C1-C2 fusion. Detailed description of the surgery.

1. Dr. FARRUKH JAVEED

2.  C1 – C2 Screw Fixation
 C1 C2Wiring Fixation
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3.  To maximize
atlantoaxial stability
 To achieve successful
arthrodesis betweenC1
and C2

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7.  Posterior C1-C2 Polyaxial Screw and Rod Fixation (Harms
Technique)
 C1 lateral mass – C2 pedicle or pars fixation
 C1-C2Transarticular Facet Screws (MagerlTechnique)
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9.  Atlantoaxial instability resulting from
 Fractures of the odontoid (types II and III) (Figs. 11.1 and 11.2)
 Adjacent fractures of C1 and C2
 Rotatory subluxation
 Rheumatoid arthritis
 Os odontoideum
 Postodontoidectomy without basilar invagination
 Congenital malformation (i.e, Klippel-Feil)
 Malignancy
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10.  Non-unions
 Odontoid nonunion (types II and III)
 Failed posterior C1-C2 fusion
 C1-C2 osteoarthritis
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11.  Vertebral artery injury ( avoid ipsilateral side)
 Aberrant vertebral artery course
 High-ridingC2 transverse foramen
 Significant anterior cord compressive
pathology
 Small C2 pars or pedicles
 Lateral mass fractures of atlas or axis
 Severely obscured bony anatomy due to
destructive or erosive pathology

12.  Detailed neurological and musculoskeletal examination.
 Preoperative imaging should include plain radiographs,
computed tomography (CT), CT angiography, and magnetic
resonance imaging (MRI) of the cervical spine.
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13.  Radiographs should include anteroposterior (AP), lateral, and
open mouth.
 Combined lateral mass displacement in excess of 7 mm or an
atlantodens interval (ADI) greater than 3 mm suggests
transverse ligament disruption.
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15.  Axial, sagittal, and coronal thin-cut (1-mm) reconstruction
images.
 Accurate detail of the bony anatomy.
 Position of the foramen transversarium through which the
vertebral artery runs.
 Measurement of the length of the screws
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17.  Visualization of any soft tissue injuries (ligaments injury,
spinal cord injuries)
 Useful in rheumatoid patients (soft tissue pannus formation)
 MR Angiogram can be used to evaluate vertebral artery injury,
patency, and/or dominance.
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19.  Intubation with fibro-optic guidance
 Pre-op anteroposterior (AP) and lateral fluoroscopic
radiographs
 Stereotaxy
 Intra-operative electrophysiological monitoring
 Somatosensory evoked potentials (SSEPs)
 Motor evoked potentials (MEPs)
 Short acting muscle relaxants
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20.  The patient is kept prone in a
Mayfield head holder.
 The neck is placed in a neutral
position.
 Inion to the mid-cervical spine.
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21.  If a definitive fusion is being performed, the posterior iliac
crest is also shaved and draped for bone graft harvesting.
 The midline is identified and marked from the occiput to C3-
C4 with a sterile marker.
 Careful subperiosteal dissection is continued from C3 to C1,
starting in the midline and proceeding laterally.
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22.  C2-3 facet joints are exposed (but not
violated), and the dorsal arch of C1 is
exposed laterally.
 The C2 nerve root is identified and is
typically mobilized inferiorly.
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23.  The inferior third of the C1 lamina is
removed with a high-speed drill.
 The entry point for the C1 lateral mass
screw is identified at the center of the C1
lateral mass.
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24.  A low-speed drill with a 3-mm-
diameter drill bit and guide is seated
on C1 lateral mass entry point, and
under fluoroscopy a pilot hole is
drilled through the C1 lateral mass.
 The trajectory of the pilot hole is 10
degrees medial angulation in the axial
plane and in parallel with the ring of
C1 in the sagittal plane.
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25.  The pilot hole is tapped with a 3.5-mm tap,
and a 4.0-mm diameterC1 lateral mass
screw is placed.
 Typical dimensions for a C1 lateral mass
screw are 4.0 mm wide and 36 mm long.
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26.  The C2 screw can be placed in the pars of
C2, in the pedicle of C2, or in the lamina of
C2.
 We place bone graft (usually iliac crest
tricortical autograft) in the interlaminar
space between C1 and C2 or laterally in the
facet joint of C1-2 or along the lateral
lamina and pars of C1 and C2 (onlay graft).
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27.  the entry point is slightly
lateral (3 mm) to the lamino-
inferior articular process
junction, and 2 to 3 mm cranial
to the inferior articular facet of
C2.
 Direction is 25- to 30-degree
cranially and up to 10 degrees
medially.
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28.  Entry point is about 6 mm
lateral from the lamino-
articular junction.
 The trajectory is angled
medially 25 to 30 degrees and
cranially ~ 25 degrees.
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34.  Vascular injury (vertebral arteries)
 Spinal cord injury
 Nonunion
 Instability
 Adjacent segment disease
 Hematoma
 Cerebrospinal fluid leak
 Painful anesthesia from C1 or C2 ganglion injury

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36.  Atlantoaxial wiring can be performed to eliminate instability
for the following indications:
 Fractures of the odontoid (type II and III)
 Select fractures of C1 and C2
 Rotatory subluxation
 Rheumatoid arthritis
 Os odontoideum
 Postodontoidectomy without basilar invagination
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37.  Absent posterior element of either C1 or C2
 Atlas assimilation
 Severe osteoporosis
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38.  Simple and inexpensive procedure
 Relatively easy exposure
 Very low or no risk of vertebral artery injury in patients with
ectatic vertebral artery
 May be useful in patients with hypoplastic pars interarticularis
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39.  Requires an intact posterior arch of C1 andC2.
 Cannot be performed when posterior decompression of the
C1-C2 complex is required or in the presence of significant
osteoporosis.
 Potential for injury to the dura or spinal cord.
 Fixation is only semi-rigid and it is least effective for axial
rotation.
 Postoperative bracing is necessary (rigid orthosis or optimally
a halo vest) to optimize the fusion rate.
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40.  Three basic cable/wire fixation
 Common techniques for C1-C2 fixation:
 the Gallie,
 the Brooks,
 and the interspinous technique
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42.  First described in 1939
 Can become unstable due to
rotational forces.
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43.  In 1978, Brooks and Jenkins refined the Gallie technique by
utilizing sublaminar wires at C1 and C2 with an interlaminar
wedge bone graft.
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45.  Immobilize the patient in a halo-vest orthosis for 6 to 12
weeks after surgery.Then, flexion and extension radiographs
should be obtained to assess the fusion.
 If there is no motion, the halo can be removed.
 The patient should be followed clinically and radiographically
until fusion has occurred.
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46.  Non union upto 30%.
 Iatrogenic fracture of the posterior arch
 Risk of dural tear
 Neurological deficit.
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47.  C1-C2 posterior wiring techniques are relatively less
challenging as compared with other newer screw-and-rod–
based techniques.
 Even though the wiring techniques are not as rigid as screw
based techniques, they do offer higher rates of fusion when
combined with halo immobilization.
 However, they require an intact posterior arch of C1 and C2,
which is not always available.
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