A retrospective Chinese study on optical–electromagnetic navigation-guided biportal endoscopic unilateral laminotomy for bilateral decompression in lumbar spinal stenosis: improving precision and efficiency

Article information

Asian Spine J. 2026;.asj.2025.0508

Publication date (electronic) : 2026 March 16

doi : https://doi.org/10.31616/asj.2025.0508

Xingchen Yao^1,*, Junpeng Liu^1,2,*, Li Guan¹, Jincai Yang¹, Aixing Pan¹, Yong Hai^1,3,4

¹Department of Orthopaedic Surgery, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China

²Department of Orthopaedic Surgery, Beijing Anzhen Hospital, Capital Medical University, Beijing, China

³Joint Laboratory for Research & Treatment of Spinal Cord Injury in Spinal Deformity, Laboratory for Clinical Medicine, Capital Medical University, Beijing, China

⁴Clinical Center for Spinal Deformity, Capital Medical University of China, Beijing, China

Corresponding authors: Aixing Pan, Department of Orthopaedic Surgery, Beijing Chaoyang Hospital, Capital Medical University, No. 8, Gongti South Road, Chaoyang District, Beijing, 100020, China, Tel: +86-10-85231229, Fax: +86-10-52011671, E-mail: lancet_007@163.com

Co-corresponding author: Yong Hai, Department of Orthopaedic Surgery, Beijing Chaoyang Hospital, Capital Medical University, No. 8, Gongti South Road, Chaoyang District, Beijing, 100020, China, Tel: +86-10-52011671, Fax: +86-10-85231229, E-mail: yong.hai@ccmu.edu.cn

*These authors contributed equally to this work as the first authors.

Received 2025 August 22; Revised 2025 October 2; Accepted 2025 October 27.

Abstract

Introduction

Degenerative lumbar spinal stenosis (LSS) is a common spinal disorder, with a prevalence of approximately 8% in the general population [1]. Decompression surgery remains the gold standard for treating LSS with predominant radiculopathy, stable biomechanics, and poor response to conservative therapy [2]. Traditional open decompression is relatively invasive and often results in persistent back pain, prolonged recovery, and potential segmental instability caused by excessive facet joint resection [3]. Over recent decades, substantial advancements in minimally invasive spine surgery have optimized therapeutic strategies for spinal disorders, offering novel and effective treatment alternatives [4]. Among these techniques, unilateral laminotomy for bilateral decompression (ULBD) achieves bilateral neural decompression through unilateral laminar resection while preserving posterior midline structures and maintaining favorable biomechanical stability [5,6]. However, conventional ULBD presents limitations such as restricted visualization and reduced access to the contralateral side [7]. Endoscopic techniques have addressed these issues by minimizing trauma and improving intraoperative visualization. The biportal endoscopic (BE) approach further minimizes instrument crowding and enhances surgical ergonomics by separating the viewing and working channels [8]. Consequently, ULBD performed via the BE approach (BE-ULBD) has become a widely adopted and effective treatment option for LSS [4].

Despite these advantages, establishing the working channel during BE-ULBD is typically performed manually and without direct visualization, making it a technically demanding due to the complex spinal anatomy. Inexperienced surgeons often encounter challenges in achieving accurate localization, necessitating repeated fluoroscopic guidance. This not only prolongs operative time but also increases radiation exposure for both the patient and the surgical team [9]. Furthermore, although BE-ULBD provides a magnified endoscopic view, it lacks the direct anatomical visualization offered by open surgery. Surgeons may become disoriented during the procedure, increasing the risk of unnecessary maneuvers, inadvertent tissue injury, and extended operative duration [10,11].

With the advancement of digital medical technologies, intraoperative navigation has emerged as a promising solution to these challenges [12]. By providing real-time visualization of anatomical structures and instrument trajectories, navigation systems have been shown to enhance surgical precision, reduce fluoroscopy usage, and improve overall procedural efficiency [13]. However, existing systems present distinct limitations: optical navigation can be compromised by light path occlusion [14], whereas electromagnetic navigation is susceptible to interference from metallic surgical instruments [15].

To address these shortcomings, a novel integrated optical-electromagnetic surgical navigation system has recently been developed [16]. By combining the advantages of both modalities, this system provides enhanced stability and accuracy. Nevertheless, its clinical application in BE-ULBD has not yet been reported in the literature. In the present study, we retrospectively analyzed clinical data from patients who underwent navigation-guided BE-ULBD (Ng-BE-ULBD) using the integrated system and compared them with those who received C-arm-guided BE-ULBD (C-BE-ULBD). The aim was to compare operative parameters and short-term clinical outcomes between the two techniques and to preliminarily assess the safety and feasibility of Ng-BE-ULBD.

Materials and Methods

Study design and patient population

A total of 180 patients who underwent BE-ULBD for LSS at our institution between August 2023 and June 2025 were retrospectively analyzed. Based on the application of intraoperative navigation, patients were classified into two groups: the C-BE-ULBD group and the Ng-BE-ULBD group. This study was conducted in accordance with the Declaration of Helsinki and approved by the Beijing Chaoyang Hospital Human Research Ethics Committee (ethical approval no., 2024-ke-22). The study was designed as a retrospective study, and written informed consent was obtained from all individual participants involved in the study. All patients were followed postoperatively by independent observers, and follow-up was completed by July 2025.

Surgical indications: (1) degenerative single-level or adjacent two-level LSS; (2) Schizas Grade C or D (severe central stenosis) on preoperative magnetic resonance imaging [11]; (3) neurogenic claudication accompanied by low back and leg pain and/or numbness of lower extremities; (4) clinical symptoms and signs consistent with imaging findings; (5) failure of conservative management for at least 3 months; and (6) American Society of Anesthesiologists physical status classification I–III.

Surgical contraindications: (1) previous lumbar fracture, infection, tumor, or spinal surgery; (2) segmental instability, severe spondylolisthesis, or osteoporosis; (3) comorbidities or general medical conditions precluding surgery.

All patients completed a minimum follow-up period of one month, with no cases of loss to follow-up or non-compliance. Patient demographics and clinical characteristics are presented in Table 1. The C-BE-ULBD group included 96 patients (53.3%), with 53 (55.2%) undergoing single-level and 43 (44.8%) undergoing two-level decompression. The Ng-BE-ULBD group consisted of 84 patients (46.7%), including 45 (53.6%) who underwent single-level and 39 (46.4%) who underwent two-level decompression. The mean age of all patients was 58.33 years. There were 102 males (56.7%) and 78 females (43.3%). Baseline characteristics were comparable between the two groups (p>0.05) (Table 1).

Table 1

General information

Surgical technique

All procedures were performed under general anesthesia with patients placed in the prone position.

C-BE-ULBD

Catheter placement: The surgical level was identified intraoperatively using C-arm fluoroscopy. After standard skin disinfection, sterile drapes were applied. A longitudinal skin incision, approximately 1 cm lateral to the spinous process and extending 1–2 cm cranially and caudally, was made according to the patient’s body habitus, maintaining an interchannel distance of about 3 cm. The soft tissue overlying the lamina was stripped using a periosteal elevator. The working and observation channels were then inserted, and the endoscope was connected. Continuous irrigation with normal saline was maintained at a pressure of 20–30 mm Hg.

Lesion exposure and decompression: Radiofrequency was used to remove soft tissue from the inferior margin of the upper lamina, the superior margin of the lower lamina, the interlaminar space, and the base of the spinous process to create adequate space for instrument manipulation. A high-speed burr and rongeur were used to remove part of the medial inferior articular process and the inferior margin of the upper lamina down to the attachment of the ligamentum flavum. The ligamentum flavum was carefully dissected and excised to expose the dural sac and nerve root. A nerve hook was then used to probe and confirm adequate decompression. In cases of lateral recess stenosis, the medial superior articular process was resected using a burr and rongeur to decompress the recess, and the neural foramen was enlarged with a rongeur when necessary. Subsequently, contralateral central canal, lateral recess, and foraminal decompression were performed. For two-level decompression, the proximal observation channel was converted into a working channel, and the same steps were repeated. After complete decompression, hemostasis was achieved, and the incision was closed in layers, followed by application of sterile dressings.

Ng-BE-ULBD (Fig. 1)

Fig. 1

(A) Integrated optical-electromagnetic surgical navigation system, from left to right: C-arm fluoroscope, electromagnetic field generator, monitor and workstation, and infrared camera. (B) Placement of the reference tracker and navigation-compatible surgical instruments. (C) Unilateral laminotomy for bilateral decompression. (D) Real-time anteroposterior and lateral navigation images showing instrument positioning during the actual surgical procedure. (E) Endoscopic view of the decompression outcome.

Catheter placement: In the Ng-BE-ULBD group, an integrated optical-electromagnetic surgical navigation system (model ZETNa; BOSSCOME, Chongqing, China) was utilized. The electromagnetic field generator was positioned caudal to the incision. After the surgical field was prepared, the reference tracker was fixed to the contralateral posterior superior iliac spine using a dedicated iliac crest clamp. The system was connected to the computer workstation, which included sensors and calibration tools. Fluoroscopic images were obtained using the C-arm and automatically registered and reconstructed by the navigation workstation. The surgical trajectory, including entry point, direction, and depth, was then planned, and all instruments were registered and calibrated. The subsequent steps were identical to those used in the C-BE-ULBD group.

Lesion exposure and decompression: The navigation system provided real-time coronal and sagittal imaging of the spinal structures and surgical instruments, thereby reducing the number of fluoroscopy shots and minimizing the risk of incomplete decompression. After decompression at one level was completed, a new observation channel could be established under navigation guidance without the need for repeated fluoroscopy or repositioning of the surgical equipment (Supplement 1).

Results

Intraoperative parameters

For single-level LSS, the mean operative time was 88.79 minutes in the C-BE-ULBD group and 81.40 minutes in the Ng-BE-ULBD group; for two-level procedures, the corresponding times were 159.53 minutes and 144.56 minutes, respectively (Table 2). Overall, the total operative time was significantly shorter in the Ng-BE-ULBD group than in the C-BE-ULBD (p<0.05). The time required for navigation system registration and setup was included in the catheter placement time, averaging 5.62±1.32 minutes. During two-level decompression, no additional fluoroscopy or equipment repositioning was required in the Ng-BE-ULBD group. Catheter placement time was shorter in the Ng-BE-ULBD group compared with the C-BE-ULBD group, with more pronounced time savings observed in two-level procedures. Although decompression time was also shorter in the Ng-BE-ULBD group, this difference did not reach statistically significance (p>0.05). The total number of fluoroscopy shots was significantly lower in the Ng-BE-ULBD group than in the C-BE-ULBD group (p<0.05).

Table 2

Efficacy indicators and surgical parameters

Furthermore, the number of fluoroscopy shots in the Ng-BE-ULBD group did not increase significantly during two-level procedures compared with single-level operations (p>0.05), demonstrating a distinct advantage in managing multilevel pathology. The complication rate showed no significant difference between single- and two-level procedures (p>0.05) (Fig. 2). All other operative parameters increased significantly with the number of decompressed levels (p<0.05).

Fig. 2

Comparison of operative parameters between single-level and two-level biportal endoscopic unilateral laminotomy for bilateral decompression (BE-ULBD). Blue areas indicate single-level values; orange areas represent the net increase in two-level procedures. TOT, total operation time; C, C-arm-guided BE-ULBD; Ng, navigation-guided BE-ULBD; DT, decompression time; CPT, catheter placement time; FT, fluoroscopy times; CC%, complications or comorbidities (%).

Clinical outcomes

At one month postoperatively, both pain and functional outcomes improved significantly compared with the preoperative baseline (p<0.05). No significant differences were observed between the Ng-BE-ULBD and C-BE-ULBD groups in any of the evaluated parameters, including MacNab classification and length of hospital stay (all p>0.05). A total of 10 (5.56%) surgery-related complications occurred during the perioperative period among the 180 patients (Fig. 3), with dural tear being the most common (40% of all complications), corresponding to an overall incidence of 2.2%. There were three complications (3.6%) in the Ng-BE-ULBD group and 7 (7.3%) in the C-BE-ULBD group, with no significant difference between groups (p>0.05) (Table 2). Among patients undergoing single-level decompression, four complications (4.1%) observed, whereas six complications (7.3%) occurred in the two-level group, again with no significant difference between groups (all p>0.05) (Fig. 2).

Fig. 3

Pooled data and subgroup analysis of postoperative complications.

Discussion

This study compared operative parameters and early outcomes between C-BE-ULBD and Ng-BE-ULBD in patients with LSS. Among the 180 patients who underwent BE-ULBD, postoperative pain, claudication, and functional impairment improved significantly. The mean hospital stay was approximately half that reported for conventional open decompression in previous studies [17]. Importantly, without compromising surgical safety or short-term clinical efficacy, the Ng-BE-ULBD group demonstrated a shorter total operative time and a significantly lower number of fluoroscopic exposures compared with the C-BE-ULBD group.

Although BE-ULBD has been widely adopted, several technical challenges persist, particularly in establishing the working channel and identifying anatomical structures and instrument positioning intraoperatively, as noted in the introduction. Reducing radiation exposure, enhancing precision, and minimizing complications remain major goals. Navigation-assisted spinal endoscopic surgery offers a promising avenue to address these issues [18]. Currently, optical-electromagnetic navigation systems are the predominant technologies applied in spine surgery [14]. While these systems have improved surgical accuracy and efficiency, each possesses distinct limitations. Optical systems rely on infrared tracking and synchronization of computed tomography images with fixed reference arrays to provide real-time visualization of instruments and anatomy [18]. However, accurate function depends on maintaining a clear line of sight, as any obstruction of reflective markers within the camera’s field can compromise precision. Moreover, reflective markers affixed on instrument handles restrict use to rigid tools [19]. Electromagnetic navigation systems, comprising a control unit, field generator, and sensors, create localized electromagnetic fields to track instruments and patient anatomy without requiring direct visual contact [14]. Despite this advantage, these systems are prone to interference from ferromagnetic materials, and registration procedures can be time-consuming [18]. In this study, we employed an integrated optical-electromagnetic navigation system that merges both technologies into a single platform. Algorithmic optimization of spatial transformation and positioning accuracy allowed unified registration and real-time verification across optical, electromagnetic, and imaging coordinate systems, ensuring high navigation precision. The system enables seamless intraoperative switching, real-time drift monitoring, and flexible instrument tracking while minimizing electromagnetic interference. By integrating the strengths of both systems, this platform effectively addresses the limitations of traditional navigation technologies.

Retrospective comparison of surgical parameters and outcomes revealed multiple advantages of navigation-assisted BE-ULBD. The optical-electromagnetic navigation system provided rapid and accurate localization, preventing segmental errors and improving overall surgical efficiency [20]. Compared with C-BE-ULBD, the Ng-BE-ULBD approach significantly shortened the total operative time for LSS treatment. Detailed analysis indicated that navigation offered its greatest benefit during catheter placement. Without navigation, surgeons depend on surface landmarks and repeated C-arm fluoroscopy for localization. In contrast, navigation supplies real-time anteroposterior and lateral imaging with instrument tracking, reducing fluoroscopy frequency and the risk of collateral tissue injury. Although decompression time was shorter in the Ng-BE-ULBD group, the difference was not statistically significant. Nevertheless, navigation aids decompression by compensating for the two-dimensional limitations of the endoscopic view, which lacks complete anatomical context. Under optical-magnetic guidance, surgeons can visualize instrument position and the maximal safe working range in real time through orthogonal navigation displays, thereby enhancing precision and efficiency while minimizing radiation exposure to both surgeons and patients [21]. Consistently, the Ng-BE-ULBD group exhibited significantly fewer fluoroscopy shots than the C-BE-ULBD group.

However, optical-electromagnetic navigation did not improve short-term clinical outcomes following BE-ULBD. Both groups achieved comparable pain relief and functional recovery, consistent with prior navigation-assisted studies [22–24]. This observation likely reflects the proficiency of spine surgeons performing standardized BE-ULBD procedures. Operative efficacy was maintained through longer operating times and more frequent fluoroscopy, restricting navigation’s measurable impact primarily to improved efficiency. Additionally, the VAS and ODI scales used in this exploratory study, though validated, may lack the sensitivity to detect subtle improvements in decompression quality and are influenced by baseline variability and psychosocial factors, potentially masking navigation-specific benefits. Future research should incorporate more sensitive outcome measures for complex pathology or extend follow-up durations to better evaluate navigation’s clinical value. With respect to safety, complications were infrequent and well controlled in both groups. Dural tear was the most common complication, consistent with AO Foundation statistics [25]. Under endoscopic visualization, muscles, facet cysts, and ligaments are difficult to distinguish, increasing the risk of complications [26]. Inadequate decompression, observed more frequently in the C-BE-ULBD group, remains a major cause of postoperative dissatisfaction [27]. Navigation enhances intraoperative safety by clearly delineating instrument direction and depth and by displaying familiar anatomical structures that guide decompression. Moreover, real-time image guidance assists surgeons in managing anatomical variations, particularly in complex cases [28], and may accelerate skill acquisition and shorten the learning curve for novice surgeons [29,30].

In summary, optical-electromagnetic navigation-assisted BE-ULBD effectively reduces operative time and radiation exposure while improving procedural precision and safety. The system also demonstrates potential for optimizing complex case management and facilitating technical training for junior surgeons. Nevertheless, several limitations must be acknowledged. First, the single-center retrospective design introduces potential bias. Second, subgroup analyses controlling for decompressed levels yielded small sample sizes in some groups. Finally, as an exploratory investigation, the follow-up duration was relatively short and outcome measures lacked granularity. Large-scale, multicenter prospective studies with extended follow-up are warranted to further validate the clinical efficacy of this novel navigation system.

Conclusions

Optical-magnetic navigation-assisted BE-ULBD provides precise intraoperative guidance, enabling spine surgeons to achieve accurate decompression while reducing radiation exposure and operative time. This approach enhances surgical efficiency and safety, with distinct advantages in multilevel or complex cases, offering surgeons greater convenience and control.

Supplementary Materials

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