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Procedure 16 | Anterior Thoracic Diskectomy and Corpectomy 157
Evidence
Anand N, Regan JJ. Video-assisted thoracoscopic surgery for thoracic disc disease:
classification and outcome study of 100 consecutive cases with a 2-year
minimum follow-up period. Spine 2002;27:871-9.
This is a case series of 100 thorascopically treated thoracic disk herniations
(TDHs) (4-year average follow-up), with techniques and clinical outcomes
outlined—showing a 70% overall long-term success rate and 84% patient
satisfaction rate.
Bohlman HH, Zdeblick TA. Anterior excision of herniated thoracic discs. J Bone
Joint Surg Am 1988;70:1038-47.
This is a case series comparing early results of transthoracic disk excision versus
costotransversectomy, with better results from the anterior decompression
group.
Brown CW, Deffer PA, Akmakjian J, et al. The natural history of thoracic disc
herniation. Spine 1992;17:S97-102.
The authors present an outline of diagnosis and treatment outcomes of
nonoperative TDHs.
Bransford R, Zhang F, Bellabarba C, Konodi M, Chapman JR. Early experience
treating thoracic disc herniations using a modified transfacet pedicle-sparing
decompression and fusion.
This is a retrospective case series describing a modified transfacet pediclesparing approach for decompression and fusion of TDHs, and it outlines surgical
techniques and initial complications and outcomes. Improved Nurick grades and
visual analog scale pain scores were noted, although six patients required
reoperation.
Khoo, LT, Smith ZA, Asgarzadie F, et al. Minimally invasive extracavitary approach
for thoracic discectomy and interbody fusion: 1-year clinical and radiographic
outcomes in 13 patients compared with a cohort of traditional anterior
transthoracic approaches. J Neurosurg Spine 2011;14:250-60.
This is a case-control study describing surgical techniques and comparing a
13-patient cohort treated with a minimally invasive extracavitary approach for
thoracic diskectomy and fusion versus a matched-control group treated with a
thoracotomy for TDHs, with a 1-year follow-up. The study showed similar
radiographic and clinical outcomes for both groups.
McCormick WE, Will SF, Benzel EC. Surgery for thoracic disc disease. Complication
avoidance: overview and management. Neurosurg Focus 2000;9:e13.
This is a comprehensive review of approaches for thoracic diskectomy, with a
comparison of complications, including death, neurologic deterioration,
postoperative vertebral column instability, incomplete disk resection,
cerebrospinal fluid leakage and fistulas, infection, misdiagnosis, pulmonary
embolism, pneumonia, and intercostal neuralgia.
Murakami H, Kawahara N, Demura S, et al. Neurological function after total en
bloc spondylectomy for thoracic spinal tumors. J Neurosurg Spine 2010;12:253-6.
This is a retrospective case series of 79 patients with spinal tumor s/p bilateral
preoperative embolization, ligation of segmental vessels, and circumferential
decompression for spine tumors. The study showed no evidence of decreased
spinal cord blood flow when segmental vessels were interrupted.
Stillerman CB, Chen TC, Couldwell WT, Zhang W, Weiss MH. Experience in the
surgical management of 82 symptomatic herniated thoracic discs and review of
the literature. J Neurosurg 1998;88:623-33.
This is a retrospective case series comparing single-institution results of 71
patients with 82 TDHs treated with four different approaches over 25 years,
with resolution of pain in 87%, bowel/bladder improvement in 76%, and motor
improvement in 58%, with a complication rate of 14%.
Wait SD, Fox DJ, Kenny JK, Dickman CA. Thoracoscopic resection of symptomatic
herniated thoracic discs: clnical results in 121 patients. Spine 2011 Feb 17. [Epub
ahead of print.]
This is a case series of 121 patients with TDHs treated thoracoscopically with an
average 2.4-year follow-up, showing 91%, 98%, and 86% improvement in
radiculopathy, myelopathy, and back pain, respectively, with 97.4% of patients
willing to undergo the procedure again.
Wakefield AE, Steinmetz MP, Benzel EC. Biomechanics of thoracic discectomy.
Neurosurg Focus 2001;11:e6.
Wood KB, Garvey TA, Gundry C, Heitkoff KB. Magnetic resonance imaging of the
thoracic spine. J Bone Joint Surg Am 1995;77:1631-8.
This is a retrospective case series of 90 asymptomatic patients, with a review
of thoracic magnetic resonance imaging (MRI). The study shows 73% of patients
having positive MRI abnormalities, including cord deformation in 29%.
P R O C ED U R E 1 7
Anterior Thoracolumbar
Spinal Fusion via
Open Approach for
Idiopathic Scoliosis
Peter G. Gabos
I N D I CAT I O NS P I T F A L L S
• Anterior surgery tends to be
“kyphogenic.” This may not be
appropriate in curves with thoracic
kyphosis greater than 40 degrees or in
cases of thoracolumbar (“junctional”)
kyphosis or lumbar hypolordosis.
• Patients weighing greater than 60 kg,
with curves greater than 75 degrees,
with or without hyperkyphosis, are not
candidates for single-rod thoracic open
or thoracoscopic fusion.
I N D I CAT I O NS
C O N T RO V E R S IE S
• Does sparing a spinal motion segment
significantly benefit the patient?
• Are there more risks/complications with
anterior surgery?
• Is there better correction of curvature
with anterior versus posterior surgery?
T R E A T M E N T OP T I O N S
• Posterior spinal fusion with dual-rod
instrumentation
• Anterior spinal fusion with single- or
dual-rod instrumentation, by open or
thoracoscopic technique
Indications
n
To halt progression of spinal curvature
n
To restore spinal alignment and balance
n
To preserve caudal motion segments (typically one to two segments) when
compared with posterior spinal fusion (PSF)
n
To prevent the crankshaft phenomenon in skeletally immature patients (Risser
0, open triradiate cartilage)
n
To allow for a thoracoscopic approach in selected cases
n
Appropriate candidates typically include Lenke type 1 (single structural thoracic)
and Lenke type 5 (single structural thoracolumbar/lumbar) curves (Figure 17-1,
A
and B).
Examination/Imaging
n
Clinical assessment of curve location, coronal and sagittal balance, trunk rota-
tion, shoulder asymmetry, pelvic obliquity, integrity of the neuraxis, and any
other associated anomalies
n
Full-length standing posteroanterior, lateral, and right and left supine bending
radiographs to assist in curve classification, assessment of curve flexibility, and
selection of fusion levels
n
Magnetic resonance imaging in selected cases (e.g., neurologic signs or symp-
toms, early- or juvenile-onset scoliosis, rapid curve progression, unusual curve
pattern)
Positioning
n
The surgical approach is always from the convex side of the curvature in the
lateral decubitus position.
Portals/Exposures
Thoracic
n
Standard thoracotomy approach gives access to vertebral levels T2 to approxi-
mately L1.
n
Expanded access can be achieved with the use of a double thoracotomy if
absolutely necessary.
Procedure 17 | Anterior Thoracolumbar Spinal Fusion via Open Approach for Idiopathic Scoliosis 159
A
FIGURE 17-1, A-B
P O S I TI O N I N G PE A R L S
• Copious padding of all bony and soft
tissue prominences, such as the axilla
(“axillary roll”) and lateral knee, is
required to prevent a compressive
neuropathy or pressure necrosis of the
upper or lower extremity or trunk.
• Electrophysiologic monitoring of the
upper extremities will allow early
detection of compressive neuropathies,
prompting immediate repositioning
and/or repadding of the upper
extremity.
• A flat radiolucent table and beanbag
positioner are utilized.
• When utilized, unobstructed
fluoroscopic access is verified before
preparation and draping.
• Neurophysiologic monitoring of
spinal cord function, using both
somatosensory evoked potential and
transcranial motor evoked potential
monitoring, is recommended to
optimize patient safety.
B
FIGURE 17-2
Thoracolumbar
n
A tenth rib thoracoabdominal approach allows the greatest exposure and ver-
satility for fusions crossing the thoracolumbar junction (Figure 17-2).
Lumbar
n
An anterior retroperitoneal flank approach gives sufficient access to vertebral
levels.
160 Procedure 17 | Anterior Thoracolumbar Spinal Fusion via Open Approach for Idiopathic Scoliosis
P O RTA L S / E X P O S U R ES
P E A R LS
• Thoracic (open technique)
• Single-lung ventilation is not required
but does allow for better visualization
during the procedure.
• Standard thoracotomy is utilized,
typically choosing the interspace
corresponding to the apex of the
deformity.
• Constructs spanning more than
seven levels may require a double
thoracotomy.
• To limit incision size and chest wall
dissection, disk excision and screw
implantation can be done through
small percutaneous accessory
incisions at the more cephalad or
caudad levels.
• Thoracolumbar
• Split the costal cartilage at the tip
of the tenth rib, maintaining the
attachments to the diaphragm
(cephalad cartilage tip) and
abdominal musculature (caudad
cartilage tip).
• Use temporary stay sutures to mark
the diaphragm as it is incised, for
later reapproximation.
• Reapproximate the split tenth rib
costal cartilage to initiate closure.
• Lumbar
• Beware of the thinning musculature
and superficial location of the
peritoneum medially near the rectus
sheath.
• Dissection should proceed medial to
the psoas muscle.
• The genitofemoral nerve lies directly
on the psoas muscle.
• The iliolumbar vein consistently
requires ligation when working at the
L4-5 level.
• Preserve paraspinous sympathetic
fibers that do not interfere with the
dissection.
Procedure: Thoracolumbar Spine Fusion via an Open Approach Using Single-Rod Instrumentation
Step 1: Anterior Release and Diskectomy
n
Once adequate spinal exposure has been obtained, transection of the anterior
longitudinal ligament and complete diskectomy is performed to, or including,
the posterior longitudinal ligament.
Step 2: Placement of the Anterior Vertebral Body Screws
n
The entry point of the vertebral body screw is preferentially the junction of
the pedicular origin and the vertebral body, crossing the center of the vertebral
body and directed perpendicularly across to the far side. At the cephalad and
caudad end vertebrae a staple can be impacted to prevent pullout or plowthrough of the screws. At intervening levels, a washer can be placed to help
distribute load.
n
The entry hole is made first with a sharp awl. A straight pedicle probe is then
directed toward the surgeon’s finger on the far side of the body. The desired
screw length is then measured. A tap is then placed, followed by screw placement. Image guidance is optional, but can assure screw placement central in
the body and parallel to the vertebral end plates.
Step 3: End-Plate Ablation
n
Complete ablation of the cartilaginous vertebral body end plates, down to a
raw, bleeding bony surface, is required for bony fusion (Figure 17-3).
S T E P 1 P EA R L S
• Release of the anterior longitudinal
ligament and complete diskectomy
allows for maximal curve flexibility and
deformity correction.
• A malleable ribbon retractor placed
around to the far side of the disk space
affords protection to the vascular
structures.
• For severe, rigid curvatures that have
developed wedging of the vertebral
bodies, vertebral osteotomy may be
required to gain maximum correction.
FIGURE 17-3
Procedure 17 | Anterior Thoracolumbar Spinal Fusion via Open Approach for Idiopathic Scoliosis 161
S T E P 2 P EA R L S
• Adequate exposure should allow easy
access to the far (concave) side of the
vertebral body for finger palpation of
the probe, tap, and blunt tip of the
vertebral body screws.
• Bicortical screw purchase should be
obtained, with no greater than 2 mm
of screw-tip protrusion.
• Instrumentation must include the entire
Cobb angle.
S T E P 2 P IT FA L L S
• The surgeon must be cognizant of the
location of the posterior vertebral wall
and the spinal canal near the base of
the pedicle, to avoid entering the canal
with the vertebral body screw.
S T E P 4 P EA R L S
• Any morselized rib autograft or
harvested iliac crest graft should be
placed around the interbody supports.
In the case of a femoral ring allograft,
the hollow center of the allograft can
be filled with autograft.
S T E P 4 P IT FA L L S
• Compression anteriorly is a kyphosing
maneuver. Be careful not to compress
the disk spaces excessively when in the
lumbar spine or at the thoracolumbar
junction.
Step 4: Placement of Anterior Interbody Structural Supports
n
Anterior interbody structural supports are important for overall strength of the
construct and for setting the desired lordosis in the lumbar spine. When using
single-rod instrumentation, a structural support is placed at each level in the
lumbar spine, starting from the apex and moving cephalad and caudad. The
graft should be impacted toward the concave side and positioned to lie flush
with the anterior aspect of the vertebral body when setting the lordosis. Upon
placement of the structural grafts, the spinal curvature is usually fully corrected
and the lumbar lordosis is “set” before rod placement.
n
In the case of single structural thoracic (Lenke 1) curves fused to the thoraco-
lumbar junction (T12 or L1), structural grafts are used one or two levels above
the last instrumented vertebra to prevent junctional kyphosis.
Step 5: Rod Placement
n
The rod is appropriately contoured to the desired sagittal and coronal plane
configuration and introduced into the screws. The rod is reduced to the screws
and captured sequentially.
n
Some degree of rod rotation or screw rotation may be necessary to “fine-tune”
the correction. This should not require much force at this stage.
n
Some final compression of the screws across the disk spaces to firmly compress
the grafts can be performed at this stage if necessary.
Step 6: Placement of Chest Tube and Wound Closure
n
A standard chest tube is placed and withdrawn from a small separate stab
incision.
n
Wound closure must allow for meticulous reapproximation of the diaphragm
(see Portals/Exposures Pearls).
n
The chest tube is maintained on wall suction until the first or second postopera-
tive day. It is removed upon resolution of the pneumothorax/hemothorax and
when output decreases to less than 75 to 100 mL over a 12-hour period.
Procedure: Thoracolumbar Spine Fusion via an Open Approach Using Dual-Rod Instrumentation
Step 1: Anterior Release and Diskectomy
n
This is performed in the same manner as described in step 1 for single-rod
instrumentation.
Step 2: Placement of the Anterior Vertebral Body Screws
n
With systems using a dual-rod construct, there is typically a two-holed tined
vertebral staple that is implanted first, which then receives the vertebral body
screws (Figure 17-4). When positioning these devices, care should be taken not
to allow the anterior screw to be too close to the anterior aspect of the vertebral
body, because vertebral body fracture can occur. The proper staple is selected
by identifying the size that maximizes the coverage of the lateral aspect of the
vertebral body without violating the adjacent disk space.
n
Anteriorly placed devices may also incur more kyphosis, which is undesirable in
the lumbar spine. The posterior screw should be placed in a position as posterior
as possible, without allowing for canal intrusion.
Step 3: End-Plate Ablation
n
This is performed in the same manner as described in step 3 for single-rod
instrumentation.
162 Procedure 17 | Anterior Thoracolumbar Spinal Fusion via Open Approach for Idiopathic Scoliosis
FIGURE 17-4
FIGURE 17-5
Step 4: Placement of Anterior Interbody Supports
n
This is performed in the same manner as described in step 4 for single-rod
instrumentation.
Step 5: Rod Placement
n
The rods are appropriately contoured to the desired sagittal and coronal plane
configuration.
n
The posteriormost rod is reduced to the screws first and captured
sequentially.
n
Some degree of rod rotation may be necessary to “fine tune” the correction,
which has already largely occurred from the meticulous diskectomy and structural graft placement.
n
The anterior screws can be used to further derotate the vertebrae at this point,
if necessary. Some final compression of the posterior screws across the disk
spaces to firmly compress the grafts before final tightening can be performed
at this stage. The anteriormost rod is then placed and captured at this point,
essentially in situ.
n
Some spinal implant systems will use a cross connector, which can be placed
at this point (Figure 17-5).
P O S T OP E R AT IV E
C O N T RO V E R S IE S
• When using a single-rod system with
rod diameter greater than 5 mm and
multilevel structural interbody support,
bracing may not be necessary in the
early postoperative phase.
Step 6: Placement of Chest Tube and Wound Closure
n
This is performed in the same manner as described in step 6 for single-rod
instrumentation.
Postoperative Care and Expected Outcomes
n
The patient is mobilized beginning on the day following surgery. If single-rod
instrumentation is utilized, a spinal orthosis is fashioned and worn for 3 to
4 months postoperatively. If dual-rod instrumentation is utilized, no brace is
employed.
n
Activity modifications are necessary for at least the first 6 months postopera-
tively, with a return to competitive sports at 12 months or when clear evidence
of fusion is seen radiographically.
n
Radiographs are taken to assess the implant stability, maintenance of correction
and maturation of the fusion at 1, 3, 6, and 12 months postoperatively (Figures
17-6, A and B, and 17-7). Yearly radiographs are obtained thereafter until
definitive fusion is seen.
Procedure 17 | Anterior Thoracolumbar Spinal Fusion via Open Approach for Idiopathic Scoliosis 163
A
FIGURE 17-6, A-B
B
FIGURE 17-7
164 Procedure 17 | Anterior Thoracolumbar Spinal Fusion via Open Approach for Idiopathic Scoliosis
Evidence
Fricka KB, Mahar AT, Newton PO. Biomechanical analysis of anterior scoliosis
instrumentation: differences between single and dual rod systems with and
without structural interbody support. Spine 2002;27:702-6.
In bovine specimens, dual-rod constructs were stiffer in torsion and flexionextension loading than in single-rod systems. Lateral bending stiffness was
similar for both constructs. When structural interbody support (SIS) was added,
stiffness in flexion increased significantly in single-rod constructs, approaching
that of dual-rod constructs.
Lowe TG, Alongi PR, Smith DA, et al. Anterior single-rod instrumentation for
thoracolumbar adolescent idiopathic scoliosis with and without the use of
structural interbody support. Spine 2003;28:2221-32.
Forty-one patients with adolescent idiopathic scoliosis underwent anterior
spinal fusion using a single-rod (6.0- or 6.5-mm) construct. SIS was used in
21 patients, and packed morselized autograft alone was used in 20 patients.
There were no rod or screw failures and no obvious pseudarthroses at 3-year
follow-up. Results were similar for both groups regarding curve correction and
restoration of sagittal balance, and the Scoliosis Research Society Outcomes
Instrument. The outcomes from use of SIS versus morselized autograft did not
appear to be significantly different when these large-diameter single rods were
used.
Lowe TG, Enguidanos ST, Smith DA, et al. Single-rod versus dual-rod anterior
instrumentation for idiopathic scoliosis: a biomechanical study. Spine
2005;30:311-17.
In human cadaveric specimens, SIS appeared to contribute the most to construct
stiffness in flexion, whether single- or dual-rod constructs were used. In lateral
bending, stiffness of single- and dual-rod constructs with and without SIS was
equivalent. In torsion, single- and dual-rod instrumentation and SIS contributed
to global stiffness. Transverse rod connectors in dual-rod constructs only
contributed to stiffness in torsion. In bovine specimens, dual rods were stiffer
than single-rod constructs, with SIS playing only a minor role.
Polly DW Jr, Cunningham BW, Kuklo TR, et al. Anterior thoracic scoliosis
constructs: effect of rod diameter and intervertebral cages on multi-segmental
construct stability. Spine J 2003;3:213-19.
In bovine specimens, single-rod constructs utilizing a 4- and 5-mm rod were
tested with a seven-level interbody cage construct and compared with
constructs using only one (apical disk), two (end disks), and three (apical and
end disks) levels. Intervertebral cages at every level significantly improved
construct stiffness when compared with increasing rod diameter alone. When
structural supports were not used, axial compression created the greatest strain.
Potter BK, Kuklo TR, Lenke LG. Radiographic outcomes of anterior spinal fusion
versus posterior spinal fusion with thoracic pedicle screws for treatment of
Lenke type I adolescent idiopathic scoliosis curves. Spine 2005;30:1859-66.
This retrospective review compared curve correction and derotation among
40 curve-matched cohorts of Lenke type 1 curves treated by spinal fusion
performed anteriorly with single-rod instrumentation versus posteriorly
with thoracic pedicle screw (PSF/TPS) constructs. Anterior surgery allowed for
an average of one less vertebral level fused. However, the PSF/TPS group
demonstrated greater correction of the main thoracic curve and greater
spontaneous correction of the uninstrumented thoracolumbar-lumbar curve,
and improved correction of thoracic torsion and rotation.
Procedure 17 | Anterior Thoracolumbar Spinal Fusion via Open Approach for Idiopathic Scoliosis 165
Rhee JM, Bridwell KH, Won DS, et al. Sagittal plane analysis of adolescent
idiopathic scoliosis: the effect of anterior versus posterior instrumentation.
Spine 2002;27:2350-6.
This retrospective study evaluated the postoperative sagittal profile of 110
consecutive patients with adolescent idiopathic scoliosis. Sixty patients
underwent posterior dual-rod instrumented fusion, and 50 patients underwent
anterior instrumented fusion using a single-rod construct. At a follow-up of 32
months, the proximal junctional (kyphosis) measurement (measured between
the proximalmost instrumented vertebra and the segment two levels cephalad)
increased most in the posterior group; thoracic kyphosis (T5-12) increased most
in the anterior group, and lumbar lordosis was enhanced with either approach.
No significant change in the distal junctional measurement (measured between
the distal instrumented vertebra and the segment two levels caudal) occurred in
either group. The authors conclude that each approach affects the sagittal
profile differently, albeit to a small degree. When properly performed, both
approaches can give an acceptable sagittal profile.
Smith JA, Deviren V, Berven S, Bradford DS. Does instrumented anterior scoliosis
surgery lead to kyphosis, pseudarthrosis or inadequate correction in adults?
Spine 2002;27:529-34.
This retrospective review of 14 consecutive adult patients with scoliosis treated
by anterior spinal fusion using a single-rod (6-mm) construct demonstrated no
cases of pseudarthrosis, progressive kyphosis, or instrumentation failure.
Average correction of the Cobb angle was 66%, and the thoracolumbar sagittal
plane alignment was maintained or improved in every patient. The patients
scored satisfactorily on the Scoliosis Research Society Outcomes Instrument in
the areas of satisfaction, pain, self-image, function, and mental health.
P R O C ED U R E 1 8
Operative Management
of Scheuermann
Kyphosis
Per D. Trobisch, Wilsa M.S. Charles Malveaux,
Alok D. Sharan, and Thomas J. Errico
I N D I CAT I O NS P I T F A L L S
• A complete neurologic workup should
be included if there are any upper
motor signs, to rule out the presence of
a cyst or thoracic disk herniation.
I N D I CAT I O NS
C O N T RO V E R S IE S
• Spondylolisthesis is sometimes
associated with Scheuermann kyphosis.
• An asymptomatic spondylolisthesis does
not require treatment.
• Neurologic dysfunction more likely
results from other causes (e.g., disk
herniation) rather than the kyphotic
deformity itself.
T R E A T M E N T OP T I O N S
• Posterior spinal fusion (PSF) (hooks,
pedicle screws, hybrid constructs)
• Combined anterior/posterior spinal
fusion
• Anterior thoracoscopic spinal fusion by
video-assisted thoracoscopic surgery
(VATS)
Indications
n
Rigid curves greater than 75 degrees
n
Curves that have progressed despite brace treatment
n
Painful kyphotic curves that progress despite nonoperative treatment
n
Neurological deficit
n
Respiratory difficulty resulting from curves greater than 100 degrees
Examination/Imaging
n
Anteroposterior and lateral radiographs on long cassettes
n
Hyperextension radiograph taken over a bolster
n
Magnetic resonance imaging (MRI) of thoracic and lumbar spine to rule out a
cyst or disk herniation
Surgical Anatomy
n
T2 to T12 can be accessed by a transthoracic approach, with vertebrae below
T12 by a retroperitoneal approach.
n
Usually two to three disks can be approached through one portal if VATS is
performed.
n
Alternatively, multiple segmental posterior osteotomies (SPOs) for posterior-only
approaches can be performed.
n
When performing SPOs, it is important to resect the inferior and the superior
facet of adjacent vertebrae.
n
The supraspinous ligament at the most cephalad level(s) should be preserved
to prevent proximal junctional kyphosis.
P O S I TI O N I N G PE A R L S
• Placing the hips in hyperextension
during the posterior approach helps to
maintain lumbar lordosis.
• The knees are flexed to 30 degrees to
relax the hamstrings.
• The upper pads should be placed
caudal to the shoulder, to passively help
correct the thoracic kyphosis.
Positioning
n
For the anterior approach, place the patient in the lateral decubitus position.
n
Left-sided approaches are preferred, because injury to the aorta is easier to
repair than injury to the vena cava.
n
For the posterior approach, place the patient prone on a four-poster frame.