Spinal Instability and Spinal Fusion Surgery Workup
- Author: Peyman Pakzaban, MD; Chief Editor: Brian H Kopell, MD more...
There are no laboratory studies that would assist in diagnosis of spinal instability. Laboratory studies can be helpful in diagnosing certain conditions that could result in spinal stability, such as spine infections (CBC, ESR, C-reactive protein, blood cultures), rheumatoid arthritis (rheumatoid factor), ankylosing spondylitis (HLA-B27), multiple myeloma (serum immunoelectrophoresis, urine Bence-Jones proteins), and others.
Laboratory studies are routinely performed as a part of preoperative preparation for spine surgery.
Spine MRI and plain x-ray films with flexion and extension are the most useful imaging studies for evaluation of spinal instability. In addition to demonstrating vertebral displacement, vertebral deformation and neural compression, MRI provides invaluable information about spinal cord injury, neoplastic and infectious processes, and ligamentous disruption. CT-myelography is used when MRI cannot be obtained or has not provided the resolution necessary to assess the extent of neural compression.
Plain CT is useful in assessing bone anatomy in the setting of vertebral fractures, spondylolysis, history of previous spine surgery, and congenital spine anomalies. CT may also be used to assess certain bony parameters (such as pedicle size in thoracolumbar spine, lateral mass anatomy in cervical spine, and vertebral artery anatomy in C1-2 region) in preparation for instrumentation of the spine.
To evaluate bone integrity prior to fusion when osteoporosis is suspected, a bone density scan is performed. Radionucleotide bone scans have been supplanted by high resolution CT for assessment of pseudarthrosis.
Electromyography (EMG) may be used to confirm nerve root compression but does not play a direct role in establishing the diagnosis of spinal instability.
Selective nerve root injections can be used as a diagnostic tool to confirm that a particular nerve root is responsible for the pain syndrome. They are also used in a therapeutic capacity in nonsurgical management of spine disorders.
CT-guided biopsy/aspiration is used when tumor or infection is suspected and when the possibility of nonsurgical treatment is being entertained. When surgery has to be performed to decompress and/or stabilize the spine, the diagnosis can be obtained intraoperatively.
Substantial controversy exists regarding the value of discography in diagnosis of discogenic pain and in patient selection for fusion surgery. When performed, it should be accompanied by measurements of intradiscal pressure, documentation of severity and concordance of pain during injection, and postdiscography CT scan.
No histological findings are relevant to the diagnosis of spinal instability, except when a neoplasm is the source of instability.
Since spinal instability is a heterogenous disorder, no uniform staging/grading system exists that would be relevant to all forms of spinal instability.
Spondylolisthesis, defined as anterior translation of a vertebral body in relation to the adjacent caudal vertebral body, is graded according to the system in Table 3.
Table 3. Grading of Spondylolisthesis (Open Table in a new window)
|Slip Distance/AP Diameter
of Vertebral Body
In the lumbar spine, spondylolisthesis is either isthmic, degenerative, or traumatic. Isthmic spondylolisthesis occurs because of a congenital weakness and subsequent fracture of pars interarticularis (usually of L5), resulting in uncoupling and glacial anterior translation of one vertebral body over another.
Degenerative spondylolisthesis occurs because of severe degeneration of facet joints and incompetence of facet capsules, which lose the capacity to resist the flexion moment, resulting in translation. Traumatic spondylolisthesis represents a fracture-dislocation of the spine.
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|C1 Jefferson fracture
|1. Isolated -->
2. With transverse ligament rupture -->
3. Widely diastatic -->
4. With odontoid fracture -->
|1. Hard collar
3. Consider occiput-C2 fusion
4. Treat according to odontoid fx
|C1-2 Rotatory subluxation
|1. Children, URI -->
2. Adults, tumor, trauma, infection -->
|1. Bedrest, analgesics, halter traction, soft collar
2. Traction, hard collar, halo, or C1-2 fusion depending on cause and duration
(flexion in young, extension in old)
|1. Type 1 -->
2. Type 2, < 6 mm displaced -->
3. Type 2, >6 mm displaced or chronic or type 2A -->
4. Type 3 -->
|1. If no atlanto-occipital instability, collar x 3 mo
2. Halo x 3-6 mo
3. C1-2 fusion or odontoid screw
4. Halo x 6 mo
|C2 Hangman fracture
|1. Pars approximated->
2. Pars separated, reducible -->
3. Pars separated, not reducible -->
|1. Hard collar x 3 mo
2. Reduce in extension, then halo x 3 mo
3. C2-3 fusion
|Unilateral jumped facet
(flexion + rotation)
|1. Reducible -->
2. Not reducible -->
3. With facet fracture -->
4. With disc herniation-->
|1. Reduce and halo x 3 mo
2. Open reduction and posterior fusion
3. Open reduction and posterior fusion
4. Anterior decompression, open reduction, and anterior fusion
|Bilateral jumped facet
|1. Reducible, without disc herniation -->
2. Not Reducible, without disc herniation-->
3. With disc herniation-->
|1. Closed reduction, then posterior fusion
2. Open anterior or posterior reduction and fusion
3. Anterior discectomy, reduction and fusion
|Subaxial spine axial loading injuries
(axial +/- flexion)
|1. Simple compression fracture -->
2. Burst fracture +/- tear drop fx -->
3. Burst + posterior column fracture -->
|1. Hard collar
2. Anterior corpectomy and fusion
3. Anterior corpectomy and fusion
(+/- posterior fusion)
|Clay shoveler fracture
|Always stable||Soft collar and analgesics|
|Anterior avulsion fracture
|Always stable||Soft collar and analgesics|
|Fracture||Denis Columns Involved||Treatment|
|Compression fracture||Anterior column||Bracing (note that >50% vertebral body height loss or Cobb angle >30 degrees predict worsening of kyphosis)|
|Compression fracture with splaying of spinous processes||Anterior and posterior columns||Posterior instrumented fusion|
|Stable burst fracture
(preserved posterior longitudinal ligament)
|Anterior column and part of middle column||If no neural compromise, treat with TLSO brace
If canal stenosis present, retropulsed fragment may be reduced by ligamentous taxis in distraction
with posterior instrumented fusion
|Unstable burst fracture||Anterior and middle columns with significant retropulsion,
or all 3 columns
|Anterior decompression and instrumented fusion|
|Flexion-distraction seat belt injury (ligamentous)||Middle and posterior columns||Posterior reduction and instrumented fusion|
|Chance fracture (osseous)||2 or 3 columns but with good bone contact||TLSO brace|
|Shear fracture dislocation||3 columns||Instrumented fusion, anterior, posterior, or both|
|Slip Distance/AP Diameter
of Vertebral Body
|1||Fracture through the odontoid tip (rare)|
|2||Fracture across the base of the odontoid process (most common)|
|2A||As in type 2, except with comminution of fracture line, reducing the possibility of healing of fracture in halo or with odontoid screw|
|3||Fracture extension into C2 vertebral body; because of larger bone contact area, fracture usually heals well in a halo|