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P R O C ED U R E 8
Anterior Cervical Disk
Arthroplasty
Paul Dohyung Kim and Rick B. Delamarter
I N D I CAT I O NS P I T F A L L S
• Cervical instability (>3 mm translation
or >11 degrees angular motion)
• Severe facet joint degeneration
• Severe cervical spondylosis
• Osteoporosis (dual energy x-ray
absorptiometry [DEXA] ≤−2.5)
I N D I CAT I O NS
C O N T RO V E R S IE S
• Multilevel pathology
• Disk replacement adjacent to fusion
E X A M IN AT I ON P E A R L S
• If patient has had previous neck surgery
and history of hoarseness or
swallowing, preoperative ear-nosethroat (ENT) evaluation may be
warranted.
E X A M IN AT I ON P I T F A L L S
• Severe cervical spondylosis
Indications
n
Symptomatic one-level herniated nucleus pulposus between C3 to C7 causing
neck pain, radiculopathy, or myelopathy (Figure 8-1)
Examination/Imaging
n
Preoperative history and physical examination must correlate with imaging
studies.
n
Facet joint degeneration must be carefully assessed on radiographs or computed
tomography (CT).
T R E A T M E N T OP T I O N S
• Anterior cervical diskectomy and fusion
(ACDF)
• Posterior cervical foraminotomy/
diskectomy
FIGURE 8-1
Procedure 8 | Anterior Cervical Disk Arthroplasty 57
P O S I TI O N I N G PE A R L S
• Use various landmarks to ensure that
the head is centered. External
landmarks include the center of chin
and top of sternum. Internal landmarks
include the proper exposure of the
uncovertebral joints to assess midline.
• Ensure that before incision the vertebral
level of interest can be visualized with
lateral fluoroscopy.
P O S I TI O N I N G EQ U I P M EN T
• Fluoroscope
• Radiolucent operating table
• Head-halter chin strap to stabilize the
head with 5- to 10-lb weight
• Donut headrest
• Axillary roll between the shoulder
blades
P O RTA L S / E X P O S U R ES
P E A R LS
• The authors prefer a left-sided
approach, but a right-sided approach
may be warranted, especially if patient
previously had left-sided surgery.
• A transverse incision is made for up to
three levels.
• Full dissection and mobilization of the
superficial layer of the deep cervical
fascia is important for exposure in
multilevel surgery.
Surgical Anatomy
n
Standard anterior Smith-Robinson approach to the cervical spine similar to an
ACDF (Figure 8-2)
Positioning
n
Patient placed supine on a radiolucent table with an axillary roll placed between
shoulder blades, donut underneath the head, and a towel underneath the neck
n
5 to 10 lb of traction with a head-halter device to provide stability
n
Both shoulders taped down to ensure proper radiographic visualization on
lateral fluoroscopy, especially at C6-7
Portals/Exposures
n
Standard anterior Smith-Robinson approach to the cervical spine is used.
n
The skin incision may be checked with a radiopaque skin marker and lateral
fluoroscopy.
n
A scalpel is used to incise skin and subcutaneous tissue; then dissect through
the platysma muscle layer.
n
The deep cervical fascia is exposed; the medial border of the sternocleidomas-
toid muscle (SCM) is exposed and fully mobilized cephalad and caudad, especially with multilevel surgery.
n
Finger dissection are used to bluntly separate the deeper lateral carotid sheath
from the medial tracheoesophageal bundle.
n
Handheld retractors are used to expose the longus colli muscles, which are
mobilized subperiostally with bipolar cautery and a Penfield elevator.
n
20-gauge needle is used to confirm level radiographically.
n
Anteroposterior (AP) fluoroscopy is used to identify midline, which is marked
with a pen or Bovie electrocautery (Figure 8-3).
P O RTA L S / E X P O S U R ES
C O N T RO V E R S IE S
• Posterior longitudinal ligament (PLL)
release
FIGURE 8-2
FIGURE 8-3
58 Procedure 8 | Anterior Cervical Disk Arthroplasty
S T E P 1 P IT FA L L S
• Removal of too much of bony end
plates may cause settling of the
implant.
S T E P 1 C ON T R O V ER S I E S
• Operating microscope versus loupe
magnification
Procedure
Step 1
n
Caspar retainer screws are used to provide controlled distraction of the disk
space (Figure 8-4).
n
Standard diskectomy is used with care to remove only the cartilaginous end
plates (Figure 8-5).
n
Curettes are used to mobilize the uncovertebral joints.
n
Posterior vertebral osteophytes are removed, and bilateral microforaminotomies
are performed with Kerrison rongeurs.
n
A power drill is rarely used.
FIGURE 8-4
FIGURE 8-5
Procedure 8 | Anterior Cervical Disk Arthroplasty 59
S T E P 2 P EA R L S
• Aim for the largest implant footprint
size and restoration of anatomic height.
S T E P 2 P IT FA L L S
• Overdistraction of the disk space with
insertion of oversized implant
S T E P 3 P EA R L S
• Ensure that the implant is inserted
midline.
• Meticulous hemostasis is needed.
S T E P 3
I N S T RU M E N T A T I O N /
I M P L AN TAT IO N
• ProDisc-C (Synthes, West Chester, Pa.)
cervical total disk replacement (Figure
8-8)
Step 2
n
Implant size and location are checked with trial implants using fluoroscopy
(Figure 8-6).
n
Central keels are created for implants on both the superior and inferior vertebral
bodies using milling guides on the trial and power drill bits.
n
Remove bony debris within the keels, and use extensive irrigation to clear bony
debris.
Step 3
n
Carefully mallet the final implant using lateral fluoroscopy, ensuring that the
implant reaches the posterior margin of the vertebral body (Figure 8-7).
n
Apply bone wax to the keels and Caspar screw holes.
A
C
FIGURE 8-6, A-C
B
60 Procedure 8 | Anterior Cervical Disk Arthroplasty
A
FIGURE 8-7, A-B
P O S T OP E R AT IV E P I T F A L L S
• Heterotopic ossification (nonsteroidal
antiinflammatory drugs [NSAIDs] may
be given for 2 weeks postoperatively).
• Early physical activity may not allow for
bony ingrowth (wait 6 weeks).
B
FIGURE 8-8
Postoperative Care and Expected Outcomes
n
Soft neck collar is used for 2 to 3 weeks for one-level cervical disk arthroplasty
and 3 to 4 weeks for multilevel cervical disk arthroplasty.
n
Physical therapy may be started 6 weeks postoperatively.
Evidence
Garrido BJ, Taha TA, Sasso RC. Clinical outcomes of Bryan cervical disc
arthroplasty—a prospective, randomized, controlled, single site trial with
48-month follow-up. J Spinal Disord Tech 2010;23:367-71.
Murrey D, Janssen M, Delamarter R, et al. Results of the prospective, randomized,
controlled multicenter Food and Drug Administration investigational device
exemption study of the ProDisc-C total disc replacement versus anterior
discectomy and fusion for the treatment of 1-level symptomatic cervical disc
disease. Spine J 2009;9:275-86.
Tumialán LM, Ponton RP, Garvin A, Gluf WM. Arthroplasty in the military: a
preliminary experience with ProDisc-C and ProDisc-L. Neurosurg Focus
2010;28:E18.
Occipital-Cervical Fusion
I N D I CAT I O NS P I T F A L L S
• Reducible versus nonreducible (e.g.,
whether traction will be necessary)
• Surgical versus external immobilization/
fusion
• Occipital-cervical fusion versus
atlantooccipital fusion (e.g., C1 lateral
mass fusion, odontoid screw)
P R O C ED U R E 9
Howard B. Levene, John Christos Styliaras,
Alexander R. Vaccaro, Jack I. Jallo, and James S. Harrop
Indications
n
This procedure is typically performed to treat instability of the occipital-cervical
joint—specifically, to ensure stability and protect the neurologic structures,
prevent deformity, and reduce or eliminate pain. The presence of occipitalcervical instability increases the risk for compression or trauma to the spinal
cord/brainstem by means of pathologic translation, longitudinal displacement,
or basilar invagination. The consequences include pain, cranial nerve palsies,
respiratory distress, paresis, paralysis, and even sudden death.
n
There are two basic presentations of occipital-cervical instability:
• Acute occipital-cervical instability—usually precipitated by trauma (Figure
9-1, A and B). Traumatic causes of such instability have a high rate of ameliora-
tion of pain symptoms following surgical intervention using the screw/rod
construct.
• Chronic occipital-cervical instability—with causes ranging from degenerative
processes to inflammatory/autoimmune, infectious, neoplastic (metastatic or
primary), or even congenital in origin (Figure 9-2, A and B).
A
FIGURE 9-1, A-B
B
62 Procedure 9 | Occipital-Cervical Fusion
A
FIGURE 9-2, A-B
T E C H NI Q U E S
C O N T RO V E R S IE S
• A successful occipital-cervical fusion can
provide a favorable outcome in most
types of occipital-cervical instability,
whether acute or chronic. There are a
variety of techniques to obtain a fusion
varying from onlay grafts, wiring,
plates, and most recent plate/rod
constructs. The screw/rod constructs
have been shown to provide improved
neurologic status postoperatively,
decreased instrumentation failure rates,
and few postoperative complications.
• However, in patients with neoplasms,
posterior wiring and rods have the
highest rate of arthrodesis, while screw/
rod constructs are associated with a
significantly less favorable rate of
arthrodesis.
• Still, in patients suffering from
inflammatory/autoimmune diseases,
screw/rod constructs provide the best
outcomes, especially when compared
with posterior wiring and inlay in situ
bone grafting, which provides poor
results postoperatively. Similar results
are found in cases of traumatic
occipital-cervical instability.
• Need for halo preoperatively
• Need for halo postoperatively
B
Examination/Imaging
n
Anteroposterior (AP) and lateral spine radiographs
n
Cervical spine computed tomography (CT) scan with sagittal and coronal
reconstructions
n
Measurement of reference lines, such as Chamberlain line (posterior of the hard
palate to the dorsum of the foramen magnum) and the Wackenheim line
(extending the course of the clivus), are of somewhat limited value.
n
Obtain magnetic resonance imaging (MRI) of the cervical spine (especially
with myelop athy) to determine degree and severity of spinal cord compression
(Figure 9-3).
n
Obtain a myelogram (CT and radiographic) if MRI is not available or is contra-
indicated (i.e., when the patient has a pacemaker or other MRI-incompatible
hardware). Although a myelogram can directly visualize the spinal cord, it also
provides valuable information on the degree of compression, or lack of, on the
spinal cord.
Surgical Anatomy
n
Occiput/inion (Figure 9-4)
n
Vertebral arteries (Figure 9-5)
n
Condyle joints and C1 and C2 bony anatomy (C2 screw placement)
n
Lateral masses (C3-6 lateral mass screw placement) (Figure 9-6, A and B)
FIGURE 9-3
Ideal Screw Locations
Procedure 9 | Occipital-Cervical Fusion 63
FIGURE 9-4
Pedicle
C1
C2
C3
C4
C5
C6
C7
Superior nuchal line
Lateral mass
Lateral mass
64 Procedure 9 | Occipital-Cervical Fusion
Basilar part of occipital bone
Anterior
atlantooccipital ligament
Capsule of
atlantooccipital joint
Lateral atlantoocciptal ligament
Articular
capsule
Posterior
atlantooccipital
membrane
Ligament nuchae
Supraspinous
ligament
Vertebra
prominens
Anterior View
Vertebral
artery
Atlantoepistrophic ligament
Anterior longitudinal ligament
Posterior atlantooccipital
membrane
Posterior View
Anterior atlantooccipital membrane
Capsule of atlantooccipital joint
Atlas (C1)
Body of axis (C2)
Anterior longitudinal ligament
Articular capsule
Anterior tubercle of C6 vertebra
(carotid tubercle)
Vertebral artery
Capsule of
atlantooccipital
joint
Atlas (C1)
Capsule of lateral
atlantoaxial joint
Axis (C2)
Ligamentum
flavum
FIGURE 9-5
A
FIGURE 9-6, A-B
T1 vertebra
Right Lateral View
C1
C2
C3
Inferior facet
Lateral mass
Superior facet
Lamina
C6
C7
B
Procedure 9 | Occipital-Cervical Fusion 65
T R E A T M E N T OP T I O N S
• External fixation (halo) only
• Combined approach (anterior resection
of dens, posterior fusion)
• Various occipital-cervical fusion devices
(bone and wire, loop and wire, screw
and rods, in-out option for occipital
screw)
P O S I TI O N I N G PE A R L S
• It is crucial to evaluate the patient’s
optimal head position, because with an
occipital-cervical fusion, they will be
locked in this position.
• The patient must adequately overhang
the operating room table.
• The patient’s chest must be supported
on gel rolls; a parallel position with
respect to the body axis is
recommended.
• If the patient is in a hard cervical collar,
roll and position him or her with the
collar on.
• Include a lower sheet that can be used
to support the arms in a sling.
• Place the cervical spine in a neutral
position.
• If the patient is in continuous traction,
start at 7 lb and increase to 15 lb
maximum as necessary.
• Monitor somatosensory evoked
potentials (SSEPs) and motor evoked
potentials prepositioning and
postpositioning.
• Avoid paralytics, because they interfere
with neuromonitoring.
Positioning
n
Place patient in prone position in three-point pin fixation.
n
Alternatively, the patient can be placed in prone position in a halo ring affixed
to the table.
n
Another option is continuous traction.
Portals/Exposures
n
Occipital inion to C5 (Figure 9-7)
n
At a minimum, lateral masses to C3 must be exposed.
P O S I TI O N I N G PI T FA L L S
• Horizontally placed rolls may interfere
with chin flexion.
• Proper alignment of cervical spine is
critical. Avoid excessive flexion or
extension.
• Be aware of chin position during
positioning.
• If SSEPs or motor evoked potentials
change during positioning, return the
patient to the supine position. An
option is to administer
methylprednisolone per the National
Acute Spinal Cord Injury Study
(NASCIS II) guidelines.
P O S I TI O N I N G EQ U I P M EN T
• Use of cervical traction is advocated by
some (Menezes and Sonntag, 1996).
FIGURE 9-7