Overview
Cervical corpectomy is a ventral cervical spine procedure for safe and effective neural decompression, deformity correction, and mechanical stabilization. The procedure typically involves removal of part or all of the cervical vertebral body over single or multiple segments and may include release of the posterior longitudinal ligament (PLL) and dural and vertebral decompression. The goal is neurologic improvement and bony fusion. Cervical corpectomy can be considered an extension of anterior cervical diskectomy and fusion procedures, and many of the same biomechanical principles apply.
However, cervical corpectomy merits more biomechanical consideration, because it destabilizes the spine and alone introduces kyphosis and deformity. It is therefore almost always necessary that cervical corpectomy be combined with a stable vertebral restoration construct. Fortunately, we now have many options for anterior column reconstruction, including autograft bone, allograft bone, and a variety of cages of different materials. Many are similar to interbody applications, but given the longer graft constructs, column reconstruction carries a higher risk of graft complications, such as graft displacement and migration and adjacent segment degeneration.
Anterior cervical diskectomy and interbody fusion was first introduced in the 1960s for anterior decompression of the spinal cord. A wide variety of operative modifications were made to the initial techniques described by Cloward and by Smith and Robinson. As anterior cervical diskectomies became well accepted, extended approaches led to cervical corpectomies. Cervical corpectomy is now a widely performed procedure used to address pathology anterior to the cervical spinal cord including trauma, tumor, infection, deformity, degenerative disease, and metabolic conditions (i.e., ossified PLL).
Cervical corpectomy can be performed from C3–C7 and involves removal of vertebral body and the adjacent and intervening disk spaces. The lateral vertebral walls can be removed or left alone, as can the PLL and posterior bone, depending on the pathology being addressed. This can be done through a straight median or oblique approach. Cervical corpectomy requires careful and thoughtful surgical technique. Given the vital structures involved during exposure and bony removal, cervical corpectomy can be associated with significant morbidity in comparison with posterior cervical decompression and simple diskectomy. Carotid and vertebral artery, esophageal, tracheal, nerve, and soft-tissue injuries can be devastating if meticulous operative technique is not adhered to.
Cervical corpectomy must be combined with a reconstructive procedure that involves insertion of a graft into the corpectomy defect. The selection of the graft relies on many factors that include surgeon preference, available selection, type of lesion, and need for deformity correction. This choice is then linked to the operative techniques needed to optimize graft positioning and, ultimately, fusion. An internal fixation device, usually a plating system, is often used to further secure the construct, and whether to use posterior supplemental fixation is also an important consideration. These decisions can affect the incidence of acute and remote graft failure, recurrent neurologic symptoms, pseudarthrosis, and instrumentation failure; all of these may require additional surgery or interventions.
Anatomy Review
Exposure for an anterior cervical corpectomy is done through an avascular fascial plane in the anterior triangle of the neck. The incision used is based on the cervical levels involved and the extent of the corpectomy. For a single-level or bilevel corpectomy, a horizontal incision along the skin crease is usually adequate. An oblique/longitudinal incision along the sternocleidomastoid (SCM) may be used for an improved exposure for corpectomy involving three or more levels. The levels and incision should be confirmed with fluoroscopy prior to incision.
Muscles
The operative exposure involves recognizing the anterior border of the SCM and the strap muscles (sternohyoid, sternothyroid, thyrohyoid, and omohyoid; Fig. 17-1 ). The omohyoid is an important landmark muscle that runs from the superior border of the scapula to its insertion into the hyoid bone. It has two bellies with an intermediate tendon. The superior belly of the omohyoid can limit retraction but can be divided in the anterior triangle, although this is rarely necessary. The operative dissection plane is usually between the anterior border of the SCM laterally and the strap muscles medially. The longus colli muscles run from the lateral vertebral bodies out over the cervical bodies and cover the vertebral arteries, sympathetic chain, and cervical nerves.
Vascular Anatomy
Once dissection is carried through the deep cervical fascia investing the SCM and strap muscles, the carotid sheath should be recognized ( Fig. 17-2 ); it can be palpated by the carotid pulse and is retracted laterally. It should be left intact during the dissection because its contents include the carotid artery, internal jugular vein, and vagus nerve. The superior thyroid artery, lingual artery, and facial artery, which are branches of the external carotid artery, may be encountered and ligated, if necessary, at high cervical levels.
The vertebral artery ( Fig. 17-3 ) courses lateral to the vertebral bodies and must be appreciated and protected during the corpectomy procedure. It contributes to the cerebral vasculature and, hence, injury to this artery can result in stroke. The vertebral artery arises from the subclavian artery on each side and enters the transverse process foramen at the level of the sixth cervical vertebra, but it can also enter at levels above and below C6. It courses through the transverse foramina lateral to the vertebral bodies, where it can potentially be injured between levels. It is crucial to be aware of the midline of the vertebral body, because erring too far laterally on either side could risk injury to the vertebral artery.
The sternal notch is used as a useful midline landmark. The uncovertebral joints at each adjoining disk level may be used to mark the midline. The corpectomy is often limited to the central 15 mm of the vertebral body to shield the vertebral artery with a wall of bone. In some instances the vertebral artery may be more medial than usual, and the extent of corpectomy should be limited in such cases. However, in some cases, skeletonization of the vertebral artery or resection of the transverse process is necessary and quite possible (i.e., total spondylectomy). An awareness of the location and course of the vertebral artery cannot be overemphasized.
Visceral Structures
The esophagus and trachea are encased in the pretracheal fascia and are retracted medially during the anterior cervical exposure ( Fig. 17-4 ). The esophagus is soft and easily retracted, but it must be protected during drilling and prolonged retraction, because excessive esophageal retraction and resultant swelling can contribute to swallowing problems postoperatively. Retractors also protect the trachea medially, and given that postoperative swelling of the trachea and esophagus can be mildly annoying to life threatening, these injuries must be recognized and addressed quickly.
Nervous System Structures
Nerves along the approach to the target disk need to be considered (see Fig. 17-2, B ). The ansa cervicalis travels around the strap muscles and can be injured, which can cause some strap muscle paresis that rarely causes functional disability. The laryngeal nerves, both recurrent and direct, can be injured; this may result in temporary or permanent vocal cord paralysis, which can result in aspiration risk. The sympathetic chain ganglia that travel along the longus colli should not be damaged, and injury should be recognized (Horner syndrome). Finally, the exiting nerve roots can be damaged near the vertebral artery with extreme lateral and posterior exposure while removing bone.
Indications and Contraindications
Indications
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Spondylotic myelopathy
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Ossified PLL
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Degenerative or posttraumatic kyphosis
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Vertebral burst or compression fracture
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Vertebral body neoplasm
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Vertebral infection: osteomyelitis, ventral epidural abscess, cases of spondylodiskitis
Contraindications (Relative)
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Cervical stenosis limited to the disk space at single or multiple levels
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Multilevel stenosis with posterior ligamentous hypertrophy
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Extensive continuous ossified PLL
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Predominantly posterior compression
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Significant lordosis
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Developmental stenosis
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Prior anterior neck surgery or severe anterior soft-tissue injury
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Severe osteoporosis
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Previous irradiation
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Aberrant vertebral artery anatomy
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Severe deformity
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Medical comorbidities
Operative Technique
Equipment
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Sliding-top flat operating table
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C-arm fluoroscopy (highly recommended)
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Gel donut, towels, or other head stabilizer
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Traction or tongs (rarely)
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Tape restraints for shoulders
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Bovie with protected tip
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Bipolar electrocautery
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Lateral retractors (Cloward handheld) for dissection and localization
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22-Gauge spinal needle for localization; avoid penetrating uninvolved levels
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Self-retaining retractor system (Shadow-Line [CareFusion, San Diego, CA], TrimLine [Medtronic, Minneapolis, MN], or Black Belt [Koros USA, Moorpark, CA]; Fig. 17-5 )
Figure 17-5
Example of a cervical self-retaining retractor system with mediolateral and superoinferior retractor blades in position.
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Caspar pins (12, 14, and 16 mm) and distractor
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High-speed drill with M8/matchstick drill bit; a 3-mm diamond bit for ossified PLL
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Hemostatics (FloSeal, Gelfoam, thrombin)
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Cottonoids half-inch and inch squares
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Operating microscope
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Neurophysiologic monitoring (recommended in many cases)
Vertebral Body Restoration Technologies
A variety of grafts can be used for vertebral body reconstruction after corpectomy ( Tables 17-1 and 17-2 ). Each has its own properties relative to biomechanics, fusion rates, and complications. The choice of a graft material is hence a critical consideration.
| Method | Pros | Cons |
|---|---|---|
| Bony autograft and allograft (tricortical iliac crest, fibular strut) |
|
|
| PMMA |
|
|
| Titanium mesh cages |
|
|
| Modular cages |
|
|
| Expandable cages |
|
|
| Bone | Static Cages | Modular | Expandable | |
|---|---|---|---|---|
| End plate fit | Poor to good | Good | Good | Good to excellent |
| Height fit | Good | Good | Good | Excellent |
| Bone channel | Excellent | Excellent | Poor to good | Poor to good |
| Settling resistance | Good | Poor | Good | Good |
| Fully variable | Yes | Yes | No | Yes |
| Ease of use | Poor | Good | Poor | Excellent |
Related posts:
Craniovertebral Junction Instabilities and Surgical Fixation Techniques
Surgical Approaches to the Craniovertebral Junction in Rheumatoid Arthritis
Thoracic Microdiskectomy: Lateral and Posterolateral Approaches
Lumbar Facet Screw Fixation Techniques
Surgical Management of Scheuermann Kyphosis
Primary Malignant and Benign Tumors of the Spine
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