Evaluating the radiological results of lumbosacral sagittal alignment and advantages of a combined operation using minimally invasive transforaminal lumbar interbody fusion and percutaneous pedicle fixation in treatment for lumbosacral spondylolisthesis.
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MINIMALLY INVASIVE TRANSFORAMINAL LUMBAR
INTERBODY FUSION FOLLOWED BY PERCUTANEOUS
PEDICLE SCREW FIXATION FOR THE TREATMENT OF SINGLE LEVEL LUMBAR SPONDYLOLISTHESIS:
RADIOLOGICAL RESULTS OF LUMBOSACRAL SAGITTAL
BALANCE PARAMETERS
Dương Thanh Tung 1 ; Nguyen Van Thach 2 ; Vu Van Hoe 3 ; Nguyen Van Hung 3
SUMMARY
Objectives: Evaluating the radiological results of lumbosacral sagittal alignment and advantages of a combined operation using minimally invasive transforaminal lumbar interbody fusion and percutaneous pedicle fixation in treatment for lumbosacral spondylolisthesis Subjects and methods: 38 consecutive single-level, low grade (Meyerding grade I or II) lumbar spondylolisthesis patients were prospectively included All patients undergone minimally invasive transforaminal lumbar interbody fusion + percutaneous pedicle fixation operations from
1 st January 2013 to 30 th April 2018 at Gia Dinh’s People Hospital Lateral lumbar spine radiographs in the pre-operative, post-operative periods of each patient were analyzed The results were evaluated by using the radiological parameters: slippage dimension, disc height, disc angle, segmental lordosis angle, lumbar lordosis angle, disc slope angle, sacrum slope Blood loss, operation time, time to first ambulation, length of hospital stays and the complications were also recorded Results: Patient’s average age was 50.66, 73.7% female, 84.2% L 4 -L 5 spondylolisthesis, 15.8% L 5 -S 1 spondylolisthesis, 73.7% degenerative spondylolisthesis, 26.3% isthmus spondylolisthesis All patients had back pain; 84.2% had leg pain; 57.9% had neurogenic claudication After operations, slippage dimension significantly decreased (0.08 mm
vs 0.59 mm pre-operation, p < 0.001) The segmental sagittal balance parameters of slipped level statistically significant increased post-operation (disc angle: 10.11 o vs 7.39 o pre-operation,
p = 0.0003 disc height: 12 mm vs 9.56 mm pre-operation, p < 0.001; segmental lordosis angle: 16.83 o vs 13.83 o pre-operation, p = 0.003) The lumbar regional sagittal balance parameters (lumbar lordosis, disc slope angle, sacrum slope) showed no significant changes post-operation Mean operation time was 182.05 minutes, mean blood loss was 140.79 mL Average time
to first ambulation was 25.89 hours and average postoperative hospital stays was 8.5 days
1 Gia Dinh’s People Hospital
2 Viet Duc Hospital
3 103 Military Hospital
Corresponding author: Duong Thanh Tung (thanhtungdr@yahoo.com)
Date received: 13/09/2019
Date accepted: 16/10/2019
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Conclusions: The minimally invasive transforaminal lumbar interbody fusion + percutaneous
pedicle fixation operation is a safe and efficient surgical technique in treatment of spondylolisthesis It can reduce slippage dimension, restore the segmental sagittal balance parameters (disc angle, disc height, segmental lordosis angle) with the advantages of minimally invasive techniques such as less complications, less blood loss and shorter time to the first ambulation post operation
* Keywords: Transforaminal lumbar interbody fusion; Percutaneous pedicle fixation; Sagittal balance parameters; Sagittal alignment parameters
INTRODUCTION
Spondylolisthesis is defined as the
slippage of one vertebra over the vertebra
immediately below it [1] It results in spinal
instability, spinal stenosis, pinch of nerve
structures that cause back pain, sciatica,
neurogenic claudication or cauda equina
syndrome [2]
Lumbopelvic malalignment plays a
significant role in multiple spinal conditions
Recently, several studies reported the
close relationship between spondylolisthesis
and sagittal alignment and the reduction
of slippage, restoration of disc height and
correction of changes of sagittal balance
parameters help to improve clinical
symptoms, increase the fusion rate, and
minimize the adjacent segment degeneration
syndrome after surgery [2, 3]
Transforaminal lumbar interbody fusion
(TLIF) followed by pedicle fixation (PF)
has been a commonly used surgical
option for treating spondylolisthesis This
operation (TLIF + PF) provided solid
fixation of spinal segments while restoring
a proper disc height and sagittal balance
[4, 5, 6]
In recent years, minimally invasive
surgery (MIS) is the new trend in spinal
fusion surgery TLIF + PF using minimally
invasive techniques (Minimally Invasive
Transforaminal Lumbar Interbody Fusion + Percutaneous Pedicle Fixation: MIS-TLIF + PPF) has gained popularity over the years with the advantages of smaller incisions, reduced trauma to paraspinal muscles, decreased intra-operative blood loss, shorter hospital stays, and decreased rates of operative site infection, all of which contribute to lower postoperative morbidity and expedite post-operative recovery [6, 7]
At Vietnam, there hasn’t been any studies about the effect of MIS on improvement of lumbarsacral sagittal balance in lumbar spondylolisthesis The
purpose of this study was: To evaluate
the radiological outcomes of lumbosacral sagittal alignment parameters and advantages of the MIS-TLIF + PPF operation in treatment for patients with low grade (Meyerding grade I or II) lumbosacral spondylolisthesis
SUBJECTS AND METHODS
1 Subjects
38 patients with a single level, low grade (Meyerding grade I or II) lumbar spondylolisthesis who underwent a MIS-TLIF + PPF operation at Gia Dinh’s People Hospital from 1st January 2013 to
30th April 2018 were included in the study
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* Inclusion criteria:
- The presence of single-level,
low-grade (Meyerding grade I or II)
spondylolisthesis
- There is surgical indication for
spondylolisthesis (persistence of significant
symptoms that correlated with the
diagnostic imaging findings, failure with
conservative treatment for at least
6 months)
* Exclusion criteria: Patients with
high grade (Meyerding grade III or IV)
spondylolisthesis, metabolic bone diseases,
scoliosis, infections, spinal traumas,
tumors, and multilevel fusions
2 Methods
* Surgical technique:
All MIS-TLIF + PPF procedures were
done via unilateral approach Under
fluoroscopic guidance, a 3 cm paraspinal
skin incision is made between the L4-5 or
L5-S1 pedicles on antero-posterior images After an incision is made on the lumbodorsal fascia between the multifidus and longissimus muscles, sequential widening
of the incision is made using tubular dilators, and a 24 mm working channel Quadrant (Medtronic, Tennessee, USA) is docked Under microscope visualization, total facetectomy and partial laminectomy are performed using a combination of osteotome and high-speed burr, and kerrison rongeurs The ligamentum flavum
is resected and nerve root is retracted medially Complete discectomy is performed, and meticulous preparation of the central and contralateral endplates is performed with angled ring curettes A banana-shaped crescent cage (Medtronic, Tennessee, USA), filled with morselized bone fragments obtained from laminofacetectomy is inserted
into the disk space (fig 1)
A B
Fig 1: Performing minimally invasive transforaminal lumbar interbody fusion
(MIS-TLIF)
(A: 24 mm working channel Quadrant is docke; B: Putting the Crescent cage in to the disc space)
(Source: Author, real operation on patient Ngo T K T., N o of hospital admission: 19.043560)
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Then, percutaneous pedicle screws (Sextant, Medtronic, Tennessee, USA) are inserted under fluoroscopic guidance, and adequate sized pre-lordosed rods are fitted,
and the wounds are sutured layer by layer (fig 2)
A B
Fig 2: Performing percutaneous pedicle fixation (PPF)
(A: Inserting the sextant screws into the pedicle; B: Manipulations are performed
under fluoroscopic guidance of C-arm images)
(Source: Author, real operation on patient Ngo T K T., N o of hospital admission: 19.043560)
* Groups of variable:
- Characteristics of single, low grade
spondylolisthesis: Age, sex, clinical
symptoms, pre-operation time of pain,
level of spondylolisthesis, type of
spondylolisthesis
- Peri-operative parameters: Operation
time, blood loss, blood infusion, drainage,
time to first ambulation, hospital stays,
complications
- The radiology spinal sagittal balance
parameters: Were measured from
conventional lumbar spine radiographs in
lateral view, at the pre-operation and
post-operation periods of each patient
using AUTOCAD software Resetting the
measurement scale to a figure so that the length of 1,000 measurement units corresponded to the actual 1-cm length
of the anatomical structures on X-ray, according to the formula:
1,000 Measurement scale =
α
α: The number of measurement units measured by Autocad software at the ratio of 1/1 of the size reference segment
on X-ray, represented the actual 1-cm length
These measured parameters included (described in fig 3):
- Slippage dimension (SD): measured dimension from posterior wall of superior
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vertebral body to posterior wall of inferior
vertebral body
- Disc height (DH): Average of the anterior
and posterior heights of the disc space
- Segmental lordosis angle (SLA): The
angle measured from the superior endplate
of the upper vertebra with the inferior
endplate of the lower vertebra However,
the SLA of the L5-S1 level was measured
between the superior endplate of L5 and
the upper endplate of the sacrum
- Lumbar lordosis angle (LLA): The angle measured between the superior endplate
of L1 and the upper endplate of the sacrum
- Disc slope angle (DSA): The angle measured between the line connecting the mid-point of anterior disc space to the mid-point of posterior disc space and a horizontal line
- Sacral slope (SS): The angle measured between the superior plate of S1 and a horizontal line
Fig 3: The radiological lumbosacral sagittal balance parameters
(A: The measured value of the size reference segment on X-ray after resetting the
measurement scale to ensure that the length of 1,000 measurement units corresponded to the actual 1-cm length; SD: Slippage dimension; DH: Disc height = (a + b/2); DA: Disc angle; SLA: Segmental lordosis angle; LLA: Lumbar lordosis angle; DSA: Disc slope angle and SS: Sacral slope)
(Source: Author, real operation on patient Ha T K N., N o of hospital admission: 16.21666)
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* Statistical analysis:
Data were expressed as mean ± standard
deviation in continuous variations or as
the number of patients with the percentage
in categorical variations, the different of
pre-operation and post-operation radiologic
parameters such as SD, DA, SLA, LLA,
DSA, SS were analyzed using either the
paired t-test or Wilcoxon signed-rank test
p < 0.05 was considered significant All
statistical analysis was performed using
SPSS version 20
RESULTS AND DISCUSSION
1 Demographic characteristics of
the patients
- Age (years): 50.66 ± 10.24
- Sex: Female 28 patients (73.7%);
male: 10 patients (26.3%)
- Clinical symptoms: Back pain:
38 patients (100%); neurogenic claudication:
22 patients (57.9%); leg pain: 32 patients
(84.2%)
- Pre-operation time of pain: 34.5 ±
31.3 months
- Level of spondylolisthesis: L4-L5:
32 patients (84.2%); L5-S1: 6 patients
(15.8%)
- Type of spondylolisthesis: Isthmus:
10 patients (26.3%); degeneration:
28 patients (73.7%)
These results were not different from
other studies Boissiere studied thirty-nine
patients, who were experienced MIS-TLIF
+ PPF for spondylolisthesis, mean age of
46 ± 10.1; 21 female (53.84%), 18 men
(46.16%); 29 patients (74%) with
degenerative spondylolisthesis, 10 patients
(26%) with isthmic spondylolisthesis [5]
In the study on 22 MIS-TLIF + PPF operations for spondylolisthesis, 8 patients had spondylolisthesis, 6 (75%) were of degenerative type, and only 2 patients (25%) were of isthmic type [6] Paul Park studied 40 symptomatic spondylolisthesis patients, who were experienced MIS-TLIF + PPF operations, the mean age was 56;
in the clinical series, 30 patients (75%) carried a diagnosis of degenerative spondylolisthesis and the remaining
10 patients (25%) had isthmic spondylolisthesis The most common level treated was L4-5 (28 patients = 70%) followed by L5-S1 (8 patients = 20%) and then L3-4 (2 patients = 5%) 2 patients underwent a 2-level fusion involving L4-L5
and L5-S1 [7]
Studies by other authors also showed that back pain is a major symptom and presented in most patients, while other symptoms such as nerve root pain, neurogenic claudication, bladder and bowel dysfunction may present in different rates Matsunaga, Ijiri, and Hayashi, in a study with at least a 5 years follow-up evaluation, reported that the most common symptoms were low back pain and gluteal pain, which were present in 98% of patients Lower extremity pain and numbness were also present in 48% of patients, whereas intermittent claudication was seen in 13% and one patient had bowel and bladder dysfunction The authors examined annually total of 145 patients with spondylolisthesis for a minimum of 10 years follow-up evaluation, showed that back pain was the main symptom, back pain accompanied with
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leg pain and neurogenic claudication in
68% of patients, with only leg pain in 32%
of patients, cauda equina syndrome was
very rare Back pain was unique symptom
in 32% of patients [1]
2 Peri-operative parameters
Mean operation time was 182.05 ±
36.22 minutes from skin incision to final
wound closure, mean blood loss was
140.79 ± 72.46 mL, no cases of blood
transfusion and drainage, mean time to
first ambulation was 25.89 ± 5.50 hrs and
mean post-operative hospital stays was
8.5 ± 3.28 days There was only 1 case
(2.63%), the cage pushed disc material to
the other side that pressed on the
opposite nerve root, required microscopic
discectomy and the subject went to get
good outcome There were no dural tears,
no postoperative infections and no
neurologic deficits observed post-operation
The average operation time in the
study was 182.05 ± 36.22 minutes, not
significantly different from Rouben's
study, the average operation time of
MIS-TLIF + PPF was 183 minutes [8] Khan also reported no difference in the duration of surgery between the conventional open surgery and MIS surgery [9]
The obvious advantages of minimally invasive surgery is that there was very little blood loss in surgery (140.78 ± 72.46 mL), no cases of blood transfusion and drainage In conventional open surgery, a lot of blood loss was common Wang recorded an average blood loss was 364
± 23 mL, post-operative drainage blood was 375 ± 26 mL, blood transfusions were required in many cases and most of them were drained in the study of conventional open TLIF + PPF [10] Limiting blood loss is an important point since it leads to reduced blood transfusions and the risks of blood transfusion [5, 10] Average time to first ambulation in the study was 25.89 ± 5.50 hrs, very early compared to conventional open surgery Rouben reported the first time to leave the bed after operation in open surgery was 67.2 ± 38.4 hours [8]
3 Post-operation and pre-operation radiologic sagittal balance parameters
Table 1: Post-operation and pre-operation radiologic parameters
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Spondylolisthesis may induce the clinical
syndromes, alter biomechanics and imaging
characteristics, reduce disc heights and
lead to abnormal compensatory postural
changes of segmental, regional, and
global sagittal balance of spine They
slowly evolve neurological deficits from
stretching or compression of neural
elements, and chronic pain [2, 5]
One of the central goals of surgery is to
correct spinal deformity of spondylolisthesis
to alleviate all these symptoms MIS is the
new trend in spinal fusion surgery The
objectives of MIS-TLIF + PPF operation
are to stabilize the spinal segment, restore
lordosis, obtain inter-vertebral fusion, and
perform decompression of the neurological
structures when required [1, 2, 5]
The majority of studies on the
effectiveness of MIS-TLIF on treatment of
lumbosacral spondylolisthesis are interested
in improving patient’s clinical symptoms
and functions However, analysis of sagittal
spinal alignment seems to be an
important factor for the full assessment of
spondylolisthesis Indeed, as shown by
Kumar et al is that neglecting the role
of sagittal alignment in treatment of
spondylolisthesis may lead to poor clinical
outcome and patient dissatisfaction [1]
Based on changes in spinal sagittal
balance parameters, Gille divided
spondylolisthesis into 3 types, with there
was a dynamic continuum from type 1
(balanced spines or a local compensation)
to type 3 (significant global malalignment)
He observed that patients mistreated as
type 1 with a single level posterior fusion,
while they actually were type 2 or 3,
required revision surgery to prolong constructs more frequently [2]
* The effects of reduction of spondylolisthesis (decreasing SD)
In this study, SD decreased significantly post-operation (0.08 ± 0.16 mm vs 0.59 ± 0.28 mm pre-operation, p < 0.001), meant the slippage was well corrected, the MIS-TLIF + PPF operation has effectively reduced spondylolisthesis The reduction of SD leads to improving the clinical symptoms and increasing the rate
of successful lumbar interbody fusion [1, 2, 5]
Because of forward slippage of the upper vertebral body, there was an accelerated degeneration of the inter-vertebral disc, resulting in a backward bulge of the annulus fibrosis The surface area of contact between the inferior endplate of upper vertebra and the superior endplate
of lower vertebra was reduced The exiting upper nerve root, which wraps around the pedicle of upper vertebral body, tends to be directly over the interspace rather than behind the body of upper vertebral body as it normally is The upper nerve root is entrapped dorsally by
a mass created by exuberant fibrous tissue at the isthmus defect (in isthmus spondylolisthesis) and ventrally by an
L5-S1 disc protrusion or the overriding postero-superior corner of the lower vertebral body In rare cases the entire caudal equine roots may be compressed
by the posterior dome of the lower vertebral body The reduction of the spondylolisthesis will correct a part of these abnormalities [1, 4]
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Furthermore, when reduction surgery
is not performed, and lumbar interbody
fusion is considered, there is a smaller
surface area of endplates for the placement
of the graft, a condition not conducive to
fusion When the slippage is corrected,
the surface area is restored, improves the
fusion rate [4]
* The effects of the restoration of
segmental sagittal balance parameters
(DA, DH, SLA):
This operation also significantly improved
segmental parameters of sliding segment
(DA: 10.11 ± 5.44o vs 7.39 ± 5.05o
pre-operation, p = 0.0003 DH: 12 ± 2.6 mm
vs 9.56 ± 2.6 mm pre-operation, p < 0.001;
SLA: 16.83 ± 6.74o vs 13.83 ± 7.29o
pre-operation, p = 0.003) Many authors
suggested the decreases of DA, DH result
in decreasing of SLA in lumbar spine, and
small SLA may lead to increase of loading
strain and adversely prompt the adjacent
segmental degeneration and restoration
of SLA prevent adjacent segment
degeneration and also to reduce the risk
of postoperative low back pain [2, 12]
Boissiere noted that the TLIF + PPF was
highly efficient to restore SLA and the
restoration of SLA is a key-factor to
prevent adjacent segment degeneration
[5] Therefore, it is believed that care and
attention should be given to introduce DA,
DH and SLA in the normal range [2, 5, 12]
In spondylolisthesis, there are patterns
of morphological changes in the disc
Spinal morphology shows a clear decrease
in DA and SLA of the spondylolisthesis
level The decreases of DA and SLA at the level of listhesis are more distinct in degenerative spondylolisthesis than isthmus spondylolisthesis The small DA of the spondylolisthesis group might be a predisposing factor to the development of spondylolisthesis or a compensatory mechanism to the ventral slippage of the vertebra [1]
Degenerative disc disease occurs later
in the natural history of spondylolisthesis, resulting in single level disc degeneration and usually induce reduction of the DH corresponding to the compromised level The reduction of DH will narrow the foraminal size and decrease SLA of affected segments [3, 11] Tang found that from normal model to mildly, moderately and severely decreased DH model, the SLA decreased 5°, 10° and 15°, respectively [12] The restoration of DH is essential to indirect decompress inter-vertebral foramen, increase the SLA, relax nerve roots, as well as improve clinical post-operatory results [2, 11, 12]
Many authors also reported that decreasing of DH was accompanied with the decreasing of SLA at fused segments post operation [2, 12] Gaffey J.L concluded that’s there was significant correlation between implant height and SLA and an increasing implant height produced a significant increase in SLA [12] In the report of 26 patients undergone lumbar interbody fusions, Kim confirmed a loss of SLA had a significant correlation with decrease of DH resulting from cage subsidence [10]
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Results of researches from other authors
also showed that the MIS-TLIF + PPF
operation significantly improved segmental
sagittal balance parameters of slipped
segments Boissiere performed this surgery
on 39 patients with spondylolisthesis, DH
increased 0.37 ± 0.80 mm vs 0.26 ± 0.9
mm pre-operatively at L5-S1 segment;
0.35 ± 0.06 mm vs 0.26 ± 0.07 mm
pre-operatively at L4-L5 segment, SLA
increased 33.8 ± 6.5o vs 25.3 ± 7.8o
pre-operatively at segment L4-L5; 31 ±
4.7o vs 19.4 ± 6.7o pre-operatively at
L5-S1 segment [5] Choi performed this
surgery on 22 patients, DH increased
8.8 ± 1.8 mm compared with 7.0 ± 1.9 mm
pre-operatively SLA increased 16.5 ± 4.9o
compared to 13.3 ± 4.3o pre-operatively,
DA increased by 10.8 ± 3.05o compared
to 8.8 ± 3.5o pre-operatively [6]
* The changes of lumbar regional
lumbar sagittal balance parameters (LL,
DSA, SS):
In this study, the lumbosacral regional
parameters (LL, DSA, SS) showed
insignificant modifications postoperatively
Progressive geometrical changes in
the lumbosacral junction are manifested
clinically by compensatory postural
changes characteristics of high-grade
spondylolisthesis Buckland et al studied
different posture patterns between patients
with spondylolisthesis concluded that
patients in mild-to-moderate malalignment
did not recruit regional parameters such
as pelvis tilt until moderate-to-severe
malalignment was present Gille proposed
a classification for spondylolisthesis
according to the changes of sagittal balance parameters (segmental, regional, and global analysis parameters) in processes
of spondylolisthesis from mind to severe stages Type 1a corresponds to balanced spines with preserved local and global sagittal balance Type 1b includes a local compensation with disc flexion and loss of segmental lordosis Type 2a and 2b include a pelvis index and LL mismatch This is due to multi-segmental degenerative disc disease responsible for a loss of LL Type 3 represents a significant global malalignment resulting from overrun local and regional compensatory mechanisms (thoracic and pelvic) More aggressive surgical treatment may be considered to correct sagittal malalignment, especially
in case of significant clinical sagittal imbalance Treating only the slippage level may lead to a poor clinical outcome [2]
In this study, the lumbosacral regional sagittal balance parameters (LL, DSA, SS) showed no significant modifications postoperatively This can be explained by the fact that all patients belong to lower grade (I, II) spondylolisthesis, processes
of disease only affect the segmental sagittal imbalance at slipped level, not in the lumbar region It is also possible that surgery is performed at the slipped level, which can restore only slipped segmental parameters Complete correction of regional
or global sagittal imbalance requires more invasive surgical procedures, such as multi-level fusion or osteotomies [5]