Comparative Efficacy of Unilateral Biportal Endoscopy vs Traditional Surgery in Lumbar Degenerative Disorders

Introduction

Lumbar degenerative diseases encompass a range of conditions characterized by the progressive deterioration of the intervertebral discs, vertebrae, and surrounding structures. This deterioration can lead to various clinical manifestations, including lumbar disc herniation, spinal stenosis, and spondylolisthesis, which often result in the compression of nerve roots or the spinal cord [1–3]. These conditions are prevalent causes of lower back pain and radiculopathy, significantly impairing the quality of life for affected individuals. Traditional surgical interventions, such as posterior lumbar interbody fusion (PLIF), have been commonly employed to alleviate symptoms and stabilize the spine. However, these approaches are associated with considerable drawbacks, including extensive tissue damage, prolonged recovery periods, and potential postoperative instability, driving the search for less invasive and more effective alternatives [4,5].

Unilateral biportal endoscopy (UBE) has emerged as a promising, minimally invasive surgical technique for treating various lumbar degenerative diseases. UBE utilizes 2 separate portals: one for endoscopic visualization and the other for surgical instrument insertion. This approach allows for direct and enhanced visualization of the affected lumbar structures, enabling precise decompression of the neural elements while minimizing collateral damage to surrounding tissues [6–8]. Unlike traditional open surgical methods, UBE offers several potential advantages, such as reduced operative time, minimal blood loss, shorter hospital stays, and quicker postoperative recovery. By preserving the paraspinal muscles and maintaining the natural spinal anatomy, UBE may also improve long-term outcomes, including spinal stability and overall function. The therapeutic efficacy of UBE in managing lumbar degenerative diseases has gained recognition in recent years. Studies have consistently reported favorable outcomes, including significant pain relief, improved neurological function, and high levels of patient satisfaction. Despite the accumulating evidence supporting the benefits of UBE, comprehensive evaluations and direct comparisons with traditional surgical methods, such as PLIF, remain necessary [9–11]. These comparisons are crucial for understanding the long-term efficacy, complication rates, and recurrence rates associated with UBE. Moreover, the learning curve for UBE, along with its applicability across diverse patient populations and various types of lumbar degenerative diseases, requires further investigation to establish its role in the broader spectrum of spinal surgeries [12,13].

We hypothesize that UBE will demonstrate superior clinical outcomes compared with PLIF in the treatment of lumbar degenerative diseases, specifically in terms of reduced perioperative complications, faster recovery, and improved patient-reported outcomes. Additionally, we anticipate that UBE, as a minimally invasive technique, will offer similar or lower complication rates compared with PLIF, with reduced tissue disruption and faster postoperative recovery. This study aims to evaluate the therapeutic efficacy of UBE in the treatment of lumbar degenerative diseases, focusing on clinical outcomes, complication rates, and patient-reported outcomes. By conducting a comprehensive analysis, this study seeks to optimize treatment strategies for lumbar degenerative diseases and contribute to the advancement of minimally invasive spine surgery techniques.

Material and Methods

STUDY DESIGN:

A comprehensive retrospective evaluation was conducted at our hospital to assess the therapeutic efficacy of UBE in the treatment of lumbar disc herniation. This study spanned from January 2020 to January 2023. Patients were divided into 2 groups based on the surgical method they received. The experimental group comprised 53 patients who underwent UBE. For comparison, a control group was established, including 56 patients from the same timeframe who were treated with PLIF, ensuring the comparability of demographic and clinical characteristics between the 2 cohorts. All surgeries in this study were performed by the same experienced surgical team, with each surgeon having 5–8 years of experience in performing spinal surgeries. The study design, objectives, and protocols were meticulously developed following the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines [14]. Ethical approval for this study was obtained from the Ethics Committee of our hospital, ensuring compliance with all relevant ethical standards for research involving human participants.

SURGICAL PROCEDURE FOR THE UBE GROUP:

Patients in the study group underwent treatment using UBE. After the induction of general anesthesia, the patient was positioned prone on the operating table. Both an endoscopic observation channel and an operational channel were established. Taking a left-side approach as an example, the surgeon positioned himself or herself on the left side of the patient and accessed the spinal canal via the left interlaminar space. Fluoroscopic guidance was employed using a C-arm to obtain standard anteroposterior and lateral images of the lumbar spine. Once the target intervertebral disc space was confirmed, a horizontal line was marked on the skin. The intersection of this line with the medial border of the pedicle was used to determine the entry points for the observation and operational channels, each placed approximately 15 mm proximally and distally from this intersection.

Under fluoroscopic guidance, an incision was made for the operational channel. The incision was extended sequentially through the skin, subcutaneous tissue, and lumbodorsal fascia. A series of 3 dilators were then inserted to gradually expand the soft tissue and separate the muscles. The dilators were removed, and a dissector was introduced to prepare the interlaminar space. Next, a proximal incision was made for the observation channel, and the endoscope was inserted. Continuous irrigation with 3000 mL of normal saline was performed to maintain a clear surgical field, and this was halted once visibility was sufficient. The soft tissues were cleared, and hemostasis was achieved. The inferior margin of the lamina of the upper vertebra and the superior margin of the lamina of the lower vertebra were exposed. Using a high-speed drill, partial laminectomy was performed, and a Kerrison rongeur was used to remove sections of the lamina until the attachment site of the ligamentum flavum at the proximal end was reached. The ligamentum flavum was then carefully dissected and removed. A retractor was placed to gently retract the nerve root, allowing access to the herniated nucleus pulposus. A pituitary rongeur was used to remove the extruded disc material. Once the decompression was deemed adequate, the instruments were withdrawn, and the incisions were sutured and closed.

SURGICAL PROCEDURE FOR THE TRADITIONAL POSTERIOR LUMBAR INTERBODY FUSION GROUP:

Patients in the control group underwent the traditional PLIF procedure. After inducing general anesthesia, patients were placed in the prone position. Standard sterilization and draping were performed to maintain a sterile surgical field. A midline incision was made over the lumbar region, and dissection was carried out through the skin, subcutaneous tissue, and lumbodorsal fascia in sequence. The paraspinal muscles were then retracted laterally to expose the facet joints while preserving both facet joints. The affected spinal segment was identified and confirmed using fluoroscopic guidance with a C-arm. Pedicle screws were then implanted into the vertebrae of the involved segment. The supraspinous ligament, interspinous ligament, spinous processes, and bilateral laminae of the affected segment were excised, while both facet joints were preserved. Scar tissue from the posterior aspect of the intervertebral space was carefully removed to enlarge the nerve root canal and lateral recess. In cases of significant foraminal stenosis, partial resection of the facet joint was performed to achieve adequate nerve root decompression. The posterior annulus fibrosus was incised, and a pituitary rongeur was used to remove the nucleus pulposus, ensuring thorough clearance of the intervertebral disc material. The cartilaginous endplate was then scraped with a curette to expose the bony surface until slight bleeding was observed, indicating adequate preparation for fusion. Autologous bone grafts were placed into the intervertebral space, and an interbody cage was inserted for fusion. The construct’s position and stability were confirmed using intraoperative fluoroscopy. The surgical site was then irrigated, hemostasis was achieved, and a negative pressure drainage tube was placed. Finally, the incision was sutured in layers and closed.

OUTCOME MEASURES:

Surgery-Related Metrics: The primary surgery-related metrics included operative time, intraoperative blood loss, postoperative drainage volume, and length of hospital stay after surgery. These metrics were used to evaluate the procedural efficiency and immediate recovery outcomes of the 2 different surgical techniques.

Pain Assessment: Pain levels in both groups were assessed preoperatively and postoperatively using the Visual Analogue Scale (VAS). The VAS is a 10-point scale where 0 indicates no pain, 1–3 points represents mild pain, 4–5 points indicates moderate pain, and 6–10 points signifies severe pain. This tool provided a quantitative measure of pain relief achieved through the surgical interventions.

Lumbar Function Evaluation: Lumbar function was evaluated using the Japanese Orthopaedic Association (JOA) score. This scoring system assesses lumbar spine function, with a total score ranging from 0 to 29 points. Scores of 0–9 indicate poor lumbar function, 10–15 indicate fair function, 16–24 indicate good function, and 25–29 indicate excellent function. A lower score corresponds to greater functional limitation, providing a clear metric for assessing the impact of the surgeries on spinal functionality.

Postoperative Complications: Postoperative complications were monitored and recorded, including incision infections, hematoma formation, cerebrospinal fluid leaks, and lower limb numbness. The overall incidence of complications was calculated to compare the safety profiles of the UBE and PLIF procedures.

STATISTICAL ANALYSIS:

The statistical analysis was conducted using SPSS software (Version 27.0) to ensure accuracy and reliability. Data were categorized into quantitative and categorical variables, and normality was assessed to determine their distribution. For quantitative variables displaying a normal distribution, independent sample t-tests were employed to evaluate differences between groups, with results expressed as mean±standard deviation. Categorical variables were summarized using frequencies and percentages. Associations or differences between these categorical variables were examined using Chi-square (χ²) tests. All statistical tests were 2-tailed, and statistical significance was defined as a P value of less than 0.05.

Results

DEMOGRAPHIC AND CLINICAL CHARACTERISTICS:

The mean age of the patients was comparable between the 2 groups, with the UBE group having a mean age of 60.5±8.5 years and the PLIF group having a mean age of 62.0±10.1 years. Both groups had a higher proportion of female patients, with 38 women in the UBE group and 40 in the PLIF group, compared with 15 and 16 men, respectively. In terms of diagnoses, lumbar spinal stenosis was the most common condition, affecting 12 patients in the UBE group and 15 in the PLIF group. Other common diagnoses included lumbar disc herniation, present in 15 patients in the UBE group and 16 in the PLIF group, and lumbar instability, which was diagnosed in 6 and 7 patients in the UBE and PLIF groups, respectively.

Neural symptoms varied significantly between the groups; the majority of patients in the UBE group (34 patients) experienced unilateral symptoms, whereas the PLIF group had a higher number of patients with bilateral symptoms (45 patients). This indicates a distinct difference in the distribution of neural symptomatology between the groups. Regarding the surgical segments involved, both groups primarily had surgeries at the L4/5 and L5/S1 levels. Specifically, 30 patients in the UBE group and 32 in the PLIF group underwent surgery at the L4/5 segment, while 20 and 22 patients, respectively, had procedures involving the L5/S1 segment. Preoperative intervertebral height was similar between the groups, with an average of 8.5±2.6 mm in the UBE group and 8.6±2.7 mm in the PLIF group (Table 1). These demographic and clinical characteristics show that the 2 groups were relatively well-matched, allowing for a valid comparison of surgical outcomes and the effectiveness of the treatment methods under study.

COMPARATIVE ANALYSIS OF SURGICAL OUTCOMES BETWEEN UNILATERAL BIPORTAL ENDOSCOPY AND POSTERIOR LUMBAR INTERBODY FUSION:

Table 2 presents a comparison of surgical outcomes between patients treated with UBE and those treated with PLIF. Notably, the UBE group exhibited a significantly shorter mean surgery time of 107.3±11.2 minutes, compared with 113.5±15.7 minutes for the PLIF group (P=0.02). This finding indicates that UBE may offer a more time-efficient surgical approach. In terms of intraoperative blood loss, patients in the UBE group experienced significantly less bleeding, with an average loss of 50.2±5.7 mL, as opposed to 91.3±9.0 mL in the PLIF group (P<0.001). This substantial reduction in blood loss suggests that UBE is a less invasive procedure, minimizing surgical trauma and potential complications.

Postoperative metrics further highlight the advantages of UBE. The average postoperative drainage volume was significantly lower in the UBE group (73.5±11.0 mL) compared with the PLIF group (120.8±16.2 mL), with P<0.001. Reduced drainage volume in the UBE group implies less fluid accumulation and a potentially smoother postoperative recovery process. Moreover, the length of hospital stay was markedly shorter for patients undergoing UBE. The UBE group had an average hospital stay of 8.8±1.5 days, whereas the PLIF group averaged 13.2±1.8 days (P<0.001). The shorter hospital stay not only indicates faster recovery but also has positive implications for healthcare resource utilization and patient turnover (Figure 1). Overall, the findings suggest that UBE offers significant advantages over PLIF in terms of reducing surgery time, intraoperative blood loss, postoperative drainage, and hospital stay duration. These outcomes point to UBE as a potentially more effective and less invasive surgical option for treating lumbar spine conditions.

EVALUATION OF PAIN LEVELS BEFORE AND AFTER SURGERY USING THE VISUAL ANALOGUE SCALE:

Table 3 provides a comparison of pain levels in patients treated with UBE and those treated with PLIF as assessed by the VAS both before and 7 days after surgery. Preoperatively, the VAS scores indicated similar pain levels in both groups, with the UBE group scoring 7.30±0.90 and the PLIF group scoring 7.20±0.80. The difference was not statistically significant (P=0.54), demonstrating comparable baseline pain severity across both treatment modalities. However, postoperative assessments revealed a significant difference in pain reduction between the 2 groups. Patients in the UBE group reported a mean VAS score of 3.50±0.85 at 7 days post-surgery, indicating substantial pain relief. In contrast, the PLIF group had a higher mean postoperative VAS score: 4.10±0.95. This difference was statistically significant, with a P value of less than 0.001, demonstrating that UBE was more effective in terms of alleviating pain in the early postoperative period compared with PLIF (Figure 2).

COMPARATIVE ASSESSMENT OF LUMBAR FUNCTION USING JOA SCORES BEFORE AND AFTER SURGERY:

Table 4 presents a comparison of lumbar function between the group treated with UBE and the group treated with PLIF, using JOA scores. Preoperatively, both groups demonstrated similar levels of lumbar dysfunction, with mean JOA scores of 9.75±1.80 in the UBE group and 9.60±1.65 in the PLIF group. The difference was not statistically significant (P=0.65), indicating that the initial functional status was comparable between the 2 groups. Postoperative evaluation, conducted 7 days after surgery, showed a marked improvement in JOA scores for both groups, reflecting enhanced lumbar function. However, the UBE group exhibited a significantly greater improvement, with a mean JOA score of 19.80±2.30 compared with 17.20±2.05 in the PLIF group. This difference was highly significant, with a P value of less than 0.001, indicating superior early postoperative recovery of lumbar function in the UBE group (Figure 3).

INCIDENCE OF POSTOPERATIVE COMPLICATIONS IN UBE VS PLIF:

Table 5 compares the incidence of postoperative complications between the group treated with UBE, and the group treated with PLIF. The overall incidence of postoperative complications was lower in the UBE group, with a total complication rate of 5.67%, compared with 14.29% in the PLIF group. Specific complications included incision infections, hematoma compression, cerebrospinal fluid leaks, and lower limb numbness. The UBE group had a notably lower occurrence of these complications, with only 1 case each of incision infection, hematoma compression, and lower limb numbness, and no cases of cerebrospinal fluid leak. In contrast, the PLIF group had higher incidences, with 3 cases of incision infections, 2 cases each of hematoma compression and lower limb numbness, and 1 case of cerebrospinal fluid leak. Although there was a clear trend towards fewer complications in the UBE group, the difference in total incidence between the 2 groups did not reach statistical significance (P=0.14). This suggests that while UBE may be associated with a lower risk of postoperative complications, the sample size may have limited the statistical power to detect a significant difference.

Discussion

Lumbar degenerative diseases, including lumbar disc herniation, spinal stenosis, and spondylolisthesis, are common conditions that can lead to significant morbidity, characterized by chronic pain, nerve compression, and impaired mobility. Traditional surgical interventions, such as PLIF, have been widely used to treat these conditions by stabilizing the spine and decompressing the affected nerve roots. However, these procedures are often associated with considerable drawbacks, including extensive tissue disruption, high rates of complications, prolonged recovery periods, and the potential for adjacent segment disease due to altered biomechanics. In recent years, there has been a growing interest in minimally invasive surgical techniques that offer the potential to reduce the complications and recovery times associated with traditional open surgery [15,16]. UBE represents one such innovation, providing direct visualization and access to the affected area through 2 small portals, thus minimizing tissue damage. UBE has been proposed as a promising alternative that combines the benefits of minimal invasiveness with effective decompression and stabilization of the spine. This study aimed to evaluate the therapeutic efficacy of UBE compared with PLIF in the treatment of lumbar degenerative diseases. The results indicated several significant advantages of UBE over PLIF, suggesting that UBE may offer a more effective and less invasive approach for managing lumbar degenerative conditions.

Our study presents a comparative analysis of UBE and PLIF in the treatment of lumbar degenerative diseases, focusing on UBE’s potential benefits as a minimally invasive technique. The findings indicate that UBE may offer clinical advantages, such as shorter surgery time, reduced blood loss, lower postoperative drainage, and faster recovery compared with PLIF. While the difference in complication rates was not statistically significant, the trend toward fewer complications in the UBE group suggests a possible improvement in patient safety. From a clinical perspective, UBE’s ability to reduce perioperative risk and support recovery highlights its relevance for improving patient outcomes and healthcare efficiency. With reduced surgical trauma and shorter hospital stays, there is potential for lower resource utilization, improved patient turnover, and cost savings. Furthermore, UBE’s favorable pain relief and functional recovery outcomes suggest its potential to enhance postoperative quality of life. As further evidence becomes available, UBE may become an increasingly viable surgical option, contributing to the development of minimally invasive spine surgery techniques.

The findings demonstrated that UBE was associated with a significantly shorter surgery time compared with PLIF. This can be attributed to the minimally invasive nature of UBE, which involves using 2 independent portals for visualization and instrument insertion, thereby allowing for direct and efficient access to the affected disc and neural structures [17,18]. The shorter operative time not only reflects the procedural efficiency of UBE but also reduces the exposure to anesthesia, which is particularly beneficial for elderly patients and those with comorbidities. Additionally, the reduced intraoperative blood loss observed in the UBE group suggests that the technique is less invasive, minimizing the risk of damage to blood vessels and surrounding tissues [19]. This is likely due to the ability of UBE to precisely target the pathology while preserving the integrity of the paraspinal muscles and ligaments, leading to fewer intraoperative complications and a more controlled surgical environment [20,21].

The advantages of UBE in terms of postoperative recovery are highlighted by the significantly lower postoperative drainage volume and shorter hospital stay compared with PLIF. These findings suggest that UBE causes less tissue trauma, leading to reduced inflammatory responses and quicker wound healing. The minimal disruption to the paraspinal musculature and the use of continuous saline irrigation during UBE not only provide a clear surgical field but also help to prevent postoperative adhesions and reduce the risk of infection [22,23]. The reduced need for postoperative drainage and a shorter hospitalization period also has important implications for healthcare resource utilization, potentially leading to cost savings and improved patient turnover. This is particularly relevant in the context of the growing demand for spinal surgeries and the need to optimize hospital resources [24,25].

The significant reduction in postoperative pain levels observed in the UBE group, as evidenced by the lower VAS scores, is another key finding. The ability of UBE to provide effective pain relief can be attributed to several factors. First, the targeted decompression achieved through UBE minimizes the damage to surrounding tissues, reducing the sources of postoperative pain. Second, the continuous irrigation used during UBE may help to cool the tissues and reduce thermal injury, further alleviating pain. The rapid pain relief observed with UBE allows for earlier mobilization and rehabilitation, which are critical components of recovery and long-term functional outcomes [26,27]. By enabling patients to return to their daily activities sooner, UBE not only improves the quality of life but also reduces the burden on caregivers and healthcare systems. The study also found that patients treated with UBE experienced significantly greater improvements in lumbar function, as measured by the JOA scores, compared with those treated with PLIF. This enhanced functional recovery can be attributed to the ability of UBE to effectively decompress the neural elements while preserving the structural integrity of the spine. Unlike PLIF, which often involves extensive removal of bone and insertion of interbody cages, UBE maintains the natural biomechanics of the spine, reducing the risk of postoperative instability and adjacent segment disease [28,29]. The preservation of spinal stability and the reduction in scar tissue formation with UBE contribute to better long-term functional outcomes and patient satisfaction.

Although the overall incidence of postoperative complications was lower in the UBE group compared with the PLIF group, this difference did not reach statistical significance. However, the trend towards fewer complications with UBE suggests that it may be a safer option for patients undergoing surgery for lumbar degenerative diseases. The lower incidence of complications such as incision infection, hematoma compression, and cerebrospinal fluid leaks in the UBE group reflects the less invasive nature of the technique and its ability to minimize surgical trauma. The absence of cerebrospinal fluid leaks in the UBE group is particularly noteworthy, as this complication can lead to prolonged hospitalization and increased morbidity [30,31]. The precise and controlled approach of UBE, combined with continuous irrigation and clear visualization, may help to reduce the risk of such complications.

In this study, we acknowledge the limited sample size; however, the power calculations for key outcome measures support the statistical validity of our findings. Specifically, for intraoperative blood loss, postoperative drainage volume, and length of hospital stay, the power was 100%, indicating that the sample size was sufficient to detect significant differences. For postoperative pain levels, as measured through the VAS, the power was 93.1%, which is close to the ideal threshold of 80%, suggesting an adequate sample size to assess pain outcomes. Additionally, the power for lumbar function scores (JOA) was also 100%, confirming the robustness of the study’s capacity to detect meaningful clinical differences in functional recovery. These results suggest that, despite the modest sample size, the study is well-powered to draw valid conclusions about the comparative efficacy of UBE and PLIF.

This study has several limitations. First, the retrospective design may introduce selection bias, despite our efforts to match patient groups by demographic and clinical characteristics. Second, the relatively small sample size, particularly in assessing complication rates, may limit the statistical power to detect significant differences. Lastly, our analysis focuses on short-term outcomes, such as perioperative metrics and early recovery, without incorporating long-term data on recurrence rates or sustained functional improvements. Future research should focus on addressing the limitations identified in this study. Larger, multicenter trials with prospective designs could provide a more robust evaluation of UBE vs PLIF. Standardizing surgeon training protocols and implementing peer-reviewed surgical checklists may further minimize variability in clinical outcomes. Moreover, extended follow-up periods are essential for assessing long-term efficacy, including recurrence rates, sustained functional recovery, and patient-reported outcomes, providing a more comprehensive comparison of the 2 surgical techniques.

Conclusions

UBE demonstrates significant clinical efficacy in the treatment of lumbar degenerative diseases. It effectively improves surgery-related outcomes, reduces postoperative pain, and exhibits a favorable safety profile. These findings suggest that UBE is a viable and advantageous minimally invasive surgical option for patients with lumbar degenerative conditions, offering improved recovery and reduced complications.