Therapy Potential of Oblique Lumbar Interbody Fusion 360 for Severe Lumbar Spinal Stenosis

ABSTRACT

Objectives

The advent of O‐arm navigation optimized the oblique lumbar interbody fusion (OLIF) procedure, allowing the operator to simultaneously perform OLIF and percutaneous posterior pedicle screw implantation without patient position change, thus improving the fluency and accuracy of the OLIF procedure (called as OLIF360). Nevertheless, a consensus regarding its suitability for patients with severe spinal stenosis remains elusive. This study aims to investigate the clinical efficacy of OLIF360 and its imaging changes in severe lumbar spinal stenosis cases.

Methods

This retrospective study analyzed clinical data from 63 patients with severe lumbar spinal stenosis. Fourteen patients were treated with OLIF360, and another 37 patients were treated with posterior lumbar interbody fusion (PLIF). Lumbar spinal stenosis was assessed using the modified Schizas classification. Clinical efficacy scale scores and postoperative imaging parameter changes were compared between the two groups. Shapiro–Wilk, t‐tests or Mann–Whitney U tests, repeated measures ANOVA, and Bonferroni post hoc tests were applied for statistical analysis.

Results

Both groups showed significant improved pain (p < 0.05). At 1‐month and 3‐month postoperative follow‐ups, OLIF360 group scores superior in Visual Analog Scale than PLIF group (p < 0.05). Greater disc height and lumbar lordosis were displayed in OLIF360 group than PLIF group (p < 0.05). No significant difference in screw placement accuracy between groups was observed. Moreover, significant increases in spinal canal area postoperatively (71.04 ± 6.27 mm² preop to 109.65 ± 12.34 mm² postop, p < 0.05) and bilateral foraminal areas were found in the OLIF360 group.

Conclusion

OLIF360 can have promising short‐term efficacy for severe lumbar stenosis treatment with shorter recovery time than PLIF.

OLIF360 surgical type is a new surgical method for the operator to complete oblique lateral lumbar fusion and percutaneous posterior pedicle screw implantation in a single position by using O‐arm navigation. The current indications for OLIF360 are mainly limited to mild to moderate non‐isthmic spinal stenosis and Grade I spondylolisthesis. Given that the research on the efficacy of OLIF360 in patients with severe spinal stenosis is still in a blank, our study shows that the OLIF360 technique demonstrates favorable clinical efficacy in treating severe lumbar spinal stenosis and accelerates patient recovery compared to PLIF. Imaging studies further explore its feasibility and superiority. Therefore, OLIF360, as a novel technology, holds significant potential for treating severe lumbar spinal stenosis.

1. Introduction

Degenerative lumbar spinal stenosis is a progressive condition characterized by the narrowing of the spinal canal, leading to compression of the dura, spinal cord, and nerve roots, which in turn results in a variety of clinical symptoms [1]. This condition is primarily caused by the degeneration of lumbar vertebrae, a process influenced by a multitude of factors, including age, mechanical stress, and other acquired environmental or physiological conditions [2]. As the spinal canal narrows, it exerts increasing pressure on neural structures, which can lead to pain, numbness, weakness, and reduced mobility. Lumbar spinal stenosis most commonly affects older adults, as the natural wear and tear associated with aging is one of the key drivers of vertebral degeneration [3]. The global prevalence of lumbar spinal stenosis varies significantly, with studies suggesting it affects between 11% and 39% of the population, depending on the diagnostic criteria and population studied [4]. This variation in prevalence underscores the importance of precise diagnosis and individualized treatment approaches for managing this debilitating condition.

Posterior lumbar interbody fusion (PLIF) is a well‐established surgical technique frequently employed in the management of degenerative lumbar spinal stenosis. This procedure is particularly effective in alleviating pain, increasing spinal canal capacity, relieving nerve root compression, and enhancing spinal stability, thus leading to improved clinical outcomes for many patients [5]. PLIF involves the removal of the degenerated intervertebral disc and the placement of an interbody cage filled with bone graft material, which helps restore disc height and achieve fusion between vertebral segments. Over time, the fusion promotes stability in the affected area of the spine, which can mitigate pain and restore function.

However, despite its widespread use and effectiveness, PLIF has notable limitations that cannot be overlooked. One major concern is the potential for significant intraoperative bleeding due to the need for substantial dissection of muscles and other soft tissues to access the spinal column. Additionally, PLIF carries the risk of damaging neural structures or vasculature, which can result in postoperative complications such as nerve injury or excessive scarring. Furthermore, residual low back pain following surgery is a relatively common occurrence, often attributed to the formation of scar tissue or incomplete resolution of the underlying pathology. These drawbacks have led to the exploration of less invasive surgical techniques that can achieve similar or improved outcomes with fewer complications.

One such technique is the oblique lateral interbody fusion (OLIF360) surgery, a more recent development in the treatment of lumbar spinal stenosis. This innovative approach allows surgeons to perform both oblique lateral lumbar fusion and percutaneous posterior pedicle screw implantation in a single position with the assistance of O‐arm navigation. O‐arm navigation provides real‐time, three‐dimensional imaging, enabling precise localization of the disc space and accurate placement of the fusion cage, which significantly enhances the surgeon's ability to achieve effective decompression and spinal fusion [6, 7]. This minimally invasive nature of OLIF360 translates into enhanced safety, faster recovery times, and shorter hospital stays for patients [8]. Despite these benefits, OLIF360 is not without its limitations. The current indications for OLIF360 are primarily restricted to patients with mild to moderate non‐isthmic lumbar spinal stenosis and Grade I spondylolisthesis [9]. This contrasts with PLIF, which, while more invasive, is often considered more appropriate for complex cases of degenerative stenosis or high‐grade spondylolisthesis [10]. While OLIF360 has shown promising results in mild to moderate cases, its application in more complex and severe conditions has yet to be fully validated.

Given this gap in the literature, our study aims to explore the clinical outcomes of OLIF360 in patients with severe spinal stenosis. Specifically, we seek to observe the preoperative and postoperative radiographic changes and clinical improvements in patients who undergo OLIF360 surgery for severe spinal stenosis. By closely examining the efficacy of this technique in a population that has not been extensively studied, we hope to expand the current understanding of OLIF360 and evaluate its potential as a viable treatment option for individuals with advanced lumbar spinal stenosis. The purposes of this study are as follows: (i) to assess and refine surgical strategies that effectively alleviate the symptoms of patients suffering from this debilitating condition, with an emphasis on reducing recovery time and improving patient comfort; (ii) to compare the outcomes and complications of less invasive techniques with traditional, more invasive procedures such as PLIF, in order to identify safer, more effective alternatives; and (iii) to contribute to the development of evidence‐based guidelines that optimize surgical approaches, ultimately improving patient outcomes and minimizing the overall burden of the disease.

2. Methods

2.1. Ethics Statement

The research was approved by the Ethics Committee of Affiliated Hospital of Qingdao University (QYFY WZLL 28571) and was carried out in compliance with the Declaration of Helsinki. All participants in the study gave their informed consent.

2.2. Patients and Design

Upon approval from the review board, we conducted a retrospective analysis of patients with severe spinal canal stenosis treated with OLIF360 or PLIF at the Spine Surgery Department of the Affiliated Hospital of Qingdao University from May 2022 to May 2023. This study included cases based on the following criteria: (a) lower back pain with radiating pain to the lower extremities, with or without numbness; (b) preoperative magnetic resonance imaging (MRI) indicating severe spinal canal stenosis, with a Schizas classification of grade C or a canal cross‐sectional area below 75 mm²; (c) receipt of single‐segment OLIF360 or PLIF treatment; (d) availability for follow‐up of at least 6 months. Cases with the following conditions were excluded: (a) symptoms inconsistent with imaging results; (b) severe osteoporosis; (c) severe facet joint hyperplasia or fusion; (d) calcification within the spinal canal, facet joint ossification; (e) congenital short pedicle roots/congenital spinal canal stenosis; (f) concurrent lumbar spine trauma, lumbar spine tumor, or previous laminectomy; (g) abdominal or pelvic surgery history.

This study included 63 cases of severe spinal canal stenosis, with 26 cases assigned to the OLIF360 group and 37 cases to the PLIF group. Comprehensive clinical data were collected for all patients.

2.3. Diagnosis Criteria

The lumbar spinal stenosis severity was assessed qualitatively using T2‐weighted axial images. Utilizing the modified Schizas classification (Figure 1A), stenosis is graded as follows: Grade A indicates mild stenosis with an irregular distribution of cerebrospinal fluid within the thecal sac, and visible cerebrospinal fluid. Grade B denotes moderate stenosis characterized by the absence of detectable nerve roots, cerebrospinal fluid signal in the gray matter of the dura, and posterior epidural fat. Grade C signifies severe stenosis where neither nerve roots nor evidence of posterior epidural fat are identified [11].

FIGURE 1.

Grading the severity of spinal canal stenosis and classifying the position of pedicle screws. (A) Grade A (mild stenosis; uneven distribution of cerebrospinal fluid in the thecal sac, visible cerebrospinal fluid); Grade B (moderate stenosis; no detectable nerve roots, absence of cerebrospinal fluid signal in the gray matter of the dura, and no posterior epidural fat); Grade C (severe stenosis; no identifiable nerve roots, and no evidence of posterior epidural fat). (B) Grade 0: Screws completely within the pedicle. Grade 1: Screws breaching the pedicle wall but < 2 mm. Grade 2: Screws breaching the pedicle wall by 2–4 mm. Grade 3: Screws breaching the pedicle wall by > 4 mm.

2.4. Surgical Procedure

2.4.1. OLIF 360 Surgical Procedure

All patients were placed in the right lateral decubitus position after successful induction of anesthesia. The surgical bed was adjusted to achieve a precise 90° angle between the patient's body and the surgical table. The right side of the waist was elevated, while the left lower limb was flexed at the hip and knee and securely fastened with adhesive tape. Ensuring alignment between the patient's back and the edge of the surgical table was deemed essential (Figure 2A,B).

FIGURE 2.

Intraoperative body positioning and navigation matching. (A) Patient positioning. The patient is placed in a right lateral decubitus position, with the back snug against the bed, fixed at a 90° angle. (B) Disinfection scope should cover the posterior percutaneous pedicle screws, anterior oblique lumbar interbody fusion (OLIF) from the lateral approach, and fixation areas of the iliac crest reference frame. (C and D) Intraoperatively, the reference frame is inserted, and percutaneous screws are slightly oriented toward the posterior and foot aspects. (E) O‐arm obtains intraoperative three‐dimensional CT images of the patient in the lateral decubitus position.

Secondly, the reference frame was oriented toward the navigation camera, securely fixed 6–12 cm behind the anterior superior iliac spine, just below the iliac crest. The skin screw was driven into the iliac bone by 1–1.5 cm, ensuring the stability of the reference frame. The percutaneous screw of the reference frame was slightly directed posteriorly and caudally, avoiding interference or obstruction during the procedure (Figure 2C,D).

Thirdly, O‐arm imaging was used to obtain intraoperative lateral decubitus computer tomography (CT) three‐dimensional images of the patient (Figure 2E).

Fourthly, the navigation device was used to mark the incision site for the planned bilateral percutaneous pedicle screw insertion and intervertebral disc region. The first assistant surgeon, seated, inserted guide wires under live visualization on the navigation screen. Surgically, screws were inserted along the guide wires, while the lead surgeon employed the navigation device for surface localization (Figure 3A–D). The midpoint between the two intervertebral spaces was shifted by 6 cm to designate the incision point. Blunt dissection of the external oblique, internal oblique, transverse abdominal, and transversalis fascia was performed to reach the retroperitoneal area. Palpation of the transverse processes and lumbar muscles was conducted, followed by dissection toward the abdominal side, retracting abdominal organs toward the abdomen and lumbar muscles toward the back, thereby exposing the lateral aspect of the vertebral bodies and adequately revealing the intervertebral region.

FIGURE 3.

Surgical procedures of oblique lumbar interbody fusion in one position. (A and B) Navigation‐guided intervertebral space positioning. (C and D) While the primary surgeon addresses the intervertebral space, the first assistant surgeon performs posterior guidewire placement under navigation guidance. (F and G) Insertion of trial cage, confirming the appropriate size of the fusion cage through navigation. (H and I) Navigation‐guided implantation of the OLIF fusion cage. (E and J) Posterior screw guidewire placement is completed before the implantation of the fusion cage.

Fifthly, under the guidance of the navigation screen, the lead surgeon utilizes a visualized intervertebral handling tool to manage the intervertebral space. This involves clearing the intervertebral disc and nucleus pulposus tissue, penetrating the contralateral fibrous ring, and using a scraping instrument to address the endplates. Through navigation, the appropriate fusion apparatus size is confirmed, and the optimal intervertebral fusion device is visually implanted, ensuring precise placement (Figure 3E–I).

Notably, to prevent navigation drift caused by variations in intervertebral space height, the first assisting surgeon is required to complete the implantation of the positioning guide wire before inserting the lateral interbody fusion device(Figure 3J).

Lastly, the first assisting surgeon completes the percutaneous screw implantation and final tightening with the patient in the lateral decubitus position.

2.4.2. The PLIF Surgical Procedure

The PLIF procedure was conducted based on previous research. Intervertebral joint fusion was achieved using interbody fusion devices loaded with demineralized bone matrix and autologous bone grafts harvested from excised spinous processes, lamina, facet joints (superior and inferior), and thin layers. Posterior stability of the lumbar spine was achieved through open pedicle screw fixation.

2.5. Evaluation Criteria

2.5.1. Clinical Assessment

To assess neurological function deficits, we employed the Japanese Orthopedic Association (JOA) Functional Disability Index, Visual Analog Scale (VAS), and modified MacNab scores for functional evaluation at preoperative, postoperative 1 month, postoperative 3 months, and postoperative 12 months. Improvement indices were used to reflect changes in spinal cord function before and after treatment, and improvement rates were employed to understand the clinical treatment outcomes.

2.5.2. Imaging Assessment

Preoperatively, standard lumbar spine anteroposterior and lateral x‐rays, lumbar spine CT scans, and lumbar spine MRI were obtained for all patients. Postoperatively, at 12 months, follow‐up lumbar spine anteroposterior and lateral x‐rays were collected to assess intervertebral disc height (DH), intervertebral foramen height (FH), and lumbar lordosis angle (LL). Six months postoperatively, lumbar spine MRIs were conducted to evaluate the cross‐sectional area of the spinal canal and intervertebral foramina (Figure 4). Twelve months after surgery, all patients underwent three‐dimensional CT scans, and measurements were performed utilizing the Picture Archiving and Communication System software. The supine position was used, and the scanning position included the transverse section of the bilateral pedicle root center. The position of each pedicle screw was analyzed and recorded, and the transverse screw angle was measured on the axial CT slices (Figure 1B). According to the classification by Gertzbein, the position of the pedicle screws was categorized into four levels: Grade 0, screws entirely within the pedicle; Grade 1, screws breaking through the pedicle bone wall but < 2 mm; Grade 2, screws breaking through the pedicle bone wall 2–4 mm; Grade 3, screws breaking through the pedicle bone wall > 4 mm [12]. Screws completely within the pedicle cortex were designated as Totally Confined.

FIGURE 4.

Measurement methods for radiological parameters and comparison of imaging data before and after OLIF360. (A) DH represents the average value of the anterior and posterior heights of the intervertebral space, with ADH and PDH denoting the anterior and posterior dimensions, respectively. FH is the distance between the lower edge of the superior pedicle and the upper edge of the inferior pedicle. LL represents the angle between the tangent lines to the upper endplate of the L1 vertebra and the upper endplate of the S1 vertebra. CSAC, spinal canal cross‐sectional area; CSAF: foraminal cross‐sectional area. LL refers to the lumbar lordotic angle, and the LL angle was significantly increased compared with the preoperative measurements (B). The cross‐sectional area of the spinal canal showed a significant increase postoperatively (C). The foraminal area was significantly increased compared to the preoperative state (D).

2.6. Statistical Analysis

The statistical analysis was conducted using IBM SPSS Statistics 26.0 software (IBM, USA). The Shapiro–Wilk test was employed to assess the normality of quantitative data at baseline and follow‐up for both groups. For normally distributed data, independent sample t‐tests were utilized; for non‐normally distributed data, the Mann–Whitney U test was applied. One‐way repeated measures analysis of variance compared differences among time points within each group. If there was a statistically significant overall difference, post hoc Bonferroni tests were conducted for pairwise comparisons to observe differences at each time point. Descriptive statistics were presented as mean ± standard deviation. A significance level of p < 0.05 was considered statistically significant.

3. Results

3.1. Baseline and Surgical Characteristics

A retrospective analysis was conducted on 63 patients, with 26 individuals in the OLIF 360 group (9 males and 17 females) and 37 in the PLIF group (16 males and 21 females). There were no significant differences in sex, age, and body mass index between the two groups (all p > 0.05) (Table 1).

TABLE 1.

The baseline and surgical characteristics.

	OLIF360 group (n = 26)	PLIF group (n = 37)	p value
Baseline demographics
Sex (male, %)	34.6%	43.2%	0.491
Age (years)	67.54 ± 6.56	63.62 ± 7.58	0.099
BMI (kg/m2)	26.38 ± 3.68	26.43 ± 3.10	0.670
Surgical characteristics
Intraoperative fluoroscopy, n	0	7.49 ± 1.17	0.000
Intraoperative blood loss (mL)	84.04 ± 48.29	207.03 ± 41.94	0.000
Average postoperative length of stay (days)	3.27 ± 0.73	6.38 ± 1.50	0.000
Surgical duration (min)	168.65 ± 48.51	89.19 ± 15.07	0.000
Japanese Orthopedic Association score
Preop	11.35 ± 2.23	10.35 ± 2.20	0.084
Postop‐1‐M	18.65 ± 2.15a	18.97 ± 2.54a	0.508
Postop‐3‐M	23.73 ± 1.82a,b	22.92 ± 2.02a,b	0.086
Postop‐12‐M	24.69 ± 1.49a,b	23.68 ± 2.35a,b	0.162
Visual Analog Scale score
Preop	8.19 ± 1.17	8.16 ± 1.17	0.778
Postop‐1‐M	4.92 ± 1.05a	5.81 ± 1.30a	0.005
Postop‐3‐M	3.04 ± 1.51a	4.11 ± 1.29a,b	0.007
Postop‐12‐M	2.07 ± 0.74a,b	2.81 ± 1.10a,b,c	0.006
Modified MacNab score
Excellent, n (%)	18 (69.2%)	26 (70.27%)	0.930
Satisfactory, n (%)	8 (30.7%)	11 (29.73%)
Intervertebral disc height (mm)
Preop	8.61 ± 2.44	7.92 ± 1.58	0.174
Postop‐12‐M	12.81 ± 2.28	10.29 ± 1.57	0.000
Ratio	33.30% ± 13.80%	22.72% ± 13.56%	0.004
p	< 0.001	< 0.001
Lumbar lordotic angle (°)
Preop	40.14 ± 5.34	42.17 ± 5.28	0.113
Postop‐12‐M	44.60 ± 4.30	45.01 ± 5.13	0.521
p	0.018	0.141

Note: a, compared to the preoperative period, p < 0.05; b, comparing to 1 month postoperatively, p < 0.05; c, compared to the postoperative period at 3 months. The bolded items indicate that the differences are statistically significant.

Abbreviations: BMI, body mass index; OLIF360, the group of patients underwent oblique lumbar interbody fusion 360 surgery; PLIF, posterior lumbar interbody fusion; Postop‐1‐M, postoperative‐1‐month; Postop‐3‐M, postoperative‐3‐month; Postop‐12‐M, postoperative‐12‐month; Preop, preoperative.

The OLIF360 group was significantly better than the PLIF group in terms of intraoperative fluoroscopy times, postoperative blood loss, and postoperative hospitalization time (all p < 0.001). However, the procedure duration was longer in the OLIF360 group than in the PLIF group (p < 0.001). In the minimally invasive group, 26 cases were enrolled, with a total of 104 screws inserted. In the open group, 37 cases were enrolled, with a total of 148 screws inserted. Both groups showed no statistically significant differences in the placement of screws (p > 0.05), and no postoperative neurological or vascular complications were observed (Figure 5A).

FIGURE 5.

Expansion of the neural channel area and the precision of the screws. (A) Proportion of screws at each grade for two surgical procedures and comparison of the proportion of TC screws in different vertebrae. (B) The cross‐sectional area of the spinal canal and the intervertebral foraminal areas on both sides significantly increased postoperatively compared to preoperative levels. CSAC, cross‐sectional area of the spinal canal; CSAF‐L, left foraminal area; CSAF‐R, right foraminal area; OLIF360, the group of patients underwent oblique lumbar interbody fusion 360 surgery; PLIF, posterior lumbar interbody fusion; TC screws, totally confined screws; “Preop” indicates the preoperative state, “Postop” refers to the postoperative condition, and “Ratio” signifies the recovery rate. *Statistical significance at p < 0.05. **There was no statistically significant difference.

3.2. Clinical Outcomes

Baseline JOA and VAS showed no statistically significant differences between the two groups initially. However, both cohorts displayed notable improvements in postoperative outcomes compared to their respective preoperative states. When comparing the results of OLIF360 and PLIF, no statistically significant disparities in JOA and VAS were detected during the final follow‐up examination. It is worth noting that the OLIF360 group exhibited significantly higher VAS scores at 3 months post‐surgery compared to the PLIF cohort, with statistical significance (p = 0.0007). The average JOA improvement rate at the last follow‐up was 75.09% for OLIF360 and 70.83% for PLIF. Both groups achieved excellent MacNab scores exceeding 69.2% during the final follow‐up, with no statistically significant discrepancies observed (Table 1).

3.3. Imaging Parameters Analysis

Compared with the preoperative values, the intervertebral space height and lumbar lordosis were significantly improved in both the OLIF360 and PLIF groups. In the OLIF360 group, the height of the intervertebral space increased from 8.61 to 12.81 mm (p < 0.001), and the lumbar lordosis angle increased from 40.14° to 44.60° (p = 0.018). There were no significant differences between the two preoperative DH and LL groups (all p > 0.05). At the 1‐year postoperative follow‐up, the OLIF360 group had better imaging measures than the PLIF group. The intervertebral space height in the OLIF360 group increased by 1.5 mm compared to the PLIF group. Lumbar lordosis angle was increased by 8° in the OLIF360 group as compared to the PLIF group (Table 1).

The preoperative average spinal canal cross‐sectional area was 71.05 mm², increasing to 109.65 mm² postoperatively, indicating a mean increase of 39.60 mm² and a recovery rate of 34.41%, with statistical significance (p < 0.001). Similarly, both right and left foraminal areas demonstrated significant increases and recovery rates (p < 0.001) (Figure 5B).

4. Discussion

Under O‐arm navigation assistance, OLIF360 can achieve visual nailing, fine intervertebral space processing, and accurate selection and placement of fusion device. Its efficacy in the treatment of mild and moderate lumbar spinal stenosis has been recognized by many scholars [13, 14]. However, the specific indications and efficacy of OLIF360 in severe lumbar spinal stenosis and advanced spondylolisthesis need further exploration. The potential for OLIF360 to address severe cases is limited by its reliance on indirect decompression, which may not provide adequate relief for nerve compression in more complex conditions. To date, there is no reports of the therapeutic effect of OLIF360 in severe lumbar spinal stenosis. In this study, we explored the therapeutic potential of OLIF360 surgery for patients with severe lumbar spinal stenosis. The OLIF360 group showed better intraoperative and postoperative outcomes, with less fluoroscopy time, lower blood loss, and shorter hospitalization (all p < 0.001). At 3 months post‐surgery, the OLIF360 group had significantly better pain relief (VAS scores) and greater improvements in intervertebral space height and lumbar lordosis (p < 0.05). Both groups had similar screw placement accuracy and no major complications.

4.1. Clinical Effect

Postoperative pain relief and lumbar function restoration (evaluated by JOA scores and lumbar pain VAS scores) are critical indicators for assessing surgical outcomes [15]. We observed that postoperative scores in both groups were significantly improved compared to preoperative scores, and there were no significant differences between the two groups at the last follow‐up visit. This suggests that OLIF360, as a novel technique, yields satisfactory clinical outcomes in terms of indirect decompression for severe spinal stenosis within 1 year postoperatively, demonstrating the effectiveness of OLIF360 in treating severe lumbar spinal stenosis.

Furthermore, we observed that the OLIF360 group experienced less intraoperative blood loss, shorter postoperative hospital stays, and more pronounced symptom improvement at the 1‐month and 3‐month follow‐up visits. These findings suggest that the OLIF360 procedure may expedite the disease recovery process for patients to some extent. The minimally invasive nature of the OLIF360 procedure can contribute to this advantage. During the OLIF360 surgical procedure, the surgeon utilizes the natural gap between the psoas muscle and the retroperitoneal vessels to advance surgical instruments to the operative site, thus avoiding extensive muscle dissection and bone structure damage. This minimizes intraoperative bleeding and greatly preserves the posterior column structures that would otherwise be disrupted in PLIF surgery [16].

4.2. Imaging Inquiry

OLIF360 holds promise as a treatment option for severe spinal stenosis. Next, we will further explore the feasibility and superiority of OLIF360 in treating severe spinal stenosis from an imaging perspective through postoperative radiological changes analysis.

The most crucial treatment method for severe spinal canal stenosis is decompression achieved by increasing the spinal canal area [17]. Unlike the direct decompression approach of PLIF, OLIF360 utilizes an indirect decompression method by implanting a large interbody fusion device, which effectively stretches the ligamentum flavum and indirectly expands the spinal canal. Our imaging results suggest that even in severe stenosis cases, the cross‐sectional area of the spinal canal significantly increased in the OLIF360 group, from 71.05 mm² preoperatively to 109.65 mm² postoperatively, representing an average increase of 38.6 mm². Additionally, there was a significant increase in the cross‐sectional area of both the left and right neural foramina, surpassing 40%. This is consistent with the findings reported by Mahatthanatrakul et al. [18]. Gagliardi et al. demonstrated that indirect decompression surgery can achieve clinical outcomes similar to those of direct decompression surgery, which is consistent with our findings [19]. Furthermore, the research findings of Fujibayashi et al. also confirm that in cases of severe spinal canal stenosis, the cross‐sectional area of the spinal canal gradually expands over time following indirect decompression [20]. Therefore, OLIF360 treatment for severe spinal canal stenosis is feasible.

Previous studies have shown that improvements in sagittal plane parameters, such as LL [8], are closely associated with improvements in patients' neurological symptoms [21]. Comparison of preoperative and postoperative x‐ray images revealed significant restoration of LL and DH in both groups of patients, with a more pronounced improvement observed in the OLIF360 group. This may be attributed to the utilization of larger interbody fusion cages during OLIF360 surgery. This could be another potential reason for the superiority of OLIF360 in improving clinical symptoms.

Additionally, the stability of the fusion stage is equally crucial for symptom improvement. The use of interbody fusion cages with supplemental pedicle screw fixation can maximize stability [22, 23]. Our results indicate that there is no significant difference in the accuracy of pedicle screw placement between OLIF360 surgery and PLIF surgery. This is significant, supporting the value of intraoperative navigation applications. Not only do such applications help to avoid the extensive use of fluoroscopy and the traction and disruption of the lumbar muscles associated with traditional open surgeries [24], but they also enable surgeons to achieve the same level of precision in pedicle screw placement in the unfamiliar lateral decubitus position as in the traditional PLIF posterior approach. However, it is important to note that O‐arm navigation requires a significant level of skill, and surgeons who are not yet proficient in its use may face challenges, such as increased operative time and potential inaccuracies in screw placement, especially in the lateral decubitus position [25]. This learning curve must be considered when implementing this technology in clinical practice. Surgeons unfamiliar with these technologies may need additional training, and the associated training time could affect surgical duration and outcomes. However, the precision and benefits offered by this technology, once mastered, can lead to improved long‐term outcomes, outweighing the initial time investment.

4.3. Surgical Complications of OLIF360

Although no significant complications were observed in either group of patients in this study, OLIF360 surgery still carries some unique postoperative complication risks that warrant further attention. First, vascular injury is a major risk, particularly damage to the abdominal aorta and inferior vena cava, which may lead to significant bleeding and affect postoperative recovery [25]. Additionally, urinary system injury, including possible damage to the bladder or urethra, is another potential complication that may increase the likelihood of postoperative issues [26]. Furthermore, nerve injury [27], infection, and spinal misalignment are also risks associated with OLIF360 surgery.

To minimize the occurrence of these complications, precise preoperative planning and real‐time intraoperative monitoring are essential. Performing the surgery under full visualization is one strategy that facilitates meticulous handling of the intervertebral space, reducing the risk of damage to the endplates and other vital structures during the procedure. Furthermore, the preoperative selection of the optimal surgical approach, fusion device, and positioning can significantly reduce the likelihood of complications.

It is also crucial to recognize that the use of O‐arm navigation plays a key role in mitigating some of these risks. By improving the accuracy of screw placement and minimizing intraoperative errors, O‐arm navigation contributes to enhanced precision, reducing the chances of complications. However, surgeons must be aware of the learning curve associated with these advanced navigation systems. Proficiency with O‐arm navigation will directly impact complication rates, as less experienced surgeons may face challenges that could affect surgical outcomes.

4.4. Limitations

This study has several limitations that should be acknowledged. Firstly, being retrospective, the study lacks robust evidential support for its conclusions. Secondly, the limited sample size potentially blocks the full manifestation of inter‐group differences. Thirdly, as a single‐center study with surgeries performed by the same surgeon, it introduces a potential bias in the results. Thus, future research should focus on prospective studies with a larger and more diverse sample from multiple centers to analyze the clinical efficacy of OLIF360 indirect decompression for severe lumbar spinal stenosis. Moreover, future studies should also consider the learning curve associated with O‐arm navigation, as the experience of the surgical team with this technology may influence both the outcomes and the surgical time.

4.5. Conclusion

The OLIF360 technique demonstrates favorable clinical efficacy in treating severe lumbar spinal stenosis and accelerates patient recovery compared to PLIF. However, it should be emphasized that the indications for OLIF360 remain more restricted compared to PLIF, and further research is needed to fully establish its role in treating severe spinal stenosis, particularly in complex cases. Imaging studies further explore its feasibility and superiority. The expansion of the spinal canal area ensures effective decompression of the nerves. Significant improvements in sagittal plane parameters and the avoidance of muscle and other tissue damage greatly ensure superior clinical outcomes. Therefore, OLIF360, as a novel technology, holds significant potential for treating severe lumbar spinal stenosis.

Author Contributions

Conceptualization: Xuexiao Ma, Lei Li, Yan Wang, and Hao Tao. Formal Analysis: Lei Li, Hao Tao, Hao Zhang, Changpeng Qu, and Yan Wang. Investigation: Lei Li, Hao Zhang, and Jialuo Han. Methodology: Lei Li, Hao Tao, Hao Zhang, Jialuo Han, and Yihao Sun. Project Administration: Xuexiao Ma. Writing – original draft: Lei Li, Changpeng Qu, and Yihao Sun. Writing – review and editing: Xuexiao Ma, Hao Tao, Hao Zhang, Jialuo Han, and Yan Wang.

Ethics Statement

The research was approved by the Ethics Committee of Affiliated Hospital of Qingdao University (QYFY WZLL 28571) and was carried out in compliance with the Declaration of Helsinki. All participants in the study gave their informed consent.

Conflicts of Interest

The authors declare no conflicts of interest.