Keywords
intervertebral disc degeneration - low back pain - sciatica - spinal diseases - spondylolisthesis
Palavras-chave
ciática - degeneração do disco intervertebral - doenças da coluna vertebral - dor
lombar - espondilolistese
Introduction
Segmental instability of the lumbar spine, a consequence of degenerative conditions,
is a well-recognized issue. It frequently affects the L4–5 and L5–S1 levels, which
possess the highest range of motion. Patients exhibiting radiographically unstable
degenerative spines typically receive a recommendation for surgical stabilization
as a treatment option.[1] However, the addition of fusion brings its own set of complications. Therefore,
a non-fusion option for decompression is desirable in degenerative lumbar spine when
indicated.[2]
X-rays, computed tomography (CT), and magnetic resonance imaging (MRI) are commonly
employed diagnostic tools to assess degenerative lumbar pathologies. While these radiological
investigations are inherently static, dynamic X-rays are increasingly utilized to
detect radiological instability. Additionally, the lumbar spine exhibits a wide range
of normal motion, which may inadvertently guide treatment toward fusion surgery. This
predicament is particularly pertinent in instances of low-grade (Meyerding grade 1)
degenerative spondylolisthesis. Various studies have attempted to define translational,
rotational, or angular abnormalities on X-rays.[3]
[4]
[5] A micro lumbar decompression and discectomy procedure is designed to minimize bone
loss, preserve motion segments, and provide adequate decompression of neural elements.[6]
Materials and Methods
The current work was approved by institutional Ethics Committee under registration
nr. ECR/836/lnst./PB/2016/RR-20, nr. IEC/29.
Fifty patients who underwent lumbar spine surgery for a degenerative lumbar spine
pathology at a single level were included. Magnetic resonance imaging was employed
to evaluate the extent of pathology. Additionally, preoperative flexion and extension
X-rays of the lumbar spine were conducted to assess any sign of radiological instability.
Lateral flexion-extension radiographs were taken as described by Putto and Tallroth.[4]
To assess the stability of the motion segment, translational and angular motion were
calculated on radiographs according to Dupuis et al.[5] Postoperative clinical follow-up was conducted at 6 weeks, 3 and 6 months, and 1
and 2 years.
Clinical evaluation pre and postoperatively was performed utilizing the Visual Analog
Scale (VAS) to assess leg pain and backache separately, and functional outcome assessment
was performed by the Oswestry Disability Index (ODI).
The included cases were adult patients (aged 18 and above) who underwent single-level
spine surgery for degenerative lumbar canal stenosis (LCS), prolapsed intervertebral
disc (PIVD), and degenerative low-grade spondylolisthesis (Meyerding grade 1).
The exclusion criteria were defined as cases of spinal instability presenting with
vertebral fractures, spinal tumors, degenerative spondylolisthesis Meyerding grade
2 or more, spinal infections, lytic listhesis, pars fractures, cases requiring revision
lumbar spine surgery, associated cervical or thoracic segment involvement requiring
surgical intervention, and intradural pathologies. Ethical committee approval was
obtained for conducting this research study.
Surgical Method
Microlumbar disectomy was performed with the patient in prone position under general
anesthesia. The level for decompression was marked using fluoroscopy. A midline approach
to the posterior lumbar spine was used. After subperiosteal dissection, the microscopically-assisted
laminotomy was performed using a burr and a Kerrison roungeur. The hypertrophic ligamentum
flavum was removed for central canal decompression. For lateral recess decompression,
a partial facet undercutting was added when required. In all patients, the nerve root
was visualized and adequately decompressed. The discectomy procedure was done after
annulotomy. Closure was done in layers.
Postoperatively, the patient was mobilized on the day following surgery. Core strengthening
exercises were initiated as tolerated by the patient. Physiotherapy and rehabilitation
were gradually intensified in accordance with the patient's clinical improvement.
Results
Patient Demographics and Baseline Characteristics
A total of 53 patients participated in the study, but 3 patients were lost to follow-up.
Group 1 consisted of 25 cases with radiologically stable lumbar segment, while group
2 included 25 cases diagnosed with degenerative low-grade spondylolisthesis (Meyerding
grade 1), as assessed through dynamic X-rays. All patients underwent single-level
midline microlumbar decompression. Clinical evaluations were conducted at 3 and 6
months, and 1 and 2 years postsurgery. The clinical outcomes of both groups were measured
using the Visual Analog Scale (VAS) and the Oswestry Disability Index (ODI) at 2 years
postsurgery.
Age and Gender Distribution
The age distribution for both groups is presented in [Table 1]. Both groups 1 and 2 had 25 patients each, with a comparable age distribution (p = 0.6808 and p > 0.05, respectively, as per the Fisher's exact test). [Table 2] summarizes the gender distribution: Group 1 included 12 males and 13 females, whereas
group 2 comprised 14 males and 11 females. Statistical analysis demonstrated no significant
difference in gender distribution between the 2 groups (p = 0.6911, Fisher's exact test).
Table 1
Distribution of patients by age in groups 1 and 2
|
Age in years
|
Number (%)
|
|
Group 1
|
Group 2
|
|
≤ 30
|
3
|
2
|
|
31–40
|
4
|
7
|
|
41–50
|
10
|
2
|
|
51–60
|
6
|
10
|
|
≥ 61
|
2
|
4
|
|
Total
|
25
|
25
|
Note: Value of p: 0.6808 according to the Fisher's exact test, with an age cut-off of 50 years.
Table 2
Distribution of patients by gender in groups 1 and 2
|
Gender
|
Number (%)
|
|
Group 1
|
Group 2
|
|
Male
|
12
|
14
|
|
Female
|
13
|
11
|
|
Total
|
25
|
25
|
Note: Value of p: 0.6911 according to the Fisher's exact test.
Lumbar Segment Involvement
[Table 3] outlines the distribution of lumbar segment involvement. In group 1, the majority
of cases involved the L4-to-L5 segment (14 cases), followed by L5 to S1 (8 cases),
L3 to L4 (2 cases), and L2 to L3 (1 case). Group 2 exhibited involvement primarily
in L4 to L5 (17 cases) and L5 to S1 (6 cases), with single cases at L2 to L3 and L3
to L4.
Table 3
Distribution of patients by level of involvement in groups 1 and 2
|
Diagnosis
|
Number
|
|
Group 1
|
Group 2
|
|
L2–L3
|
1
|
1
|
|
L3–L4
|
2
|
1
|
|
L4–L5
|
14
|
17
|
|
L5–S1
|
8
|
6
|
Clinical Presentation
Patient's chief complaints are presented in [Table 4]. In group 1, all 25 patients reported radiculopathy, with 19 experiencing additional
backache along with radiating leg pain. Similarly, all 25 patients in group 2 reported
radiculopathy, with 21 patients experiencing associated axial backache. Claudication
distance was also recorded, revealing that 33 patients experienced claudication at
≤ 50 m, 7 patients at 100 m, and 10 patients at 200 m.
Table 4
Distribution of chief complaints in groups 1 and 2
|
Complaints
|
Number (%)
|
|
Group 1
N = 25
|
Group 2
N = 25
|
|
Backache
|
19 (76%)
|
21 (84%)
|
|
Radiculopathy
|
25 (100%)
|
25 (100%)
|
Clinical Outcomes
[Table 5] presents the clinical outcomes for group 1. The mean ODI score improved significantly
from 75.36 ± 13.59 preoperatively to 22.64 ± 17.2 at 2 years postsurgery (p < 0.0001). Visual analogue scale scores for backache and leg pain also demonstrated
significant improvements. The mean VAS for backache reduced from 5.92 ± 3.45 preoperatively
to 2.04 ± 1.86 (p = 0.0002), while the mean VAS for leg pain decreased from 8.9 to 1.56 (p < 0.0001).
Table 5
Comparison of ODI, VAS for backache and for leg pain preoperative and at the 2 years
follow-up in group 1
|
Group
|
Group 1
|
p-value*
|
|
Preoperative
|
Postoperative (at 2 years)
|
|
Statistical measures
|
N
|
Mean
|
SD
|
Range
|
N
|
Mean
|
SD
|
Range
|
|
|
ODI
|
25
|
75.36
|
13.59
|
50–96
|
25
|
22.64
|
17.2
|
0–54
|
< 0.0001
|
|
VAS for backache
|
25
|
5.92
|
3.45
|
0–10
|
25
|
2.04
|
1.86
|
0–5
|
0.0002
|
|
VAS for leg pain
|
25
|
8.92
|
1.61
|
2.50–10
|
25
|
1.56
|
1.97
|
0–5
|
< 0.0001
|
Abbreviations: ODI, Oswestry Disability Index; SD, standard deviation VAS, Visual Analogue Scale.
Note: *Wilcoxon signed rank test.
Clinical outcomes for group 2 are summarized in [Table 6]. The mean ODI improved from 68.75 ± 11.81 preoperatively to 24 ± 10.6 at 2 years
postsurgery (p < 0.0001). The mean VAS for backache significantly decreased from 8 ± 1.22 to 2.12 ± 1.43
(p = 0.0009). Furthermore, the mean VAS for leg pain improved from 7.87 preoperatively
to 2.56 at 2 years postsurgery (p = 0.0008).
Table 6
Comparison of ODI, VAS for backache and for leg pain preoperatively and after the
2-year follow-up in group 2
|
Group
|
Group 2
|
p-value
|
|
Preoperative
|
Postoperative (at 2 years)
|
|
Statistical parameters
|
N
|
Mean
|
SD
|
Range
|
N
|
Mean
|
SD
|
Range
|
|
|
ODI
|
25
|
68.75
|
11.81
|
46–84
|
25
|
24
|
10.6
|
10–38
|
< 0.0001
|
|
VAS for backache
|
25
|
8
|
1.22
|
6–10
|
25
|
2.12
|
1.43
|
0–4
|
0.0009
|
|
VAS for leg pain
|
25
|
7.87
|
1.57
|
5–9
|
25
|
2.56
|
1.35
|
0–5
|
0.0008
|
Abbreviations: ODI, Oswestry Disability Index; SD, standard deviation VAS, Visual Analogue Scale.
Note: *Using Wilcoxon signed rank test.
[Table 7] displays the comparative outcomes between the 2 groups at the 2-year follow-up.
The mean ODI for group 1 (22.64 ± 17.2) was statistically comparable to group 2 (24 ± 10.6),
with a p-value of 0.7924. Similarly, VAS scores for backache (2.04 ± 1.86 in group 1 versus
2.12 ± 1.43 in group 2; p = 0.7154) and leg pain (1.56 in group 1 versus 2.56 in group 2; p = 0.0945) showed no significant differences.
Table 7
Comparison of ODI, VAS backache and for leg pain between groups 1 and 2 at 2-year
follow-up
|
Condition →
|
At the 2-year follow up
|
p-value*
|
|
Group →
|
Group 1
|
Group 2
|
|
Statistical parameters →
|
N
|
Mean
|
SD
|
Range
|
N
|
Mean
|
SD
|
Range
|
|
|
ODI
|
25
|
22.64
|
17.2
|
0–54
|
25
|
24
|
10.6
|
10–38
|
0.7924
|
|
VAS for backache
|
25
|
2.04
|
1.86
|
0–5
|
25
|
2.12
|
1.43
|
0–4
|
0.7154
|
|
VAS for leg pain
|
25
|
1.56
|
1.97
|
0–5
|
25
|
2.56
|
1.35
|
0–5
|
0.0945
|
Abbreviations: ODI, Oswestry Disability Index; SD, standard deviation VAS, Visual Analogue Scale.
Note: * Wilcoxon rank sum test.
Follow-Up
At the final follow-up, 34 patients reported no claudication symptoms. Sixteen patients
experienced minimal symptoms, such as heaviness or slight numbness in their legs,
yet were able to walk distances exceeding one kilometer with conservative management
of symptoms.
Discussion
The degenerative instability process unfolds through three distinct phases: dysfunction,
instability, and re-stabilization. Segmental instability arises from the degeneration
of facets and discs, leading to laxity and resulting in abnormal motion under the
physiological load of daily activities.[7] Panjabi[8] proposed a tri-modal concept of spinal stability and clinical manifestations of
segmental instability are characterized by nonspecific symptoms, including low back
pain accompanied by radicular pain, particularly during changes in posture.
A recent study by Van Grafhorst et al.,[9] in 2025, reported the outcome of a 9-year follow-up of decompression without fusion
in patients with lumbar spinal stenosis, with or without coexisting low-grade (grade
I) degenerative spondylolisthesis. A total of 250 cases with low-grade spondylolisthesis
had a 69% satisfaction rate, which was comparable to the group of 200 cases of degenerative
stenosis (68%). Decompression alone yielded durable and satisfactory outcomes with
reoperation rates as low as 7% in the spondylolisthesis group and 6% in the stenosis
group.
A systematic review and meta-analysis of 6 randomized controlled trials (RCTs) was
conducted by Abdel-Fattah et al.[10] in 2023 for the total of 531 patients with mean age of 66.2 years and mean follow-up
of 27.4 months. The study showed decompression alone (DA) is not inferior to decompression
with fusion (DF) in terms of pain, disability, or reoperation rates in elderly patients
with spinal stenosis and low-grade degenerative spondylolisthesis. Decompression alone
is associated with fewer surgical complications, shorter surgery, and lower perioperative
burden. Hence, clinical decisions should balance surgical risks, patient comorbidities,
and functional goals.
A finite element model study to assess the biomechanical impact of decompressions
on lumbar stability was conducted by Liu et al.[6] The study tested normal lumbar segment versus grade 1 spondylolisthesis each with
three surgical scenarios: hemilaminectomy, total laminectomy, one-third facetectomy.
Hemilaminectomy and ⅓ facetectomy were biomechanically safe for low-grade spondylolisthesis,
maintaining segment stability with minimal changes to spinal mechanics. However, total
laminectomy significantly altered biomechanics and should be used cautiously in spondylolisthesis
due to increased motion, disc pressure, and stress on posterior elements. Finite element
modeling supported minimally invasive strategies that preserve stability while achieving
decompression.
A multicenter RCT called Swedish Spinal Stenosis Study, published in 2024 by Karlsson
et al.,[11] presented long-term (5-year) outcomes of decompression alone (DA) versus decompression
with fusion (DF) in patients with lumbar spinal stenosis with or without degenerative
spondylolisthesis. Of 247 patients aged between 50 to 80 years, 124 in were included
in DA group and 123 in DF group. The ODI, VAS, and European Quality of Life-5 Dimensions
(EQ-5D) quality of life (QoL) assessment scores showed fusion does not provide superior
clinical outcomes as QoL and leg pain relief were better with DA at 5 years. Decompression
alone is preferable, offering similar or better results with lower complication risks,
shorter hospital stays and fewer adjacent segment issues. Reoperations rates were
similar in either group but different in cause, in DF group 24% (mainly adjacent level
stenosis) and DA group 22% mainly due to restenosis.
The study by Kgomotso et al.[12] in 2024 aimed to evaluate the long-term effectiveness of decompression alone versus
decompression with instrumented fusion for patients with degenerative lumbar spondylolisthesis
(DS) over a 5-year follow-up. It was structured as a multicenter, non-inferiority
RCT (NORDSTEN-DS) to determine if decompression alone is non-inferior to decompression
with fusion. The study included 267 patients aged 18 to 80 years with lumbar spinal
stenosis and spondylolisthesis of at least 3 mm at the stenotic level. Cases were
randomly assigned to decompression alone (n = 134) or decompression with fusion (n = 133). The study concluded that decompression alone is non-inferior to decompression
with instrumented fusion for treating degenerative lumbar spondylolisthesis at 5 years,
without significant differences in clinical outcomes or reoperation rates.
A recent study by Unterfrauner et al.[13] aimed to compare the effectiveness of decompression alone versus decompression with
fusion for patients with lumbar degenerative spondylolisthesis (DS) and spinal stenosis
over a 3-year follow-up period, using data from the Lumbar Stenosis Outcome Study
(LSOS). It employed a target trial emulation with benchmarking against the NORDSTEN-DS
RCT to improve causal inference in observational data. The study concludes that decompression
alone should be considered the primary surgical option for patients with lumbar DS
and spinal stenosis, given that fusion did not provide additional benefits in terms
of health-related QoL (HRQoL), pain reduction, or satisfaction at 3 years, while increasing
physical therapy needs. This finding challenges the routine use of fusion in these
cases, suggesting that decompression alone is effective and less resource intensive.
Systematic review and meta-analysis including 3 RCTs and 9 cohort studies by Cheng
et al.[14] (2024) aimed to evaluate the efficacy and safety of decompression alone versus decompression
plus fusion in patients with single-level lumbar spinal stenosis with spondylolisthesis.
The analysis included 6,182 patients with 2,339 in the decompression-alone group and
3,783 in the decompression plus fusion group. The findings indicate that decompression
alone is not inferior to decompression plus fusion for single-level lumbar spinal
stenosis with spondylolisthesis. Given the shorter operation time, less intraoperative
blood loss, and no increase in complications or reoperation rates, decompression alone
is advocated as the primary surgical option.
A retrospective cohort study by Van Grafhorst et al.[2] aimed to assess the effectiveness of decompression alone as a treatment for symptomatic
lumbar stenosis with low-grade degenerative spondylolisthesis and to evaluate the
incidence and outcomes of reoperation, with or without subsequent instrumented fusion.
A total of 934 patients undergoing surgery for lumbar spinal stenosis, including 253
patients with degenerative spondylolisthesis. All patients initially received decompression
alone; only 3 patients with spondylolisthesis underwent primary decompression with
fusion. After this first procedure, 80% of stenosis patients and 74% of spondylolisthesis
patients reported satisfaction after initial decompression (p = 0.059). Reoperation rates were 12% in the stenosis group (1.2% underwent fusion) and
17% in the spondylolisthesis group (38.1% underwent fusion). The study concludes that
decompression alone is an effective treatment for symptomatic lumbar stenosis with
low-grade degenerative spondylolisthesis. When reoperations were necessary, secondary
decompression sometimes with extended resection of the superior arch was often sufficient.
Fusion was only occasionally required, supporting the argument that instrumented fusion
is not routinely necessary for most patients.
The study by Khashan et al.[15] aimed to evaluate the clinical outcomes, complication rates, and reoperation rates
of minimally-invasive (MI) tubular decompression for lumbar spinal stenosis (LSS)
with or without stable low-grade degenerative spondylolisthesis. It specifically examined
if the presence of stable spondylolisthesis compromised the outcomes of MI decompression.
Of 96 patients, 53 patients with stable low-grade degenerative spondylolisthesis and
43 patients with spinal stenosis. The presence of stable spondylolisthesis did not
compromise clinical outcomes, increase complication rates, or elevate reoperation
rates. The study concluded that MI tubular decompression is an effective and safe
procedure for patients with lumbar spinal stenosis, regardless of the presence of
stable low-grade degenerative spondylolisthesis.
Ghiselli et al.[16] conducted a study involving 215 cases of posterior lumbar fusion and observed a
prevalence of symptomatic adjacent segment degeneration that necessitated either decompression
or arthrodesis. The study predicted a 16.5% incidence of symptomatic adjacent segment
degeneration at 5 years and a 36.1% incidence at 10 years. Carreon et al.[17] observed that decompression with fusion in individuals over the age of 65 years
was associated with an elevated incidence of major complications, such as surgical
site infections (prevalence, 10%) and minor complications, including urinary tract
infections (prevalence, 34%). Furthermore, as the fusion levels increased, there was
a concurrent rise in blood loss and operative time.
Our findings align with the conclusions of these studies, which all questioned the
significance of fusion and advocated for a favorable perspective on a non-fusion and
a less invasive decompression approach.
However, our study has some limitations, such as its retrospective nature, which restricts
the generalizability of its findings. While dynamic flexion-extension X-rays of the
lumbar spine are commonly employed in decision-making processes for lumbar fusion,
radiographic parameters such as global sagittal balance evaluation are increasingly
utilized. Absence of a fusion group is another limitation, as results depicted are
only for a non-fusion surgery.
Conclusion
Lumbar spine bears the brunt of body weight as compared with other spinal regions,
while simultaneously facilitating a wide range of flexion and extension movements.
Consequently, preserving lumbar motion is important. Surgical procedures aimed at
preserving the motion of the lumbar spine have garnered significant attention, encompassing
a range of techniques. It is crucial to identify a patient population that may benefit
from avoiding a fusion procedure. In our study, a comparative analysis of degenerative
low grade spondylolisthesis versus a stable lumbar canal stenosis undergoing a similar
non fusion surgical procedure demonstrated comparable clinical outcomes. Consequently,
microlumbar decompression emerges as a viable treatment option for preserving the
lumbar motion segment in degenerative low-grade spondylolisthesis.
Bibliographical Record
Ajaybir Singh. Analysis of the Clinical Outcome of Microlumbar Decompression in Degenerative
Grade-1 Spondylolisthesis versus Stable Lumbar Canal Stenosis. Rev Bras Ortop (Sao
Paulo) 2025; 60: s00451810036.
DOI: 10.1055/s-0045-1810036
