Lumbar interbody fusion (LIF) has evolved into a key surgical approach for treating degenerative spinal disorders [1,2]. While these procedures relieve pain and restore spinal stability, conventional open approaches, such as posterior LIF and transforaminal LIF, are associated with substantial complications, including blood loss, prolonged recovery, and extended hospital stays [3–5]. To overcome these challenges, minimally invasive surgery (MIS) techniques, including minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) and oblique LIF, have been developed [3,5]. Although MIS-LIF reduces muscle injury and blood loss with comparable outcomes, its single-portal approach constrains visualization and maneuverability [6]. In this context, biportal endoscopic lumbar interbody fusion (BE-LIF) has emerged as a promising surgical alternative. This technique employs endoscopic tools to achieve lumbar fusion through smaller incisions, potentially reducing tissue disruption and accelerating recovery times [7]. Unilateral biportal endoscopic lumbar interbody fusion (UBE-LIF) and BE-LIF refer to the same minimally invasive lumbar fusion technique, which uses two portals—one for endoscopy and the other for instruments. While UBE-LIF refers to a unilateral approach, no significant differences in technique or outcomes exist between the two, and the terms are used interchangeably [8,9].

Previous studies consistently report significant differences between BE-LIF and MIS-LIF in key intraoperative metrics and postoperative recovery. Research indicates that BE-LIF leads to significantly lower intraoperative blood loss, decreased postoperative drainage, and shorter hospital stays [6,10,11]. However, it has longer operative times than MIS-TLIF [6,10]. Additionally, BE-LIF provides better early postoperative pain relief, particularly for low back pain, and enables faster functional recovery [6,12]. Despite these differences, both techniques yield comparable long-term outcomes in terms of fusion rates, leg pain relief, and complication rates [10,11]. These findings reveal the distinct advantages of BE-LIF for early recovery, whereas MIS-LIF remains a viable, time-efficient option for certain patients.

Despite the advancements in these surgical techniques, the comparative efficacy and safety of BE-LIF and MIS-LIF continue to be areas of ongoing investigation. Existing systematic reviews and meta-analyses have yielded inconsistent results, underscoring the need for a comprehensive umbrella review to synthesize the available evidence. This umbrella review aimed to evaluate and compare the clinical outcomes, complication rates, and recovery times associated with BE-LIF and MIS-TLIF. By consolidating data from existing systematic reviews and meta-analyses, this review seeks to offer a clearer understanding of the relative advantages and limitations of these two minimally invasive approaches, thereby informing clinical decision-making and guiding future research directions.

This scoping review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 [13] and PRISMA extension for Scoping Reviews guidelines [14]. The review protocol was established before the study commenced and is available upon request from the corresponding author.

This umbrella review synthesized six systematic reviews [6,8–10,12,15], all conducted in China and published between 2023 and 2025. Collectively, these reviews included 65 primary studies involving 4,671 patients with lumbar degenerative diseases. Of these, five studies directly compared BE-LIF and MIS-TLIF techniques. The mean age (±SD) of 2,202 patients (771 males) who received BE-LIF was 58.6±0.39 years, whereas that of 2,469 patients (712 males) who underwent MI-TLIF was 58.25±1.23 years. Follow-up duration varied from 16 to 22 months, with BE-LIF patients typically observed for 15–17 months and MI-TLIF patients for 17–22 months. A detailed summary of the study characteristics and data is presented in Table 1 [6,8–10,12,15]. The quality assessment of the included studies based on the AMSTAR checklist is shown in Table 2 [6,8–10,12,15,16].

In recent decades, UBE/BE-LIF and MIS-LIF have gained prominence as two of the most widely adopted minimally invasive surgical techniques for managing lumbar degenerative disease. This umbrella review, which systematically compared the clinical outcomes of these two techniques, discovered that UBE/BE-LIF represents a beneficial and effective alternative to MIS-LIF, demonstrating comparable or superior results in terms of operative parameters, pain relief, complication rates, and functional recovery.

This umbrella review and meta-analysis demonstrated that UBE/BE-LIF is associated with a significantly extended operative time compared to MIS-LIF. This observation aligns with multiple systematic reviews and can be attributed to several technical features inherent to the endoscopic technique [6,8–10,12]. First, setting up and maneuvering percutaneous working portals, precisely locating anatomical landmarks, achieving thorough decompression, and placing pedicle screws under endoscopic visualization are time-consuming and technically demanding steps, which may prolong surgical duration and increase procedural risk [20].

Second, minimizing intraoperative blood loss and maintaining a clear surgical field are critical in endoscopic surgery, requiring saline irrigation and radiofrequency hemostasis to preserve adequate visualization. These actions also extend operative time, particularly when performed by inexperienced surgeons [15]. Finally, UBE methods require single-handed instrument handling, rendering intricate maneuvers more difficult and increasing the risk for complications, such as dural tears or nerve root damage, particularly during the early learning curve [21,22]. Research indicates that surgical proficiency plateaus and operative time decreases after approximately 24–40 UBE cases; before this learning phase, operations tend to take longer and carry a higher risk of complications [22–24]. Within the context of this umbrella review, the comparison between BE-LIF and MIS-LIF demonstrates a consistent and clinically relevant benefit of BE-LIF in minimizing intraoperative blood loss. Several meta-analyses have demonstrated that BE-LIF is associated with significantly lower blood loss. For example, a recent synthesis found a weighted MD of −78.7 mL (95% CI, −98.5 to −59 mL; p<0.001), indicating a lower blood loss with BE-LIF [12]. The results are also supported by individual studies: a comparative analysis indicated a mean intraoperative blood loss of 89±22 mL with BE-LIF and 128±33 mL with MIS-LIF (p<0.001), as well as significantly lower hidden blood loss (HBL) in the BE-LIF group (472±64 mL vs. 575±73 mL) [25]. This blood-conserving effect of BE-LIF is primarily due to its muscle-sparing approach and continuous saline irrigation at 30–50 mm Hg throughout the endoscopic procedure, which enhances visualization while also providing tamponade of small bleeding vessels [23]. In contrast, MIS-LIF may entail greater retraction force and muscle injury, contributing to greater total and HBL. Notably, HBL can account for as much as 40%–60% of the overall blood loss in MIS procedures and is particularly pronounced in patients with osteoporosis or frailty [26].

These results imply that BE-LIF provides an advantage in reducing blood loss, which may lower transfusion requirements, expedite postoperative recovery, and mitigate anemia-related complications. However, the prolonged operative duration and learning curve of BE-LIF may partially offset these advantages and should be considered in clinical decision-making [27].

Meta-analytic evidence suggests that both BE-LIF and MIS-TLIF substantially improve postoperative leg and low back pain. Importantly, this umbrella analysis identified that BE-LIF exhibited a significantly larger effect size in VAS score reduction when compared with MIS-TLIF at short-term (approximately 1 month postoperatively) and long-term follow-up (approximately 1 year postoperatively). The pooled MD was −0.06 for VAS (leg) and −0.09 for VAS (back), both indicating sustained pain relief with BE-LIF. These statistically significant improvements should be interpreted with caution, as the observed MDs are minimal and may fall below the threshold for the minimal clinically important difference. These results are partly in agreement with those of previous meta-analyses, which reported a short-term benefit of BE-LIF in relieving back pain. For instance, Guo et al. [28] reported reduced early postoperative back pain with BE-LIF (SMD, −0.81; 95% CI, −1.33 to −0.30), but no statistically significant difference was observed beyond 12 months (SMD, −0.49; 95% CI, −1.13 to 0.16). Although BE-LIF seems to offer a clinically significant benefit in early postoperative low back pain relief, both procedures demonstrate similar long-term results for leg pain and overall disability improvement. This early benefit could be due to the reduced paraspinal muscle trauma, lower retraction pressure, and continuous saline irrigation inherent to BE-LIF, all of which likely cause lesser tissue injury and, consequently, decreased early postoperative pain. Nevertheless, these benefits tend to diminish as the follow-up period is prolonged beyond 3 months [25,27]. Clinical decision-making should balance these early differences in pain relief against other considerations, such as operative time, learning curve, cost, and surgeon experience.

This umbrella review demonstrated that BE-LIF yields superior ODI outcomes in than MIS-TLIF, in both the short-term and long-term follow-up periods. A recent meta-analysis by Hu et al. [9] in 2025, comprising ten studies involving 736 patients, revealed substantially lower early postoperative ODI in the BE-LIF group (p=0.007), corresponding with faster functional recovery compared to the MIS-TLIF group. Huang et al. [25] in 2023 pointed out that although early ODI improvements were more significant with BE-LIF, the long-term differences were modest and not consistently significant. Although BE-LIF exhibited statistically superiority over MIS-TLIF in certain outcomes, such as long-term VAS leg scores, the magnitude of the differences was minimal (e.g., MD=−0.06). From a patient-centered perspective, such small effect sizes, despite their statistical significance, are unlikely to represent clinically important improvements.

The superior early postoperative ODI observed with BE-LIF is likely attributable to its minimally invasive approach, paraspinal musculature preservation, and lower intraoperative trauma. These advantages may be particularly relevant for patients with significant preoperative disability or frailty, in whom expedited recovery can translate into meaningful improvements in quality of life.

Consistent with our study, among 11 comparative studies in a recent meta-analysis, Luan et al. [12] demonstrated that fusion rates were comparable between BE-LIF and MIS-TLIF, with no statistically significant difference (OR, approximately 1.10; 95% CI, 0.71 to 1.71; I²=0%). These results suggest that BE-LIF achieves spinal fusion rates comparable to MIS-TLIF, indicating noninferior structural outcomes while providing additional perioperative benefits. More precise endplate preparation and utilization of larger cages enabled by a dual-portal technique may help explain these findings despite concerns regarding saline irrigation affecting graft material integrity [9].

The pooled OR of the overall complications was 0.74 (95% CI, 0.61 to 0.91). This result indicates that the odds of developing postoperative complications in patients undergoing BE-LIF are about 26% lower than in patients undergoing MIS-TLIF. Previous meta-analyses have indicated similar complication profiles between the two methods (e.g., OR, approximately 0.63; p=0.07) [12]. The lower complication rate in BE-LIF can be explained by its muscle-sparing approach, constant irrigation, and improved visualization, which enable accurate decompression and minimize iatrogenic trauma. Notably, although BE-LIF involves a steep learning curve, high-volume centers have demonstrated consistently safe results, indicating that with proper training, complication risk can be minimized even in the early learning phase [29].

This umbrella review offers a modern and comprehensive summary of the comparative outcomes between MIS-TLIF and BE-LIF, integrating evidence from recent high-quality studies and meta-analyses. The pooled estimates from our meta-analyses generally demonstrated acceptable certainty, with most analyses incorporating data from all six included studies and benefiting from predominantly high-quality reviews based on AMSTAR-2 assessments. However, the fusion rate analysis, which was based on only two studies (one rated high and one moderate in methodological quality), may be associated with a lower certainty. This suggests a more cautious interpretation of findings related to fusion rates.

This study has several limitations that must be acknowledged. First, heterogeneity in surgical technique, surgeon experience, and perioperative protocols across the included studies—including the learning related to BE-LIF—may have impacted reported complication rates. Second, outcomes were not consistently defined, and methods of fusion assessment and pain/disability scoring intervals were not uniform, which may have led to measurement bias. Third, most studies were retrospective, which limits causal inference and increases the potential for selection bias. Fourth, fusion rates were reported in only two of the included studies, constraining the strength of the evidence. Fifth, of the six meta-analyses, four were rated as having “low” to “moderate” methodological quality based on AMSTAR-2 appraisal. This raises concerns regarding potential bias in their results, which may affect the overall certainty of the synthesized evidence. Moreover, a formal GRADE (Grading of Recommendations Assessment, Development, and Evaluation) assessment was not undertaken, and the certainty of evidence was interpreted primarily from AMSTAR-2 methodological quality ratings. Finally, the small number of studies included in this meta-analysis and language limitations (most studies were in English) may have impacted the comprehensiveness of the evidence base.

In conclusion, this umbrella review demonstrated that BE-LIF is a safe and effective alternative to MIS-TLIF for lumbar interbody fusion, offering several evident advantages in the perioperative setting. From a statistical perspective, our review indicates that BE-LIF is associated with significantly lower intraoperative and HBL, decreased postoperative back pain, and improved functional recovery measured by ODI. Furthermore, BE-LIF demonstrated a statistically significant lower rate of complications and sustained advantages in both leg and back pain at long-term follow-up. However, the observed effect sizes are small and may be of limited clinical relevance. The fusion rates among the two techniques were comparable, confirming the stability of BE-LIF. Although the individual studies included in the meta-analysis showed clinical heterogeneity, including variations in surgical experience and duration of follow-up, the collective evidence in our umbrella review supports BE-LIF as a minimally invasive procedure with equivalent or superior outcomes in appropriately selected patients compared to other minimally invasive lumbar spinal interbody fusion techniques. Given these findings, future high-quality prospective studies and randomized trials are needed to corroborate these benefits in broader clinical populations, as well as to evaluate long-term cost-effectiveness and patient-reported outcomes.