12 Buttockectomy - Sarcoma.org

1 12 ButtockectomyMartin Malawer and Paul SugarbakerOVERVIEWT umors of the gluteus maximus (buttock) are often extremely large before diagnosis. Traditionally, low- and high-grade soft-tissue sarcomas of the buttock were treated by a posterior cutaneous flap hemipelvectomy. Today,however, most low-grade soft-tissue sarcomas of this muscle can be resected with safe margins. Hemipelvectomyis not required. Resection involves complete removal of the gluteus maximus muscle and ligation of the inferiorgluteal vessels. The underlying sciatic nerve is preserved. Most high-grade sarcomas of the gluteus maximus cansimilarly be treated by surgical resection. Preoperative induction chemotherapy, intra-arterial chemotherapy, orradiation therapy is required. Radiation therapy may also be required depending on final gluteus maximus is a quiet area for soft-tissue sarcomas.

2 The only significant structure that must beevaluated is the sciatic nerve. Minimal reconstruction is required. During the postoperative period it is importantto take measures to prevent the formation of large postoperative seromas. The functional outcome of a resectionof the gluteus maximus is a minimal deficit in hip extension only. The gait is a hemipelvectomy is rarely required for most soft-tissue sarcomas unless they are extremely large and/orare accompanied by fungation, infection, or extension into the ischiorectal space, pelvis, and hip. Direct sacral oriliac bone involvement, which is rare, necessitates an amputation. Malawer Chapter 12 21/02/2001 15:34 Page 233 INTRODUCTIONThe gluteus maximus is a common site for high- andlow-grade soft-tissue sarcomas. Such lesions are oftenconfined to the gluteus maximus and do not extend tothe underlying retrogluteal space or involve the sacrumor femur.

3 Therefore, a majority of them have tradition-ally been treated by a wide local resection. Extremelylarge tumors of the gluteus maximus were, by contrast,traditionally treated by a posterior fasciocutaneous flaphemipelvectomy. An anterior myocutaneous flapmodification has been devised by Sugarbaker et of limb-sparing procedures has reducedthe need for hemipelvectomy for tumors in this approximately 90% of soft-tissue sarcomasarising in the buttocks can be resected and adequatelytreated by a limb-sparing resection. Low-grade soft-tissue sarcomas of the gluteus maximus require surgeryonly; high-grade soft-tissue sarcomas in this region, likethose in other anatomic areas, are treated by eitherinduction chemotherapy and/or radiation therapypreoperatively followed by postoperative chemother-apy.

4 We favor the use of induction chemotherapyfollowed by a limb-sparing resection when field is treated with postoperative radiation ifrequired. The major indications for an amputation areextremely large sarcomas that involve the adjacentbone, sciatic nerve, or the ischiorectal ANATOMIC CONSIDERATIONSThe gluteus maximus arises from the sacral lamina andalar iliac crest and obliquely passes to its insertion ontothe proximal portion of the iliotibial band. This inser-tion begins above the greater trochanter, passes 4 5cmbelow the greater trochanter, and then attaches to theadjacent femur. The gluteus maximus does not attachto the retrogluteal structures as it passes over permits easier surgical dissection of the retrog-luteal plane and preservation of the sciatic nerve inmany situations.

5 As it passes from the sacrum to the femur the gluteusmaximus covers the sacroiliac joint and the sacrospinousand sacrotubulous ligaments, as well as a portion of theischiorectal fossa. The area underneath the gluteusmaximus is termed the retrogluteal space . This areaconsists of the posterior hip musculature, including theexternal rotators and portions of the gluteus mediusmuscle. Most important, the sciatic nerve exits thepelvis through the sciatic notch and passes inferiorly tothe piriformis muscle. This nerve lies in close proximityto the posterior fascia of the gluteus maximus; therefore,large tumors of the gluteus maximus may involve thesciatic nerve. The sciatic nerve is rarely involved by thetumor; most often it is displaced around the capsule orpseudocapsule. The inferior vessels pass below thepiriformis muscle to enter the midportion of the gluteusmaximus.

6 The inferior gluteal vessels are routinelyligated. INDICATIONSA gluteus maximus resection is indicated for patientswith low- and high-grade sarcomas confined to thegluteus contraindications to gluteus maximus resectioninclude the following:1 Large tumors that involve the true pelvis or ischiorec-tal of the sacrum or nerve involvement (although, on occasion, thesciatic nerve may be resected).4 Pelvic extension through the sciatic STUDIESC omputer Tomography (CT) and MagneticResonance Imaging (MRI) These studies are most useful in determining the extentof tumor involvement of the gluteus maximus ( ). Close evaluation will determine the involve-ment of the adjacent sacrum, femur, and sciatic should be placed on the evaluation of thestructures of the retrogluteal space, including the hipjoint and sciatic nerve, and ischiorectal fossa.

7 Buttocktumors may extend into the pelvis through the sciaticnotch. Bone Scan Tumor involvement may extend to the crest of theilium, the sacrum, and the proximal femur. These areasshould be evaluated by bone is not routinely performed when eval-uating tumors of the gluteus maximus (Figure ). Itmay be useful in preoperative embolization orpreoperative intra-arterial chemotherapy. BiopsyThe biopsy site must be in line with the incision for thehemipelvectomy should one be required (FigureMusculoskeletal Cancer Surgery234 Malawer Chapter 12 21/02/2001 15:34 Page ). Surgeons performing a biopsy of tumors of thebuttock must therefore be familiar with the surgicalincisions for both posterior flap hemipelvectomy andanterior flap hemipelvectomies. The anterior flaphemipelvectomy, as described by Sugarbaker et al.

8 , ispreferred for large sarcomas of the buttock area. In thisprocedure the entire musculature and skin is removedwith the amputation and the anterior myocutaneousflap consisting of the quadriceps muscle is utilized toclose the defect. If a posterior flap is utilized, care mustbe taken not to contaminate the posterior skin or biopsy site, must therefore be along the lateralaspects of a posterior incision and must avoid thegreater trochanter, sciatic nerve, ischiorectal fossa, andgreater trochanter. SURGICAL large curvilinear incision is made beginning at theposterior aspect of the crest of the ilium, curving dis-tally following the gluteus maximus muscle alongthe iliotibial band (Figure ), passing over thegreater trochanter to about 6cm distal, and thencurving posteriorly back toward the inner aspect ofthe thigh along the gluteal fold.

9 This incision makesit possible to elevate a large posterior flap. determine resectability or operability, the sciaticnerve is identified distal to the resection site. This canbe identified between the medial and lateral ham-string muscles or just lateral to the ischium before itpasses underneath the gluteus maximus evaluation of a patient with a large buttock sarcoma. (A,B) T1 and T2 weighted MRI images of a largebuttock sarcoma. Note that on the T1 the lesion is extremely large, involving the entire gluteus maximus but without extensioninto the pelvis or into the anterolateral aspects of the thigh. The T2 weighted image shows a blood-filled cavity that is the resultof a spontaneous bleed into the tumor following induction chemotherapy. (C) CT scan of a large buttock sarcoma involving theentire gluteus maximus but not involving the abductor muscles or showing any evidence of intrapelvic extension.

10 (D) Late-phase angiography showing a typical tumor blush of the left buttock tumor. This represents extremely viable tumor despiteinduction chemotherapy. This patient was still a good candidate for a limb-sparing procedure. Note (arrow) the main vascularsupply is from the gluteal vessels that supply the buttock area. These vessels are exposed and ligated early in the Chapter 12 21/02/2001 15:34 Page 235 The nerve is palpated below the gluteus maximusmuscle toward the piriformis gluteus maximus is detached from the iliotibialband throughout its length and from the femurdistally. This muscle is then flapped medially toexpose the superior and inferior gluteal vessels thatare then sciatic nerve is displacedanteriorly to protect it during the dissection.