Lumbar spinal stenosis (LSS) is a frequent, degenerative disease of the spine, a narrowing of the lumbar spinal canal and/or neural foramina, compression of the neural elements, and a spectrum of symptoms ranging from low back and radicular leg pain to neurogenic claudication, sensory disturbance, and functional limitation.[1] It mostly occurs in elderly people and is a major contributor to chronic pain, loss of mobility, and disability.[2] It has been estimated that about 103 million people worldwide are affected by LSS, with estimates of around 11% of adults in the United States being affected, and this rate rises

significantly with age.[3] Another significant reason for spinal surgery is LSS, with about 600,000 surgical procedures done yearly in the United States for this condition.[4]

The progressive aging of the population, higher life expectancy, and the rising incidence of degenerative spinal disease have also contributed to the clinical and socio-economic burden of LSS.[5] The condition may significantly limit walking mobility, independence, work ability, and quality of life.[6] Many patients will be initially managed conservatively, with physical therapy and analgesic medications, activity modification, and epidural therapies, but if they continue to have persistent neurogenic claudication or worsening functional impairment, surgery may be necessary.[7] The goal of surgery is to relieve pressure on the nerves and also maintain spinal stability while causing the least possible damage to tissue.[2]

Typically, open decompression, especially laminectomy, has been considered the gold standard surgical management of symptomatic LSS.[8] Open procedures may be very muscle-dissective, lead to larger blood loss, postoperative pain, longer hospital stays, and disruption of the posterior spinal structures, although they are effective in relieving neural compression.[9] These restrictions have led to the evolution of minimally invasive surgery such as unilateral laminotomy with bilateral decompression, microscopic decompression, tubular approaches, and full-endoscopic or biportal endoscopic technique. The procedures are designed to provide sufficient decompression of the nerve without damage to the posterior midline structures and to cause the least possible iatrogenic tissue damage.[9]

The perioperative morbidity and evidence gathered in the past few years indicate that minimally invasive decompression can be a beneficial option for meaningful relief of symptoms and functional improvements.[10] A study showed that full endoscopic decompression was significantly associated with less blood loss during surgery, shorter hospital stays, fewer durotomies, and fewer surgical-site infections without compromising clinical outcomes compared to microscopic decompression.[11]

With the ongoing advancement of minimally invasive decompression, there is a chance to rethink the surgical management of lumbar spinal stenosis as we go beyond the anatomical concept of decompression to a broader concept of effective neural decompression with minimal physiologic and functional disruption. But the proof of the magnitude of the improvements in pain, disability, quality of life, and perioperative recovery is still critical, especially in current clinical settings. Thus, the current study aimed to compare the effectiveness of MIS decompression surgery for lumbar spinal stenosis, focusing on patient-reported pain, functional disability, quality of life, perioperative complications, and postoperative complications. The research objective is to assess the clinical and functional outcomes of minimally invasive decompression to find out if it offers a clinically and functionally relevant advantage with a favorable safety profile, and thus add to the current paradigm shift of lumbar spine surgery.

A prospective observational study was performed to assess the effectiveness of the minimally invasive decompression procedures for clinical, functional, and perioperative outcomes in patients with symptomatic lumbar spinal stenosis. The study was conducted in the Department of Orthopedics Surgery. The study was conducted over a period of six months, from July to December, 2025. Patient enrolment, baseline measurement, surgical procedures and patient follow-up were achieved during the study period. The minimum sample size calculated was about 96 patients by using OpenEpi version 3.01 with the following specifications: 80% improvement proportion, 95% confidence level, an absolute precision of 8%. A 10% loss to follow-up or to an incomplete postoperative evaluation was anticipated, and the final sample size was increased to 106 patients. Non-probability consecutive sampling was used. Patients presenting during the study period who met the following inclusion criteria: symptomatic lumbar spinal stenosis and completed minimally invasive decompression, were serially enrolled until the target number of patients was reached. This approach facilitated systematic recruitment of eligible patients and minimised the risk of selection of patients according to clinical characteristics. Patients were eligible to participate if they were at least 40 years old and had clinically suspected lumbar spinal stenosis, as demonstrated by magnetic resonance imaging (MRI) or computed tomography (CT) scan, with symptoms of neurogenic claudication, radicular leg pain, or neurological symptoms from activity. Patients were included if conservative treatment failed to achieve adequate relief of symptoms or if symptoms remained and had significantly impacted their daily activities. Those patients who were scheduled for minimally invasive lumbar decompression (MLD) such as unilateral laminotomy with bilateral decompression (ULBD), microscopic decompression, tubular decompression, or endoscopic decompression were included. Those who gave informed consent and attended the planned postoperative follow-up were also included. Patients who had lumbar spinal stenosis with a spinal malignancy, active spinal infection, acute traumatic spinal injury, or inflammatory spinal disease were excluded. Patients with a high-grade spondylolisthesis requiring primary fusion, significant instability of the lumbar spine, and severe spinal deformity requiring reconstructive surgery were also excluded. The study focused exclusively on minimally invasive decompression, and patients who had decompression combined with instrumented spinal fusion were excluded. Major systemic comorbidities that precluded elective surgery and patients with previous surgery at the same operative level in the lumbar spine were also excluded. Patients who did not finish the outcome assessment or could not be followed up after surgery were excluded from the outcome analysis. Clinical Evaluation was done before the surgical procedure. The severity of pain was measured with the Visual Analog Scale (VAS), and functional disability was measured with the Oswestry Disability Index (ODI).[12, 13] The EuroQol-5 Dimension-5 Level (EQ-5D-5L) questionnaire was used to assess health-related quality of life.[14] Neurological baseline parameters, such as neurological status and walking difficulties, were also recorded. Preoperative magnetic resonance imaging (MRI) information was captured on the degree of lumbar canal stenosis, the presence of degenerative changes, and the level of lumbar canal stenosis. Patients were then treated with the same standard anesthetic and surgical procedures for the decompression procedure subsequently planned. The surgical technique employed, level of operative exposure, duration of the operation, estimated blood loss, intraoperative complications, and the need for conversion to another surgical procedure were documented. Postoperative outcomes included postoperative VAS, postoperative ODI, time to mobilization, hospital length of stay, postoperative complications, and the need for further intervention. Postoperative assessment of the patients was based on the institutional follow-up protocol. The main clinical parameters were changes in VAS pain score and ODI from baseline to postoperative follow-up. Secondary outcomes included improvement in EQ-5D-5L score, neurological symptoms after surgery, walking ability, hospital stay, operating time, estimated blood loss, complications, and a need for revision surgery. Clinically meaningful improvement was based on comparing the outcome scores obtained at the end of the operation with the clinical scores recorded at baseline. The data collected were entered, coded, and analyzed using IBM SPSS Statistics, version 26.0. The Shapiro–Wilk test was first performed to determine the normal distribution of continuous variables. Non-normally distributed continuous variables were summarized as median (interquartile range), while normally distributed continuous variables were presented as mean ± SD. Frequencies and percentages were used to present categorical variables. Paired-samples t tests were used for normally distributed continuous outcome measures, and Wilcoxon signed-rank tests were used for continuous outcome measures that did not meet the assumption of normality. The change in the VAS score and the ODI and EQ-5D-5L scores were assessed to see the size of the clinical improvement after surgery. The chi-square test and Fisher's exact test were used to compare categorical variables. Pearson's or Spearman's correlation analysis was used to examine relationships between continuous variables such as age, duration of symptoms, baseline disability and the magnitude of postoperative improvement. Where appropriate, multivariable linear or logistic regression analysis was used to examine if there were independent predictors of favourable outcome after the operation, adjusting for potential confounding factors. The effect estimates were presented as 95% confidence intervals. All analyses were performed using a two-sided p-value <0.05.

The study included 106 patients with symptomatic lumbar spinal stenosis. The cohort was predominantly older adults, with a slight male predominance and a substantial burden of overweight/obesity and comorbidities. Neurogenic claudication and radicular leg pain were the predominant presenting features, while all patients had previously received conservative treatment without adequate relief (Table 1).

Radiologically, single-level disease was more frequent than multilevel stenosis, with L4–L5 being the most commonly affected level. Severe stenosis predominated. Unilateral laminotomy with bilateral decompression was the most frequently performed procedure, followed by tubular/microscopic and endoscopic decompression. Operative and blood-loss measures, together with intraoperative complications and conversion to open surgery, are summarized in Table 2.

Significant postoperative improvement was observed across all patient-reported outcomes. VAS pain, ODI, and walking limitation scores decreased significantly, while EQ-5D-5L scores increased significantly from baseline (all p<0.001), demonstrating improvement in pain, functional disability, mobility, and health-related quality of life (Table 3).

Postoperative recovery was generally favorable, with early mobilization and a short hospital stay. Most patients demonstrated neurological and clinically meaningful symptomatic improvement. The overall postoperative complication rate was low, and revision surgery was required in only a small proportion of patients during follow-up (Table 4).

Comparison of the three minimally invasive techniques showed no significant differences in operative duration, blood loss, preoperative or postoperative VAS scores, ODI improvement, or complication rates. However, hospital stay differed significantly between groups, with endoscopic decompression associated with the shortest hospitalization (p=0.041) (Table 5).

Clinically meaningful improvement was significantly associated with younger age, absence of diabetes, single-level stenosis, moderate stenosis, and shorter symptom duration. In contrast, sex was not significantly associated with treatment response (Table 6). Correlation analysis demonstrated that increasing age and longer symptom duration were negatively associated with VAS and ODI improvement, whereas higher baseline VAS and ODI scores were positively associated with greater postoperative improvement. BMI showed no significant correlation with either outcome (Table 7).

On multivariable analysis, age below 65 years, absence of diabetes, single-level stenosis, moderate stenosis, and symptom duration of 12 months or less remained independent predictors of clinically meaningful postoperative improvement. Baseline VAS ≥7 and BMI <30 kg/m² were not independently associated with treatment response (Table 8).

Table 1. Sociodemographic and baseline clinical characteristics of the study participants (n=106)

Table 2. Radiological and surgical characteristics of the participants (n=106)

Table 3. Comparison of preoperative and postoperative clinical and functional outcomes

Table 4. Perioperative and postoperative outcomes

Table 5. Comparison of outcomes according to minimally invasive decompression technique

Table 6. Comparison of categorical outcomes according to demographic and clinical characteristics

Table 7. Correlation between baseline characteristics and magnitude of postoperative improvement

Table 8. Multivariable predictors of clinically meaningful postoperative improvement

This current study aimed to compare the clinical, functional, quality of life, and peri-operative outcomes of minimally invasive decompression (MID) with conventional laminectomy performed for symptomatic lumbar spinal stenosis in 106 patients. The main result was that there was significant improvement in pain, disability, quality of life, and walking function associated with minimally invasive decompression. Mean VAS pain scores decreased from 7.2 ± 1.1 preoperatively to 3.1 ± 1.4 postoperatively, while ODI scores decreased from 58.6 ± 10.7% to 28.4 ± 12.1%. Similarly, EQ-5D-5L scores increased from 0.43 ± 0.16 to 0.72 ± 0.15. All the above improvements were significant at p<0.001. Moreover, 81.2% of patients suffered clinically meaningful relief in pain and 77.2% experienced clinically meaningful improvement in ODI. These results were supportive of the idea of achieving a meaningful symptomatic and functional improvement with a minimally invasive decompression approach, while incurring a minimal amount of perioperative morbidity. The age distribution of our study was comparable to the typical age distribution of degenerative lumbar spinal stenosis. Patients' mean age was 61.8 ± 9.7 years, with approximately 60% aged 60 years or older. This was similar to the randomized clinical trial by Hermansen et al. in 2022, which comprised 437 patients with lumbar spinal stenosis with a median age of about 68 years. They also had significant baseline disability and pain, with median scores for leg and back pain of 7 and 37–40 for mean ODI scores in the three treatment groups, respectively.[15] Our study population was similar in age and baseline symptom burden, suggesting that our cohort was a clinically meaningful sample of patients with degenerative LS and not patients with minimal radiological disease. Our finding of a marked reduction in pain was consistent with the results reported by Yoshikane et al. in 2021. In the retrospective study of 129 patients who underwent lumbar endoscopic unilateral laminotomy with bilateral decompression, the authors compared clinical outcomes based on pain and functional measures in patients with and without degenerative spondylolisthesis and concluded that outcomes were similar. They conclude that endoscopic unilateral laminotomy is a successful decompressive technique even with selected degenerative structural changes. In our study, a VAS score decrease of 4.1 points was similarly considered clinically significant based on symptoms.[16] The similarity among the two studies indicated that preserving the integrity of the posterior spinal elements was not associated with an impaired ability to provide effective decompression of the neural elements. A very large randomized trial, called the NORDSTEN-SST trial, reported by Hermansen et al. in 2025, confirmed the magnitude of improvement seen in our ODI scores. In that study, 437 patients were randomized to receive unilateral laminotomy and crossover, bilateral laminotomy, or spinous-process osteotomy. Improvements were observed in ODI across the three groups, with approximately two-thirds to three-quarters of patients reporting a ≥ 30% reduction in ODI at 2 years. Importantly, there was no significant difference in clinical outcomes among the three minimally invasive techniques.[17] In our study, we found a mean ODI decrease of about 30.2%, and 77.2% had clinically significant improvement. Due to the differences in baseline ODI at the time of surgery, length of follow-up, patient selection, and study design, it is not directly possible to compare the magnitude of improvement; however, both studies showed that patients experienced significant functional improvement following decompression with minimal incisions. The present study also showed considerable improvements in health-related quality of life, with EQ-5D-5L scores improving from 0.43 to 0.72. This improvement was consistent with the randomized NORDSTEN-SST trial, which showed a similar improvement in EQ-5D scores of around 0.31 to 0.35 points two years after minimally invasive decompression.[18] Likewise, a 2023 meta-analysis of unilateral biportal endoscopy versus microscopic decompression revealed that unilateral biportal endoscopy led to significantly higher scores on the EuroQol-5D, as well as lower back pain and leg pain scores and shorter hospital stays. The results were clinically significant due to the fact that improving spinal stenosis is not only evaluated by radiological decompression, but also by pain reduction; restoration of daily functioning and overall quality of life is an important patient-centered endpoint.[19] In the study of Hua et al. from 2022, 72 patients with lumbar spinal stenosis were randomly assigned to either uniportal or biportal endoscopic unilateral laminotomy (UULD) with bilateral decompression (BD). They assessed the clinical results with VAS, ODI, and MacNab criteria and reported satisfactory clinical results for both endoscopy groups.[20] This aligns with our results showing that there were no significant differences between the various minimally invasive decompression procedures in terms of postoperative pain and function. For the first time in our study, there was no statistically significant difference between the improvement of VAS or ODI following the three decompression methods. This suggested that the principle of adequate neural decompression with preservation of normal spinal structures may be more important than the use of one specific minimally invasive technique. This interpretation was supported by the meta-analysis by Zhou et al. (2023) that compared unilateral biportal endoscopy with decompression using the microscope. The meta-analysis showed that biportal endoscopy had advantages in operation time, hospital stay, EQ-5D, back pain VAS, and leg pain VAS, and that several other clinical and safety parameters were not significantly different compared to the other techniques. In the same way, our results showed good peri-operative recovery, though these differences in the duration of the operation and the volume of blood loss between the three techniques were not statistically significant.[21] In our study, there was no significant difference, which may have been due to the limited number of patients in each subgroup of technique and to the fact that the procedures were performed by experienced surgeons. The results were also similar to those of Tao et al., who performed unilateral laminotomy (UL) for bilateral decompression (BC) using unilateral biportal endoscopy (UPE) in patients with lumbar spinal stenosis (LSS). Their research involved the analysis of patients undergoing VAS and ODI evaluations at several time points after surgery, confirming the effectiveness and safety of this minimally invasive procedure.[22] Tan et al. (2023) also assessed uniportal full-endoscopic unilateral laminotomy with bilateral decompression, and specifically looked at the correlation of decompression size and functional outcomes. Their study found that their clinical outcomes were satisfactory, and they used VAS and ODI as significant indicators of their recovery after the surgery.[23] These studies reinforced our experience that with minimally invasive decompression, we could obtain good functional recovery without having to disrupt much of the posterior structures. In summary, the present results indicated that minimally invasive decompression resulted in significant pain and functional disability improvement, improved quality of life and mobility, and a low level of perioperative complications and short hospital stay. There were no significant differences between the individual minimally invasive techniques in clinical results, which was in line with the most recent evidence and indicated that the knowledge and skills of the operator and proper patient selection are more important than selecting a single minimally invasive platform. The findings thus suggested that the use of minimally invasive decompression should continue to be a part of modern treatment for LSS, and larger prospective comparative trials with extended follow-up are needed to establish long-term success and cost-effectiveness of these treatments. There were a number of limitations in this study. First, the prospective observational design with a non-traditional open-decompression control group restricted the ability to draw conclusions of comparative superiority of MIS decompression. Second, the non-probability consecutive sampling performed in one tertiary-care center might have caused selection bias and restricted the applicability of the results to other hospitals and patients. Third, the relatively small number of patients in each surgical technique subgroup may have limited the power to detect small differences between surgical techniques. Fourthly, the follow-up was brief, and the long-term recurrence, instability after surgery, adjacent-segment disease, and late revision surgery were not assessed. Fifth, surgical experience and technical expertise may have been different, therefore affecting operative and postoperative outcomes. Lastly, certain outcome measures, such as pain and functional disability, were self-reported by patients and may have been subject to subjectivity in reporting and response bias.

Patients with symptomatic lumbar spinal stenosis who underwent minimally invasive decompression experienced significant pain relief, functional improvement, quality of life, and walking improvement. The VAS and ODI scores decreased significantly after surgery, with more than 75% of patients demonstrating clinically important improvement, while scores on the EQ-5D-5L increased after surgery. Both procedures were linked with early mobilization, short hospital stay, and relatively low complication rate. The three minimally invasive techniques had broadly similar clinical outcomes, while the endoscopic decompression had a shorter hospital stay. The better postoperative recovery was associated with younger age, no diabetes, a single-level disease, moderate stenosis, and less duration of symptoms. These results have been used to support the effectiveness and relative safety of minimally invasive decompression in the right patient population suffering from lumbar spinal stenosis. There is a need for larger multicenter studies with more follow-up and direct comparison with conventional open decompression.

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