10 Overview of Pelvic Resections: Surgical …

1 10 Overview of Pelvic Resections: Surgical considerations andClassificationJacob Bickels and Martin MalawerOVERVIEWThe bony pelvis and its enveloping soft tissues are a common site for bone and soft-tissue tumors. Extensive pelvicsurgeries, either for oncologic reasons or following trauma, are highly demanding because of the irregular andcomplex shape of the bony pelvis, numerous muscle attachments, and the proximity of major blood vessels,nerves, and visceral organs (Figure ). Until the late 1970s most Pelvic tumors were treated with hemipelvectomy, a procedure that was associatedwith a significant percentage of complications and a dismal functional and psychological outcome. Because of theavailability of more accurate modalities for imaging of the pelvis, use of neoadjuvant chemotherapy, improvedresection techniques, and prosthetic reconstruction, limb-sparing procedures are now performed in the majorityof these cases.

2 An important consideration, because of the use of adjuvant chemotherapy and, occasionally,radiation therapy, is that the patient's postoperative recovery period be short and uncomplicated. This chapterdicusses specific anatomic and clinical considerations , related to surgery in the Pelvic area, as well as the variousclassifications of Pelvic Chapter 10 21/02/2001 15:28 Page 203 INTRODUCTIONL esions in the pelvis usually attain considerable sizebefore they are diagnosed. Most patients with lesions ofthe iliac crest that extend into the pelvis, or lesions thatarise in the Pelvic fossa, complain initially of vagueabdominal pain or fullness. Patients may present withsymptoms that are related to pressure on a specificanatomic structure within the pelvis. Rarely do patientspresent with systemic signs of advanced , a large, asymptomatic mass is felt onabdominal or Pelvic most cases a wide excision of a Pelvic or proximalthigh tumor may be performed without comprom-ising anyvital structure of the lower is indicated in cases where a severecompromise following wide excision is inevitable.

3 Afunctionally impaired lower extremity is preferable to anamputation, and even patientswhose sciatic or femoralnerves have to be sacrificed do well with propertraining, orthoses, and physical therapy. A local recur-rence of a previously resected soft-tissue or bone sarcomais no longer a clear indication for an amputation,because its impact on survival is questionable. LocalMusculoskeletal Cancer Surgery204 Figure bony pelvis and its relation to the major blood vessels, nerves, and visceral organsMalawer Chapter 10 21/02/2001 15:28 Page 204recurrences are, therefore, treated with wide excision,and amputations are performed with the sameindications as for primary tumors. IMAGING OF THE PELVISS taging studies for Pelvic lesions, as for those elsewherein the musculoskeletal system, are aimed at deter-mining local tumor extent, its relation to the specificanatomic structures within the pelvis, and the presenceof metastatic disease.

4 The combination of thesefindings, along with the histopathologic diagnosis, willdetermine whether surgery is indicated and, if so, towhat extent. The extent of a Pelvic tumor can be evalu-ated only by combining multiple imaging modalities,and even then the full extent of most tumors isunderestimated (Figure ).Plain RadiographyPlain radiography is of limited value in the assessmentof Pelvic girdle lesions. The images are frequentlyobscure and confusing. The pelvis, and particularly thesacrum, is a difficult structure in which to recognizeearly bone lesions because of the almost universalpresence of overlying intestinal gas. Many lesions areoverlooked initially. For these reasons there should be alow threshold for performing computed tomography(CT), magnetic resonance imaging (MRI), or bone scanin patients presenting with deep pain around the pelvicgirdle or an atypical pattern of sciatic pain (Figure ).

5 CT and MRIC ontrast CT is the key modality for assessment of bonylesions of the Pelvic girdle. The extent of bonedestruction, cortical breakthrough, characteristics ofthe tumor matrix, and reactive changes in the host boneand soft tissues can be determined. MRI is used toevaluate soft-tissue tumors and the extent of medullaryand extraosseous components of bone tumors. It isaccurate within approximately 1cm of the tumormargin. A notable exception is chondrosarcoma, whichis typically understaged when it occurs in the pelvis. CTwas shown to underestimate their size by up to 40 50%(Figure ). Great caution should therefore be used inthe Surgical planning of resection of these tumors. It isalso important to note that chondrosarcoma is the mostcommon primary bone sarcoma of the Pelvic chondroid-containing tumor of the pelvis is extre-mely likely to be a chondrosarcoma, and any diagnosisof an enchondroma should be seriously questioned.

6 AngiographyAngiographic studies are valuable in evaluating therelation of the major blood vessels to a tumor, theirpatency, as well as assessing tumor vascularity. TheseOverview of Pelvic Resections205 Figure 75-year-old patient with a 1-year history of right hip pain. Past medical history includes a subtotal thyroidectomythat was performed for an unclear diagnosis. The patient was told that the lesion was benign, and no further treatment wasindicated. The patient was referred for total hip replacement and plain radiographs revealed a large lytic lesion of the rightperiacetabular region (A arrows). On the basis of this radiograph one might assume that the cortices are intact. (B) CT showedextensive bone destruction and extension of the tumor to the pelvis and the right gluteal region. Complete staging demonstratedtwo lung metastases, and CT-guided core needle biopsy revealed a metastatic thyroid carcinoma.

7 Following preoperativeembolization the patient was treated with resection curettage (curettage and meticulous burr drilling) and cementation. ABMalawer Chapter 10 21/02/2001 15:28 Page 205data are crucial in planning the resection of deep-seated Pelvic tumors, especially large tumors that maydisplace the major blood vessels. These tumorsoccasionally form mural neoplastic thrombi, the pre-sence of which must be confirmed prior to surgery. Inaddition, reduction in tumor vascularity, as revealed byserial angiographs, was shown to be indicative of goodresponse to preoperative chemotherapy. Embolizationof highly vascularized lesions, metastatic hyper-nephromas, can significantly reduce tumor size, bloodloss in surgery, and alleviate symptoms in patients whoare not candidates for surgery (Figures and ).ANATOMIC CONSIDERATIONSE valuation of the full anatomic extent of a Pelvic tumorcannot be based on a single imaging modality.

8 Combineddata, gained from two or more imaging modalities,allow a realistic appreciation of the exact anatomicextent. Even when that information is available,however, the full extent of a Pelvic tumor is commonlyunderestimated preoperatively. The review of anyimaging study of the pelvis, because of the numerousanatomic details, must be performed very method-ically. The authors review the structures from the back(midsacral region) and follow the Pelvic girdle to thefront (symphysis pubis), as described in the followingparagraphs. , sacral alae, and sacroiliac joint. Most patientswho undergo extended hemipelvectomy, whichnecessitates transection of the sacrum through theipsilateral neural foramina, regain function of thegastrointestinal and genitourinary tracts. Adding acontralateral compromise of the sacral nerve rootwill create a severe dysfunction.

9 Tumors that pene-trate the sacrum and cross the midline are consideredunresectable because of the involvement of bilateralnerve roots(Figure ). The tumor can be resected,but the morbidity will outweigh the questionableoncologic benefit from surgery. The common iliac vessels are just anterior to thesacral ala, and any cortical breakthrough by a tumorin that site may be expected to extend directly to theblood vessels. The sacroiliac (SI) joint is a key ana-tomic landmark. The major nerves and blood vesselsare medial to it: therefore, any tumor or Pelvic resec-tion that is lateral to the SI joint may be expected notto violate the major neurovascular of the SI joint must be documentedprior to surgery by using the combination of CT,MRI, and bone scan. Pelvic blood vessels and structures. The commoniliac artery bifurcates along the sacral ala, and theureter crosses the bifurcation in each side.

10 Largetumors around the sacral ala frequently displace andoccasionally invade these structures. The merepresence of a major blood vessel or a Pelvic viscusinvolvement is not an indicator of unresectability. Ifcurative resection is planned, both structures can beexcised en-bloc with the tumor and be repaired witha graft. However, when a compound resection (bonyMusculoskeletal Cancer Surgery206 Figure 55-year-old male with a low back and posterior thigh pain. (A) Anteroposterior plain radiograph of the pelviswas read as normal. (B) CT of the pelvis revealed a large destructive lesion of the sacrum. CT of the abdomen revealed a renalmass, and a CT-guided core needle biopsy of the sacral lesion confirmed the diagnosis of metastatic hypernephroma. Completestaging revealed additional asymptomatic vertebral metastases. The patient was treated with embolization of the sacral lesionwith complete resolution of his Chapter 10 21/02/2001 15:28 Page 206pelvis and viscus resection) is anticipated, the patienthas to be informed and the Surgical assistance andnecessary equipment have to be prepared in plexus.