteal muscles overlie the outer iliac table.

 

 

 

 

FIG 2 • Muscle attachments and relevant structures around the innominate bone.

 

 

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Acetabulum

 

 

The upper medial mechanical support of the hip joint No muscle attachments

Pubis

 

Origin of hip adductors from its inferior aspect

 

The neurovascular bundle runs along the anterior aspect of the pubis.

 

The urinary bladder attaches to its posterior wall.

INDICATIONS

Pathologic fracture of the acetabulum

Impending pathologic fractures of the acetabulum, which are defined as lesions that extend to the acetabular roof and are associated with cortical destruction and considerable pain on weight bearing

Intractable pain associated with locally progressive disease that had shown inadequate response to narcotics and preoperative radiation therapy

Solitary bone metastasis in selected patients

 

 

IMAGING AND OTHER STAGING STUDIES

 

Plain radiographs and computed tomography of the pelvis and hip joints are mandatory to evaluate the full extent of bone destruction, soft tissue extension, and integrity of the hip joint. Magnetic resonance imaging rarely adds additional information: It is indicated in lesions which have diffused intramedullary extension that is commonly underestimated by computed tomography, such as multiple myeloma. Total body bone scintigraphy is done for detecting synchronous metastases elsewhere in the skeleton. At the conclusion of imaging, the surgeon should be able to answer the following questions:

 

What is the full extent of bone destruction and soft tissue extension that are related to the tumor? Is the lesion an impending fracture? If not, it should probably be treated nonsurgically.

 

What incision should be used to obtain optimal exposure (FIG 3)?

 

What would be the best technique for resection and reconstruction, if required?

 

Are there additional skeletal metastases and, if so, can they be managed by nonoperative techniques or do they require surgery?

 

 

 

FIG 3 • Plain radiographs and computed tomographies with coronal reconstruction showing acetabular metastases with their most pronounced cortical destruction at the lateral acetabular wall (A-C) and medial acetabular wall (D-F). The former lesion is exposed after reflection of the glutei from the outer iliac table and the latter after reflection of the iliacus from the inner iliac table.

 

 

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FIG 3 • (continued)

 

 

Hypervascular lesions (eg, metastatic renal cell or thyroid carcinomas) can bleed profusely and cause a life-threatening blood loss within a few minutes upon tumor exposure and curettage. Preoperative embolization of

these tumors is strongly advised to reduce intraoperative blood loss.4,5

 

SURGICAL MANAGEMENT

Positioning

 

Types I, II, and III resection: The patient is placed supine on the operating table with a slight elevation of the ipsilateral hip.

 

Type IV resection: The patient is placed in a true lateral position with the affected side of the pelvic girdle uppermost. The operating table is bent with the breakage point just below the contralateral hip: Such a position widens the space between the iliac crest and the lower aspect of the chest wall, allowing a comfortable approach and easier maneuvering at that site (FIG 4).

 

Approach

 

The most useful approach to pelvic resections is the utilitarian pelvic incision. All or part of the incision can be

used for adequate exploration and resection of pelvic girdle metastases.

 

 

The incision begins at the posterior inferior iliac spine and extends along the iliac crest to the anterior superior iliac spine. It is then separated into two arms: One extends along the inguinal ligament up to the symphysis pubis, and the other turns distally over the anterior thigh for one-third the length of the thigh and then curves laterally just posterior to the shaft of the femur below the greater trochanter and follows the insertion of the gluteus maximus muscle.

 

Reflection of the posterior gluteus maximus flap exposes the proximal third of the femur, the sciatic notch, the sacrotuberous and sacrospinous ligaments, the origin of the hamstrings from the ischium, the lateral margin of the sacrum, and the entire buttock (FIG 5A).

 

Posteriorly, the incision extends along the posterior iliac crest, posterior superior iliac spine, and ipsilateral hemisacrum (FIG 5B).

 

 

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FIG 4 • A. Metastatic carcinoma of the posterior ilium. B,C. The patient is placed in a true lateral position and the operating table is broken at the hip level to allow easier access to the flank.

 

 

 

 

 

FIG 5 • A. The utilitarian pelvic incision. B. The posterior component of the incision, used for exposure and resection of tumors of the posterior ilium and sacrum.

 

 

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TECHNIQUES

• Exposure

Type I Resection

 

The middle component of the utilitarian incision is used to expose the iliac crest. Using electrocautery, the glutei are detached and reflected from the outer iliac table. The iliacus muscle is similarly detached and reflected from the inner table (TECH FIG 1).

Type II Resection

 

Lesions with lateral cortical destruction

 

The middle component of the utilitarian incision up to the anterior superior iliac spine with a 5-cm extension along the lateral thigh arm of the incision is used for these lesions.

 

 

 

TECH FIG 1 • A,B. Metastatic sarcoma of the ilium. C. The tumor is exposed after detachment and

reflection of the glutei and iliacus from the outer and inner iliac tables, respectively. D. Intraoperative photograph showing the exposed ilium after reflection of the glutei and iliacus muscles.

 

 

Electrocautery is applied to detach and reflect the glutei from the outer iliac table, exposing the lateral wall of the acetabulum (TECH FIG 2).

 

Lesions with medial cortical destruction

 

The middle component of the utilitarian incision up to the anterior superior iliac spine with a 5-cm extension along the inguinal arm of the incision is used for these lesions.

 

Electrocautery is applied to detach and deflect the iliacus from the inner iliac table, exposing the medial wall of the acetabulum (TECH FIG 3).

 

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TECH FIG 2 • A. Exposure of an acetabular metastasis that has a lateral cortical destruction is accomplished by using the middle component of the utilitarian incision up to the anterior superior iliac spine with a 5-cm extension along the lateral thigh arm of the incision. B,C. Using electrocautery, the glutei are detached and reflected from the outer iliac table, exposing the lateral wall of the acetabulum.

 

Lesions that have similar extent of lateral and medial cortical destruction are preferably approached from their lateral aspect because performance of the surgery is technically easier from that side.

Type III Resection

 

The inguinal component of the utilitarian incision, from the anterior superior iliac spine to 2 cm across the symphysis pubis, is used for this resection.

 

The neurovascular bundle is isolated, marked with vessel loops, and mobilized.

 

The retropubic space is exposed, and a pad is inserted between the urinary bladder and the pubis. Muscle attachments are then detached from the inferior aspect of the pubis (TECH FIG 4).

Type IV Resection

 

The posterior component of the utilitarian incision is used for this resection. Electrocautery is applied to detach the glutei from their origin at the posterior iliac crest and to reflect them (TECH FIG 5).

 

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TECH FIG 3 • A. Exposure of an acetabular metastasis that has a medial cortical destruction is achieved by using the middle component of the utilitarian incision up to the anterior superior iliac spine with a 5-cm extension along the inguinal arm of the incision. B,C. Using electrocautery, the iliacus is detached and reflected from the inner iliac table, exposing the medial wall of the acetabulum.

 

 

 

TECH FIG 4 • A. Exposure of a pubic metastasis is accomplished by using the inguinal component of the utilitarian incision from the anterior superior iliac spine to 2 cm across the symphysis pubis. B. The affected bone is reached after isolation and mobilization of the neurovascular bundle from the anterior aspect of the pubis, reflection of the urinary bladder from its posterior aspect, and detachment and reflection of the adductors origin from its inferior aspect.

 

 

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TECH FIG 5 • A,B. Exposure of a metastasis at the posterior ilium is achieved by using the posterior component of the utilitarian incision. C. The glutei are detached from their origin from the posterior iliac crest and outer table. D. Reflection exposes the outer iliac table.

• Tumor Removal

Type I Resection

 

This resection involves an osteotomy of the ilium around the lesion, and 1- to 2-cm margins are sufficient for resection of metastases at that site (TECH FIG 6).

 

Tumor curettage is neither feasible nor justified at that site because a resection of the ilium that does not impair acetabular or sacroiliac joint integrity rarely has an impact on function.

Type II Resection

Curettage

 

 

A wide cortical window is made above the lesion (TECH FIG 7A). Gross tumor is removed with hand curettes (TECH FIG 7B,C).

 

Curettage should be meticulous and leave only microscopic disease in the tumor cavity. It is followed by high-speed burr drilling of the tumor cavity walls (TECH FIG 7D,E).

 

 

 

TECH FIG 6 • Plain radiograph showing the ilium following a type I resection. The sacroiliac joint and the acetabulum are intact and function is, therefore, expected to remain intact.

 

 

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TECH FIG 7 • A. A wide cortical window is created. B,C. Gross tumor is meticulously removed with hand curettes, leaving only microscopic disease. D,E. Curettage is followed by high-speed burr drilling of the tumor cavity.

 

 

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Resection

 

When the entire acetabulum is destroyed and no cortices are left to contain an internal fixation device and cement, a formal resection is done in the same manner as for primary sarcomas of bone (see the chapter on pelvic resection).

 

The incision is extended along the upper thigh, the joint capsule is opened, the femur is dislocated, and an acetabular osteotomy and resection are carried out.

Type III Resection

Curettage

 

A longitudinal cortical window with oval edges is made above the lesion, and tumor curettage and high-

speed burr drilling are done in the same manner as in a type II resection (TECH FIG 8).

Resection

 

When the pubis is destroyed and no cortices are left to allow curettage and burr-drilling, the incision is extended to exposed intact cortices from both sides of the lesion, followed by formal resection of the pubic segment.

 

 

 

TECH FIG 8 • A. Plain radiograph showing metastatic carcinoma of the superior pubic ramus. B. Curettage of the tumor cavity. The femoral vessels and nerve are marked with red and yellow vessel loops, respectively. C. Curettage is followed by high-speed burr drilling.

Type IV Resection

Curettage

 

A longitudinal cortical window with oval edges is made above the lesion, and tumor curettage and high-speed burr drilling are done in the same manner as in a type II resection (TECH FIG 9).

Resection

 

When the posterior ilium is destroyed and no cortices are left to allow curettage and burr-drilling, wide resection of the posterior iliac segment is carried out.

 

These resections commonly require the en bloc removal of the adjacent component of the sacroiliac joint and potentially can impair stability of the posterior pelvic girdle.

 

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TECH FIG 9 • A. Plain radiograph, (B) computed tomography, and (C) magnetic resonance imaging showing metastatic carcinoma of the right posterior ilium. D. Gross tumor at the posterior ilium is meticulously removed with hand curettes, leaving only microscopic disease. E. Curettage is followed by high-speed burr drilling of the tumor cavity.

• Mechanical Reconstruction

Type I Resection

 

Type I resections require no reconstruction.

Type II Resection

Curettage

 

After completion of tumor removal with burr-drilling, the tumor cavity is reconstructed with cemented Steinmann pins, which are introduced through the iliac crest.

 

Following placement of the pins tips against the subchondral bone, the tumor cavity is filled with cement (TECH FIG 10).

 

Acetabular metastases may destroy the subchondral bone and dissociate the articular cartilage. In such cases, reconstruction of the articulating surface of the acetabulum can be done with a prosthetic

polyethylene insert that had been shaped with a high-speed burr to match the convexity of the femoral head (TECH FIG 11).

Resection

 

Reconstruction following resection of the acetabulum may include a saddle prosthesis or leaving a flail extremity with no reconstruction.

Type III Resection

 

Following curettage, the tumor cavity is filled with cement, which does not contribute to pelvic stability but allows easier determination of tumor extent on the postoperative imaging studies and subsequent planning of radiation fields as well as early detection of local tumor recurrence at the cement-bone interface.

 

No reconstruction is required if resection of a pubic segment had been performed.

Type IV Resection

Curettage

 

Following curettage, the tumor cavity is filled with cement, the purpose of which is similar to cementation of a pubic defect.

 

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TECH FIG 10 • A,B. Steinmann pins are introduced through the iliac crest into the tumor cavity up to the subchondral bone. After placement of the pins, the tumor cavity is filled with bone cement. C. Plain radiograph showing the acetabular cavity reconstructed with cemented Steinmann pins.

Resection

 

Small defects of the sacroiliac joints do not require reinforcement.

 

Medium-sized defects, however, require such reinforcement with a plate to prevent dissociation of the joint.

 

Complete resection of the sacroiliac joint compromises stability of the posterior pelvic girdle.

 

Gradual upward migration of the ilium on weight bearing and limb length discrepancy will most likely occur (TECH FIG 12). Traction of the lower extremity followed by a protected weightbearing protocol is implemented in order to reduce the extent of limb shortening.

 

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TECH FIG 11 • Deficient articular cartilage may be reconstructed with a polyethylene insert.

 

 

 

TECH FIG 12 • A. Small defects of the sacroiliac joint following a type IV pelvic resection does not compromise pelvic girdle stability and, therefore, does not require reconstruction. Medium-sized defects require reinforcement (B), and complete resection of the sacroiliac joint requires skin traction and protected weight bearing (C). This protocol is intended to allow scarring of the surgical field with the operated extremity pulled to its full extent, which may prevent upward migration of the lower extremity and limb length discrepancy.

 

 

 

• Soft Tissue Reconstruction and Wound Closure

P.236

 

The glutei and iliacus are sutured over the innominate bone and both are sutured to the abdominal wall musculature (TECH FIG 13).

 

It is important to properly attach these three muscle groups to restore muscle origin attachment and abdominal wall continuity, thereby allowing function of the glutei and iliacus and preventing herniation of the pelvic viscera to the flank, respectively.

 

 

 

TECH FIG 13 • Plain radiograph (A) and computed tomography (B) showing metastatic carcinoma of the left ilium. C. The iliac stump that remains after osteotomy (the femoral nerve is lifted with a vessel loop and a clamp is passed through the sciatic notch). D. The glutei are sutured to the iliacus muscle to cover the iliac stump and both are sutured to the abdominal wall musculature to avoid herniation of the pelvic viscera into the flank.

 

 

The surgical wound is closed over suction drains, and an abduction pillow is used to enable wound healing with minimal stress at the muscle suture line.

 

In the case of a complete resection of the sacroiliac joint and loss of posterior pelvic continuity, skin traction is used to pull the extremity and avoid limb shortening.

 

 

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PEARLS AND PITFALLS

 

Indications

• Detailed preoperative imaging and anatomic tumor classification

• Choice of resection type and extent (curettage vs. resection) and technique of reconstruction, if required

Special considerations

• Preoperative embolization of hypervascular lesions

Resection and

reconstruction

• Tumor removal by curettage and high-speed burr drilling; resection when curettage is not feasible

• Reconstruction with cemented hardware

• Functional reconstruction of muscle groups

Adjuvant treatment and

rehabilitation

• Early ambulation with unrestricted weight bearing with the only exception being patients who had complete

  resection of their sacroiliac joint

• Postoperative radiation therapy

 

 

POSTOPERATIVE CARE AND REHABILITATION

 

Continuous suction is required for 3 to 5 days, and perioperative intravenous antibiotics are continued until the drainage tubes are removed.

 

Rehabilitation should include early ambulation with unrestricted weight bearing as well as passive and active range of motion of the hip joint.

 

In the case of a complete resection of the sacroiliac joint, skin traction is applied for the first 10 postoperative days, and weight bearing is allowed only after 3 weeks postsurgically have passed: This protocol allows the formation of scar tissue around the sacroiliac defect, which may decrease the extent of iliac migration.

 

Upon wound healing, usually 3 to 4 weeks after surgery, the patients are referred to adjuvant radiation therapy.

 

OUTCOMES

Most patients who undergo resection of pelvic metastases experience a substantial relief of pain and are able to ambulate with full weight bearing. Most of them do not, however, reach their full functional capability because of a relatively slow recovery and muscle weakness due to their progressing oncologic disease and general wasting.

Hardware failures are rarely seen if internal fixation devices had been chosen correctly, used properly, and reinforced with cement. Local recurrence rates are less than 10% if there has been adequate tumor

removal and if postoperative radiation had been administered.2,3

 

 

COMPLICATIONS

Deep infection

Wound dehiscence due to poor nutritional and catabolic states Deep vein thrombosis

Sacroiliac dissociation and upward migration and shortening of lower extremity on weight bearing Herniation of pelvic viscera to the flank

Local tumor recurrence

 

 

REFERENCES

1. Enneking WF. The anatomic considerations in tumor surgery: pelvis. In: Enneking WF, ed. Musculoskeletal Tumor Surgery, vol 2. New York: Churchill Livingstone, 1983:483-529.

    

    

2. Harrington KD. Impending pathologic fractures from metastatic malignancy: evaluation and management. Instr Course Lect 1986;35:357-381.

    

    

3. Harrington KD, Sim FH, Enis JE, et al. Methylmethacrylate as an adjunct in internal fixation of pathological fractures. J Bone Joint Surg 1976;58(8):1047-1055.

    

    

4. Kollender Y, Bickels J, Price WM, et al. Metastatic renal cell carcinoma of bone: indications and technique of surgical intervention. J Urol 2000;164:1505-1508.

    

    

5. Roscoe MW, McBroom RJ, Louis E, et al. Preoperative embolization in the treatment of osseous metastases from renal cell carcinoma. Clin Orthop Related Res 1989;238:302-307.