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156
S.J. Johans et al.
Fig. 19.1 Preoperative lateral x-ray in neutral position of
a patient with grade I spondylolisthesis at L4–L5
Table 19.1 Meyerding grading system of spondylolisthesis
Grade I 25 % sagittal translation of vertebral body
Grade II 50 % sagittal translation of vertebral body
Grade III 75 % sagittal translation of vertebral body
Grade IV 100 % sagittal translation of vertebral
body
Grade V Spondyloptosis: >100 % sagittal
subluxation
Table 19.2 Wiltse classifi cation of spondylolisthesis
27 ]
[
Type 1 Dysplastic or congenital spondylolisthesis
Type 2 Isthmic spondylolisthesis (IS): defect in the
isthmus or pars interarticularis
2A Lytic: fatigue fracture of the pars
interarticularis
2B Elongated pars: which may result from pars
fracture with subsequent union in the
distracted position
2C Acute fracture: traumatic fracture of the
pars
Type 3 Degenerative spondylolisthesis (DS):
resulting from long-standing instability
Type 4 Traumatic spondylolisthesis: acute fracture
of a posterior element (pedicle, lamina, or
facets) other than the pars interarticularis
Type 5 Pathologic spondylolisthesis: structural
weakness of the bone secondary to a
disease process such as a tumor or other
bone disorders
Type 6 Postsurgical
Fig. 19.2 Preoperative lateral standing scoliosis x-ray of
a patient with grade I spondylolisthesis at L4–L5
been shown, reproducibly, to offer patients substantial relief of symptoms [ 25 ].
For more than a generation, posterior decompression including bilateral facetectomies was
thought to be necessary to treat symptoms related
to neuronal compression from spondylolisthesis
[ 9 ]. More recently, studies have documented that
such extensive posterior boney resection and
wide muscle dissection predisposed patients to
progressive deformity, spinal instability, and
symptom recurrence. Spinal fusion with decompression has since become the standard of care
for symptomatic spondylolisthesis [ 8 , 14 , 20 ].
Since 2005, several studies have compared the
effi cacy of various techniques, some of which
19 Lateral Approach for Spondylolisthesis
157
introduce the placement of lumbar interbody
devices. To date, the lack of Level 1 studies proving effi cacy has made it diffi cult to guide standard of care [ 17 , 18 ]. Minimally invasive surgical
techniques have also been employed to address
patients with symptomatic spondylolisthesis.
One of these techniques, extreme lateral interbody fusion (XLIF) or direct lateral interbody
fusion (DLIF), has been demonstrated to be a
safe, minimally invasive alternative to traditional
open fusion procedures to treat spondylolisthesis
[ 2 , 16 , 19 ].
19.3 Surgical Technique
Lateral lumbar interbody fusion (LLIF), either
XLIF or DLIF, is a true lateral retroperitoneal
approach to the spinal column that allows for
large interbody graft placement and excellent
disk height restoration and provides indirect
decompression at the stenotic motion segment
[ 4 ]. The patient is positioned in the right lateral
decubitus position with the left side up. Using the
left side is preferred to access the spine as the
aorta and iliac arteries are sturdier than the vena
cava and iliac veins and are more likely to withstand surgical handling without being injured. In
patients with scoliosis, the aorta may lie on the
lateral aspect of the vertebral bodies and thus
would require access from the right side.
The intended surgical level is localized by
fl uoroscopy. The surgical site is marked, prepped,
and draped in sterile fashion. Baseline EMG
recordings are performed. Following the skin
incision, the abdominal musculature is bluntly
divided. Gentle blunt dissection allows one to traverse the retroperitoneal space with minimal disruption of the surround tissues. As the psoas
muscle is approached, the lumbosacral plexus is
localized by the use of automated electrophysiology. Directional EMG is used to ensure the surgeon docks the retractor anterior to the femoral
nerve [ 22 ]. Establishing a safe corridor through
the psoas muscle requires imaging, real-time
EMG, understanding of the regional anatomy
with its variations, and surgeon experience. In an
approach to the L4–L5 disk space in the well-
aligned spinal column, the access corridor is
slightly more anterior than that at rostral levels.
In a patient with anterolisthesis, however, the
regional anatomy may be altered, underscoring
the importance of directional EMG as a navigational tool [ 21 ].
Preservation of the anterior and posterior longitudinal ligaments and avoidance of the neural
foramen are critical to the success of LLIF for
symptomatic spondylolisthesis. Exposure is
achieved with an expandable three-bladed retractor, which allows for direct illuminated visualization facilitating diskectomy and complete anterior
column stabilization using a large load-bearing
implant. After the diskectomy and interbody
graft placement, fusion is achieved by either
placement of vertebral body screws and plate or
from posterior lateral pedicle screw fi xation
(Figs. 19.3 and 19.4 ). For high-grade spondylo-
listhesis, restoration of disk height by the interbody cage often provides only partial reduction
of the listhesis; the rest of the correction can be
performed using a cantilever maneuver during
posterior supplementation [ 2 ].
Fig. 19.3 Postoperative lateral x-ray in neutral position
of a patient with grade I spondylolisthesis at L4–L5 after
LLIF
158
S.J. Johans et al.
Fig. 19.5 Gaining access to disk space during oblique
lumbar interbody fusion (OLIF)
(Fig. 19.6 ) for anterior column support and seg-
mental sagittal alignment while minimizing the
nerve, muscle, and bone obstacles associated
with traditional direct lateral approach. At the
same time, this approach also avoids the risk of
injury to the aorta, iliac vessels, and genitourinary structures that are encountered in a traditional anterior approach [ 7 ].
Fig. 19.4 Postoperative lateral standing scoliosis x-ray of
a patient with grade I spondylolisthesis at L4–L5 after
LLIF
Another option is the oblique lumbar interbody fusion (OLIF) procedure, which is an alternative to the traditional anterior lumbar interbody
fusion (ALIF) procedure with the convenience of
the less-invasive lateral approach. Utilizing an
oblique lateral trajectory (Fig. 19.5 ) away from
the posterior nerves within the psoas muscle, this
procedure is an alternative to approaches dependent on neuromonitoring to traverse the psoas
muscle. By utilizing an oblique lateral approach
to the spine, this procedure enables placement of
a large interbody graft into the disk space
19.4 Outcomes
Several studies, albeit with limited sample sizes,
have reported excellent radiographic and clinic
outcomes in patients with symptomatic
spondylolisthesis treated with an LLIF procedure. The studies published clinical outcomes
such as estimated blood loss, operative time,
length of hospital stay, integrity of construct,
complications, fusion rates, and improvement in
visual analog scale (VAS) of LLIF and compared
the results to other fusion procedures, including
anterior lumbar interbody fusion (ALIF), posterior lumbar interbody fusion (PLIF), and transforaminal lumbar interbody fusion (TLIF). Like
many other minimally invasive techniques, LLIF
has been associated with less blood loss, shorter
hospitalizations, and earlier mobilization of
patients than similar open surgery.
The additional advantages of LLIF include
being able to decompress the neural elements via
indirect decompression of the spinal canal and
19 Lateral Approach for Spondylolisthesis
159
Fig. 19.6 Placement of interbody graft during oblique
lumbar interbody fusion (OLIF)
restoring disk height without violating the stabilizing posterior structures of the spine. Another
advantage of LLIF is the ability to place a large
interbody graft, which can improve fusion rates,
restore disk height, and improve lumbar lordosis. Segmental lumbar lordosis is improved
through the restoration of disk height with larger
lordotic interbody cages, which is possible in
both ALIF and LLIF. Unlike ALIF, LLIF avoids
the need to retract the great vessels. One challenge with traditional techniques such as PLIF
and TLIF is the anterior placement of the interbody cage, which can be crucial to the restoration of segmental lordosis [ 3 ].
Ahmadian et al. reviewed patients with grade
I and II L4–L5 spondylolisthesis who had undergone elective LLIF between 2008 and 2011. The
results focused on 26 adults with grade I and 5
adults with grade II L4–L5 spondylolisthesis
who had undergone elective LLIF and subsequent
posterior percutaneous pedicle screw fi xation
without surgical manipulation of the posterior
elements (laminectomy, foraminotomy, facetectomy). No motor weakness or permanent neurologic defi cits were reported. Transient anterior
thigh numbness was noted in 22.5 % of patients.
All patients exhibited radiographic and clinical
evidence of fusion as determined by static and
dynamic radiographs, or CT scans when available, at 6 months [
2 ].
In another study, 63 patients with grade II
spondylolisthesis and spinal stenosis were
treated with LLIF with supplemental posterior
pedicle screw fi xation and were available for
12-month follow-up. Early postoperative transient upper thigh pain and hip fl exion weakness
were common, as expected consequences to
operative trauma to the psoas muscle, but these
symptoms were not persistent. There were no
neurologic defi cits. Two (3.4 %) patients of the
total cohort underwent further surgery within
1 year: both for adjacent segment disease, one
treated with posterior fusion, the other with
LLIF. At 12 months, there was no radiographic
instability noted on dynamic radiographs, and all
patients appeared to have bridging bone across
the interbody space [ 19 ].
Posterior pedicle screw placement following
LLIF provides a construct that promotes circumferential fusion while resisting graft subsidence [ 10 ]. LLIF access to the intervertebral
space without disrupting posterior musculature
or facet joints has permitted the use of standalone constructs in a carefully selected patient
population. Some authors have presented data
that suggests that stand-alone MIS-LIF can be
considered for those patients without signifi cant preoperative instability and with high
operative/anesthetic risk for traditional or MISopen hybrid techniques. In patients with mobile
spondylolisthesis on dynamic fi lms, or with
pars interarticularis defects, stand-alone constructs are contraindicated. Marchi et al. suggested that stand-alone lateral constructs are
feasible in low-grade (Meyerding grade I/II)
listhesis with a 13 % revision rate largely
related to graft subsidence and persistent instability [
13 ]. Lateral interbody fusion should be
avoided for high-grade spondylolisthesis (grade
III), especially as an anterior alone fusion as
there have been rare cases of vertebral body
split fracture and cage migration. One study
concluded that LLIF alone might prove benefi cial for treatment of neurogenic symptoms by
indirect decompression [ 1 ] in elderly patients
where direct decompression could lead to progression of sagittal deformity and avoid open
instrumentation, which is associated with a
higher complication rate due to patients’ preexisting medical comorbidities.
160
S.J. Johans et al.
19.5 Complications
Although lumbar LLIF has been effectively used
to treat adult degenerative spinal deformity, concerns remain as to whether the lateral approach
exposes the lumbosacral plexus to injury as it
travels within the psoas muscle. The nerves of the
lumbosacral plexus pass through the psoas muscle fi bers and may be unknowingly damaged
when accessing the spine using a transpsoas
approach. Thigh symptoms such as numbness,
pain, and weakness have been noted to be relatively common postoperatively, especially when
involving the L4–L5 level [ 6 , 23 ]. The rates of
thigh symptoms vary signifi cantly from 0.7 to
62.7 % among published studies [ 5 , 6 , 11 , 12 ].
According to the case series by Le et al., they
found the overall incidence of postoperative ipsilateral thigh numbness to be 19.7 % for a single surgeon during a 3-year study period. With increased
experience over time, the most recent incidence of
postoperative numbness decreased to 10.7 %. Of
the patients who had postoperative ipsilateral thigh
numbness, 35.7 % had symptom resolution by
3 months and 57.1 % had resolution by 6 months
and 64.3 % by 1 year. Of the remaining patients,
one patient had resolution from 12 to 24 months,
and 28.6 % (four patients) had persistent sensory
symptoms beyond 2 years. All patients with numbness had a fusion construct that involved L4–L5.
Thirty-nine (54.9 %) of the 71 patients devel-
oped postoperative motor weakness involving the
iliopsoas muscle. All patients had complete resolution during the postoperative period. Thirty-six
(92.3 %) of the 39 patients had complete resolution by 3 months, 37 (94.9 %) of the 39 patients
had complete resolution by 6 months, 38 (97.4 %)
of the 39 patients had complete resolution by
1 year, and 39 (100 %) of the 39 patients had
complete resolution by 2 years [
Conclusion
Lateral interbody fusion is a minimally invasive
approach by which the spine surgeon may treat
patients with symptomatic spondylolisthesis.
There is mounting evidence, based on both relevant clinical and radiographic follow-up data, that
LLIF constructs provide patients with good radio-
11 ].
graphic outcomes. Long-term follow-up studies
that demonstrate improved functional outcome in
patients undergoing lateral interbody fusion for
treatment of spondylolisthesis would add to the
current literature.
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Lateral Lumbar Interbody Fusion (LLIF) for the Treatment of Adult Spinal Deformity (ASD)
Joseph M. Zavatsky , David Briski , and
Juan S. Uribe
2 0
20.1 Introduction
Adult scoliosis (AS) may be defi ned as a coronal
deformity with a Cobb angle >10° in a skeletally
mature patient. Although AS can develop from
the progression of idiopathic scoliosis (IS) in
adolescence, more commonly AS develops as the
result of a degenerative cascade later in life that
terminates in asymmetric disc collapse, vertebral
body wedging, facet degeneration, spondylolisthesis, and rotary subluxation. This degenerative
cascade has the potential to lead to spinal stenosis, instability with progressive deformity in the
coronal and sagittal planes, loss of lumbar lordosis, and the development of sagittal imbalance.
Patient symptoms can include radiculopathy,
neurogenic claudication, and back pain [ 1 ].
Advances in medical science and patient care
have dramatically improved over the last
50 years, which has signifi cantly increased the
life expectancy of Americans. With an increasing
aging population, the prevalence of degenerative
J. M. Zavatsky , MD
Spine & Scoliosis Specialists , Tampa , FL , USA
josephzavatsky@yahoo.com
e-mail:
D. Briski , MD
Department of Orthopaedic Surgery , Ochsner
Medical Center , New Orleans , LA , USA
J. S. Uribe , MD
Associate Professor, Director Spine Section
Department of Neurosurgery , University of South
Florida , Tampa , FL , USA
disorders, including adult degenerative scoliosis
(ADS), has also increased. Although the prevalence of scoliosis in the adult population has been
reported as ranging from 2 to 32 %, a recent study
targeting elderly volunteers showed a prevalence
of more than 60 % [ 2 ]. With an increasingly aging
population in the United States and an increased
focus on maintaining patients’ quality of life,
adult scoliosis is becoming a considerable healthcare concern.
Aside from the aesthetic considerations of
scoliosis in the adult, signifi cant pain and disability can develop [ 3 ]. Several authors have corre-
lated radiographic parameters with clinical
symptoms in adults [ 1 , 4 ]. Loss of normal lumbar
lordosis can lead to sagittal plane imbalance,
which has been associated with increases in pain
and decreases in quality of life measures [ 1 , 5 ].
Surgical restoration of a patient’s sagittal spinal
balance can lead to improvements in quality of
life measures [
ment of adult degenerative spinal deformity are
neural element decompression, correct and maintain global sagittal and coronal balance, and
arthrodesis. Restoration of spinal balance is associated with improved outcomes and is one of the
principal goals of ADS surgery.
Operative interventions require evaluation of
the unique needs and goals of each individual
patient. ADS surgery is technically challenging
and poses signifi cant risk to patients, particularly
those who are elderly and with medical comorbidities. Complication rates have been reported as
6 ]. The main goals for the treat-
© Springer International Publishing Switzerland 2017
M.Y. Wang et al. (eds.), Lateral Access Minimally Invasive Spine Surgery,
DOI 10.1007/978-3-319-28320-3_20
163
164
J.M. Zavatsky et al.
high as 61 % and can vary with a given procedure.
More complex procedures, including longer fusion
constructs and osteotomies, are associated with
higher complication rates [ 7 ]. Complication rates
increase with older patient populations [ 8 ] and
have been reported as high as 95 % in patients
older than 70 years [ 9 ]. More senior patients often
have multiple medical comorbidities, which are
associated with higher preoperative American
Society of Anesthesiologists (ASA) grades.
Higher ASA scores have been associated with an
increase in perioperative complication rates [ 10 ,
11 ]. Complications can result in increased patient
morbidity, hospital readmission, and reoperation
[ 12 , 13 ] which can negatively impact health-
related quality of life (HRQOL) outcomes [ 12 ].
Despite the high rates of complications seen in
ADS surgery, overall patient HRQOL and functionality improve postoperatively, even in the older
patient population [ 14 ].
Traditional approaches used to treat spinal
deformity include anterior-posterior approaches
and posterior-only approaches, both of which have
been shown to be effective [ 15 – 17 ]. However,
open anterior thoracoabdominal approaches are
associated with up to 40 % risk of complications
including incisional pain, abdominal hernia, vascular injury, ileus, retrograde ejaculation, ureter
and bladder injury, and ilioinguinal and iliohypogastric nerve injuries [ 17 , 18 ]. Open posterior
approaches incorporate dissecting most of the
musculotendinous structures of the posterior bony
spine resulting in a large open wound with dead
space and increased blood loss. Pedicle screw
instrumentation, decompressive laminectomies,
interbody fusion, and osteotomies can then be performed after the open exposure. Interbody fusion
and graft placement have traditionally been
achieved through anterior lumbar interbody fusion
(ALIF), posterior lumbar interbody fusion (PLIF),
or transforaminal lumbar interbody fusion (TLIF).
Over the past decade, minimally invasive surgical approaches to neural decompression and
fusion have been popularized and recently have
been utilized in the treatment of adult spinal
deformity. Minimally invasive surgery (MIS) of
the spine not only implies surgery performed
through smaller incisions but also seeks to reduce
approach-related perioperative complications and
morbidity associated with traditional open surgical techniques [
19 – 21 ]. MIS often utilizes smaller
incisions, which can reduce soft-tissue trauma
and intraoperative blood loss. This can result in
decreased rates of complications including surgical site infection, postoperative pain, and narcotic
consumption, along with quicker patient mobilization after surgery [ 22 ]. Perioperative morbidity
is compounded by the complexity of the ADS surgical procedure, as well as patient-specifi c comorbidities [ 23 – 26 ]. Smith et al. reported that
outcome measures after ADS surgery in elderly
patients improve more dramatically than in
younger patients [
14 ], and with an increasing
elderly population, MIS techniques may provide a
safer surgical alternative in qualifi ed candidates.
Recent advances in surgical techniques and
instrumentation allow for long-segment fusion
constructs to be placed less invasively and still
allow segmental spinal manipulation in select
ADS patients [ 27 ]. Posterior pedicle screw
instrumentation can be performed through percutaneous incisions, which does not require stripping off the spine’s soft-tissue envelope. Posterior
or posterior lateral fusion is diffi cult to achieve
when performing MIS pedicle screw instrumentation and requires interbody augmentation to
obtain arthrodesis. Prior reports have shown that
minimally invasive spinal fusion may result in
higher rates of pseudarthrosis if interbody fusion
is not performed at every lumbar level [ 28 – 31 ].
Interbody augmentation in MIS ASD surgery can
be accomplished through MIS anterior lumbar
interbody fusion (ALIF), transforaminal lumbar
interbody fusion (TLIF), or lateral lumbar interbody fusion (LLIF) techniques. Interbody augmentation can provide anterior structural support,
assist in deformity correction, restore lumbar lordosis, and increase fusion rates [
32 – 36 ].
The transpsoas LLIF approach provides an
alternative to more traditional ALIF, PLIF, and
TLIF interbody techniques. The theoretical
advantages that make this technique attractive
include powerful deformity correction particularly in the coronal plane, decreased blood loss,
more complete discectomy larger graft placement which can span the stronger ring apophysis
decreasing subsidence and increasing fusion
rates, and avoidance of the spinal canal resulting
20 Lateral Lumbar Interbody Fusion (LLIF) for the Treatment of Adult Spinal Deformity (ASD)
165
in decreased risk of nerve and dural injury.
Although the LLIF technique is not without risk,
it does use a corridor that is designed to protect
the vital structures both anterior and posterior to
the vertebral body. The use of the MIS LLIF
approach may decrease the morbidity of traditional anterior approaches while decreasing the
invasiveness of the posterior approach. The risks
and benefi ts of the MIS LLIF technique in the
treatment of adult scoliosis will be the focus of
this chapter.
20.2 MIS Treatment Algorithm
Unlike patients with adolescent idiopathic scoliosis (AIS) where the decision for surgical intervention is driven by curve magnitude, patients
with adult degenerative scoliosis (ADS) are
treated based on clinical symptoms including a
declining quality of life and increasing pain with
disability [
37 ]. Primary degenerative scoliotic
curves are located in the lumbar spine as opposed
to progressive adolescent idiopathic scoliotic
curves that often have an additional thoracic
deformity. Degenerative scoliosis can have both
rotation and rotary subluxation, with the apex
commonly at L3–L4 (Fig. 20.1 ).
Additionally, there can be a loss of the normal
lumbar lordosis, and patients can become sagittally imbalanced and lean forward. To compensate and regain balance in order to stand erect and
bring their head over their pelvis, patients will
attempt to maximize hip extension and retrovert
their pelvis (tucking their buttocks). In severe
cases of positive sagittal imbalance, patients will
also fl ex their knees to stand erect. Patients with
>5 cm of positive sagittal imbalance often report
Fig. 20.1 ( a ) Full-length
scoliosis AP x-ray revealing
signifi cant coronal (75°) and
rotational deformity, along
with rotatory subluxation at
L3–L4 ( yellow arrow ).
Lateral x-ray demonstrating
loss of the normal lumbar
lordosis and a positive sagittal
vertical axis (SVA) of +7 cm
166
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a signifi cant functional decline due to the energy
expenditure required to maintain spinal sagittal
homeostasis. Patients can experience early
fatigue, intolerance of standing, and walking
with compensation through other joints. This
constant hip extensor and quadriceps eccentric
contraction can lead to muscle fatigue and intolerance of most activities.
Understanding the etiology, anatomic features, and clinical presentation of the adult patient
with scoliosis is important in determining an
appropriate surgical strategy.
However, not every adult patient with spinal
deformity can be managed with MIS techniques.
Prior reports have shown that MIS techniques
have limitations in the ability to adequately correct and restore sagittal spinal parameters, along
with increased pseudarthrosis rates if interbody
fusion is not performed at every lumbar level
28 – 31 , 38 , 39 ]. Appropriate patient selection for
[
less invasive correction techniques is critical to
optimize successful patient outcomes in the treatment of adult deformity. Relative contraindications for this approach include previous
retroperitoneal dissection, previous pyogenic
kidney infection, or retroperitoneal infection.
This may result in adhesions of the kidneys, peritoneum and bowel, and vasculature. Additionally,
unfavorable anatomy may restrict access to the
planned operative level.
Full-length scoliosis x-rays capturing the base
of the skull down to the femoral heads, along
with magnetic resonance imaging (MRI) and
computed tomography (CT) scans of the planned
instrumented areas, should be obtained for preoperative planning. Careful review of the imaging
should be performed to identify any obstacles to
the planned surgical levels. High-riding iliac
crests may block access to L4–L5 and can usually be detected on preoperative x-rays, but may
also be identifi ed intraoperatively with fl uoroscopic x-ray. Ankylosed facets can be identifi ed
on computed tomography (CT) scans and may
limit the ability of the LLIF technique to restore
disk height, lordosis, and coronal Cobb angle due
to facet hypertrophy, osteophytes, or fusion.
Additionally, unrecognized ankylosed facet
joints may result in endplate and ring apophysis
violation when performing the disk preparation
or implant insertion resulting in suboptimal
deformity correction and indirect decompression
(Fig. 20.2 ).
abc
Fig. 20.2 ( a ) Preoperative standing x-ray revealing the
iliac crest ( red line ) blocking access to the L4–L5 disk
space ( yellow line ). ( b ) Intraoperative fl uoroscopic x-ray
with a fl exible guide wire held against the patient’s skin
outlining the iliac crest, which is blocking access to L4–
L5. ( c ) CT scan of the lumbar spine reveals hypertrophic,
osteophytic, ankylosed facet joints, which could limit the
restoration of disk height, lordosis, and deformity correction, (Arrows) reveal hypertrophic, osteophytic, ankylosed
facet joints, which could limit restoration if disc height,
lordosis, and deformity correction utilizing the LLIF
technique