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P R O C ED U R E 1 4
Posterior Cervical
Osteotomy Techniques
Neel Anand and Brian Perri
I N D I CAT I O NS P I T F A L L S
• Infection
• Tumor
• Anterior neural compression—may
require anterior decompression before
deformity correction
• Ossification of the posterior longitudinal
ligament—may be adherent to or
penetrate ventral dura
• Osteoporosis—may require longer
fixation construct
• Chronic steroid dependency—may
require use of bone morphogenetic
protein in addition to local autograft
T R E A T M E N T OP T I O N S
• Pedicle subtraction osteotomy (PSO)—
single, posterior-only approach, and
focal deformity correction
• Combined procedures—posterior only:
thoracic osteotomies (Ponte or
Smith-Petersen with or without C7 or
T1 PSO); combined anteroposterior (AP)
deformity correction: one or more
anterior cervical diskectomy and fusion
combined with posterior thoracic
osteotomies (Ponte, Smith-Petersen,
PSO)
Indications
n
Midcervical or upper cervical kyphosis; may have normal C7 plumb line over
sacrum
n
Cervical-thoracic kyphotic deformity
• Degenerative sagittal plane deformity pain
• Chin-on-chest deformity
• Loss of forward gaze
• Dysphagia from mechanical block to jaw opening
• Myelopathy or radiculopathy secondary to cervical-thoracic kyphosis
• Postlaminectomy kyphosis
• Postinfection kyphosis
• Posttumor kyphosis
• Posttrauma kyphosis
• Postsurgical fusion kyphosis
• Nonunion of anterior spine fusion
• Ankylosing spondylitis
• Rheumatoid arthritis
• Supraadjacent thoracic fusion kyphosis (junctional kyphosis)
Procedure Notes
n
The cervical-thoracic PSO can be performed following a lumbar PSO in a patient
with global spinal kyphosis—C7 plumb line anterior to the L5-S1 disk space—
that still displays forward cervical decompensation. Figure 14-1, A is a preoperative lateral radiograph showing cervical-thoracic and thoracic-lumbar
kyphosis in this patient with advanced ankylosing spondylitis. Figure 14-1, B
shows a preoperative computed tomography (CT) scan in this patient with
ankylosing spondylitis having cervical-thoracic kyphosis and forward decompensation. Figure 14-1, C is a lateral radiograph showing cervical-thoracic kyphosis.
Figure 14-1, D is a lateral radiograph showing L2 PSO and T1 PSO with achieve-
ment of good sagittal balance.
n
Figure 14-2, A and B show a patient with a history of advanced rheumatoid
arthritis and scoliosis with hardware failure after a Luque sublaminar wiring
scoliosis correction with bilateral rods removal. The patient developed progressive cervical-thoracic and thoracic kyphosis and underwent an initial revision
C
). The cervical-thoracic
kyphosis worsened, causing sagittal imbalance and fatigue-related pain. Figure
14-2, D is a full-length scoliosis radiograph showing the sagittal correction fol-
lowing a cervical-thoracic PSO. Figure 14-2, E and F show the preoperative and
postoperative PSO, respectively.
Procedure 14 | Posterior Cervical Osteotomy Techniques 127
A
C
FIGURE 14-1, A-D
B
D
A
FIGURE 14-2, A-F
B
C
D
Continued
128 Procedure 14 | Posterior Cervical Osteotomy Techniques
E
FIGURE 14-2, cont'd
E X A M IN AT I ON / I M A GI N G
P E A R LS
• Intraoperative correction of deformity
can be performed by controlled
repositioning in the Mayfield
headholder. The spine surgeon or
assistant should scrub out and carefully
adjust the Mayfield to enable a gradual
spinal correction under both direct
visualization and fluoroscopic imaging
for coronal and sagittal alignment.
Check the spinal cord to ensure that
only minimal wrinkling of dural occurs.
F
n
A progression of surgical osteotomies can be performed to the extent needed
to obtain adequate kyphosis correction, beginning with upper thoracic Ponte
osteotomies, one or more Smith-Petersen osteotomies, and cervical-thoracic
PSO. Preoperative (Figure 14-3, A) and postoperative (Figure 14-3, B) show
midsagittal CT scans following Ponte and Smith-Petersen osteotomies for
cervical-thoracic kyphosis correction in an achondroplastic dwarf who developed
progressive cervical-thoracic kyphosis after C1-T12 laminectomy for central
spinal stenosis (25 years earlier), and after a C3-C7 fusion (2 years earlier). Note
that a PSO was not necessary in this patient. Note the preoperative (Figure 14-3,
C
) versus postoperative (Figure 14-3, D) paraspinal CT scan showing the anterior
column lengthening at C7-T1 that occurs following Smith-Petersen osteotomies.
This is in contrast to posterior column shortening that occurs following a PSO
(see Figure 14-2, F ).
Examination/Imaging
n
Full-length standing scoliosis radiographs: AP and lateral radiographs with hips
and knees in full extension
• The chin-brow to vertebral angle is measured to calculate desired angle of
deformity correction needed to obtain a horizontal gaze. Undercorrection is
better tolerated than overcorrection.
• Measure the C7 plumb line, if anterior to sacral promontory; may require
addressing lumbar or thoracic kyphosis.
n
Cervical AP and lateral neutral, flexion, and extension radiographs
• Performed to localize region of kyphosis (cervical thoracic junction versus
midcervical).
• Dynamic views help determine intervertebral motion (i.e., movement between
spinous processes).
• An AP radiograph is used to assess for coronal imbalance.
Procedure 14 | Posterior Cervical Osteotomy Techniques 129
A
C
FIGURE 14-3, A-D
B
D
E X A M IN AT I ON / I M A GI N G
P I T F A L L S
• It could be dangerous to perform
this deformity surgery without
immobilization in a Mayfield
headholder. Severe neurologic injury
could result from a rapid, uncontrolled
movement.
n
Magnetic resonance imaging (MRI) is used to delineate cord compression and
the course of the vertebral artery (verify entry into transverse foramen of C6
versus anomalous C7 entry point; rule out commonly encountered aberrant
course if performing C2 pedicle instrumentation).
n
Computed tomography
• To provide detailed anatomic relationships and measurements of cervical and
thoracic vertebral anatomy (pedicles, location of vertebral arteries, registration
for intraoperative navigation if used)
• To identify ossification of the posterior longitudinal ligament
130 Procedure 14 | Posterior Cervical Osteotomy Techniques
P O S I TI O N I N G EQ U I P M EN T
• Intraoperative somatosensory
evoked potentials and continuous
electromyography are used to monitor
cord and nerve root function, with
special attention given at the time of
deformity correction.
• A Cell Saver instrument is used to
salvage blood loss from the osteotomy.
• Minimize use of bone wax during
vertebral osteotomy, because this may
interfere with bone fusion.
• Use thrombin-soaked Gelfoam or
Floseal with cotton pledgets to control
bleeding.
FIGURE 14-4
Surgical Anatomy
n
PSO bone resection includes bilateral lamina, facets, and pedicles with wedge
resection of anterior vertebral body (Figure 14-4).
n
Bony apposition of the posterior elements occurs once the osteotomy is closed.
Two nerve roots will exit one foraminal opening (C7 and C8 if the PSO is at C7;
C8 and T1 if the PSO is at T1) (Figure 14-5).
Positioning
n
The patient is positioned prone with a Mayfield headholder.
Portals/Exposures
n
PSO at C7 or T1—major correction at single level
n
Multiple Smith-Petersen osteotomies—any spine level(s)
Procedure 14 | Posterior Cervical Osteotomy Techniques 131
FIGURE 14-5
S T E P 1 P EA R L S
• An anterior cervical diskectomy at
one or more levels and lordotic
implant(s) can be performed for neural
decompression and to obtain direct
correction of the kyphotic deformity.
• An anterior cervical plate can be used
to augment to the anterior cervical
fusion if needed.
• Uncovertebral joint resection can also
be performed with anterior cervical
decompression and fusion to obtain
additional correction of deformity.
S T E P 1 P IT FA L L S
• At C7 and T1, the spinal canal–to-cord
ratio is greater than at more cranial
levels of the cervical spine. Thus there is
more room for the spinal cord at C7
and T1 and less potential for spinal
cord injury.
• The vertebral artery typically enters the
transverse foramen at the level of C6.
Procedure
Step 1
n
A midline incision is made for the approach from C2 (or C3 if there is good
bone quality, dysplastic C2 pedicles, or an anomalous vertebral artery) to T2 (or
T3 if the PSO is performed at T1).
n
For a C7 PSO, place polyaxial facet screws from C3 to C6 and polyaxial pedicle
screws at C2, T1, and T2.
n
For a T1 PSO, place polyaxial facet screws from C3 to C7 and polyaxial pedicle
screws at C2, T2, and T3.
n
The PSO level is not instrumented.
132 Procedure 14 | Posterior Cervical Osteotomy Techniques
S T E P 2 P EA R L S
• Remove the posterior vertebral cortical
bone to complete the osteotomy.
Resection of this bone bridge, just
ventral to the dural sac, is the last
step of the vertebral body osteotomy.
This segment of bone maintains an
open posterior vertebral window for
completion of the vertebral wedge
osteotomy. Once the posterior cortex
is broken, the posterior vertebral body
closes down and access to the vertebral
body is decreased.
• Lateral intraoperative fluoroscopy is
used to verify the depth of the vertebral
osteotomy. Sequential images can be
taken as the instruments employed for
osteotomy are advanced anteriorly. A
small curette can be placed anteriorly
within the apex of the V-shaped
osteotomy and imaged to verify depth,
for example.
• Asymmetric osteotomy may be
performed to correct for both sagittal
and coronal deformity.
Step 2
n
Bilateral laminectomy and facetectomy is completed at the PSO level, exposing
the dura and bilateral nerve roots.
n
Bilateral laminectomy is completed two levels above and two levels below the
PSO level. This provides room for the spinal cord shortening after the deformity
correction without experiencing compression from posterior bony elements.
n
Bilateral pedicles at the PSO level are sounded and drilled down to the vertebral
body. In Figure 14-6, bilateral laminectomies have been completed at the PSO
level and two levels above and below. Bilateral C7 and T1 facet joints have been
resected for this T1 PSO. The pedicles are drilled bilaterally, and the cortical
margins are thinned and then removed.
n
Cortical margins are resected with a combination of thin-lipped rongeur, pitu-
itary rongeur, and curettes.
n
A V-shaped wedge of cancellous bone is resected from the vertebral body with
straight and curved curettes carried down through the pedicles and into the
vertebral body (Figure 14-7). Resection of cancellous bone should be carried
FIGURE 14-6
FIGURE 14-7
Procedure 14 | Posterior Cervical Osteotomy Techniques 133
S T E P 2 P IT FA L L S
• Preoperative MRI and/or CT are
necessary to evaluate the course of the
vertebral artery. Aberrant coursing of
the vertebral artery can occur such
that it enters the transverse foramen
of C7 or takes an anomalous course,
endangering pedicle screw placement
in C2.
• Failure to place a temporary rod may
lead to translational instability and
consequent neurologic deficit.
• Inadequate laminectomy, especially
proximal and distal to the PSO level,
may place the spinal cord at risk as
reduction is obtained.
• Failure to maintain the posterior and
lateral wall until the very end will cause
premature instability and difficulty in
controlling reduction.
• Hemostasis is critical throughout the
procedure. Blood loss, which can
be rapid and excessive during the
osteotomy, especially from the
cancellous vertebral bone, must be
controlled.
out to the anterior cortex. The cancellous osteotomy is carefully performed,
staying within the margins of the vertebral body. Fluoroscopy is used to verify
that the depth of the osteotomy is carried to the cortical margins of the vertebrae. The transverse processes of T1 can be vertically resected, and a careful
cortical resection can be performed around the posterior lateral portion of the
vertebral body bilaterally to complete the wedge osteotomy of the vertebrae.
This is performed by subperiosteal dissection using a curved curette, followed
by use of a 2-mm Kerrison rongeur. The segmental artery can be cauterized if
necessary. This lateral cortical bone resection can help mobilize and close the
wedged osteotomy.
n
A temporary malleable rod can be attached to the pedicle screws and lateral
mass screws to prevent anterior translation or sudden movement of the spinal
cord before the posterior vertebral cortex is resected.
n
Down-pushing Epstein curettes are used to depress the posterior and lateral
vertebral cortices into the void of the vertebral body (Figure 14-8). This should
be performed bilaterally and as the last step in the osteotomy. Following this
step, the posterior osteotomy wedge will close down, and access to the osteotomy region is limited. A unilateral, temporary, malleable rod should be in place
before performing this step. This rod will prevent complete collapse of the
osteotomy.
S T E P 2
I N S T RU M E N T A T I O N /
I M P L AN TAT IO N
• Midas Rex high-speed drill with an M8,
side-cutting drill bit
• Kerrison rongeurs (2 mm, 3 mm)
• Straight and curved curettes
• Pituitary rongeur
• Down-pushing (Epstein) curettes
• Bone wax, Floseal, and thrombinsoaked Gelfoam for hemostatic control
FIGURE 14-8
134 Procedure 14 | Posterior Cervical Osteotomy Techniques
FIGURE 14-9
Step 3
n
The osteotomy is closed by releasing the Mayfield clamps, followed by con-
trolled, manual elevation of the Mayfield headholder, then reclamping of the
headholder. Watch the thecal sac and nerve roots to avoid compression injury.
n
Obtain a lateral radiograph to check sagittal alignment.
n
An appropriately contoured rod is fixed to the pedicle/lateral mass screws on
the side opposite the malleable temporary rod.
n
The malleable rod is removed, and a second contoured rod is attached.
n
Further reduction and compression across the osteotomy site is performed with
the compression instrumentation (Figure 14-9). An infolding of the dura occurs
following reduction of the kyphotic deformity.
n
Cross-linked attachments can be used to increase stability of fixation.
Postoperative Care and Expected Outcomes
n
A closing-wedge osteotomy creates cervical lordosis.
n
Posterior elements are removed at the level of the osteotomy, and laminectomies
two levels above and below are performed.
n
Bony apposition of anterior, middle, and posterior columns is established.
n
Posterior instrumentation stabilizes the spine and maintains compression across
the osteotomy site to increase fusion rate and success. A postoperative halo
may be used if the patient is osteoporotic.
n
Postoperatively, the spinal column is shortened.
n
The fulcrum for PSO is the anterior column; so, there is less risk for spinal cord
injury versus a Smith-Petersen osteotomy, in which the fulcrum is the middle
column.
Evidence
Mummaneni PV, Mummaneni VP, Haid RW, Rodts GE Jr, Sasso RC. Cervical
osteotomy for the correction of chin-on-chest deformity in ankylosing
spondylitis. Neurosurg Focus 2003;14:e9.
Webb JK, Sengupta DK. Posterior cervicothoracic osteotomy. In: Vaccaro AR,
Albert TJ, editors. Spine Surgery: Tricks of the Trade. New York: Thieme; 2003,
p. 35-7.
P R O C ED U R E 1 5
Posterior Cervical
Laminoplasty
Paul Dohyung Kim and Hyun Bae
I N D I CAT I O NS P I T F A L L S
• Preoperative kyphosis of greater than
10 degrees. Figure 15-3 shows
preoperative cervical kyphosis not
suitable for cervical laminoplasty.
• Significant preoperative axial neck pain
• Preoperative instability (Figure 15-4)
I N D I CAT I O NS
C O N T RO V E R S IE S
• Surgical approach for the treatment
of spondylotic myelopathy (anterior,
posterior, or combined)
• Type of laminoplasty (“open-door” vs.
“French door,” etc.)
Indications
n
Multilevel cervical spondylotic myelopathy in three or more motion segments
(Figure 15-1)
• Requires no postoperative bracing compared to fusion alternative
• Requires neutral to lordotic sagittal spine alignment
• Best in patients who have little or no preoperative neck pain
n
Ossification of the posterior longitudinal ligament (OPLL) (Figure 15-2)
n
Removal of subaxial spine mass lesions
FIGURE 15-1