Lumbar spinal stenosis (LSS) is a frequently encountered degenerative spinal disorder in the elderly population. It results from progressive narrowing of the spinal canal, primarily due to intervertebral disc degeneration, facet joint hypertrophy, and buckling or thickening of the ligamentum flavum [1]. These degenerative changes lead to mechanical compression of the cauda equina and nerve roots, often manifesting clinically as neurogenic claudication, lower extremity radiculopathy, and varying degrees of axial back pain. These symptoms substantially impair patients’ quality of life and mobility [2]. For patients with mild symptoms, conservative treatment including physical therapy, analgesics, neuropathic agents, and epidural steroid injections (ESIs) may provide symptomatic relief [3]. However, for moderate-to-severe cases or those with progressive neurologic compromise, surgical decompression remains the standard of care, with numerous randomized controlled trials (RCTs) supporting its superiority over non-operative management in terms of pain relief and functional recovery [4]. Traditional open laminectomy, considered the gold standard for decompression, has significant drawbacks, including extensive paraspinal muscle dissection, increased intraoperative blood loss, postoperative pain, and prolonged recovery time, which are major concerns in the elderly population with multiple comorbidities [5]. To overcome these limitations, spinal surgery has evolved toward less invasive techniques, with biportal endoscopic spine surgery (BESS) being a promising advancement. BESS utilizes two independent working portals—one for the endoscope and one for surgical instrumentation—allowing effective neural decompression with minimal soft tissue disruption. Studies have shown that BESS achieves comparable or superior outcomes to conventional microscopic decompression, with fewer complications, less muscle injury, and shorter hospital stays [6-8]. Meanwhile, technological advancements like intraoperative navigation systems and robot-assisted pedicle screw placement are improving instrumentation accuracy, especially in complex or revision cases [9,10]. Artificial intelligence (AI) is also enhancing spinal care by enhancing imaging analysis and clinical decision-making, enabling automated detection of stenosis, risk stratification, and surgical outcome prediction, which can lead to more precise and personalized treatment [11]. Given the pace of technological innovation and the growing body of clinical evidence, this article provides an updated review of LSS, covering its pathophysiology, diagnostic evaluation, and treatment options, with a focus on the evolving role of BESS and emerging digital technologies in optimizing surgical outcomes.

The progressive narrowing of the spinal canal and neural foramina in LSS typically results from a combination of intervertebral disc degeneration, facet joint hypertrophy, and ligamentum flavum thickening or infolding [12]. These structural changes reduce the available space for neural elements, leading to mechanical compression, venous congestion, and ischemia of the cauda equina and exiting nerve roots [13]. From a biomechanical standpoint, aging triggers a degenerative cascade in the spine, involving annular fissuring, disc space collapse, and vertebral instability. This leads to compensatory hypertrophy of facet joints and the ligamentum flavum. Loss of disc height reduces lumbar lordosis (LL) and contributes to relative kyphosis, increasing stress on the posterior spinal elements and further exacerbating central canal narrowing [14]. The ligamentum flavum, normally tense in extension, becomes redundant and folds inward with disc height loss, significantly contributing to central stenosis [15]. These pathoanatomic changes often culminate in the hallmark symptom of neurogenic claudication— exertion-induced lower extremity pain relieved by rest or lumbar flexion [16]. LSS can be anatomically classified based on the site of neural compression into central canal stenosis, lateral recess stenosis, foraminal stenosis, and extraforaminal (far-out zone) stenosis [17]. Pathologically, stenosis can result from congenital abnormalities (e.g., short pedicles or achondroplasia), degenerative spondylosis, inflammatory arthropathies, or metabolic disorders like Paget’s disease or fluorosis [18]. The anatomical and pathological classification of LSS is summarized in Table 1. Importantly, the severity of radiographic stenosis does not always correlate with symptom intensity, a phenomenon attributed to dynamic components such as posture-induced mechanical loading, transient vascular compromise, and altered pain processing involving central sensitization [19]. Contemporary understanding of LSS recognizes its dynamic nature, with symptom exacerbation often occurring during lumbar extension (which narrows the canal) and improvement during flexion (which enlarges it) [20] (Table 1). This understanding highlights the importance of dynamic imaging, such as upright or axial-loaded magnetic resonance imaging (MRI) and supports minimally invasive decompression strategies that prioritize neural element preservation while minimizing iatrogenic destabilization.

LSS prevalence increases with age, and it is a leading cause of pain and disability in adults aged over 60 [21]. While radiological evidence of spinal stenosis is common in those over 70 (up to 78% [22]), estimates of symptomatic prevalence range between 11% and 38%, depending on the diagnostic criteria and modalities, with a higher incidence in women than men [23,24]. Population-based studies using administrative databases (e.g., the 10th revision of the International Classification of Diseases codes), imaging, and clinical assessments suggest that LSS is significantly underdiagnosed in its early stages, partly because initial symptoms, such as intermittent leg pain or fatigue during walking, may be attributed to other musculoskeletal or vascular conditions like peripheral arterial disease or hip osteoarthritis [25]. Moreover, MRI frequently reveals moderate-to-severe stenosis in asymptomatic individuals, particularly in the elderly, highlighting the imperfect correlation between imaging severity and clinical presentation [26,27]. The natural history of LSS is highly variable. Some patients experience a gradual worsening of symptoms, while others remain stable or show spontaneous improvement, particularly with non-surgical management. Longitudinal cohort studies show that approximately 50% of conservatively-treated patients remain stable or improve over 4–10 years [28]. However, 30%–40% of these patients eventually require surgery due to worsening neurogenic claudication, radiculopathy, or functional decline [29]. Surgical intervention, particularly decompression with or without fusion, has shown superior outcomes in terms of pain relief, walking capacity, and quality of life compared to continued non-operative care. In the landmark Spine Patient Outcomes Research Trial, surgically treated patients showed significantly greater improvement in leg pain, Oswestry Disability Index (ODI), 36-Item Short Form Survey physical function, and satisfaction scores at 2- and 4-year follow-ups [4]. The burden of LSS is expected to rise due to the progressive population aging and increasing demand for mobility-preserving interventions. In this context, understanding the epidemiologic trends and variable natural course of LSS is crucial for guiding individualized clinical decision-making and informing public health strategies and resource allocation in spine care systems worldwide.

LSS typically presents with a characteristic constellation of symptoms, including neurogenic claudication, lower extremity radiculopathy, and chronic lower back pain [2]. Neurogenic claudication—often described by patients as bilateral or unilateral leg pain, numbness, tingling, or heaviness worsened by standing or walking and relieved by lumbar flexion or sitting—is the hallmark symptom of LSS [30]. Many patients report decreased walking distance and adopt a forward-flexed posture while ambulating, sometimes using support like shopping carts or railings, a phenomenon referred to as the “shopping cart sign” [31]. Pain distribution varies with stenosis location: central canal stenosis typically causes bilateral, often symmetric leg symptoms associated with claudication, while foraminal or lateral recess stenosis leads to radicular pain following a dermatomal distribution [17]. In more severe cases, symptoms may progress to gait disturbance, motor weakness, or rare but concerning symptoms like bladder and bowel dysfunction, suggesting cauda equina syndrome [32]. Clinical evaluation involves a comprehensive history and physical examination, including neurologic testing of strength, deep tendon reflexes, and dermatomal sensory function. Provocative maneuvers like the walking test, two-stage treadmill test, and extension-based exercises (e.g., standing back extension) can help reproduce symptoms and differentiate neurogenic claudication from vascular etiologies [33]. To rule out peripheral arterial disease, palpation of distal pulses and measurement of ankle-brachial index (ABI) are recommended. An ABI <0.9 indicates arterial insufficiency, warranting vascular evaluation [34]. Standardized clinical criteria have been proposed to improve diagnostic accuracy. The N-CLASS (Neurological Claudication caused by LSS) criteria emphasize the presence of: (1) leg or buttock symptoms during walking or standing, (2) relief with lumbar flexion, (3) motor or sensory changes in the lower extremities, and (4) intact dorsalis pedis pulses to rule out vascular claudication [24]. Additionally, physical performance measures such as grip strength, Timed Up and Go test, and Functional Mobility Scale are objective correlates of symptom severity and risk of falls in LSS populations, particularly in elderly individuals [35,36]. Differential diagnosis is crucial in elderly patients, as they often present with coexisting musculoskeletal and neurologic disorders like diabetic peripheral neuropathy, hip or knee osteoarthritis, sacroiliac joint dysfunction, and vascular claudication. A comprehensive approach, integrating patient history, focused examination, and functional assessments, is necessary for accurate diagnosis. Because patient-reported symptoms and imaging findings do not always correlate perfectly, clinicians must interpret symptoms in the context of neurologic deficits, gait impairment, and functional limitation to guide management strategies [26].

Evaluating LSS requires combining clinical judgment with multimodal imaging to determine the anatomical level, severity, and surgical indications. Recent technological advancements, including navigation systems, robotic platforms, and AI, have expanded the diagnostic and therapeutic landscape.

LSS treatment involves a stepwise, patient-centered approach, starting with conservative strategies and progressing to surgical intervention when necessary. Clinical decisions are based on symptom severity, duration, functional impairment, radiographic findings, and comorbidities. Despite advancements in surgical techniques, a thorough understanding of pharmacological, interventional, and operative modalities remains crucial for effective treatment.

The shift toward minimally invasive surgical strategies has revolutionized the treatment paradigm for LSS, driven by the need to reduce tissue damage, enhance postoperative recovery, and improve outcomes in elderly patients. Among various minimally invasive techniques, BESS has gained substantial international traction and is now one of the most rapidly evolving spinal decompression modalities [6]. BESS employs two independent working portals for the endoscope and instrumentation, enabling triangulated manipulation and wide-angled visualization [8]. In contrast to conventional microscopic decompression, which offers a linear view, BESS provides a panoramic endoscopic view under continuous saline irrigation, facilitating precise dissection and safe removal of hypertrophied ligamentum flavum, facet overgrowth, and laminar spurs [70]. Importantly, the approach also enables preservation of posterior elements—such as the paraspinal musculature, interspinous ligaments, and facet joints—which are often compromised in open laminectomy or even microscopic laminotomy. Several studies have demonstrated the effectiveness of BESS in treating LSS. In an RCT, Park et al. [71] compared BESS with microscopic decompression for patients with central and lateral recess stenosis. The BESS group had significantly less early postoperative pain, faster ambulation, and shorter hospital stays, with comparable long-term functional outcomes (ODI and Visual Analog Scale [VAS] scores) [71]. Beyond decompression, BESS is increasingly being utilized in fusion procedures, particularly BESS-TLIF. Early reports indicate that BESS-TLIF may cause less paraspinal muscle atrophy and lower serum creatine kinase levels compared to MI-TLIF, suggesting reduced muscular trauma. In a prospective cohort study by Park et al. [7], patients undergoing BESSTLIF exhibited significant postoperative improvements in ODI and VAS scores. The reported fusion rate at 12 months was comparable to that of traditional MI-TLIF, further underlining its effectiveness [7]. Despite its rising popularity, BESS is operator-dependent with a steep learning curve, especially in complex cases like high-grade foraminal stenosis or severe epidural scarring. However, dedicated training programs, cadaver-based simulation labs, and digital navigation platforms are helping mitigate these challenges, driving broader adoption in Asia, Europe, and North America [72]. Notably, BESS is highly compatible with emerging technologies such as intraoperative navigation and robotic systems. Navigation-integrated BESS platforms are being developed to provide real-time anatomical guidance during decompression and increase safety in complex or revision surgeries [73]. Additionally, AI-enhanced preoperative planning systems are being explored in conjunction with BESS, allowing for personalized targeting, risk prediction, and automated segmentation, reinforcing its role at the intersection between MISS and digital medicine [73,74]. In summary, BESS has progressed from an experimental endoscopic technique to a validated surgical option for decompression and fusion in LSS, supported by a growing body of high-quality clinical evidence. Its adaptability and synergy with other cutting-edge technologies position BESS at the forefront of contemporary MISS (Figs. 2, 3).

Integration of digital technologies like navigation systems, robotics, and AI has transformed surgical practice, including spine surgery, over the past decade. These tools are being increasingly used in treating LSS, where precise decompression and accurate instrumentation are vital for maximizing patient outcomes while minimizing surgical complications [75]. Navigation-assisted spine surgery has gained widespread acceptance, particularly for pedicle screw placement. Intraoperative systems—whether fluoroscopy-based or CT-based—provide real-time guidance, enhancing accuracy of screw trajectory, implant positioning, and safe decompression margins [47]. Studies have consistently shown that navigated techniques outperform traditional freehand approaches. A multicenter prospective cohort study found O-arm–based navigation reduced pedicle breach rate from 10.6% to 2.3% and lowered radiation exposure for the surgical team [46]. Robotic platforms like Mazor X (Medtronic), ExcelsiusGPS (Globus Medical), and ROSA Spine (Zimmer Biomet) further enhance precision by integrating preoperative CT with intraoperative fluoroscopy for patient-specific screw trajectories [49]. Robotic-guided procedures for LSS decompression and fusion have demonstrated high screw accuracy, reduced surgeon variability, and lower reoperation rates. A meta-analysis of over 2,000 patients found robotic assistance significantly improved screw placement accuracy and reduced complications such as dural tears and neurological deficits [47]. Importantly, these technologies are not limited to open or MI-TLIF but are now being explored in endoscopy-assisted procedures. Early pilot studies indicate the feasibility and safety of robot- and navigation-assisted biportal endoscopic TLIF, demonstrating precise cage placement and effective decompression under direct endoscopic visualization [76]. Although AI is still in early clinical adoption, it shows promise in diagnostics, risk stratification, and surgical planning. For example, deep learning algorithms can automatically detect and quantify LSS on MRI with accuracy comparable to expert radiologists. A CNN model developed by Jamaludin et al. [11] achieved over 90% sensitivity in detecting central canal and foraminal stenosis on T2-weighted axial MRI. AI-based preoperative prediction models are also emerging to forecast fusion success, postoperative complications, and functional outcomes based on clinical, radiographic, and intraoperative data. Integrating navigation, robotics, and AI within a single digital surgical ecosystem marks a shift toward data-driven, patient-specific spine care. Particularly in LSS, where anatomical variability, comorbidity burden, and surgical precision intersect, these tools can improve preoperative planning, intraoperative safety, and postoperative care. Despite barriers like cost, accessibility, and training, the growing evidence supports their potential integration into routine spinal surgical practice [48,51].

As spinal surgery advances with technology, LSS management is poised for further evolution. Current evidence supports the efficacy and safety of BESS and other minimally invasive techniques. Future research will likely refine indications, enhance patient selection, and seamlessly integrate digital platforms [74]. A promising area is combining endoscopic techniques with real-time navigation and robotic systems. Preliminary pilot studies suggest that integrating robotic trajectory planning with endoscopic decompression or interbody fusion could improve implant accuracy while maintaining endoscopy’s tissue-sparing benefits [36,74]. This hybrid approach may be particularly beneficial in complex anatomies or revision cases where normal landmarks are disrupted. AI is also expected to play a major role in standardizing diagnostics and surgical planning. While existing AI models focus on automated MRI grading, future AI models may integrate multimodal data, such as gait analysis, EMG, patient-reported outcomes, and genomic profiles, to create personalized treatment algorithms [11]. These tools can help surgeons choose the optimal surgical approach, estimate complication risks, and predict functional recovery trajectories. Customizing care for elderly and frail patients with LSS is crucial, as they often have sarcopenia, frailty, and comorbidities, requiring personalized operative planning. Minimally invasive procedures like BESS—especially when combined with intraoperative neuromonitoring and image-guided navigation—may help minimize morbidity and accelerate recovery in these high-risk patients [77]. However, there is a need for more robust prospective data on outcomes in octogenarians or medically complex cohorts. As endoscopic surgery expands globally, education and standardization efforts must keep pace. This includes developing validated training curricula, cadaver-based simulations, and international consensus guidelines on indications, contraindications, and outcomes reporting [72]. Setting proficiency benchmarks and credentialing standards will help maintain uniform standards of care. Lastly, large-scale, multicenter RCTs directly comparing BESS, MI-TLIF, navigation-augmented fusion, and traditional open surgery would also advance the field. While current evidence supports the clinical utility of BESS, variations in technique, instrumentation, and surgeon experience limit its generalizability. Future studies should examine cost-effectiveness, return-to-work rates, patient-reported quality of life, and long-term reoperation risks, which are crucial in value-based care models.

LSS is a complex degenerative disorder characterized by progressive neural compression and functional decline, particularly in the elderly. Its clinical presentation varies and does not always correlate with imaging severity, requiring individualized diagnosis and treatment. Conservative treatment, including pharmacological therapy, structured rehabilitation, and ESIs, is often the first-line approach. For those who do not respond or have progressive neurologic compromise, surgical decompression with or without fusion has consistently shown superior outcomes in terms of pain relief, walking capacity, and quality of life. The choice between decompression alone and decompression with fusion must be tailored based on the presence of segmental instability, sagittal imbalance, and patient-specific factors such as age, frailty, and functional demands. Recent advancements in MISS, such as BESS, have altered the surgical landscape. BESS offers a less invasive yet effective alternative to conventional open or microscopic surgery, supported by growing high-level evidence across diverse clinical scenarios, including decompression and fusion. In parallel, the integration of navigation systems, robotic assistance, and AI is enhancing spinal care by enabling more precise, reproducible, and personalized surgical planning and execution.