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Spinal chondrosarcoma
Introduction
Chondrosarcomas are primary malignant tumors that may arise from the cranial skull base or axial skeleton and are characterized by neoplastic growth of hyaline cartilaginous tissue. Primary spinal tumors such as chondrosarcoma only account for about 4% to 13% of all primary bone tumors, but their ability to cause compression of the spinal cord and propensity to recur make them difficult to manage. Primary malignant bone tumors include chordoma, osteosarcoma, and chondrosarcomas, with chondrosarcomas being the most infrequent of these. Chondrosarcomas are a heterogeneous group of tumors with five known subtypes, as follows: conventional, dedifferentiated, clear-cell, mesenchymal, and myxoid. An analysis of the SEER database found that the dedifferentiated subtype had the highest rate of metastasis and shortest progression-free survival among all of the subtypes. There are no U.S. Food and Drug Administration (FDA)-approved drugs to combat this aggressive tumor, and unresectable chondrosarcomas have a 5-year survival rate of just 2%. In the past decade there has been a surge of interest in identifying molecular targets for various tumors including chondrosarcoma. Many mutations and pathways have been studied for their role in development and progression of oncogenesis in patients with chondrosarcoma, including isocitrate dehydrogenase (IDH) mutations, sonic hedgehog (SHH) pathway, and the PI3K–Akt–mTOR pathway. Despite an increased understanding of potential targets for chondrosarcoma treatment, patients must all undergo staging of their tumor with consideration of potential en bloc curative resection. Enneking developed a system for staging of sarcomatous tumors that incorporates tumor grading and compartment. This system divides benign tumors into three stages and malignant tumors into four stages. Although the Enneking staging system was created for long bone tumors, it has been applied to tumors of the mobile and fixed spine ( Table 46.1 ). The sin qua non of surgical management for these tumors is en bloc curative resection, but due to the rarity of these lesions, few surgeons have adequate expertise to complete these challenging surgeries. These cases are typically referred to academic tertiary care institutions with multidisciplinary teams able to manage these complex patients.
Example case
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Chief complaint: back and leg pain
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History of present illness: This is a 65-year-old female with back pain who presents after a computed tomography (CT)-guided biopsy of a T10 lesion that demonstrated chondrosarcoma ( Fig. 46.1 ).
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Medications: acetaminophen
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Allergies: no known drug allergies
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Past medical history: none
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Past surgical history: none
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Family history: no history of malignancies
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Social history: none
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Physical examination: awake, alert, and oriented to person, place, and time; cranial nerves II–XII intact; bilateral deltoids/triceps/biceps 5/5; interossei 5/5; iliopsoas/knee flexion/knee extension/dorsi, and plantar flexion 5/5
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Reflexes: 2+ in bilateral biceps/triceps/brachioradialis with negative Hoffman; 2+ in bilateral patella/ankle; no clonus or Babinski; sensation is intact to light touch
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Laboratories: all within normal limits
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| Preoperative | ||||
| Additional tests requested |
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| Surgical approach selected | En bloc T10 spondylectomy, T7-L2 posterior instrumentation and fusion | En bloc T10 spondylectomy, T8-12 posterior fusion | En bloc T10 posterolateral extracavitary resection with T9-T11 posterior fusion | En bloc T10 vertebrectomy via bilateral extracavitary approach with anterior reconstruction and T8 12 fusion |
| Goal of surgery | En bloc resection, reconstruction of the spine, stabilization | En bloc resection | En bloc resection, spinal fusion | En bloc resection, stabilization |
| Perioperative | ||||
| Positioning | Prone on Jackson table | Prone | Prone on Jackson table | Prone on Jackson table |
| Surgical equipment |
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| Medications | Maintain MAP | Steroids, cisplatin (1:1 with distilled water) | Steroids, maintain MAP, osteoporotic medication if needed | Tranexamic acid, MAP >90 |
| Anatomical considerations | Pleura, spinal cord | T10 vertebral level, T10 nerve roots, great vessels | T10 vertebral level, Aorta, azygous vein, spinal cord, dura, pleura | Aorta, pleura, dura/spinal cord, inferior vena cava |
| Complications feared with approach chosen | Violation of the tumor, spinal cord injury | Injury to spinal cord/great vessels/dura | Vascular injury, spinal cord injury, dural tear and CSF leak, pneumothorax, lung injury | CSF leak, pleural injury, spinal cord injury/infarction, vascular injury |
| Intraoperative | ||||
| Anesthesia | General | General | General | General |
| Exposure | T7-L2 | T8-12 | T9-T11 | T8-12 |
| Levels decompressed | T9-10 | T10 | T10 | T10 |
| Levels fused | T7-L2 | T8-T12 | T9-11 | T8-12 |
| Surgical narrative | Positioned prone, reference array attached and intraoperative CT once appropriate levels exposed, fuse CT with preoperative MRI, place pedicle screws from T7-L2 with navigation but skip T10 pedicles, expose bilateral 3–4 cm of T9-T10 ribs, dissect bilateral T10 ribs from pleura, cut 3 cm of the body of bilateral T10 ribs, bilateral facetectomy at T9-10 and T10-T11, complete T10 laminectomy and inferior T9 laminectomy, cut bilateral T10 pedicles flush with vertebral body, cut T10 nerves after tying with silk ties, dissect between pleural and vertebral body until ventral vertebral body reached bilaterally to create circumferential plane between vertebral body and great vessels anteriorly and lungs laterally, pass Silastic sheath around vertebral body from one side to other to protect vital structures, separate ventral dura from PLL, pass Tomita saw around disc space underneath ventral dura from one side to the other and then around ventral vertebral body back to side, discectomy using Tomita saw at T9-10 and T10-11, place temporary rod on one side, completely disconnect T10 vertebral body using #15 blade to disconnect discs/PLL/ALL, rotate and deliver T10 vertebral body away from temporary rod, inspect that no end plate violation occurred and tumor was not entered, place expandable cage, ensure position and size with fluoroscopy, place permanent rods on contralateral side and secure in place, connect two additional side rods onto primary rods to achieve four-rod construct, final tighten screws, split fibula graft placed in posterior defect to protect spinal cord and enhance fusion, place cross-link connectors between rods and final tighten, decorticate and place morselized allograft over all exposed bony surfaces, pulse lavage, place vancomycin powder, close in anatomical layers with plastic surgery with subfascial drains | Positioned prone, posterior median longitudinal incision, pedicle screws from T8 to 9 and T11-12 bilaterally, place right titanium rod, remove posterior structures of T10 with ultrasonic bone scalpel, ligate left T10 nerve root with nonabsorbable suture and section with scalpel, protect paravertebral muscles with saline-soaked gauze, resect part of the T10 rib, monitor for pleural defect, dissect bluntly between vertebral body and surround tissues including great vessels, place drain between vertebral body and great vessels, pass threadwire saw through the drain, divide T10 vertebral body with saws after confirming appropriate location of saws, remove vertebral body from left side by rotating the dissociative vertebral body, place titanium mesh cage filled with allograft bone, place contralateral rod with cross connectors, confirm location of internal fixation with x-ray, close in layers | Preoperative level marking using medical markers followed by AP and lateral x-rays to confirm level, position prone, confirm level with fluoroscopy, midline incision from one level above and below tumor site, subperiosteal dissection to exposure posterior elements including facet capsule/transverse processes/costovertebral joints/medical 4 cm of ribs, register navigation, place drill holes under navigation guidance one level above and below, decorticate spinous process/lamina/facet joints, T10 laminectomy as well as bottom of T9 and top of T11, resect ligamentum flavum and bilateral transverse processes of T10, preserve T10 nerve root if possible, remove bilateral T10 pedicles and superior articular facets with Leksell rongeur, remove T9-T10 and T10-T11 discs with annulotomy followed by discectomy using osteotome and pituitary rongeurs, slide surgical gauze to anterior aspect of vertebral body, separate the vertebral body using a 0.25-inch osteotome and high-speed drill, place screws on ipsilateral side with slightly kyphotic rod, same technique on opposite side until vertebral body separated, completely dissect PLL at T10 level, curettage inferior end plate of T9 and superior end plate of T11, separated 10th rib head from underlying pleura, resect rib 4 cm lateral to costovertebral junction using Kerrison rongeur, remove vertebral body en bloc by pushing it laterally and backward and avoid tension on the cord, place expandable cage of appropriate size filled with bone graft, place screws and rods on this side, intraoperative spin and fluoroscopy to confirm hardware location, place autograft on decorticated bone, closure in layers with subfascial drain | Position prone, plan incision with intraoperative x-ray, midline incision from T8 to 12, subperiosteal dissection, confirm levels with x-ray, cannulate pedicle screws T8-9 and T11-12 using anatomical landmarks, place screws in T8 and T12 for temporary rod, dissect laterally to expose T9 and T10 ribs and resect T10 ribs at angle by disarticulating from joint, transect bilateral T10 nerve roots proximal to dorsal root ganglion by first temporarily ligating nerve root containing radicular artery and running baseline MEP, circumferential dissection around T10 vertebral body paying attention to aorta and pleura, place remainder of screws, check position on x-rays, vertebroplasty trough fenestrated screws if poor bone quality, rods placed and distract, radical discectomies at T9-10 and T10-11, remove entire T10 vertebrae, prepare end plates, place titanium expandable cage with fibular allograft that is sized and in midline of anterior column, confirm position with x-ray, place final rods and compress, closure in layers with drain |
| Complication avoidance | Surgical navigation, fuse intraoperative CT with preoperative MRI, sacrifice T10 nerve roots, Silastic sheath to protect vital structures before using saw, discectomy with Tomita saw, temporary rods to stabilize spine, inspect for tumor violation, en bloc resection, four-rod construct, use split fibular graft, plastics surgery closure | Placement of temporary unilateral rod, ligate T10 nerve roots retract paraspinal muscles with saline-soaked gauze, use of a drain to safely place wired saws, en bloc resection | Preoperative level marking, surgical navigation, attempt to save T10 nerve root, protect anterior structures with surgical gauze, alternate rod placement to prevent spine translation after corpectomy, use rib for graft material, en bloc resection | Anatomical placement of pedicle screws, temporary rod, transect bilateral T10 nerve roots after confirming by temporarily ligating and running MEP, vertebroplasty if necessary, en bloc resection |
| Postoperative | ||||
| Admission | ICU | ICU | Floor | ICU |
| Postoperative complications feared | Pleura violation, hardware migration, wound infection | CSF leak, neurological deficit, spinal instability | CSF leak, neurological deficit, hardware malposition, pneumothorax | CSF leak, spinal instability, nonunion |
| Anticipated length of stay | 3–4 days | 10 days | 3–4 days | 3–5 days |
| Follow-up testing | Standing x-rays before discharge and 3 months after surgery |
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CT T-spine within 1 day of surgery |
| Bracing | None | Thoracic brace for 3-4 weeks | None | None |
| Follow-up visits | 2 weeks, 3 months after surgery | CT and MRI at 3 and 6 months after surgery, followed by 6 month intervals for next 2 years, then annually | 10–14 days, 4 weeks, 3 months, 6 months, 1 year after surgery | 3 weeks after surgery |
ALL , Anterior longitudinal ligament; AP , anteroposterior; CSF , cerebrospinal fluid; CT , computed tomography; DEXA , dual-energy x-ray absorptiometry; ICU , intensive care unit; IOM , intraoperative monitoring; MEP , motor evoked potential; MIS , minimally invasive surgery; MRI , magnetic resonance imaging; PET , positron emission tomography; PLL , posterior longitudinal ligament; SSEP , somatosensory evoked potential.
Table 46.1
Summary of Enneking Surgical Staging Score
| Surgical Grade (G) | Surgical Sites (T) | ||||
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| Low G1 | High G2 | Intracompartmental (T1) | Extracompartmental (T2) | ||
| Secondary chondrosarcoma | Primary chondrosarcoma | Intraosseous | Soft-tissue extension | ||
| Chordoma | Classic | Intraarticular | Extrafascial planes or spaces | ||
| Fibrosarcoma | Pleomorphic liposarcoma | Superficial to deep fascia |
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| Giant-cell tumor, bone | Hemangiopericytoma | Paraosseous | |||
| Hemangiopericytoma | Osteosarcoma | Intrafascial compartments | |||
| Kaposi sarcoma | Radiation sarcoma | ||||
| Atypical malignant fibrous histiocytoma | Paget sarcoma | ||||
| Myxoid liposarcoma | Neurofibrosarcoma | ||||
| Synovial sarcoma | |||||
| Rhabdomyosarcoma | |||||
| Surgical Stages | |||||
| IA | G 1 | T 1 | |||
| IB | G 1 | T 2 | |||
| IIA | G 2 | T 1 | |||
| IIB | G 2 | T 2 | |||
| III | Any G with metastasis | Any T | |||
Adapted from Enneking WF, Spanier SS, Goodman MA. A system for the surgical staging of musculoskeletal sarcoma. Clin Orthop Relat Res . 1980;106-120.
Differential diagnosis
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Primary bone tumors (chordoma, chondrosarcoma)
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Metastasis
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Multiple myeloma
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Infection
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