Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_6019_Библиотеки_им_академика_М_И_Перельмана.pdf
298
A.S. Kanter and M.M. McDowell
82. Li Y, Hresko MT. Lumbar spine surgery in athletes:
outcomes and return-to-play criteria. Clin Sports
Med. 2012;31(3):487–98.
83. Bohlman HH, Cook SS. One-stage decompression and
posterolateral and interbody fusion for lumbosacral
spondyloptosis through a posterior approach. Report of
two cases. J Bone Joint Surg Am. 1982;64(3):415–8.
84. Gaines RW. L5 vertebrectomy for the surgical treatment of spondyloptosis: thirty cases in 25 years.
Spine. 2005;30(6 Suppl):S66–70.
85. Gaines RW, Nichols WK. Treatment of spondyloptosis by two stage L5 vertebrectomy and reduction of
L4 onto S1. Spine. 1985;10(7):680–6.
86. Papanastassiou ID, Jain S, Baaj AA, Eleraky M,
Papagelopoulos PJ, Vrionis FD. Vertebrectomy and
expandable cage placement via a one-stage, oneposition anterolateral retroperitoneal approach in L5
tumors. J Surg Oncol. 2011;104(5):552–8.
87. Gandhoke GS, Kasliwal MK, Smith JS, Nieto JARN,
Ibrahimi D, Park P, Lamarca F, Shaffrey C, Okonkwo
DO, Kanter AS. A multicenter evaluation of clinical and radiographic outcomes following highgrade
spondylolisthesis reduction and fusion. Clin Spine
Surg. 2017;30(4):E363–9.
88. Tobler WD, Gerszten PC, Bradley WD, Raley TJ,
Nasca RJ, Block JE. Minimally invasive axial presacral
L5-S1 interbody fusion: two-year clinical and radiographic outcomes. Spine. 2011;36(20):E1296–301.
89. Ogilvie JW. Complications in spondylolisthesis
surgery. Spine. 2005;30(6 Suppl):S97–101.
Surgical Management of Lumbar Spondylolisthesis
Jad G. Khalil, Jeffrey S. Fischgrund,
and Richard V. Roberts
24
Introduction
Spondylolisthesis, from the Greek roots of spondylos, meaning vertebrae, and olisthesis, mean-
ing to slip, refers to the anterior or posterior
translational displacement of the vertebral body
compared to the level inferior to the defect [1, 2].
In terms of the adult lumbar spine, this displacement results from a causative defect in bony
architecture, trauma, or degenerative changes
over time [3–6]. Spondylolisthesis was first
described by Herbiniaux, a Belgian obstetrician,
in 1782 as a bony prominence anterior to the
sacrum [7]. Later in 1853 a German physician
Robert reported on specific defects in the pars
interarticularis, which were first labeled in 1854
by Killian as spondylolysis [2, 8]. Then in 1881
Neugebauer suggested that lysis, the elongation
and angulation of the pars interarticularis, could
lead to spondylolisthesis [9]. Following in 1888,
the phenomenon spondyloptosis, Greek root of
ptosis meaning falling off or down, was termed
by Neugebauer to describe a vertebra that is completely displaced [
J.G. Khalil, MD (*) • J.S. Fischgrund, MD
R.V. Roberts, MD
Department of Orthopaedic Surgery,
William Beaumont Hospital, 3535 West
13 Mile Rd., Suite 744, Royal Oak, MI 48073, USA
jadkhalil@gmail.com;
e-mail:
jsfischgrund37@gmail.com
richardrobertsmd@gmail.com
1, 9]. It was then in 1893 that
;
Lane posited that spondylolisthesis was due to
the modification of the interarticular part of the
fifth lumbar vertebra by pressure from both the
inferior facet of the fourth lumbar vertebra above
and the superior sacral process below [
1].
Classification
The most widely used classification system today
was described by Wiltse (Fig. 24.1), in which he
divided spondylolisthesis into five main categories [10–13]. Type I (congenital spondylolisthesis) is derived from an inherited defect of either
the superior sacral facet, the inferior facet, or
both, with a gradual anterior translation of the
vertebra, most commonly seen in L5-S1. Type II
(isthmic spondylolisthesis) implies the defect to
be in the isthmus, also known as the pars interarticularis. This type is further subdivided into
three subtypes: type IIA denotes a stress fracture
of the pars region, referred to as a spondylolysis;
type IIB refers to an elongated pars that is the
product of bony remodeling from repetitive
stresses; and type IIC, the rarest of the isthmic
spondylolistheses, is due to an acute traumatic
fracture of the pars leading to anterolisthesis.
Type III (degenerative spondylolisthesis) is a disease of the aging spine that progresses due to
facet arthritis and remodeling that can result in
anterolisthesis, retrolisthesis, or rotational deformities and instability. Type IV (post-traumatic
© Springer International Publishing AG 2017
L.T. Holly, P.A. Anderson (eds.), Essentials of Spinal Stabilization,
DOI 10.1007/978-3-319-59713-3_24
299
300
J.G. Khalil et al.
Fig. 24.1 Wiltse classification (From Wiltse et al. [10])
spondylolisthesis) results from acute trauma and
failure to the posterior elements; in contrast to
isthmic, traumatic spondylolisthesis is not related
to a direct pars injury. Type V (pathologic spondylolisthesis) is a result of the destructive nature
of posterior elements from a pathologic process,
i.e., chronic disorders, infections, malignancy, or
iatrogenic processes, over a period of time.
In 1982 Marchetti and Bartolozzi then categorized spondylolisthesis into developmental and
acquired subtypes [14]. The acquired etiologies
contained iatrogenic (now considered postsurgical), pathologic, traumatic, and degenerative conditions, whereas the developmental etiologies
comprised of the elongation of the pars or lytic
lesions. In 1994 a revised classification system
further organized the developmental group based
on the grade of dysplasia, either high or low dysplasia [
1]. Degenerative spondylolisthesis,
reported initially by MacNab and later by
Newman and Stone, is a subtype of the acquired
form later described by Marchetti and Bartolozzi
[14, 15]. In that classification, degenerative spondylolisthesis may be either primary or secondary.
Primary is typically seen in middle-aged women
presenting with clinical signs of spinal stenosis,
while secondary is related to a predisposing
factor, such as adjacent segment degeneration,
24 Surgical Management of Lumbar Spondylolisthesis
301
causing a slip above a preexisting fusion [1, 14,
15].
In combination with developmental susceptibilities, certain activities place patients at risk for
spondylolysis because of the nature of the biomechanical stresses imparted on the pars interarticularis [1]. Biomechanical analyses have shown
that hyperextension and persistent lordosis
increases shear stresses at the neural arch [16–
19]. This stress during hyperextension of the
lumbar spine can be seen in activities such as
gymnastics, weightlifting, diving, football, soccer, cricket, and volleyball [19–29], as well as
Scheuermann kyphosis, owing to the exaggerated
lumbar lordosis [30]. The progression of slippage
during adolescence and the observation that
females are several times more likely to have an
increase in deformity suggests a hormonal role in
the development of spondylolisthesis [31]. The
slippage can occur as the lumbar spine rotates
around the sacral dome due to the body’s center
of gravity being anterior to the lumbosacral joint
[1]. The age of the patient when these defects
occur and the individual’s sagittal alignment of
the spine influence the degree of deformity progression. Pelvic incidence seems to play an
important role in the progression of the spondylolisthesis, with a statistically significant increase
in the chance of slippage as the pelvic incident
angle increases [32, 33].
Adult spondylolisthesis presents in predominately two patterns: the isthmic type, resulting
from abnormalities of the pars intra-articularis;
and the degenerative type, an outcome of lumbar
spondylosis with its disc degeneration and instability causing a physiologic uncoupling of the
facets in the sagittal plane [34–36].
Incidence
The incidence of defects in the pars interarticularis is seen in 4% to 6% in the general population, which can progress to isthmic
spondylolisthesis. Isthmic spondylolisthesis,
with a reported incidence between 2.6% and
4.4% of general population, is more common in
males [37]. It is most frequently seen at the L5-S1
level [
38–40]. Around 50% of patients presenting
with a pars defect do not show evidence of anterior listhesis [
1]. Female patients exhibit a lower
incidence of isthmic defects; however they show
a higher propensity for slip progression [
1]. The
incidence of isthmic spondylolisthesis also varies
according to race with 6.4% in white American
males, 2.8% in black males, 2.3% in white
females, and 1.1% in black females [1]. Eskimos
have been shown to have a rate as high as 50% [1,
3]. Additionally, spina bifida occulta has been
associated with spondylolysis of the lumbar spine
in 11.8–35% of patients [41–43]. Although there
are reports of greater frequency of posterior spine
defects connected to isthmic spondylolisthesis,
no etiologic link has been accepted [10, 44, 45].
The risk of spondylolisthesis progressing is
greater in patients that have a midline lumbosacral defect due to the decreased stabilizing effects
associated with the lack of attachment of the multifidus muscles to the deficient spinous processes
[45, 46]. Hence, the deficient or dysplastic posterior elements in spina bifida defects actually
increase the amount of pars loading, leading to
the development of isthmic spondylolisthesis and
thus serve as a risk factor to high-grade (>50%)
olisthesis progression [41, 47–49].
Degenerative spondylolisthesis is approximately four to five times more common in
females than in males (8.4% in females and 2.7%
in males) and more common in black females
than in white females [
3, 34]. This female preva-
lence is thought to be due to greater ligamentous
laxity and hormonal effects [
50–52]. Degenerative
spondylolisthesis rarely affects those younger
than 40 years of age and most frequently involves
the L4-L5 level. Unlike isthmic spondylolisthesis, degenerative spondylolisthesis occurs much
less frequently at the L5-S1 level [1]. Factors that
have been reported to predispose to anterolisthesis at the lumbosacral junction include: a fifth
lumbar vertebral body that is less deeply seated
within the pelvis, slim transverse processes of the
fifth lumbar vertebral body, and an increased
sacral inclination, all of which are more common
in women than men [53]. The factors associated
with an increased risk in women were elevated
body mass index (BMI), increased age, and
302
J.G. Khalil et al.
increased angle of lordosis, whereas in men only
an increased age was associated with a higher
risk of degenerative spondylolisthesis [
54]. The
effect of facet joint orientation is also seen as a
potential factor in the development of degenerative spondylolisthesis with a more sagittal orientation at the L4-L5 facet joints being associated
as a cause [
55–57]. Even in the absence of symp-
toms from the pars defects themselves, spondylolisthesis may lead to clinically significant
radiculopathy and progressive neurologic deficits
secondary to nerve root impingement [1].
Imaging
Initial imaging of the patient can be established
with plain radiographs, including anteroposterior, lateral, and oblique views. For the anteroposterior views, a Ferguson view of 15° of
inclination optimizes the evaluation of lumbar
transverse process size and disc height at the
L5-S1 level [58]. When the lateral view is
obtained with the patient standing, it allows for
ideal appreciation of the degree of olisthesis in
spondylolisthesis; additionally, the flexionextension in lateral views helps evaluate the presence of instability [1]. The benefits of an oblique
lateral view are the increased ability to detect the
pars defect, with an oblique lateral view detecting the pars defect in 84% of cases [59], whereas
the standard lateral view is able to identify it 19%
of the time [60, 61]. Oblique radiographs are
associated with significant radiation exposure,
and they should be sparingly used, as directed by
a specialist; this holds especially true in the adolescent population. Furthermore, unless the preoperative lateral radiographs are obtained with
the patient standing, it cannot be determined if
the presence of postoperative spondylolisthesis
in a patient with poor pain relief after surgery was
the result of destabilization from the surgery or if
it was a preexisting condition [1]. Relying only
on supine MRI imaging for the identification of
degenerative spondylolisthesis has been demonstrated to miss the diagnosis in almost one third
of cases [62]. Table 24.1 [1, 63–67] reviews the
different choices of imaging techniques and their
associated benefits in outlining various findings
in cases of patients with suspected
spondylolisthesis.
There have been several biomechanical studies that have successfully recognized that lumbosacral facet joint disease and degenerative disc
disease may cause degenerative spondylolisthesis [68–72]. While standing lateral flexionextension lumbar radiographs are used to identify
lumbar spine instability, supine lumbosacral MRI
is routine in evaluating various lumbar disorders.
Though degenerative spondylolisthesis is not
always present in the supine position, the axial
T2-weighted MRI can detect increased fluid in
the lumbar facet joints [73–76]. Extensive facet
effusion (>1.5 mm) is highly predictive of degenerative spondylolisthesis at the L4-L5 level in the
absence of measureable anterolisthesis on the
supine MRI [74].
In 1932 Meyerding proposed a radiographic
grading system for spondylolisthesis [77]
(Fig. 24.2), which is now the most common system in use, with the degree of slippage being
measured as the percentage of distance the anteriorly translated vertebral body has moved forward [38]. This classification by Meyerding
grades the olisthesis as it increases from grades I
to IV. Spondyloptosis, in which the fifth lumbar
vertebra has slipped forward over 100% of the
gliding plane past the sacral promontory, is given
a grade V; instances of spondylolysis without
olisthesis is noted as a grade 0 [
1]. Other impor-
tant measurements to quantify the sagittal rotation of a vertebral body that may also exist in
spondylolisthesis are the slip angle and pelvic tilt
which, like the Meyerding classification, are best
analyzed using standing lateral radiographs.
Calculation of the slip angle is achieved by measuring the angle formed by the intersection of
two lines: the first being a line perpendicular to
the posterior cortex of the sacrum and the second
being a line paralleling the inferior end plate of
L5 [
1]. In the normal spine, slip angle values
should be close to zero, whereas a slip angle
greater than 55° is associated with a high probability and increased rate of progression [78].
Pelvic tilt, also known as sacral inclination,
denotes the vertical position of the sacrum. It is
24 Surgical Management of Lumbar Spondylolisthesis
Table 24.1 Imaging modalities
Imaging modality Benefits Notes
Radionuclide (Technetium
99 mm) Bone Imaging [
SPECT (Single Photon
Emission Computed
Tomography) [
CT (Computed Tomography)
66, 67]
[
MRI (Magnetic Resonance
Imaging) [1]
Imaging techniques and their relative roles in assessing patients with spondylolisthesis [
63–65]
1]
Identify pars interarticularis stress
fractures without a visible bony
defect
More sensitive than plain
radiographs or technetium bone
scan
Gauge degree of spondylolisthesis
Assess healing potential of
identified pars defect
Soft tissue
Neural structures
Recent trauma/symptomatic with
strenuous activity: increased uptake in
spondylolytic area
Chronic LBP: normal scan if defect is
chronic, sclerotic, and avascular
“Hot scan” suggests increased activity
(orthotic immobilization may be
beneficial)
“Cold scan” suggests chronic lesion/not
metabolically active (unlikely to respond
only to orthotic immobilization)
Superior to plain radiographs in revealing
dysplastic facets, pars defects, changes in
apophyseal joints
No exposure to radiation
303
1, 63–67]
Fig. 24.2 The five grades of the Meyerding grading system [77]. Grade 1, 0–25% of the vertebral body; grade II,
26–50%; grade III, 51–75%; grade IV, 76–100%; grade V, spondyloptosis
the angle formed by the intersection of two lines:
(a) a line perpendicular to the floor and (b) a line
part of evaluation of the progression of the defor-
79] (Figs. 24.3 and 24.4).
mity [
parallel to the posterior cortex of the sacrum [1].
Normal values usually are greater than 30°; yet
with an increasing slip, the lumbosacral kyphosis
Indications and Patient Selection
is increased; therefore the sacrum is forced into a
more vertical orientation and decreases the pelvic
1]. Proper documentation of the Meyerding
tilt [
class, slip angle, and pelvic tilt are advocated as
Initial treatment should consist of pain relief,
strengthening of core muscle groups, and return
of range of motion in the lumbar spine. This is
304
Fig. 24.3 Pelvic parameters. SS sacral slope; PT pelvic tilt; PI pelvic incidence (From Oh et al. [79], with
permission)
J.G. Khalil et al.
their prolonged use can adversely affect recovery,
SS
lead to continued disability, and increase the risk
of addiction [1]. The conservative management of
spondylolysis includes cessation of strenuous
activity, rehabilitation with strengthening of the
PT
abdominal and paraspinal musculature, minimization of pelvic tilt, and perhaps anti-lordotic
bracing [80]. There are many factors that influence potential treatment protocols. Conservative
management protocols also depend on several
PI
factors, such as disease involvement (spondylolysis vs. spondylolisthesis), the level and laterality
of the defect (unilateral vs. bilateral pars defects),
duration since injury (acute vs. chronic), and the
age of the patient [81]. Exercises should be
focused on strengthening the abdominal and paraspinal musculature, as the local muscular system
Fig. 24.4 Mathematical relation between pelvic parameters [79]. PI = PT + SS (From Oh et al. [79], with
permission)
that controls the lumbar spine consists of lumbar
multifidus, internal oblique, and transversus
abdominis [82]. Along with exercises that target
specific core muscle groups with the spine in neu-
typically initiated with nonsteroidal
anti- inflammatory drugs (NSAIDs), pain management, and physiotherapy. Steroid injections into
the facet joint and epidural space are helpful in the
acute phase but not recommended for prolonged
usage, as there are potential complications of this
medication with long-term use [1]. This is similarly true with the use of narcotic medications, as
tral position, a stretching program to improve
flexibility and strengthening of hip flexors and
hamstring stretching is frequently recommended
[83–85]. Weight loss and aerobic conditioning
programs are added as necessary. Individual
patient goals may vary, but in general the ability
to return to normal activity without restrictions is
the main objective. The severity of symptoms
24 Surgical Management of Lumbar Spondylolisthesis
305
tends to dictate the management of spondylolysis
and spondylolisthesis, as most lesions do not heal
with bony union, but rather become a stable
fibrous union that remains relatively asymptomatic [1]. Patients with low-grade dysplastic spondylolisthesis are less likely than patients with
isthmic spondylolisthesis to benefit from conservative methods; however conservative therapy is
still recommended as the initial modality [37].
Surgical Treatment
The main goals of surgical treatment in spondylolisthesis consist of stabilization of the affected
levels and decompression of the involved neural elements. Surgery should be considered in
patients who have failed a full course of conservative treatment and have persistent severe
back and predominant leg pain, evidence of
instability on imaging, documented progressive
spondylolisthesis, a progression of the neurologic deficit, or cauda equina symptoms [1].
Surgical treatment options may be broadly
divided into two categories: direct repair of the
pars defects versus arthrodesis of the involved
segments to prevent slip progression with or
without decompression of affected neural
structures.
Direct Pars Repair
Procedures for direct fixation of pars defects
24.5) include the Buck’s technique [86],
(Fig.
Scott wiring [
cle screw and hook [88, 89], and U-rod technique
90, 91]. The Buck’s method is an open technique
[
in which the fibrous tissue at the pars defect is
identified, thoroughly debrided, and stabilized
with a 4.5 mm stainless steel cortical screw in
compression [86]. In the Scott wiring technique,
a stainless steel wire is looped from the transverse processes to the spinous process of the level
involved and tightened, in conjunction with local
iliac crest bone graft [
bilateral pedicle screws are connected through a
U-shaped rod around the spinous process, thus
87], repair with an ipsilateral pedi-
87]. In the U-rod technique,
applying compressive forces to enhance healing
of the bone graft across the defect [90, 91].
Posterior Fusion with Pedicle Instrumentation
Transpedicular fixation has been shown to
increase the rate of fusion, and a positive correlation has been reported between successful fusion
and clinical outcomes [93–99]. A trend for
improved clinical outcome with increased rigidity of fixation has been noted [94]. Pedicle screw
fixation systems have been shown to be mechanically superior to other fixation devices, while
allowing for the selective segmental force without extension to adjacent levels [100].
High-Grade Spondylolisthesis
Multiple factors must be considered in the treatment of high-grade spondylolisthesis [1].
Symptomatic patients with high-grade spondylolisthesis do not seem to achieve a satisfactory
outcome with non-operative treatment as compared to those with low-grade spondylolisthesis
[101]. In high-grade spondylolisthesis, reduction
of the slip angle rather than the degree of anterior
listhesis should be the main concern [1]. While
studies show that patients with greater than 50%
of slippage may have a poor non-operative outcome, fusion is in general the treatment of choice
among spinal surgeons [102]. In determining the
most appropriate procedure, one must take into
account all presenting symptoms, neurologic
function, radiographic findings, clinical deformity, age of the patient, and the surgeon experience. Treatment approach is influenced by the
level of spinal maturity, degree of slippage,
symptoms, the patient’s activity level, and
expected progression [
through arthrodesis of the affected segment can
result in improvement and even resolution of the
neural deficit by alleviating impingement of neural elements and increasing the stability [
While the treatment of an asymptomatic adult is
very rarely surgical, an asymptomatic adolescent
1]. Surgical stabilization
103].
306
Fig. 24.5 Procedures
for direct fixation of pars
defects (From Warner
and Leahy [
92])
J.G. Khalil et al.
Scott Wiring Pedicle Screw-
Hook
Buck Screw U rod technique
may be a candidate for surgical intervention
because of expected progression of deformity in
a high-grade slip, which may lead to mechanical
and neurologic dysfunction [1]. The long-term
effects of fusion in a young patient must be considered due to the potential for future adjacent
segment degeneration [104, 105]. In a skeletally
immature patient with slippage greater than 50%
or a mature adolescent with a slip greater than
75%, operative intervention is recommended
even if the patient is asymptomatic [
106–108].
Surgical decompression is also indicated when a
patient has neural compromise, with a severe
radiculopathy or bowel/bladder dysfunction
[
109–111].
Reduction of spondylolisthesis has been a
controversial topic. It has been shown that partial
slip reduction occurs with the positioning and
administration of general anesthetic/muscle
relaxation [112]. Active reduction can also be
performed after placement of the instrumentation. There has not been a compelling indication
to perform an active reduction in cases of degenerative spondylolisthesis. In isthmic spondylolis-
thesis partial reduction that aims to correct the
slip angle has been associated with improved
postoperative outcomes [113]. Reducing a spondylolisthesis also has limitations and drawbacks.
The most common postoperative complication is
neurapraxia of the L5 nerve root. It has been suggested that a wide decompression and thorough
excision of the Gill fragment may decrease the
incidence [113–115].
Fusion of the involved level has been widely
advocated as the definitive treatment of symptomatic spondylolysis [106, 116]. In the Spine
Patient Outcomes Research Trial (SPORT), a
prospective evaluation of the 2-year [
4-year [
118, 119] outcomes of 607 patients with
117] and
degenerative spondylolisthesis, patients were
divided into two enrollment groups, with 50% in
a randomized cohort and 50% in an observational
cohort. Pre-enrollment non-operative care was
not specified, and the type of surgery or nonoperative treatment during the study period was
left to the discretion of the treating physicians.
The study was laden with a significant crossover
and nonadherence to treatment between the two
24 Surgical Management of Lumbar Spondylolisthesis
307
groups, leading to both an as-treated and an
intent-to-treat analysis of the data. When both the
randomized and observational cohorts were combined, the as-treated analysis revealed that the
surgically treated patients had significantly better
outcome for both pain and function at 2-year and
4-year follow-ups. This study did not allow comparison of types of treatments; therefore it did not
answer the question of which surgical treatments
provided better outcomes.
Treatment options in isthmic spondylolisthesis consist of a direct repair of the pars intraarticularis [120–123], decompression of the
neural elements alone [109, 110, 124, 125],
decompression of the neural elements in conjunction with an in situ posterior lateral fusion
[96, 122, 126, 127], decompression of posterior
lateral fusion with associated pedicular instrumentation [96, 128, 129], and decompression and
reduction of the spondylolisthesis with instrumentation and interbody fusion [130–132].
Although all patients should be initially
treated with non-operative management, large
multi-institutional studies have demonstrated that
surgical treatment tends to result in more favorable outcomes [117]. While a fusion is firmer and
solid with instrumentation, prior to these large
multi-institutional studies, the incremental benefits of instrumentation on clinical outcome were
not as clear. Although it had seemed rational with
radiographic imaging showing evidence of instability, the direct stability offered by instrumentation was found to increase surgical time, expense,
and potential morbidity [1]. On the other hand,
indications for using instrumentation in a patient
with a collapsed disc space, no motion at the
spondylolisthetic level, or the presence of osteoporotic bone are not as clear [
1]. The SPORT
study successfully recognized an advantage of
surgical treatment over nonsurgical treatment in
stenotic patients who had degenerative lumbar
spondylolisthesis. A comparison of surgically
treated patients and the control cohort demonstrated improved outcomes of the surgically
treated patients at intervals of 3 months and
12 months, with marginally reduced improvement at 24 months [
117]. Additional breakdown
of this data from the SPORT trial gave insight to
significant findings. It was demonstrated that
operatively treated patients with degenerative
lumbar spondylolisthesis had better outcomes
than symptomatic stenosis without spondylolisthesis [133]. Furthermore, surgical outcome was
superior in patients with predominately leg pain
compared to those that presented with primarily
back pain [134].
In a prospective, randomized study by
Herkowitz, the comparison of decompression
alone versus decompression and noninstrumented posterolateral spinal fusion in the
treatment of lumbar spine levels L3-L4 and
L4-L5 degenerative spondylolisthesis with spinal
stenosis reported superior clinical results when
concomitant fusion was performed with the
decompression [135]. They found that a satisfactory outcome was more than twice as common in
the fused group (96%) as compared to the decompression without fusion group (44%). The authors
concluded that the results of surgical decompression with in situ arthrodesis were superior to
those of decompression alone.
Lumbar fusion for spondylolisthesis can be
accompanied by unintended consequences. In
elderly patients, either vertebral compression fractures of adjacent levels or stress fracture due to the
bone stock in the osteoporotic bone can occur [1].
Instrumentation may also directly harm the superior facet by either capsular disruption or articular
facet damage; thus the use of less rigid instrumentation or no instrumentation may be of interest
because of the theoretical reduction of stress on
adjacent levels by the presence of a less rigid
fusion or even a stable pseudarthrosis [1]. A multilevel decompression without any fusion is certainly a sensible option for some patients,
depending on age and comorbidities, even though
the literature generally supports concomitant
fusion. A multilevel non-instrumented fusion
increases the incidence of pseudarthrosis at one or
more levels, as well as the possibility of flat-back
deformity; therefore, in some cases, it may be
appropriate to decompress all of the stenotic levels
that are symptomatic and perform an instrumented
fusion at the spondylolisthetic level only [1].