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Procedure 33 | Transforaminal Lumbar Interbody Fusion 309
S T E P 2 P EA R L S
• Gently palpating the curvature of the
annulus from within the disk space with
a blunt instrument helps to obtain
a three-dimensional vision of the
interbody space and margins.
• Minimizing retraction of the nerve roots
reduces the risk of nerve root irritation
or injury.
• Slightly curved curettes and up-biting
rongeurs are useful in removing disk
material from the contralateral side.
Especially if using a microscope, the
table should be neutral during this
portion of the procedure. One should
not use the up-biting rongeurs too
superficially in the disk space, because
this may result in a punctured annulus
and possible neural injury.
• The authors use bone wax on the
osteotomized lip of the inferior
vertebral, the remaining superior
surface of the superior articular facet,
and the medial surface of the pedicle
to reduce bleeding. This also,
theoretically, as necessary reduces the
risk of heterotopic ossification in the
foramen. In addition, use of fibrin glue
or hydrogel sealant to seal the contents
of the disk space in place may reduce
the risk of heterotopic ossification and
bone morphogenetic protein (BMP)related radiculitis.
segment’s superior articular facet. This corresponds to the disk space and is well
below the superior segment’s pedicle.
n
A second caudal cut is made parallel to the inferior facet, and the inferior facet
is then removed, exposing the foramen and the superior articular facet tip of
the caudal vertebrae.
n
The superior facet of the caudad level is resected as needed, to access the disk
space. If need be, this can be resected flush with the pedicle.
n
The inferior aspect of the lamina and the ligamentum are resected as needed,
to perform a decompression and to visualize the nerve roots.
Step 2
n
The superior lip of the inferior vertebral body is osteotomized to expand the
access to the disk space.
n
A radical diskectomy is performed (Figure 33-5) using TLIF instrumentation,
including down-pushing curettes, rasps, ring curettes, pituitaries, and Kerrison
rongeurs. The initial annulotomy is performed with a no. 11 scalpel.
n
Occasionally, as in the case of an especially collapsed disk, blunt rotating dilators
are used to sequentially distract the disk space. Shavers may also be used in
this manner. Great care must be taken with the shavers not to cut the end plates.
Figure 33-6 is a lateral fluoroscopic image showing the shaver in the disk space.
Small shavers may facilitate removal of disk in the setting of a tall disk space.
The authors recommend avoiding larger shavers in this setting, because the
cutting edges may damage the end plates.
FIGURE 33-5 FIGURE 33-6
310 Procedure 33 | Transforaminal Lumbar Interbody Fusion
n
S T E P 2 P IT FA L L S
• Exiting through the anterior or lateral
annulus while removing disk material
can cause vascular, viscus, or neural
injury. During the diskectomy, especially
if using a microscope, the table should
be neutral. One should not use the
up-biting rongeurs too superficially in
the disk space, because this may result
in a punctured annulus and possible
neural injury. Several fluoroscopic
checks should be performed while
performing the diskectomy.
• Partial removal of the cartilage end
plate and disk will reduce the chances
for a successful fusion.
• Breech of the end plate will lead to
implant or graft subsidence.
Interbody spacer trials are sequentially malleted into place. When the trial fits
very snuggly, this indicates the height of the implant chosen (Figure 33-7).
n
The end plates are scraped with ring curettes to free any remaining cartilage
and expose bleeding subchondral bone.
Step 3
n
Collagen sponges containing recombinant human-BMP-2 (rh-BMP-2) are placed
in the most anterior part of the prepared disk space, just behind the anterior
longitudinal ligament (ALL) or within a polyether ether ketone (PEEK) spacer.
n
Alternatively, structural autograft may be used.
n
Local autograft, augmented with allograft or autogenous iliac crest graft, if
necessary, is then tightly packed into the disk space, before inserting the interbody structural allograft or spacer. Alternatively, bone dust and demineralized
bone matrix may be packed in the middle column behind a C-shaped graft,
where the ideal graft position is anterior in the disk space.
n
TLIF C-shaped (banana) PEEK spacer or structural allograft is placed as anterior
as possible under fluoroscopic guidance. Figure 33-8 shows the position of a
C-shaped TLIF graft. The C-shaped graft (spacer) is then rotated (Figure 33-9).
The authors use a small down-pushing curette under the microscope to start
S T E P 3 P EA R L S
• Removing the posterior osteophytes or
concave ridge of the posterior vertebral
body will help in placing the proper-size
implant.
• Anterior placement of the interbody
graft achieves the most lordosis
possible.
• Choose an implant that gives maximal
surface area of contact and fits snuggly.
rotation of the graft. An impactor is then used, aiming perpendicular to the floor
on the edge of the graft. Under fluoroscopic guidance, the graft is then rotated.
Should there be any forward translation of the graft, or should it not move,
the authors stop this portion of the procedure at this point. Recently spacers
have become available, allowing rotation while still connected to the spacer
insertion handle.
FIGURE 33-7 FIGURE 33-8
Impactor
Cage
Bone graft
S T E P 3 P IT FA L L S
• Breeching the annulus and inserting the
implant anterior to the disk space into
the retroperitoneal space
• Inserting an oversized implant can
disrupt the end plate and lead to
settling and loss of sagittal alignment.
• Inserting the implant at an incorrect
angle (not parallel to the end plates)
will disrupt the subchondral bone and
lead to settling.
• Impinging on a nerve root while
inserting the implant
Procedure 33 | Transforaminal Lumbar Interbody Fusion 311
n
Recently, expandable implants have become available. Figure 33-10 shows
lateral (A) and AP (B) lumbar radiographs of a patient who underwent a twolevel TLIF with the Staxx XD expandable device (Spine Wave, Shelton, Conn.).
These may reduce the risk of end-plate and neural injury by avoiding
impaction.
n
As an alternative to C-shape implants, a PLIF-type implant may be used, inserted
obliquely. Recently, these have become available as insert-and-rotate type
prostheses.
A
FIGURE 33-9, A-B
S T E P 3 C ON T R O V ER S I E S
• The use of BMP for TLIFs is controversial
and is considered an off-label
application of BMP. Overgrowth of
bone into the epidural space has been
reported. Using a fibrin glue or
hydrogel sealant along the posterior
disk and keeping the collagen sponge
contained in the implant and/or
anteriorly in the interspace may reduce
the risk of this complication and
may reduce the risk of BMP-related
radiculitis. Waxing of the osteotomized
lip of the inferior vertebrae and the
remaining superior surface of the
superior articular facet or surface of the
inferior pedicle may also reduce the risk
of heterotopic ossification.
• Options for structural interbody spacers
include machined allograft, shaped
autograft, titanium cages, PEEK, and
resorbable cages.
A
FIGURE 33-10, A-B
B
B
312 Procedure 33 | Transforaminal Lumbar Interbody Fusion
S T E P 4 P EA R L S
• Final anteroposterior and lateral
radiographs before closure are
recommended to confirm satisfactory
alignment and instrumentation.
S T E P 4 C ON T R O V ER S I E S
• Some sources recommend placement
of the contralateral pedicle screws and
rod, and achieving distraction of the
disk space before diskectomy. The
authors have not found this step to
be necessary.
• If performing a laminectomy at the
level of the interbody fusion, a laminar
spreader may facilitate insertion of the
interbody graft.
Step 4
n
Ipsilateral pedicle screws are placed using anatomic and fluoroscopic
guidance.
n
The contralateral screws are placed likewise. Figure 33-11 shows lateral (A) and
AP (B) fluoroscopic images, confirming excellent pedicle screw and TLIF graft
placement. Figure 33-11, C shows a lateral image at 1 year, revealing maintenance of lumbar lordosis and a solid interbody arthrodesis. A preoperative
image (Figure 33-11, D) is shown for reference, showing two-level degenerative
spondylolisthesis.
Step 5
n
Posterolateral fusion is achieved by decortication of the contralateral facet, pars
interarticularis, and transverse process. Any remaining bone graft and BMP may
be placed in this location.
A
C
FIGURE 33-11, A-D
B
D
Procedure 33 | Transforaminal Lumbar Interbody Fusion 313
S T E P 5 P EA R L S
• Placement of the posterolateral bone
graft on the side contralateral to the
TLIF helps to prevent migration of bone
fragments into the spinal canal or
foramen and subsequent neuronal
compression.
P O S T OP E R AT IV E P E A R L S
• Nonsteroidal antiinflammatory drugs
(NSAIDs) are avoided for 12 weeks,
because they can compromise bony
fusion.
P O S T OP E R AT IV E P I T F A L L S
• Early return to strenuous exercise
before a solid fusion can lead to
implant loosening and a failed fusion.
• Complications related to TLIF include
neurologic deficit/nerve root injury,
instrumentation misplacement,
hematoma/seroma, radiculitis, wound
infection, vertebral osteolysis, ectopic
bone formation, and complications
related to hip graft harvest. In one
study where BMP was used, radiculitis
was observed in 20.4% of patients
when BMP was used without a
hydrogel sealant, and radiculitis was
observed in 5.4% when BMP plus
hydrogel sealant was used. In patients
where hip graft was used, the radiculitis
rate was 3.0%.
P O S T OP E R AT IV E
C O N T RO V E R S IE S
• Some surgeons advocate the use of
an external orthosis postoperatively,
especially in patients who are at high
risk of nonunion (e.g., smokers).
Postoperative Care and Expected Outcomes
n
Patients are mobilized the same day of surgery or the following morning without
external orthosis.
n
Physical therapy is started on postoperative day 1 to aid with ambulation.
n
Excessive bending, lifting, or twisting is discouraged until 8 to 12 weeks, when
a solid fusion is expected.
n
Successful fusion can be expected in greater than 90% of patients, and typically
a majority of patients will report improvement in functional outcome.
Evidence
Anand N, Hamilton JF, Perri B, Miraliakbar H, Goldstein T. Cantilever TLIF with
structural allograft and RhBMP2 for correction and maintenance of segmental
sagittal lordosis. Spine 2006;31:748-53.
This study looked at the effectiveness of the cantilever TLIF to maintain
sagittal lordosis, avoid nerve root injury, and achieve successful fusion in 100
consecutive patients. The authors found that 97% of patients were satisfied
with their outcome and would recommend the surgery. They also found
significant improvement in segmental sagittal lordosis from 2 to 9 degrees, and
significant disk height restoration. Solid fusion was achieved in 99% of patients
with mean follow-up of 30 months. All patients had improvement in radicular
pain, and no neural injuries occurred.
Hackenberg L, Halm H, Bullmann V, et al. Transforaminal lumbar interbody fusion:
a safe technique with satisfactory three- to five-year results. Eur Spine J 2005;
14:551-8.
In 52 patients undergoing TLIF, the radiographic fusion rate was 89%. Using the
Visual Analogue Scale and Oswestry Disability Index, significant improvement in
pain was demonstrated after TLIF.
Owens K, Glassman SD, Howard JM, et al. Perioperative complications with
rhBMP-2 in transforaminal lumbar interbody fusion. Eur Spine J 2010;20:612-7.
This is a retrospective review of 204 patients undergoing TLIF with rhBMP-2.
Complications were observed in 47 of 204 patients (21.6%) during the 3-month
perioperative period. Major complications occurred in 13 patients (6.4%) and
minor complications in 34 patients (16.7%). New or more severe postoperative
neurologic complaints were noted in 13 patients (6.4%), 6 of whom required
additional surgery. Overall, this study demonstrates a modest complication rate
for TLIF using rhBMP-2.
Potter BK, Freedman BA, Verwiebe EG, et al. Transforaminal lumbar interbody
fusion: clinical and radiographic results and complications in 100 consecutive
patients. J Spinal Disord Tech 2005;18:337-46.
This study found that TLIF is a safe and effective method of achieving lumbar
fusion with a 93% radiographic fusion rate. Although 81% of patients reported
greater than 50% decrease in their symptoms, and 76% would choose to have
the procedure again, only 29% were entirely pain free. Complications from the
procedure were found to be uncommon and generally minor and transient.
Rihn JA, Patel R, Makda J, et al. Complications associated with single-level
transforaminal lumbar interbody fusion. Spine J 2009;9:623-9.
This is a retrospective study of 119 patients undergoing single-level TLIF with
iliac crest or rhBMP-2. Average follow-up was 27.6 months. Thirty-three patients
received iliac crest autograft, and 86 patients received rhBMP-2. Complications
occurred in 40 of the 119 study patients (33.6%). The autograft group had
a higher complication rate (45.5% vs. 29.1%), but the difference was not
statistically significant (P =.09). Complications in the autograft group included
persistent donor-site pain (30.3%), donor-site infection (3.1%), lumbar wound
infection (6.1%), and postoperative radiculitis (3.0%). Complications in the
rhBMP-2 group included postoperative radiculitis (14.0%), vertebral osteolysis
(5.8%), ectopic bone formation (2.3%), and lumbar wound infection (3.5%). A
hydrogel sealant (Duraseal; Confluent Surgical, Waltham, Mass.) was used in 37
of 86 patients in the rhBMP-2 group. The use of this sealant decreased the
rate of postoperative radiculitis in the rhBMP-2 group from 20.4% to 5.4%
(P = .047). The radiographic nonunion rate at most recent follow-up was 3.0%
in the autograft group and 3.5% (P = .90) in the rhBMP-2 group.
Schwender JD, Holly LT, Rouben DP, Foley KT. Minimally invasive transforaminal
lumbar interbody fusion (TLIF): technical feasibility and initial results. J Spinal
Disord Tech 2005;18(Suppl 1):S1-6.
In this series, minimally invasive TLIF was performed in 49 patients and was
shown to be safe and effective, resulting in a 100% radiographic fusion rate.
Pain also significantly improved following surgery, as measured by the Visual
Analogue Scale and Oswestry Disability Index.
P R O C ED U R E 3 4
The Transpsoas Approach
for Thoracolumbar
Interbody Fusion
Eli M. Baron, Timothy Davis, and Neel Anand
I N D I CAT I O NS P I T F A L L S
• Anatomically, the transpsoas approach
is limited at the caudal levels by the
iliac crest. A low-seated L4-5 disk may
be inaccessible by this approach.
• The L5-S1 disk space is usually
inaccessible by this approach because
of the iliac crest and the neural
structures of the lumbosacral plexus.
• Prior retroperitoneal surgery
contraindicates this approach.
• High-grade spondylolisthesis is a
contraindication to this approach.
For grade 2 and higher, the authors
typically do not use this approach
secondary to higher risk of neural
injury.
I N D I CAT I O NS
C O N T RO V E R S IE S
• Typically, rotational abnormalities of
the spine will not be corrected by a
transpsoas diskectomy and interbody
fusion.
• Although there are surgeons who
advocate standalone procedures, the
authors have had most success with
supplementation with posterior pedicle
screw–based instrumentation.
Indications
n
The transpsoas approach for lumbar interbody fusion is indicated as an alterna-
tive to lumbar interbody fusion. It can be performed from T10 down to L5.
n
It is commonly performed as an alternative to anterior lumbar interbody fusion,
and is particularly useful with degenerative scoliosis.
n
It is useful as an alternative corridor to the lumbar spine where prior posterior
procedures or anterior abdominal procedures have been performed. It has also
been described as a useful salvage for a failed arthroplasty.
n
Typical indications include
• Scoliotic deformities
• Lateral listhesis
• Degenerative disk disease
• Low-grade degenerative spondylolisthesis
• Low-grade isthmic spondylolisthesis
Examination/Imaging
n
Plain radiographs should be performed preoperatively, as should magnetic reso-
nance imaging (MRI).
n
The authors typically will also perform computed tomography (CT) imaging.
n
In cases of deformity, 36-inch standing radiographs are performed.
Surgical Anatomy
n
This approach to the lumbar segments is limited rostrally by the 12th rib and
caudally by the superior edge of the iliac crest. This window of access is easily
increased during lateral positioning by elevating a kidney rest just above the
iliac crest or having a “table break” at the level of the iliac crest.
n
Relevant neuroanatomic structures in the transpsoas approach include branches
of the lumbar plexus. The lumbar plexus consists of the iliohypogastric (L1),
ilioinguinal nerve (L1), genitofemoral nerve (L1-2), lateral femoral cutaneous
nerve (L2-3), obturator nerve (L2-4 ventral divisions of ventral rami), and the
femoral nerve (L2-4 dorsal divisions of ventral rami). Each of these structures
passes through the psoas along an independent path.
n
Lumbar plexus branches originate from the ventral rami (motor) and dorsal rami
(sensory) of L1-4 segments and travel through the psoas musculature. The neural
structures enter the psoas posteromedially and then pass anterolaterally. Many
of these fibers are adjacent to the posterior lateral border of the disk space.
Anatomic variations are seen up to 20% of the time.
Procedure 34 | The Transpsoas Approach for Thoracolumbar Interbody Fusion 315
T R E A T M E N T OP T I O N S
• In the setting of lumbar degenerative
scoliosis, unilateral radiculopathy
(resulting from foraminal narrowing),
unilateral laminoforaminotomy with
medial facetectomy should be
considered.
• Alternative fusion techniques to the
transpsoas approach include anterior
lumbar interbody fusion and
transforaminal interbody fusion.
• Posterior lumbar interbody fusion may
also be useful.
• Posterolateral instrument fusion with
instrumentation can also be considered.
n
Avoiding neural structures during disk localization is of paramount importance.
A safe window of access to the lumbar disks through the psoas has been previously described. The size of this access window decreases in anterior to posterior
diameter from rostral (L1-2) to caudal (L4-5).
n
The safe window of access is intended to describe the recommended target area
for each disk when using the initial disk localization probe. Most neural structures will be manipulated and displaced to a variable degree once dilators and
retractors are placed.
n
Significant neural injuries at L1-3 are less likely due to the course of the upper
branches of the lumbar plexus. However, L2 motor contribution to the obturator
and femoral nerve can still be encountered if entering the disk space too far
dorsal at L2-3.
n
The genitofemoral nerve commonly pierces the anterior belly of the psoas at the
level of the L3 vertebral body. Therefore, during access to the L3-4 disk, the disk
localization probe will be posterior to the genitofemoral and anterior to all other
neural structures, including the L2 and L3 motor contribution to the obturator
and femoral nerves.
n
L4-5 disk space has the smallest access window and may also be hampered by
a high-riding iliac crest, which is more common in males. In the majority of
subjects, the bulk of the neural structures are located dorsal to the midpoint of
the L4-5 intervertebral disk. Thus the authors recommend targeting the junction
of the anterior and middle one third of the disk space when choosing a trajectory for the transpsoas approach. This will help in avoiding the obturator and
femoral nerves as they cross the L4-5 disk space. Triggered electromyography
can assist with identification of these motor nerves during disk localization.
n
Thigh paresthesias have been reported frequently but are commonly transient
in nature, resolving within 6 weeks. This is considered to be consistent with a
transient neuropraxia, probably because of traction or compression during the
procedure. Along the same lines, transient meralgia paresthetica occurs at a
relatively high rate during posterior lumbar spine procedures.
n
Thigh paresthesias can occur in variable patterns with injury to sensory fibers
of any of the following nerves: genitofemoral, lateral femoral cutaneous, obturator, and femoral.
n
The kidneys and ureter lie anterior to the psoas musculature. The aorta and vena
cava descend anterior to the L1-4 vertebral bodies. The transpsoas approach
allows access to the lumbar disk space while avoiding manipulation of the major
vascular structures along the prevertebral plane, compared with an anterior
lumbar interbody fusion, which requires significant vascular manipulation.
n
Preservation of the anterior longitudinal ligament will inherently reduce the
likelihood of injury to other prevertebral structures.
n
A true lateral fluoroscopic image of the disk space before disk localization, with
proper end plate and neuroforaminal alignment, can help to avoid inaccurate
trajectory during disk localization. This will decrease the potential for violation
of the anterior longitudinal ligament as well as decrease the possibility of vascular or visceral injury.
n
Anatomic keys to success
• True lateral fluoroscopic imaging with properly aligned end plates and
neuroforamen
• Retroperitoneal dissection that avoids
◆
Neural structures: iliohypogastric, ilioinguinal, genitofemoral, lateral
femoral cutaneous
◆
Visceral peritoneum
◆
Kidney and ureter
• Proper targeting at the center of the disk space at L1-2 and L2-3
• Proper targeting at the junction of the anterior and middle third of the disk
space at L3-4 and L4-5
316 Procedure 34 | The Transpsoas Approach for Thoracolumbar Interbody Fusion
• Triggered electromyographic assistance with localization of motor nerve structures (obturator and femoral nerve), especially important at L4-5
• Proper placement of retractor along the same trajectory as localization probe
to avoid violation of the anterior longitudinal ligament, vascular, and visceral
structures during diskectomy stage
• Awareness of neural and vascular structures during annular release from the
end plates on the contralateral side
• In a small percentage of subjects, the femoral nerve may be quite large and
anterior at L4-5, and it may require too much retraction to proceed.
P O S I TI O N I N G PE A R L S
• It is crucial that the surgeon work
directly perpendicular to the floor
to maintain a safe trajectory of all
instruments and have a better sense
of the intraoperative spinal anatomy.
Therefore the table is rotated as needed
while keeping the C-arm perpendicular
to the floor.
• An airplane-style arm-holder is used to
hold the patient’s top arm in position.
The bottom arm is maintained resting
on an arm board.
• An axillary roll is always placed.
• The authors use a radiolucent slider
table with a kidney rest. Again, the
kidney rest is elevated just above the
iliac crest to maximize the distance
between the iliac crest caudally and the
rib cage rostrally.
• Lateral fluoroscopic images should
always be used to confirm appropriate
visualization of the disk space before
preparing and draping the patient.
Sometimes the patient will need to
be placed in a reverse Trendelenburg
position to achieve a more optimal
angle of axis to the disk space. This is
especially true when it comes to L4-5,
which may be low riding relative to
the iliac crest. In this case, reverse
Trendelenburg imaging may allow
access to the L4-5 disk space, where
the iliac crest would be seemingly in
the way.
• Alternatively, a radiolucent table with a
table break may be used; this table is
inverted with the patient’s head at the
foot of the bed.
• The table break is performed to
increase the access window between
the inferior ribs and the iliac crest.
This break angle is more extreme in
cases of the high-riding iliac crest.
• When a significant “table break” is
required for access to multiple levels,
consider performing the L4-5 first.
Once this level is completed, the
“table break” can be lessened,
thereby decreasing traction forces on
the lumbar plexus for the rest of the
case.
Positioning
n
The patient is placed in the lateral decubitus position.
n
An axillary roll is placed to reduce the risk of axillary nerve injury.
n
In addition, the patient is positioned with hips orthogonal to the ground. The
spine is kept as orthogonal to the ground as possible.
n
The authors use bolsters made from rolled-up patient blankets secured with
tape to support the patient’s torso.
n
Strapping tape is then used circumferentially to secure the patient to the bed.
n
To avoid injuring the skin, towels are placed over the skin surface where the
tape would contact the skin.
n
Before strapping the patient into position, the hips are positioned just below a
kidney rest that is elevated to maximize the distance between the iliac crests
caudally and the rib cage rostrally. Figure 34-1 shows a patient positioned in
the lateral decubitus position. Note the elevated kidney rest and the higher
arm being supported by an airplane-style arm-holder. Also note the strapping
tape securing the patient and making contact with towels rather than with the
patient’s skin.
n
Then the strapping tape is placed into position, with one person manipulating
the tape and another person holding the tape roll; in addition, a third person
is used to stabilize the patient’s body to make sure it does not fall either forward
or backward.
FIGURE 34-1
Procedure 34 | The Transpsoas Approach for Thoracolumbar Interbody Fusion 317
S T E P 1 P EA R L S
• Alternatively a posterior incision can
also be made just lateral to the rectus
median musculature. The surgeon’s
gloved finger can enter the
retroperitoneum along the iliac crest
and mobilize the peritoneum away
from the retroperitoneal space; the
transverse processes are palpated.
n
After securing the patient to the bed with strapping tape, additional strapping
tape is used in a cruciate manner to secure the patient’s top leg to the bed.
n
The top hip is flexed to maximize laxity of the psoas muscle.
n
Ample padding is placed around the fibular head of the bottom leg to minimize
the risk of peroneal nerve injury.
n
Lateral fluoroscopic imaging is used to confirm excellent visualization of the disk
spaces. If there is a rotational deformity, the bed is rotated so that the disk
space is oriented parallel to the ground. The C-arm is not rotated; rather, the
bed is rotated so that the surgeon can work perpendicular to the floor.
n
Based on extensive experience with this technique, the authors invariably have
the left side positioned upward, because this minimizes risk to any anterior
vascular or visceral structures.
Procedure
Step 1
n
After a true lateral image is obtained, the skin is marked. The authors prefer to
mark the skin along the grain of the external abdominal oblique musculature.
Figure 34-2 shows a radiopaque marker; in this case, a no. 10 blade is placed
between the disk spaces of L2-3 and L1-2 to plan a single incision where both
disk spaces would be accessible.
n
The authors make an incision that extends roughly
It is centered over the relevant disk space, although it can be centered between
two disk spaces, and thus, two disk spaces can be targeted from a single
incision.
n
A no. 10 blade is used to incise the skin.
n
Subcutaneous bleeders are gently coagulated with a Bovie.
n
The surgeon’s gloved finger then descends to the most caudal level through the
retroperitoneal space.
n
The finger enters posteriorly on the inside of the iliac crest and sweeps along
the inside of the iliac crest, persuading the peritoneal contents and the peritoneum anteriorly. The finger is then extended rostrally to palpate the transverse
processes and confirm clearance of the retroperitoneal space.
1
inches along the flank.
2
2
FIGURE 34-2
318 Procedure 34 | The Transpsoas Approach for Thoracolumbar Interbody Fusion
S T E P 2 P EA R L S
• It is crucial to save the image of
the guidewire/pack needle in the
disk space. When performing the
diskectomy, this is the surgeon’s
landmark as to how far anteriorly and
posteriorly he or she is within the disk
space.
• Alternatively, a small tapered probe,
rather than a PAK needle, can be used
to target the disk space. The thoracic
cavity is typically entered at T12-L1 and
above. While passing the PAK needle
into the thoracic cavity, the authors
would ask the anesthesiologist to hold
inspiration to keep the lung away and
then dock the PAK needle into the disk
space. Once the retractors are in, the
procedure is the same as for the lumbar
spine, regarding the diskectomy and
interbody fusion.
Step 2
n
A PAK (percutaneous access kit) (Medtronic, Minneapolis, Minn.) needle is
escorted down to the level of the psoas musculature under lateral fluoroscopic
guidance.
n
The needle is held steadily by placing a Kocher clamp on the patient’s skin while
grasping the needle.
n
The target of the disk localization probe is at middisk at L1-2 and L2-3, and
at the junction of the anterior and middle third of the disk space at L3-4 and
L4-5. The junction of the anterior and middle third of the disk space is targeted
with a PAK needle (Figure 34-3). Triggered electromyography through the tip
of the probe assists with detection of motor nerve stimulation during disk
localization.
n
A guidewire is then placed through the needle and confirmed in position under
lateral fluoroscopic imaging. The image is saved.
FIGURE 34-3