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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_6031_Библиотеки_им_академика_М_И_Перельмана.pdf
194
M.Y. Wang
Fig. 20.3 Kambin’s triangle
through this route. Because use of this corridor
does not require neural retraction (or potentially
even visualization), it is an important confi ne.
The typical maximal cylindrical passage through
Kambin’s triangle is 7 mm. Thus, cages that can
be inserted through this space and expanded
inside the disc space present the opportunity for
truly MIS or percutaneous interbody fusion.
this action can be controlled. Furthermore, these
devices can often be reduced in height as well
to adjust placement. Disadvantages include a
more limited footprint on the endplates and an
inability to fuse the contact surface between cage
and bone.
In Situ Assembly Modular – These devices are
mechanical in nature and are assembled with the
body. Modularized components are attached
together after placement into the disc space. These
devices have the same footprint disadvantages as
micromechanical cages but have the potential to
be placed from a smaller access route (Fig. 20.5 ).
In Situ Assembly-Contained Deformables –
These devices are assembled in the disc space.
However, the components are “fl owable” either
due to their small size or their liquid nature.
Semisolid implants rely on the concept of “granular packing” within a containment bag to
achieve a fi nal solid structure (Fig. 20.6 ) [ 6 ].
Liquid implants are still theoretical for ASD and
polymerize in situ. These implants are currently
limited to the application of annular repair after
microdiscectomy, but they hold a promising
future for deformity correction.
20.6 Case Illustration
20.5 The Role of Expandable Cages
One of the “Holy Grails” of MIS surgery has been
the ability to place a relatively large implant through
a smaller soft tissue or bony opening. Proper contact of the endplates is necessary for anterior load
sharing and a successful arthrodesis. For ASD, this
also affords the opportunity to distract the disc
height symmetrically or asymmetrically in order
to correct a kyphoscoliosis. In general three types
of expandable cages are available:
Micromechanical – These cages are typi-
cally of a lower height that can be “jacked up”
after placement to elevate the intradiscal space
(Fig. 20.4 ). Because of the mechanical nature of
these devices, they can typically place signifi cant
force selectively in the rostral-caudal plane and
A 53-year-old male presented with severe and
intractable back and leg pain. He had failed all
conservative measures and was found to have
symptoms predominantly due to a spondylolisthesis. After full discussion on the various surgical alternatives for treatment, the patient elected
to undergo an L4/5 MIS TLIF (Fig. 20.7 ).
The surgical technique involved a midline
skin incision followed by selective unilateral
opening of the soft tissue envelope at the levels
of the disc space. A hemilaminotomy was used
on the side of the leg pain to expose the exiting
L4 and traversing L5 nerve roots. The disc is then
removed in a fashion similar to an aggressive
microdiscectomy, with care to properly prepare
the vertebral endplates for fusion by denuding
them of cartilage. Disc space preparation was
accomplished using “insert and rotate” shaver
dilators, rongeurs, and curettes through a 7 mm
20 Expandable Cages for Lumbar Spinal Deformity
a
195
b
c
d
Fig. 20.4 ( a ) Intervertebral height restoration using a micromechanical cage elevates the disc space similar to a car
jack. ( b – d ) Example of a micromechanical expandable TLIF cage
ab
Fig. 20.5 ( a ) Example of an in situ assembly modular cage inserter. ( b ) The implant is composed of PEEK leafl ets
which stack together to elevate the disc space after insertion
196
M.Y. Wang
annular opening. After the vertebral endplates
had been denuded of cartilage, 1/2 of a small
rhBMP-2 kit (2.1 mg) was placed into the anterior disc space, followed by autograft bone saved
from the decompression.
A 25 mm expandable interbody cage
(Spineology™, Minneapolis, Minnesota)
was fi lled internally with allograft paste
( demineralized bone matrix). This elevated the
disc space providing for fusion, correcting the
ab
spondylolisthesis, and indirect decompression of
the nerve roots bilaterally. It should be noted that
the use of rhMP-2 and Spineology™ cages in
this setting is an off-label use per Food and Drug
Administration (FDA) guidelines [ 3 , 4 ]. After
crimping the cage shut to seal it, the area was
washed with irrigation to remove any allograft
carrier matrix. This is followed by percutaneous
screw and rod placement without manipulation
of the hardware to correct the spondylolisthesis.
c
d
Fig. 20.6 ( a – e ) Example of an in situ assembly-contained deformable cage that is composed of a polymeric sac that is
fi lled internally with allograft after insertion into the disc space
20 Expandable Cages for Lumbar Spinal Deformity
197
e
Fig. 20.6 (continued)
a
Postoperatively the patient had a rapid recovery
with improvement of both leg and back pain.
Conclusions
Expandable cages offer the opportunity to signifi cantly reduce the morbidity of MIS ASD
surgeries. Powerful anterior corrective forces
can potentially be applied through these
implants, and several options already exist and
are commercially available. In addition, a tall
cage can be inserted through a collapsed disc
space more easily. The ideal implant has yet to
be developed, but regardless of the spacer
used, successful arthrodesis is critical to the
long-term success of any ASD surgery.
b
c
Fig. 20.7 ( a – c ) Treatment of an L4/5 spondylolisthesis using an infl atable cage to restore anterior column height. This
method allows easy access through Kambin’s triangle into a collapsed disc space without nerve root retraction
198
M.Y. Wang
References
1. Barnes B, GE R, Haid R, Subach B, McLaughlin M.
Allograft implants for posterior lumbar interbody
fusion: results comparing cylindrical dowels and
impacted wedges. Neurosurgery. 2002;51:1191–8.
2. Brantigan J, Neidre A, Toohey J. The lumbar I/F cage
for posterior lumbar interbody fusion with the variable screw placement system: 10-year results of a
Food and Drug Administration clinical trial. Spine J.
2004;4:681–8.
3. Burkus JK, Transfeldt EE, Kitchel SH, Watkins RG,
Balderston RA. Clinical and radiographic outcomes
of anterior lumbar interbody fusion using recombinant
human bone morphogenetic protein-2. Spine. 2002;
27:2396–408.
4. Glassman SD, Carreon L, Djurasovic M, Campbell
MJ, Puno RM, Johnson JR, Dimar JR. Posterolateral
lumbar spine fusion with INFUSE bone graft. Spine J.
2007;7:44–9.
5. Heary R, Karimi R. Correction of lumbar coronal
plane deformity using unilateral cage placement.
Neurosurg Focus. 2010;28:E10.
6. Wang MY. Improvement of sagittal balance and
lumbar lordosis following less invasive adult spinal
deformity surgery with expandable cages and percutaneous instrumentation. J Neurosurg Spine.
2013;18:4–12.
Lumbar Endoscopic Fusion
Gun Choi , Guilherme Pereira Corrêa Meyer ,
and Daniel H. Kim
2 1
21.1 Introduction
Spinal fusions have been performed for nearly a
century for a variety of conditions. Interbody
fusion is an effective method and it is associated
with high fusion rates [ 1 ]. Traditionally, the abil-
ity to achieve adequate exposure to perform these
procedures required an open surgical approach.
However, with the advent of newer techniques and
technology, combined with an improved understanding of surgical anatomy, newer minimally
invasive techniques have been developed [ 2 , 3 ].
At the same time, the endoscope is a powerful tool. It allows us a good illumination and
visualization of spaces that were only seen
through large exposures. For this reason it is used
in several different medicine fi elds. For lumbar spine it is not different. Several advantages
are related to minimally invasive approaches
G. Choi , MD, PhD
Director of Endoscopic Spine Center,
Hanyang Medical College,
Wooridul Spine Hospital , Seoul , Korea
G. P. C. Meyer , MD
Hospital Albert Einstein ,
Av. Jurua, 706 , Alphaville Industrial , São Paulo
D. H. Kim , MD, FAANS, FACS (*)
Department of Neurosurgery,
Reconstructive Peripheral Nerve Surgery ,
University of Texas Medical School at Houston ,
6400 Fannin, Suite 2800 , Houston , TX 77030 , USA
Baylor College of Medicine , Houston , TX , USA
e-mail: daniel.h.kim@uth.tmc.edu
like less intraoperative blood loss, less postoperative pain, decreased postoperative narcotic
usage, early ambulation, and decreased length of
hospital stay [ 3 – 6 ].
Indications for an endoscopic fusion are similar to a conventional fusion surgery. It includes
grade I or II spondylolisthesis, recurrent disc herniations, severe discogenic back pain, instability,
and pseudarthrosis. There are relatively few contraindications to minimally invasive instrumentation: obesity (body mass index (BMI) >40),
advanced spondylolisthesis (grade 3 or 4), three
or more levels, and previous surgery if instrumentation removal is needed.
Here we describe four different types of lumbar endoscopic fusions: endoscopically assisted
transforaminal lumbar interbody fusion (ETLIF),
laparoscopic anterior lumbar interbody fusion
(LALIF), endoscopic lateral lumbar interbody
fusion (ELLIF), and percutaneous endoscopic
lumbar interbody fusion (PELIF) (Fig.
21.1 ).
21.2 ETLIF
In 1952 Cloward described the posterior lumbar
interbody fusion procedure (PLIF) [ 7 ], and later
Harms and Rolinger introduced the transforaminal lumbar interbody fusion (TLIF) in 1982
for the management of degenerative spinal disorders that necessitate interbody fusions [
has the advantage of less neural retraction in
comparison to PLIF during the cage insertion [
Moreover there is no need to expose the epidural
8 ]. TLIF
9 ].
M.Y. Wang et al. (eds.), Minimally Invasive Spinal Deformity Surgery,
DOI 10.1007/978-3-7091-1407-0_21, © Springer-Verlag Wien 2014
199
200
G. Choi et al.
4
3
Fig. 21.1 Different endoscopic approaches to the spine: 1 ,
endoscopically assisted transforaminal lumbar interbody fusion (ETLIF); 2 , endoscopic lateral lumbar inter-
body fusion (ELLIF); 3 , laparoscopic anterior lumbar
interbody fusion (LALIF); 4 , percutaneous endoscopic
lumbar interbody fusion (PELIF)
1
space bilaterally [ 10 ]. ETLIF combines the
advantages of TLIF with a minimal access exposure. The inherent muscle damage from subperiosteal dissections and retraction that have been
demonstrated objectively through several studies
is believed to adversely affect clinical outcomes
[ 11 – 15 ]. ETLIF decreases muscle damage by
splitting the muscles fi bers without cutting or signifi cantly retracting them. Tubular retractors with
the assistance of an endoscope view can provide
a minimally invasive exposure. There is no need
for a microscope once it is possible to see clearly
the neuro structures and even inside the disc
space in order to check the adequate endplate
preparation. Moreover, the microscope has a propensity for contamination because of unknown
contact with unsterile parts of the surgeon, and it
can be a source of infection [ 16 ].
21.2.1 Indications: Special Considerations
ETLIF is specially indicated in case of unilateral
foraminal stenosis. This allows direct foraminal
decompression. If bilateral foraminal decompres-
sion is needed, a bilateral approach for adequate
decompression should be used [ 17 – 19 ]. It’s also
a particularly useful approach because there is no
need for an access surgeon.
21.2.2 Surgical Technique
2
After a carefully preoperative planning and evaluation, the patient is brought to the operation
room. Somatosensory evoked potential (SSEP)
can be used to increase the safety of the procedure in special cases. Patient is prone positioned
and care is made to insure adequate padding of
all pressure points. The surgeon should stand on
the same side of the approach that usually corresponds to the most symptomatic side. In case
there is no difference between sides, a righthanded surgeon should stay on the patients left
side. Fluoroscopy is used to confi rm the level.
The 2.5-cm incision is placed 3–4 cm from the
midline, and it goes from the superior pedicle to
the inferior pedicle centered on the disc space.
A Steinmann is placed vertically under lateral
fl uoroscopy toward the facet complex over the
pathological disc space. After confi rming the
correct positioning, serial soft tissue dilators are
introduced (METRx; Medtronic Sofamor Danek,
Memphis, TN). For ETLIF a 20-mm or larger
working channel is needed.
A monopolar cautery is used to dissect the soft
tissue and expose the lamina, isthmus, and facet
joint (Fig. 21.2a ).
It is safer to begin laterally where bone is
apparent. To maximize the working space is
essential to remove all the soft tissue overhanging
the anatomic structures. If the medial facet, lateral
interlaminar window, and lamina are not clearly
seen, the working channel should be repositioned.
Next step consists in a generous hemilaminectomy and facetectomy to expose the lateral aspect
of the dural sac and the superior and inferior
nerve roots (Fig. 21.2b ).
The endoscope magnifi es the view. Surgeon
hands may obstruct the vision when working in
small fi elds like tubular retractors with a microscope. Endoscopic vision eliminates this drawback. High-speed drills, osteotomes, and Kerrison
punches are used. The bone removed and spared is
21 Lumbar Endoscopic Fusion
ab
c
201
Fig. 21.2 ( a ) The working channel should be centered on
the facet joint with the disc space beneath it. It is important to see the medical facet, lateral interlaminar window,
and lama. ( b ) After removing the facet joint and some
later used as autograft in the interbody fusion.
After visualization of the nerve roots, the exiting
nerve root is protected or gently retracted laterally.
Dural sac and traversing nerve are gently retracted
medially to expose the disc space (Fig. 21.2c ).
Epidural veins overlaying the disc space may
be cauterized with a bipolar cautery. At this
moment discectomy is done with a scalpel no.15.
The disc material and endplate preparation is
done with curettes, pituitary rongeurs, reamers,
and plate scrapers using standard technique. The
cage’s size is measured in preoperative exams
and confi rmed using a trial. Disc space is then
partially fi lled with graft. We usually use allograft
lamina, the disc, exiting and traversing root, is exposed.
( c ) Gently retracting and protecting the neuro structures,
we can access the disc and proceed with the discectomy
mixed with autograft collected from the laminotomy site. The cage is also fi lled up with this mixture of grafts. Chisel is then used to create space
for the cage insertion. Endoscopic view allows a
better visualization and increases the safety during these steps (Fig. 21.3 ).
Fluoroscopic view is used in the lateral position to confi rm the appropriate cage depth. At this
step the working channel should be angled to the
opposite side. This allows a better angle for the
cage placement (Fig. 21.4 ).
After the cage insertion, the pedicle screws are
inserted percutaneously. Insertion of pedicle
screws through a midline approach requires
202
G. Choi et al.
Fig. 21.3 Endoscopic
images. ( a ) Exposure.
( b ) Discectomy. ( c ) Bone chip
insertion. ( d ) Cage insertion
a
Cranial
b
Cranial
c
Cranial
Medial
Lateral
Medial
Lateral
Medial
Caudal
Caudal
Caudal
Dura
Suction
Root
Dura
Root
Retractor
Disc
Discectomy site
Dura
Bone chip
insertion
Lateral
d
Cranial
Medial
Lateral
massive retraction of the multifi dus muscle, subjecting the muscle to high retraction pressures
and disruption of its osseo-tendinous attachments
and neurovascular supply [ 14 ]. Percutaneous
screws avoid such muscular injuries. The working channel and endoscope are removed and the
procedure is done using the C-arm.
The percutaneous pedicle screw technique
begins with a Jamshidi-type trocar needle that is
placed under fl uoroscopic control through the
previous incision. In the opposite site, the screws
Root
Dura
Cage
Caudal
Root
are placed through separate incisions. A true
anteroposterior view with the spinous process
centered between each pedicle and a fl at superior
endplate of the corresponding vertebra and a lateral view with the pedicles and endplate parallels
are essential. This can avoid inadvertent malpositioning of the screws. Once the needles are correctly positioned inside the pedicle, the stylets
are removed and guide wires inserted (Fig. 21.5 ).
The guide wire is then used to direct cannu-
lated taps and screws into the pedicle. C-arm
21 Lumbar Endoscopic Fusion
Fig. 21.4 After preparing the
endplate, the retractor and
endoscope are angled. We
should see bleeding endplates
without breakage. The
endoscope is removed and the
cage is inserted
203
1
2
Fig. 21.5 Percutaneous placement of Jamshidi needles
through the pedicle. Needle stylets are replaced by guide
wires. The needles are removed and taps create the pathway for the screws
l ateral view is important to ensure that the K wire
is not advancing. Once the pedicle screws are
positioned, the rods are placed percutaneously
and then connected. We change the patient’s
position into lordosis to avoid a “fl at back” before
fi xing the rods. C-arm is used in lateral view and
then in AP view to confi rm the appropriate
implants positioning (Fig. 21.6 ).
The wound is irrigated, hemostasis is confi rmed, and the fascia and skin are closed in a
layered fashion. A subfascial drain might be
placed for 24 h.
21.3 LALIF
Laparoscopic lumbar discectomy was described in
1991 by Obenchain [ 20 ]. The technique was then
modifi ed to allow anterior fusion and posterior
instrumentation. The use of an anterior approach
preserves the posterior muscles and avoids related
complications. Moreover, the cages can be bigger when compared to posterior and posterolateral
approaches. In addition the laparoscopic approach
allows good visualization, decreases the blood loss,
and has excellent cosmetic results. However anterior approaches have potential injury to large vessels
and retrograde ejaculation as their main drawbacks,
and LALIF requires long learning curve [ 21 ].
Due to the vascular anatomy at the L4–5 disc
level where the large abdominal vessels bifurcate
and override the disc space, the technical feasibility differs signifi cantly between L4–5 and L5–S1
levels.
For L5–S1 LALIF have good results quite
similar to mini-open ALIF. Blood loss and hospital stay are decreased, and the clinical outcome is