Amputative Sacral Resections

Panayiotis J. Papagelopoulos

Andreas F. Mavrogenis

Peter S. Rose

Michael J. Yaszemski

Amputative sacral resections are an extension of the sacrectomy techniques described in Chapter 7. These are complex oncologic procedures performed for curative resection of sacral malignancies, which extend into the pelvis.

INDICATIONS

To determine the need for external hemipelvectomy coupled with sacral resection, one carefully defines the extent of the tumor. Tumors may require such a resection if their epicenter is within the ilium but disease extends across the sacroiliac joint, or if their epicenter is in the sacrum but removal requires resection of the femoral nerve as well as the lumbosacral trunk or the lumbosacral trunk as well as the hip joint articulation.
In general, when patients require resection, which disrupts spinopelvic continuity and either resects both the lumbosacral trunk and femoral nerve or the lumbosacral trunk and hip joint, the ultimate function of the limb is so poor that external hemipelvectomy is often indicated in conjunction with the sacral resection. This technique also allows the maximal oncologic margin to be obtained and provides for healthy and robust flap coverage from the limb.

CONTRAINDICATIONS

Contraindications are as outlined in the chapter on sacrectomy. These center on carefully assessing patients for any evidence of metastasis, as procedures of this magnitude are generally considered too great to be considered for noncurative intent. Similarly, surgeons should have a strong plan in place to obtain a tumor-free margin of resection. This frequently requires resection of adjacent visceral organs.
The medical fitness of the patient for a surgery of this magnitude should be carefully considered before proceeding with these resections.

PREOPERATIVE PLANNING/GENERAL CONSIDERATIONS

Tumor staging, diagnosis, and imaging are as outlined in the Chapter 7 on sacrectomy. We have classified major spinopelvic resections in four types (Fig. 8.1). Type 1 and 2 resections (total sacrectomy, hemisacrectomy) may proceed as outlined in Chapter 7 (Sacrectomy). Type 3 and 4 resections (partial and total sacretomies in conjunction with external hemipelvectomy) are the subject of this chapter.

The amputative part of the procedure is performed in a single setting. Patients undergoing type 3 resections are considered for an instrumented spinopelvic arthrodesis to the remaining limb if >50% of the lumbosacral articulation is resected. It is our preference to perform this fusion procedure in a second operation staged approximately 48 hours after the amputation to allow time for final margins to be ascertained and to minimize the physiologic impact on the patient. In type 4 resections, the amputative resection is carried out in a single
stage and the tumor-free portion of the amputated femur is stored sterilely in a liquid nitrogen freezer until a second stage of the surgery at which time an instrumented fusion between the remaining lumbar spine and remaining limb is performed.

Careful consideration is given preoperatively to the flap, which will allow closure after the amputation. In the majority of cases, the buttock flap is contaminated by the presence of tumor extending in and around the sciatic notch and the gluteal vessels. However, in most cases, the external iliac vessels are free of tumor allowing a flap based upon the quadriceps of the amputated femur pedicled off the external iliac/femoral artery system to provide for robust closure. In rare cases, tumor extent is such that either free flap coverage or vascular bypass techniques are necessary because of compromised soft tissue in the flap or tumor encasement of both the internal and external iliac vessels.

Similar to patients who are undergoing conventional sacral resections, patients undergoing amputative sacral resections are at high risk for thromboembolic complications. We prefer to place a removable inferior vena cava (IVC) filter after the index surgery. This is deliberately not placed prior to the index surgery to allow maximum mobilization of the vena cava without risk of luminal injury.

TECHNIQUE

Positioning

Ureteral stents are placed preoperatively, and patients complete a bowel preparation. The anus is sewn shut and prepped into the field only if it is to be excised as part of the tumor resection. After robust vascular access is obtained, patients are positioned in a very sloppy lateral position on the operating table. We have found that rather than using a conventional beanbag positioner, it is more successful to place a large sandbag both in front of and behind the patient’s chest to allow them to be rolled to a near supine and a near prone position during the procedure.

SURGICAL TECHNIQUE

The surgical incision goes midline over the sacrum and then courses up and around the posterior iliac crest to come over the lateral aspect of the pelvis to the anterior superior iliac spine (Fig. 8.2). The incision curves down distally over the greater trochanter down to the lateral epicondyle of the knee. The line of dissection then crosses the front of the distal femur just proximal to the patella, over to the intermuscular septum, and courses up the medial aspect of the thigh to the harvest of the entire quadriceps group as an anterior flap. We initially
begin by mobilizing the anterior thigh flap as it provides robust access to the pelvis once this is lifted up in conjunction with the pelvic/iliac incision (Fig. 8.3

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