Original article
Ukrainian Neurosurgical Journal. 2026;32(1):106-112
https://doi.org/10.25305/unj.341960
Comparison of microdiscectomy and microdiscectomy with cage interbody fusion in lumbar–sacral disc herniation
Ievgenii I. Slynko, Roman V. Chamata
Spinal Department, Romodanov Neurosurgery Institute, Kyiv, Ukraine
Received: 23 October 2025
Accepted: 17 January 2026
Address for correspondence:
Roman V. Chamata, Spinal Department, Romodanov Neurosurgery Institute, 32 Platon Mayboroda St., Kyiv, 04050, Ukraine, e-mail: chamataroman@gmail.com
Objective: To optimize the selection of surgical treatment strategy for patients with lumbar and lumbosacral disc herniation by performing a comparative analysis of the outcomes of microdiscectomy and microdiscectomy with interbody cage fusion in order to improve treatment results.
Materials and methods: The study included 200 patients with lumbar and lumbosacral disc herniation treated at the Romodanov Neurosurgery Institute of the National Academy of Medical Sciences of Ukraine between 2015 and 2022. Neurological status was assessed based on the severity of pain syndrome, the presence of segmental instability was determined. Magnetic resonance imaging, computed tomography, and radiographic findings were evaluated. The following surgical techniques were used: microdiscectomy for lumbar and lumbosacral disc herniation.
Results: Microdiscectomy with interbody cage fusion eliminated manifestations of instability and provided more effective stabilization of the lumbosacral spine compared with microdiscectomy alone. The recurrence rate of disc herniation after microdiscectomy with cage fusion lower (3%) compared with microdiscectomy alone (9%). In the group treated with microdiscectomy and cage fusion, a more pronounced reduction in pain intensity (–82%) and a greater decrease in the Oswestry Disability Index (–81%) were observed, indicating higher effectiveness of the stabilization technique. According to the Macnab and Prolo scales, excellent and good outcomes were recorded more frequently in the microdiscectomy with cage fusion group than in the microdiscectomy group (91% vs 78% and 91% vs. 77%, respectively). The Wilcoxon test confirmed a high level of within-group improvement (p<0.001), while the t-test demonstrated statistically significant differences between the groups.
Conclusions: The lumbosacral segment with an implanted cage is more stable and withstands greater mechanical loads during motion, reduces the recurrence rate of disc herniation, and decreases pain severity. Microdiscectomy with interbody cage fusion may be considered in carefully selected patients with signs of segmental instability as an approach that combines decompression and stabilization and is associated with better long-term clinical outcomes.
Keywords: lumbar–sacral disc herniation; microdiscectomy; microdiscectomy with cage interbody fusion
Introduction
According to statistical data, herniation localized in the lumbosacral region of the spine occurs most frequently. Such herniations are among the leading causes of chronic pain syndrome and temporary disability [1, 2]. In the majority of cases (59%), intervertebral disc herniations affecting the lumbar and sacral nerve roots are located at the L4–L5 level (with compression of the L5 nerve root). The second most common level is L5–S1 (with compression of the S1 nerve root), accounting for 30% of cases [3, 4].
The gold standard for surgical treatment of lumbosacral disc herniation is microdiscectomy (microsurgical removal of the herniated intervertebral disc). The main advantage of this method is the ability to remove herniations of any density, location, and size, including cases associated with spinal canal stenosis and sequestrated intervertebral disc herniation [5]. However, this technique does not prevent the development of recurrent herniation or instability of the lumbosacral spine, which may necessitate repeat surgical intervention [6, 7]. Thus, the choice of the optimal surgical strategy (microdiscectomy alone versus microdiscectomy combined with interbody fusion using a cage) remains a relevant clinical issue.
Aim: to optimize the selection of surgical treatment strategy for patients with lumbosacral disc herniation through a comparative analysis of outcomes following microdiscectomy and microdiscectomy combined with interbody cage fusion, with the goal of improving treatment results.
Materials and methods
Study participants
The study included 200 patients with lumbosacral disc herniation who were treated at the A.P. Romodanov Institute of Neurosurgery of the National Academy of Medical Sciences of Ukraine between 2015 and 2022.
Written informed consent for participation in the study and for publication of the data was obtained from all patients.
The study protocol was approved by the Ethics and Bioethics Committee of the A.P. Romodanov Institute of Neurosurgery of the National Academy of Medical Sciences of Ukraine (Minutes No. 3, dated November 24, 2022).
Inclusion criteria:
Exclusion criteria:
Group characteristics
All patients underwent surgical treatment for lumbosacral disc herniation. Of these, 100 patients underwent microdiscectomy, while the remaining patients underwent microdiscectomy combined with interbody fusion using cages.
Indications for microdiscectomy (MD):
Thus, microdiscectomy was predominantly performed in patients with isolated disc herniation without structural instability.
Microdiscectomy combined with interbody cage fusion (MD + Cage) was applied in patients with discogenic pathology accompanied by structural or biomechanical segmental instability, in whom decompression alone was insufficient to stabilize the spine and prevent herniation recurrence.
Main indications for microdiscectomy with interbody cage fusion:
Thus, microdiscectomy with interbody fusion using a cage was performed in patients for whom decompression alone was insufficient to stabilize the spinal segment and prevent recurrence.
Contraindications to microdiscectomy:
Contraindications to microdiscectomy with interbody fusion using a cage:
Study design
A comparative study was conducted involving two groups of patients who underwent microdiscectomy and microdiscectomy with cage fixation, respectively. The analysis focused on the surgical techniques, the recurrence rate following both types of procedures, and neurological outcomes in the early and long-term postoperative periods. Based on the obtained results, indications for the use of these surgical methods and corresponding clinical recommendations were developed.
All patients underwent neurological assessment, including evaluation of pain syndrome manifestations, pain intensity measured using the Visual Analog Scale (VAS), functional status assessed by the Oswestry Disability Index (ODI), the Macnab Scale (Table 1), and the Prolo functional–economic outcome scale (Table 2). In addition, recurrence rates were recorded. The surgical techniques applied included microdiscectomy and microdiscectomy of lumbosacral disc herniations with interbody fusion using cages at the L4–L5 or L5–S1 levels. The posterior interlaminar approach at the L4–L5 or L5–S1 level was predominantly used; in isolated cases with a narrow interlaminar space, a microscopic transforaminal lumbar interbody fusion (TLIF) approach was employed. Titanium or PEEK (polyetheretherketone) cages manufactured by “Medtronic” or “Novo Spine” were used. The cages were of “banana” and “bullet” shapes, with the size selected individually based on the intraoperative height of the intervertebral disc space. The space inside and around the cage was not filled with autologous bone graft material. No additional fixation was applied. In the comparison group, only the stand-alone cage technique was used.
Table 1. Macnab scale [13]
|
Rating |
Outcome characteristics |
|
Excellent |
Complete relief of pain; the patient has returned to normal daily activities and work |
|
Good |
Occasional mild pain that does not limit daily activities; the patient is able to work in the same position; |
|
Fair |
Persistent pain, but significantly reduced compared with the preoperative level; activity is partially limited, and the patient must change to less physically demanding work |
|
Poor |
No improvement or worsening of pain compared with the preoperative condition; the patient is unable to work |
Note.* Patient-reported assessment of treatment outcomes.
Table 2. Prolo functional–economic outcome scale [11]
|
1. Economic scale (E) |
|
|
Score |
Description |
|
1 |
The patient is unable to work and is completely disabled |
|
2 |
Work capacity is partially preserved; the patient performs light or part-time work |
|
3 |
The patient is able to work with limitations (change of profession or working conditions) |
|
4 |
The patient works in the previous occupation with minor limitations |
|
5 |
Full work capacity; return to previous professional activity |
|
2. Functional scale (F) |
|
|
Score |
Description |
|
1 |
Severe pain; constant need for analgesics |
|
2 |
Moderate pain; significant limitation of daily activities |
|
3 |
Intermittent pain; partial limitation of activity |
|
4 |
Mild pain; preservation of everyday activity |
|
5 |
No pain; normal physical activity without limitations |
|
Interpretation of the total score (E + F) |
|
|
Total score |
Outcome assessment |
|
9–10 |
Excellent |
|
7–8 |
Good |
|
5–6 |
Fair |
|
<5 |
Poor |
Note. * Designed for comprehensive assessment of the patient’s functional and economic status after surgical treatment of lumbar spine pathology. The scale consists of two subscales: economic (E) and functional (F). Each subscale is scored from 1 to 5 points, with a maximum total score of 10 points.
Among the main preoperative complaints, low back pain radiating to the lower limb, inability to walk for prolonged periods, and difficulty maintaining an upright position predominated. Foot paresis was observed in 12.5% of patients, while pelvic dysfunction was identified in 4.2%.
Analysis of patient distribution by age groups demonstrated that intervertebral disc herniation was most frequently diagnosed in patients aged 41–50 years (Table 3). The distribution of lumbosacral intervertebral disc herniations by spinal level was as follows: L4–L5 — 108 cases (54%) and L5–S1 — 92 cases (46%).
Table 3. Patient distribution by age groups
|
Age groups, years |
Number of patients |
|
|
Abs. |
% |
|
|
19–30 |
25 |
12,5 |
|
31–40 |
51 |
25,5 |
|
41–50 |
53 |
26,5 |
|
51–60 |
49 |
24,5 |
|
61–70 |
22 |
11,0 |
|
Total |
200 |
100,0 |
In the late postoperative period (12 months after surgery), patients completed a questionnaire-based assessment.
For analytical purposes, VAS scores were conditionally categorized into the following pain intensity levels:
- 0 mm — no pain;
- 1–20 mm — mild pain;
- 21–60 mm — moderate pain;
- 61–100 mm — severe pain.
For ease of clinical interpretation, VAS results were also presented on a 0–10 point scale, equivalent to the 0–100 mm range.
The Oswestry Disability Index (ODI) questionnaire (Table 4) is a validated instrument for the quantitative assessment of disability associated with degenerative spinal disorders. In the present study, ODI version 2.0 [8] was used. This version comprises 10 items, each scored from 0 to 5 points. Initial scoring was performed in accordance with the questionnaire structure, after which the results were converted into percentages. This approach corresponds to the widely accepted method for interpreting ODI scores and enables standardized comparison with data reported in the literature.
Table 4. Interpretation of ODI scores [12]
|
Level of disability |
ODI% |
Interpretation |
|
Minimal disability |
0–20 |
Patient is able to perform most activities of daily living |
|
Moderate disability |
21–40 |
Reduced activity level, predominantly due to pain |
|
Severe disability |
41–60 |
Significant limitation of work capacity |
|
Crippling disability |
61–80 |
Substantial functional limitations |
|
Bed-bound state/ complete immobility |
81–100 |
The patient is unable to work |
The total ODI score (0–50) was converted into a percentage disability score using the following formula: ODI% = (Obtained score: 50) ×100.
Statistical analysis
Statistical data processing was performed using the Statistica 6.0 software package. Differences between the groups for all primary indicators (VAS, ODI, ΔVAS, ΔODI) were assessed using Welch’s t-test, a statistical method for comparing the means of two independent samples that does not assume equality of variances. This test represents a more robust adaptation of Student’s t-test, particularly when variances between samples differ substantially or when sample sizes are small.
Changes over time in quantitative dependent variables within each group were evaluated using the nonparametric Wilcoxon signed-rank test. Differences were considered statistically significant at p < 0.05.
Results
According to the assessment of pain intensity using the VAS, the mean pain level in the MD group decreased by 5.3 points (corresponding to approximately 63.1% reduction), whereas in the MD + Cage group the decrease amounted to 7.1 points (82.6%). Thus, patients who underwent MD + Cage demonstrated a more pronounced postoperative reduction in pain, as well as a lower recurrence rate of intervertebral disc herniation (Table 5).
Table 5. Dynamics of pain syndrome and recurrence rate
|
Group |
Mean VAS score (points) |
Reduction, % |
Recurrence rate, % |
|
|
before treatment |
at 12 months |
|||
|
MD |
8,4 |
3,1 |
63,1 |
9 (9 out of 100) |
|
MD + Cage |
8,6 |
1,5 |
82,6 |
3 (3 out of 100) |
Prior to surgical treatment, the mean ODI values were high in both groups, indicating substantial functional limitation among patients (Table 6). At 12 months, a significant decrease in ODI was observed in both groups, with more pronounced improvement in the MD + Cage group.
Table 6. Dynamics of ODI, %
|
Indicator |
MD (n=100) |
MD+Cage (n=100) |
Improvement |
|
ODI before surgery |
62 |
64 |
— |
|
ODI at 12 months |
24 |
12 |
— |
|
Δ (reduction) |
38 |
52 |
61/81 |
The relative improvement in functional status was 61% in the MD group and 81% in the MD + Cage group, suggesting greater effectiveness of the combined surgical approach using cages in reducing disability as measured by the ODI.
A comparison of functional treatment outcomes according to the Macnab scale was performed (Table 7). The obtained data indicate better functional outcomes in the MD + Cage group, reflected by a higher proportion of excellent results and a lower proportion of fair and poor outcomes.
Table 7. Functional outcomes according to the Macnab scale, %
|
Outcome category |
MD (n=100) |
MD+Cage (n=100) |
|
Excellent |
46 |
63 |
|
Good |
32 |
28 |
|
Fair |
14 |
7 |
|
Poor |
8 |
2 |
|
Total |
100 |
100 |
Evaluation using the Prolo functional–economic outcome scale was conducted across four categories depending on the degree of return to work, presence of pain syndrome, and functional limitations (Table 8). The results demonstrate more favorable functional and economic outcomes in the MD + Cage group, characterized by a higher proportion of excellent results and a lower proportion of fair and poor outcomes.
Table 8. Assessment according to the Prolo functional–economic outcome scale
|
Outcome category |
Description |
MD (n=100) |
MD+Cage (n=100) |
|
Excellent (9–10 points) |
Complete return to work, absence of pain |
42 % |
61 % |
|
Good (7–8 points) |
Mild pain, preservation of most functions, return to work achieved |
35 % |
30 % |
|
Fair (5–6 points) |
Moderate residual symptoms, partial work limitation |
15 % |
7 % |
|
Poor (≤4 points) |
Persistent disability, loss of working capacity |
8 % |
2 % |
|
Total |
— |
100 % |
100 % |
The application of the Wilcoxon signed-rank test demonstrated statistically significant improvement in both pain syndrome (VAS) and functional status (ODI) in both groups (p < 0.001). The magnitude of the effect was high (r = 0.79–0.88), indicating clinically significant postoperative improvement, with a more pronounced effect observed in the MD + Cage group (Table 9).
Table 9. Results of the Wilcoxon signed-rank test
|
Group |
Indicator |
n |
W (Statistics) |
p-value |
Effect size (r) |
Interpretation |
|
MD |
VAS (before–after) |
100 |
0 |
<0,001* |
0,82 |
Significant reduction in pain |
|
ODI (before–after) |
100 |
120 |
<0,001* |
0,79 |
Improvement in functional status |
|
|
MD+Cage |
VAS(before–after) |
100 |
0 |
<0,001* |
0,88 |
Marked reduction in pain |
|
ODI (before–after) |
100 |
45 |
<0,001* |
0,84 |
Substantial functional improvement |
Discussion
The obtained results confirm that both surgical methods—conventional microdiscectomy and microdiscectomy with cage-assisted interbody fusion—provide significant reduction of pain syndrome and improvement in functional status in patients with lumbosacral intervertebral disc herniation.
Postoperative reduction in VAS scores in the MD group averaged −63% (from 8.4 to 3.1 points), whereas in the MD + Cage group it reached −82% (from 8.6 to 1.5 points). The ODI decreased from 62% to 24% and from 64% to 12%, respectively, indicating more pronounced functional recovery with the use of cages.
Analysis according to the Macnab and Prolo scales demonstrated the superiority of microdiscectomy with cage-assisted interbody fusion:
- 91% of patients achieved “Excellent” or “Good” outcomes on the Macnab scale compared with 78% after conventional microdiscectomy;
- According to the Prolo scale, favorable outcomes were observed in 91% of patients in the MD + Cage group and in 77% in the MD group.
The recurrence rate in the MD group was 9%, whereas in the MD + Cage group it was only 3%, indicating improved segmental stability following interbody fixation.
A statistically significant difference (p < 0.001) between the groups was established using Welch’s t-test for all primary indicators (VAS, ODI, ΔVAS, ΔODI).
Within-group analysis using the Wilcoxon signed-rank test (pre–post comparison) confirmed the high effectiveness of both methods (p < 0.001), with a larger effect size (r = 0.84–0.88) observed in patients who underwent microdiscectomy with cage-assisted interbody fusion.
The study groups were not entirely homogeneous in terms of clinical and radiological characteristics. Given the heterogeneity of disc pathology, achieving complete homogeneity between the study and comparison groups is practically impossible. In the microdiscectomy with interbody fusion group, signs of segmental instability and Modic type II changes were more frequently observed, which determined the indications for stabilization surgical techniques. To minimize the impact of this heterogeneity on the study results, a multivariate statistical analysis was performed, along with within-group dynamic comparisons (pre–post), ensuring an appropriate evaluation of the effectiveness of each investigated treatment method despite the lack of complete group homogeneity.
Based on the obtained results, the indications for microdiscectomy may include:
- the presence of clinical symptoms of nerve root compression (lumbosciatic pain syndrome, positive tension signs);
- the presence of L4–L5 or L5–S1 intervertebral disc herniation confirmed by MRI;
- absence of pronounced degeneration of adjacent structures (Modic type 0–I changes, without significant loss of disc height);
- ineffectiveness of conservative treatment for 6–8 weeks;
- stability of the motion segment on functional radiographs (displacement <3 mm, angular deformation <10°).
Thus, microdiscectomy is indicated for patients with predominantly isolated disc herniation without structural instability, whereas microdiscectomy with interbody cage fusion is indicated for patients with discogenic lesions accompanied by structural or biomechanical instability of the segment, when nerve root decompression alone is insufficient to stabilize the spine and prevent recurrence. These include the following conditions:
- disc herniation combined with radiological signs of segmental instability (vertebral body displacement >3 mm or pathological mobility >10° on functional testing);
- Modic type II changes on MRI (signs of endoplastic degeneration, cystic remodeling, or fibrosis);
- recurrent disc herniation after previous discectomy;
- significant loss of disc height (>50%) or post-discectomy segmental deformity;
- clinical manifestations of mechanical pain relieved in an unloading position (a sign of motion segment instability).
Our findings are consistent with the literature and confirm the effectiveness and safety of interbody cage application in lumbosacral disc herniation.
According to F. Lei et al. (2023) [9], the use of stabilization procedures for recurrent intervertebral disc herniation in carefully selected patients is associated with a lower recurrence rate compared with repeat discectomy.
Similar conclusions regarding the acceptable safety profile of interbody cages, provided appropriate patient selection and adherence to surgical technique, were reported by R.J. Mobbs et al. (2015) [10].
Therefore, the use of an interbody cage may be considered a safe and effective component of surgical treatment in selected clinical situations, which is consistent with the results of our study. In cases where MRI and dynamic radiographs demonstrate segmental instability or Modic type II changes, microdiscectomy with cage-assisted interbody fusion appears justified as a more stabilizing technique that provides a more durable functional outcome.
Conclusions
Disclosure
Conflict of interest
The authors declare no conflict of interest.
Informed consent
Informed consent was obtained from each patient.
Ethical standards
All procedures performed in studies involving human participants were conducted in accordance with the ethical standards of the institutional and national research committee and with the 1964 Declaration of Helsinki and its subsequent amendments or comparable ethical standards.
Funding
The study received no external funding.
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