current concepts and an update on the surgical management

8
119 © 2019 Journal of Natural Science, Biology and Medicine | Published by Wolters Kluwer ‑ Medknow 119 Abstract Review Article INTRODUCTION The skeleton represents one of the most common sites of tumor metastasis. Sacral metastases are an uncommon presentation of metastatic disease in the spine; however, they represent about half of all sacral tumors. [1] They present a diagnostic challenge and incur significant morbidity and mortality. The distribution of hematopoietic marrow plays an important role in the distribution of bone malignancy. The sacrum, as a site of hematopoietic or red marrow in the adult, is a common site for metastatic disease as well as hematologic malignancies including myeloma, Ewing’s sarcoma, and lymphoma. Metastatic lesions are usually osteolytic, although sclerotic lesions can be observed, especially from prostate or breast carcinoma. Contiguous spread from advanced pelvic neoplasms to the sacrum is not uncommon and may be seen with rectal, uterine, prostate, and bladder carcinoma. [1] Spinal infiltrates occur in 5%–10% of all cancer patients, with sacral metastases representing a minority of spinal secondaries. [2] Intradural tumors can cause drop metastases within the thecal sac, which grow into the sacrum. [3-5] Breast, lung, renal, thyroid, and prostate tumors contribute the predominant primary sources. [2,6,7] Other primaries may include melanoma, lymphoma, and tumors of unknown origin as shown in Table 1. INVESTIGATIONS Imaging Plain radiographs have a low accuracy of diagnosis because it is difficult to evaluate the sacral spine on plain films. It is often obscured by the overlying stool or bowel gas. [3] The sacrum does not have a distinctive trabecular pattern that can be assessed for disruption. [4] Thus, conventional radiography has a limited sensitivity and is only significant when it is abnormal, showing the degree of osteolysis and sclerosis and gross calcification or ossification within bone or adjacent soft tissue, or a pelvic mass. [7-10] The absence of the sacral foramina and the sacro-iliac This review article endeavors to provide an update on the current concepts pertaining to the presentation, investigation, and management of sacral metastases. A review of the English language literature from 1995 to 2015 was undertaken. PubMed electronic database, SCOPUS, EMBASE, Medline OVID, and Cochrane database were searched to identify relevant studies using the terms “sacral metastases” and “metastatic sacral tumours.” Sacral metastasis can present in a variety of ways. Pain in the sacral region can be associated with neurology and mechanical instability. Multidisciplinary involvement is crucial to thoroughly work up the patient. This involves a variety of imaging modalities. Radiotherapy is often used as the first-line treatment. Surgical intervention is based on tumor location, infiltration of surrounding structures, expected outcomes based on primary malignancy, and pelvic stability. Adjuvant cryosurgery and radiosurgery have demonstrated promising results. This is a challenging entity to appropriately diagnose and treat. An appreciation of the disease stage, the clinical burden, and the implications for the individual patient are necessary to deliver patient-centered care. Keywords: Metastasis to the sacrum, sacral metastasis, sacral tumor Address for correspondence: Ms. Evelyn P. Murphy, Department of Trauma and Orthopaedics, Saolta Hospital Group, Galway, Ireland. E‑mail: [email protected] Access this article online Quick Response Code: Website: www.jnsbm.org DOI: 10.4103/jnsbm.JNSBM_104_18 This is an open access journal, and arcles are distributed under the terms of the Creave Commons Aribuon‑NonCommercial‑ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non‑commercially, as long as appropriate credit is given and the new creaons are licensed under the idencal terms. For reprints contact: [email protected] How to cite this article: Murphy EP, Lyons RF, Curtin M, Munigangaiah S, McCabe J, Devitt A. Current concepts and an update on the surgical management of metastasis to the sacral spine. J Nat Sc Biol Med 2019;10:119-26. Current Concepts and an Update on the Surgical Management of Metastasis to the Sacral Spine Evelyn P. Murphy, Rebecca F. Lyons, Mark Curtin, Sudarshan Munigangaiah, John McCabe, Aiden Devitt Department of Trauma and Orthopaedics, Saolta Hospital Group, Galway, Ireland

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Page 1: Current Concepts and an Update on the Surgical Management

119© 2019 Journal of Natural Science, Biology and Medicine | Published by Wolters Kluwer ‑ Medknow 119

Abstract

Review Article

IntroductIon

The skeleton represents one of the most common sites of tumor metastasis. Sacral metastases are an uncommon presentation of metastatic disease in the spine; however, they represent about half of all sacral tumors.[1] They present a diagnostic challenge and incur significant morbidity and mortality.

The distribution of hematopoietic marrow plays an important role in the distribution of bone malignancy. The sacrum, as a site of hematopoietic or red marrow in the adult, is a common site for metastatic disease as well as hematologic malignancies including myeloma, Ewing’s sarcoma, and lymphoma. Metastatic lesions are usually osteolytic, although sclerotic lesions can be observed, especially from prostate or breast carcinoma. Contiguous spread from advanced pelvic neoplasms to the sacrum is not uncommon and may be seen with rectal, uterine, prostate, and bladder carcinoma.[1]

Spinal infiltrates occur in 5%–10% of all cancer patients, with sacral metastases representing a minority of spinal secondaries.[2] Intradural tumors can cause drop metastases within the thecal sac, which grow into the sacrum.[3-5] Breast, lung, renal, thyroid, and prostate tumors contribute the

predominant primary sources.[2,6,7] Other primaries may include melanoma, lymphoma, and tumors of unknown origin as shown in Table 1.

InvestIgAtIons

ImagingPlain radiographs have a low accuracy of diagnosis because it is difficult to evaluate the sacral spine on plain films. It is often obscured by the overlying stool or bowel gas.[3] The sacrum does not have a distinctive trabecular pattern that can be assessed for disruption.[4] Thus, conventional radiography has a limited sensitivity and is only significant when it is abnormal, showing the degree of osteolysis and sclerosis and gross calcification or ossification within bone or adjacent soft tissue, or a pelvic mass.[7-10] The absence of the sacral foramina and the sacro-iliac

This review article endeavors to provide an update on the current concepts pertaining to the presentation, investigation, and management of sacral metastases. A review of the English language literature from 1995 to 2015 was undertaken. PubMed electronic database, SCOPUS, EMBASE, Medline OVID, and Cochrane database were searched to identify relevant studies using the terms “sacral metastases” and “metastatic sacral tumours.” Sacral metastasis can present in a variety of ways. Pain in the sacral region can be associated with neurology and mechanical instability. Multidisciplinary involvement is crucial to thoroughly work up the patient. This involves a variety of imaging modalities. Radiotherapy is often used as the first-line treatment. Surgical intervention is based on tumor location, infiltration of surrounding structures, expected outcomes based on primary malignancy, and pelvic stability. Adjuvant cryosurgery and radiosurgery have demonstrated promising results. This is a challenging entity to appropriately diagnose and treat. An appreciation of the disease stage, the clinical burden, and the implications for the individual patient are necessary to deliver patient-centered care.

Keywords: Metastasis to the sacrum, sacral metastasis, sacral tumor

Address for correspondence: Ms. Evelyn P. Murphy, Department of Trauma and Orthopaedics, Saolta Hospital Group,

Galway, Ireland. E‑mail: [email protected]

Access this article online

Quick Response Code:Website: www.jnsbm.org

DOI: 10.4103/jnsbm.JNSBM_104_18

This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution‑NonCommercial‑ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non‑commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms.

For reprints contact: [email protected]

How to cite this article: Murphy EP, Lyons RF, Curtin M, Munigangaiah S, McCabe J, Devitt A. Current concepts and an update on the surgical management of metastasis to the sacral spine. J Nat Sc Biol Med 2019;10:119-26.

Current Concepts and an Update on the Surgical Management of Metastasis to the Sacral Spine

Evelyn P. Murphy, Rebecca F. Lyons, Mark Curtin, Sudarshan Munigangaiah, John McCabe, Aiden Devitt

Department of Trauma and Orthopaedics, Saolta Hospital Group, Galway, Ireland

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Murphy, et al.: Sacral metastasis concepts: Update

Journal of Natural Science, Biology and Medicine ¦ Volume 10 ¦ Issue 2 ¦ July-December 2019120

joint, as well as the posterior iliac wing, is considered a radiographic sign of lytic lesions of the sacral ala.[5,10]

Computed tomography (CT) has an important role to play in defining bony anatomy and in the planning of reconstructive procedures. It offers the opportunity of three-dimensional reconstruction of the image and also can improve the accuracy of needle biopsy, increasing the diagnostic value of the procedure.[6] Involvement of the sacroiliac joints and the extent of the tumor are important factors in planning because they influence outcomes and strategy.[11]

Magnetic resonance imaging (MRI) is invaluable in visualizing the relationship between the tumor, bone, and soft-tissue structures. Diffusion-weighted MRI imaging and T1 and T2 sequences are sensitive for the detection of pathological lesions and may be relied upon to distinguish between insufficiency fractures as well.[4] CT angiography and MR angiography prove useful in delineating the vessel architecture.

Nuclear bone scan (scintigraphy) is useful to determine if a lesion is monostotic or polyostotic. However, it lacks specificity in identifying the nature of the lesion in comparison to MRI.[7] It is a cost-effective tool as part of a larger workup for systemic disease rather than a standalone tool.[8]

Single-photon emission CT (SPECT) may be useful in identifying and distinguishing benign from metastatic lesions that are difficult to appreciate on CT, MR, or plain films.[12,13]

In cases of recurrent cancer after previous surgery and radiation, positron emission tomography can be useful in determining which part of the CT or MRI image is tumor recurrence and what is just scar tissue.[7] Angiography facilitates the

embolization of feeding vessels, potentially reducing the risk of intraoperative blood loss.

BiopsyThe diagnosis may be established by obtaining a tissue sample. Three main options exist for obtaining this sample. Biopsies may be obtained through open incisional procedures, percutaneously (tru-cut needle), or with CT guidance. Percutaneous CT-guided biopsy provides the least risk and is the method of choice.[14,15] In general, the surgeon who performs the definitive tumor resection should perform or direct the biopsy procedure. The needle puncture should be planned along the estimated surgical incision to facilitate the resection of the bioptical tract and tumor at the time of surgery.[16]

clInIcAl PresentAtIon

The complexity of the sacral neurological anatomy and its close relationship with vital organs lead to a variety in the presentation of sacral metastases. Diagnosis may be delayed. Patients may present to a variety of specialists including orthopedic surgeons, urologists, plastic surgeons, radiotherapists, and colorectal surgeons.[16-18] Sacral neoplasms can cause ambiguous symptoms in the early stages, until they expand out of the sacral cortex limits. Symptoms of bowel, bladder, epigastric, and sacral plexus compression become evident later and often the patient has been treated for more common pathologies such as lower-back pain and constipation.[1,16,18,19] Ozdemir et al.[6] reported distal organ involvement and widespread spinal metastases in 61% and 43%, respectively, at the time of diagnosis. The sacral canal has wide dimensions, which may permit tumor expansion. Pain may emanate from periosteal stretching due to local tumor expansion

Table 1: Sacral primary and secondary tumors and their surgical management

References Type Evidence level Numbers in study AssessmentQuraishi et al., 2012 Review 1 N/A Review of medical and surgical managementFeiz-Erfan et al., 2012 Clinical article IV 25 Case series of 25 patients’ surgical experienceVarga et al., 2009 Clinical review/narrative V N/A Expert opinion/narrativeBakx et al., 2004 Expert opinion/case report

seriesV 26 Case series review of surgical technique

Ozdemir et al., 1999 Retrospective review/case series

IV 65 Surgical management of both primary and secondary sacral tumors

Arıkan et al., 2014 Retrospective review/case series

IV 73 Primary, metastatic sacral tumors and infections. Review of characteristics and treatments

Gerszten et al., 2007 Prospective cohort II 393 patients/103 sacral lesions

Evaluation of radiosurgery; outcomes and complications

Nader, Rhines, and Mendel, 2004

Case series/literature review

III 19 Surgical treatment of sacral metastatic lesions; outcomes

Akasu et al., 2007 Prospective case series III 44 Evaluation of abdominal sacral resection for locally recurrent rectal carcinoma

Nebreda, Vallejo, Aliaga, and Benyamin

Case report V 1 Case report on technique and outcomes of percutaneous sacroplasty under fluoroscopy

Lee et al., 2013 Case report V 1 Case report of management of sacral metastasis using combined technique of embolization, cryoablation, alcohol ablation, and sacroplasty

Masala et al., 2006 Case report V 1 Case report on combined CT and fluoroscopy to perform sacroplasty

CT: Computed tomography, N/A: Not available

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or as a result of instability. Tumor may infiltrate nerve roots, which can lead to radiculopathy. This may radiate unilaterally or bilaterally. The natural history of an expanding sacral lesion is usually characterized by sensory and multiradicular deficits that can progress to a motor deficit and eventually cause bladder, bowel, and/or sexual dysfunction.[1,5,6,20] An increase in pain associated with mobility is concerning for a pathological fracture of the sacrum. Thus, there exists a complex constellation of symptoms and signs which can herald infiltration.

MAnAgeMent strAtegIes

The management goals of metastatic disease to bone are to maximize pain control, achieve functional preservation and restoration, stabilize the skeleton, and control the tumor locally.[11] Asymptomatic bone metastasis with no risk of pathological fracture or spinal instability is often observed.[21-23] The choice of treatment depends on several factors, including the overall clinical condition, life expectancy, and quality of life of the patient. Appropriate analgesia, corticosteroids, and systemic bisphosphonates may provide some relief from symptoms.[23-26] However, sacral metastases often present late and carry a significant burden of disease.

For metastatic sacral lesions, the treatment is often palliation, aiming to preserve neurological function while weighing up the potential complications of a surgical intervention. Pain is often quite significant in metastatic sacral disease, and surgery aims to target this. Currently, there are two traditional methods for localized intervention in the case of sacral metastases namely radiotherapy and surgery.[27]

RadiotherapyRadiotherapy may be chosen as the initial therapy for sacral metastases in patients without spinal instability or acute neurological deficit where significant pain reduction and neurological improvement are attainable.[18,19,25,26,28]

Radiosensitivity varies among tumor types. As a general rule, prostate and lymphoid tumors are radiosensitive, breast cancer is 70% sensitive, whereas gastrointestinal and renal cell cancers are radioresistant.[27,29,30] Indications for radiotherapy would include pelvic stability, no major neurological impairment or bony compromise of the canal, no overwhelming mechanical pain, and obviously the presence of a radiosensitive malignancy.[3,28,29]

RadiosurgeryRadiosurgery is an emerging field, which is proving promising in cases where pain is the predominant symptom and further conventional irradiation is not possible. Spinal stereotactic surgery is an emerging form of radiotherapy, which allows precise radiation delivery and high-dose hypofractionation.[4,5,7,24] It is even of benefit in conventionally radioresistant tumors whereby tumoricidal doses can be administered without damage to the adjacent structures.[31] Examples of commercially available systems include the CyberKnife.[4,7,13] A recent study of 500 cases with spinal

metastases, which included 103 sacral cases, demonstrated radiosurgery to be safe with a more durable symptomatic response and local control independent of the histology.[31,32]

Limitations, however, with this technique include inability to deliver radiation to larger lesions and it does not address neurological deficit and spinal instability.

The use of chemotherapy for the management of sacral spinal tumors is unfortunately limited.[33]

surgIcAl tecHnIques

The sacral bone plays an important role in load transmission from the lumbar spine to the pelvic girdle. Resection can disrupt the lumbosacropelvic stability.[16,18,34]

The sacral segment involved, histopathology of the tumor, condition of the peripheral tissues, and survival expectancy contribute to the decision-making process. All patients must be considered on a case-by-case basis. Concerns regarding operative intervention include uncontrollable blood loss if the presacral vertebral venous plexus is opened. Surgeons worry about extensive neurological damage and instability of the pelvic ring. Tumors that extend into the sacrum often have a poor prognosis, and extensive radical resection may not translate into a gain in survival. There may be a potential accompanying decline in the quality of life.[14,17,21,22]

Anatomical considerations include the strong ligamentous structures, the pelvic floor, the sacral canal containing the terminal part of the dural sac, the rich venous plexus (Batson), and the autonomic nerve system. The rectum is also in close proximity.[30,35] Thus, it is easy to imagine why it is difficult to obtain en bloc resection with adequate margins.[20,34] The goals of resection revolve around palliation as opposed to complete curative resection. The margins, therefore, are predominantly intralesional.[6]

Essentially, it is necessary to preserve the corpus of the first sacral vertebra and the lateral wings of S1 and S2 for stability. If more than this is involved/resected, then complicated osteosynthetic reconstructions are needed to confer stability.[1,20,35]

Operative considerations and approaches of sacral resectionsPreoperative angioembolization of hypervascular metastatic lesions helps reduce blood loss and improves the surgeon’s ability to resect the tumor. Embolization may also cause tumor growth arrest, pain alleviation, and shorter hospital stays. Best results are achieved when surgery is performed within 24–48 h after embolization.[36,37] The morbidity and mortality are greatly dependent on prior radiation therapy. If high-dose radiotherapy has been used, then there is an increase in the associated wound healing problems, with input needed from plastic surgical colleagues.[6]

Indications for surgical intervention in sacral malignancy include progressive neurological dysfunction, persistent pain

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unresponsive to radiation therapy, the need for a diagnostic biopsy, and pathologic instability.[1,5,6,15,23,27,30]

For the purposes of operative intervention, tumor location is often characterized by the uppermost level of involvement.[35] Mechanical failure of the lumbosacropelvic junction can give rise to a significant burden of pain, and surgical stabilization targets this. Surgical stabilization with a modified Galveston technique offers symptom control and can restore ambulatory function.[11,20,30,34,35]

One of the problems the surgeon encounters after resection is a potentially significant dead space. The sacral paraspinal muscles may be devitalized. There is a challenge to obtain adequate soft-tissue coverage. Mobilization of healthy tissue into the defect is very important.

Innervation to the sacral plexus is rather complicated and forms part of the decision-making process in resection. S1 contributes to the sciatic nerve and is motor and sensory to the leg. S3 is for anal function, S4 for sexual function, and S2–S5 together give sensation to the saddle area.[17,38-40] Careful consideration to the overall stability of the pelvis must be considered, with the extent of the resection in mind. A modified Galveston technique may be employed. Allen and Ferguson[41] originally described the technique in the treatment of scoliosis, to achieve rigid spinal-pelvic fixation in patients with lumbosacral neoplasms. Jackson and Gokaslan,[11] however, modified it to achieve fixation by intraoperative placement of contoured titanium rods bilaterally into the ilium. These rods were attached to the lumbar spine with pedicle screws and subsequently cross-linked with arthrodesis being performed. Kazim et al.[34] have also described a polyaxial pedicle screw construct which has been successfully used for lumbo-iliac fixation after sacral tumor resection. This case series involved five sacral tumors, which underwent surgical resection. Reconstruction was done with hardware using vertical rods placed alongside the spine bilaterally, transfixing monoaxial and polyaxial pedicle screws in the lower lumbar levels and polyaxial screws into the ilium bilaterally. Cross-links were also used to connect the two vertical members, thus enhancing the biomechanical stability of the construct. Use of autologous bone grafts was relied upon to fill the gap created by sacral resection. They had no instrumentation failure, and the continuity of the spine and pelvis was well established with the instrumentation and autografts.

Operative approach of the resection S1‑S2‑S3 considerationsThe majority of the sacral metastases involve S1–S3, so aggressive intralesional resection is often applied instead of en bloc resection.[25,35,38,42]

In general, a combined anterior and posterior approach is employed. The tumor location will have an impact on the extent of the dissection. The goal of the anterior approach is to ligate the main tumor vessels, to expose the anterior aspect of the tumor, and to help identify the proper plane of the resection

at the anterior cortex of the involved bony structures.[19] An omental transposition may be utilized to fill the defect. If necessary, a colostomy, urinary deviation, or both are made. The dissection should reach the pelvic floor, and the abdomen should be reviewed for metastases. The dorsal approach allows for the laminectomy and identification of the sacral nerve roots. Reconstruction of the pelvic floor ensues using the omentum with or without a mesh. Gluteus maximus or abdominal myocutaneous flaps have been proposed for the definitive closure of large defects, and occasionally a transpelvic rectus abdominus musculocutaneous flap can be used.[18,20,27,33]

Operative approach of sacral resection S4–S5This dissection is often possible from the anterior side. However, there is no need to turn the patient; instead, the dissection is carried from inside the perineum.[18,20,39,42] It again follows as above dissecting out the lesion, with care given to the sacral nerves. The nerves to be sacrificed will be identified in advance. Pelvic stabilization is often not needed if the integrity of sacro-iliac joints and pelvic ring is maintained.[14]

SacroplastySacroplasty may represent a minimally invasive alternative to open procedures, but is only applicable in cases without instability or neurologic compromise. Only case report data are available, which report improvement in pain relief with an increase in patient mobility.[40] Patchell et al.[40] Patchell et al., published on the advance of compared to radiotherapy alone for spinal metastases regarding the ability to walk.[40,41,43] Other techniques in poor surgical candidates are emerging. Percutaneous sacral cryoablation coupled with alcohol ablation followed by sacroplasty was used in a poor surgical candidate with metastatic renal cell carcinoma. Adequate neurological monitoring of neurovascular structures throughout the procedures is essential. However, the instillation of alcohol is unpredictable, and patients should be counseled appropriately.[43] Good outcomes were achieved in that case, with the pathological fracture stabilized, neurological deficit avoided, and the patient being successfully ambulating again. Sacroplasty and iliac osteoplasty may be performed under combined fluoroscopy and CT guidance.[44] Masala et al.[44] described a technique whereby the targeted lesion was marked using Kirschner wires (K-wires) placed under CT guidance. Following this, biopsy needles were advanced over the K-wires to facilitate the accurate instillation of polymethyl methacrylate. The patient in question experienced immediate relief. Sacroplasty is a well-recognized technique for insufficiency fractures; however, its benefits in pathological fractures are being realized.

The majority of sacral metastases involve S1–S3.[1,17] En bloc resection, however, is too morbid to consider for palliation.[22] In rare instances where just the distal sacrum is involved, en bloc resection with preservation of nerves S1–S3 may be considered. This achieves optimal local control with a diminished risk of neurological deficit.[20,23,27]

Todd et al.[45] followed up 53 patients who underwent major sacral resection over a 10-year period. In patients with a

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unilateral sacrectomy, in whom the contralateral sacral nerves were preserved, normal bowel and bladder functions was retained in 87% and 89%, respectively. In patients who had bilateral S2–S5 nerve roots sacrificed, all had abnormal bowel and bladder functions. In patients who had bilateral S3–S5 resection, normal bowel and bladder functions were retained in 40% and 25%, respectively. In patients who had bilateral S4–S5 resection, with preservation of the S3 nerves bilaterally, normal bowel and bladder functions were retained in 100% and 69%, respectively. These results show that unilateral resection of sacral roots or preservation of at least one S3 root in bilateral resection preserves bowel and bladder functions in the majority of patients.[45]

Feiz-Erfan et al.[27] reviewed 25 patients undergoing surgery for metastatic sacral tumors. They performed piecemeal surgery in the majority, with a minority performed en bloc. There was a high complication rate of 40%. This group noted that patients who had undergone prior radiotherapy had a significantly increased risk of complications Table 1 highlights some of the key articles in the current literature regarding sacral primary and secondary tumors and their surgical management. Emerging techniques such as sacroplasty are showing promising outcomes. The level of evidence supporting this technique is Level IV. There have been a number of case reports in the literature; however, there does not exist any randomized controlled trials to date on this technique. As imaging techniques continue to advance, techniques such as sacroplasty will also continue to improve.

coMPlIcAtIons of PAtIents undergoIng surgIcAl MAnAgeMent

Complex surgical techniques, long operating times, and intraoperative bleeding contribute to complications. Death, unplanned nerve injury, rectal perforations, bladder complications, cerebrospinal fluid leak, and wound infections are common complications.[1,6,20,27,34,35] Resection often leaves a large potential space in the perineum which is filled with omentum or rectus flap. The closure of the wound can be difficult and predispose to hematomas, increasing blood loss and deep infections. The large surface area of the wounds is prone to infection, leading to potential wound breakdown. This needs to be managed conjointly with plastic surgeons and the primary surgeons to achieve optimal outcomes.

Rehabilitation following sacrectomyIt is recommended that rehabilitation be instigated immediately in the postoperative period with motor and sensory evaluation of the lower limbs. Physical and occupation therapists will aid the patient in making functional gains.[3] The level of neurological deficit will determine the clinical and functional outcome, which will contribute to the patient-experienced outcomes. As mentioned above, bowel and bladder problems are very common postsurgery. Patients, however, with intact L5 nerves can usually walk without external support.

Depression and other psychological conditions often develop in patients with severe functional loss postsacrectomy. These patients will require multidisciplinary and psychosocial support.

outcoMes

Recurrence and survival rates are multifactorial. Ozdemir et al.[6] reported on a 19% recurrence with a 23% complication rate following surgery (in 34 cases). Nader et al.[46] investigated 19 patients who underwent resection and 8 patients (42%) had an improvement, while 3 (16%) had not improved. The mean survival rate was 21.8 months for this cohort. Survival rates vary from 6 to 36 months.[13,15] This includes patients who underwent radiosurgery and surgical resection. Resection of certain tumors, which infiltrate the sacrum, can confer significant longevity to the patient. Locally advanced rectal carcinoma may infiltrate the sacrum. Milne et al.[39] reviewed 240 exenteration patients with locally advanced rectal carcinoma, 79 underwent sacrectomy, with 49 for recurrent rectal cancer. Achievement of clear operative margins (R0) conferred a large and significant benefit for disease-free survival compared with R1 (microscopic margins) and R2 resections (macroscopic margins) (median 45 months vs. 19 and 8 months, respectively; P = 0.045). Complications were reported in 40 (82%) patients, with major and minor complications in 19 (39%) and 38 (78%) patients, respectively. The proximal level of the sacrectomy (high vs. low) did not significantly impair the ability to achieve a clear margin and was not associated with an increase in major or minor complications. Extended pelvic exenteration involving sacrectomy has excellent R0 margins and survival rates for recurrent rectal cancer.[39] Older presentations had shown that radiotherapy alone was as effective as a combination of decompression surgery with adjuvant radiotherapy; updates in recent literature have demonstrated that decompressive surgery with/without reconstruction and stabilization followed by postoperative radiotherapy is superior than radiotherapy alone.[25,32] The Spine Oncology Study Group defines spine instability as the “loss of spinal integrity as a result of a neoplastic process that is associated with movement-related pain, symptomatic or progressive deformity and/or neural compromise under physiological loads.” The principles underpinning the Spinal Instability Neoplastic Score will help guide the decision-making process in deeming a lesion stable or unstable. This score is a reliable and reproducible tool.[47] There are major surgeries for which different techniques have been described. Multidisciplinary involvement is key. Buraimoh et al.[48] described the results of a small case series of three patients treated with spinopelvic fixation. One patient had a neurologic deficit and two remained independently mobile. Each treatment carries its own morbidity. Balagamwala et al.[49] described the phenomenon of a pain flair after stereotactic radiotherapy for the treatment of sacral metastasis.

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cAse PresentAtIon

The following is an example of a case from our institution which demonstrates the presentat ion, diagnosis , multidisciplinary involvement, surgical outcomes, and follow-up. A 66-year-old female presented with a history of Her2-positive, Estrogen receptor/Progesterone receptor (ER/PR)-negative pT2pN2Mo, Grade III infiltrating ductal breast cancer. She was diagnosed with carcinoma in

2011. She underwent a wide local excision with axillary lymph node clearance. This was followed by adjuvant chemotherapy (Taxotere, carboplatin and herceptin (TCH) ×6) and external beam radiotherapy. She was reviewed by general/breast surgeons and kept under review by radiation oncologists. She presented in 2013 with

Figure 1: Magnetic resonance imaging T2‑weighted mid‑sagittal and axial images of lumbosacral spine showing sacral metastasis

Figure 3: Computed tomography image of sacrum showing extensive lytic metastatic lesions in the sacrum with pathological fracture

Figure 2: Magnetic resonance imaging short tau inversion recovery sequence mid‑sagittal images and T1‑weighted axial section showing sacral metastasis

Figure 5: Postoperative anteroposterior radiograph showing lumbopelvic fixation

Figure 4: Computed tomography image of sacrum showing further extensive lytic metastatic lesions in the sacrum with further pathological fractures

Figure 6: Postoperative lateral radiograph showing lumbopelvic fixation

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deranged liver function tests and malaise. She went on to develop severe lumbar and pelvic pain with radiculopathy worse on the right side versus the left. She needed the assistance of a frame for mobilization secondary to severe pain. Imaging included isotope bone scan, CT, and MRI. CT demonstrated a pathological fracture of the sacrum secondary to metastasis from breast carcinoma. Her MRI confirmed diffuse spinal metastases with the addition of a T10–T12 metastatic infiltration. There was diffuse infiltration of the right-sided S1 nerve root in keeping with the patient’s complaints. Her case was discussed at a multidisciplinary team meeting, and the decision to proceed with surgery was undertaken. She had an incision from L3 to the sacrum to gain access to the field. A modified Galveston technique was employed. The right-sided S1 nerve was decompressed given the extent of the infiltration. She was discharged after a total inpatient stay from diagnosis of metastasis to surgery of 15 days. She required a blood transfusion of two units in the postoperative period. Physiotherapy, occupational therapy, and the pain teams were integral to facilitating the accelerated discharge of this patient back to her home. She is now 19 months postsurgery and is mobilizing pain free using a stick for long distances only. Figures 1-8 depict CT scans demonstrating the stability of the fixation from her diagnosis to surgery and postoperative follow-up.

conclusIon

Sacral metastasis is a complex disease, and each case must be considered on an individual basis with the input of multidisciplinary team involvement.

The sacral spine is the least common site in the spine for metastasis to occur. Metastatic lesions are usually osteolytic, although sclerotic lesions can be observed, especially from prostate or breast carcinoma. Contiguous spread from advanced pelvic neoplasms to the sacrum is not uncommon and may be seen with rectal, uterine, prostate, and bladder carcinomas. Pain is the predominant symptom and may be radicular reflecting

the infiltration of nerves. It may be associated with mobility, implying an instability component. Pathological fractures are a prominent feature of this disease process. The aims of surgery for metastases are the palliation of pain, which can be significant, histological diagnosis, neurological decompression, debulking, and stabilization of the lumbopelvic structures.

Radiotherapy is the mainstay of treatment for stable lesions. Radiosurgery has been shown to be promising, and sacroplasty provides good pain relief for those with no instability or neurological symptoms.

Palliative surgery is offered when indications such as intractable pain and progressive neurological deficit ensue or lumbosacropelvic instability occurs. The modified Galveston technique is an appropriate fixation method. Angioembolism can be used as an adjunct. This review details the pathology, investigations, clinical picture, and treatment options available for sacral metastases.

Declaration of patient consentThe authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorshipNil.

Conflicts of interestThere are no conflicts of interest.

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