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The study cohort was 56.7% women, and the mean patient age was 50.98 ± 18.23 years. The mean VAS (the back and leg), MacNab score, and ODI improved significantly from the preoperative period to the last follow-up (12.92 ± 3.92) in both groups (p < 0.001). One week after operation, the back VAS score in the UBE group showed significantly more improvement than that in the OLM group. However, the 1-week, 3-month, and 12-month VAS (the back and leg), ODI improvement, modified MacNab score, and OT were not significantly different between the two groups. In the UBE group, EBL (34.67 ± 16.92) was smaller and HS (2.77 ± 1.2) was shorter than that of the OLM group (140.05 ± 57.8, 6.37 ± 1.39). However, OT (70.15 ± 22.0) was longer in the UBE group than in the OLM group (60.38 ± 15.5), and the difference was statistically significant. Meanwhile, the differences in the rate of surgical conversion and complications between the two groups were not statistically significant.
This study included 141 patients with degenerative disc disease requiring discectomy at a single level from L2&#;L3 to L5&#;S1. A total of 60 and 81 patients underwent UBE and OLM, respectively. Analysis was based on comparison of perioperative metrics, operation time (OT); estimated blood loss (EBL); length of hospital stay (HS); clinical outcomes, including assessment using the Visual Analogue Scale (VAS) and Oswestry Disability Index (ODI); patient satisfaction (the MacNab score); and the incidence of reoperation and complications.
The unilateral biportal endoscopic (UBE) technique is a minimally invasive procedure for spinal surgery, while open microscopic discectomy is the most common surgical treatment for ruptured or herniated discs of the lumbar spine. A new endoscopic technique that uses a UBE approach has been applied to conventional arthroscopic systems for the treatment of spinal disease. In this study, we aimed to compare and evaluate the perioperative parameters and clinical outcomes, including recovery from surgery, pain and life quality modification, patient&#;s satisfaction, and complications, between UBE and open lumbar microdiscectomy (OLM) for single-level discectomy procedures.
Lumbar disc herniation (LDH) is a clinically symptomatic condition caused by the compression of the spinal nerve root from a protruded disc material. Almost 70&#;85% of patients experience at least one episode of lower back pain with or without leg pain during their lives [ 1 ]. Some studies have reported that LDH can be naturally absorbed [ 2 , 3 ]. However, surgery is required when symptoms refractory to medical treatment or combined neurological deficits, including sensory or motor problem, persist. The current standard surgery for LDH is open lumbar microdiscectomy (OLM) with partial laminotomy. However, OLM results in increased risks of postoperative spinal instability and chronic back pain [ 4 ]. This procedure is more invasive and is similar to open discectomy. OLM requires bone removal, entrance to the spinal canal, manipulation of neural and vascular tissues, and large fenestration to the annulus. Currently, the popularity of minimally invasive spine surgery for the treatment of LDH is growing. Percutaneous endoscopic discectomy is a minimally invasive spinal surgery (MISS) technique that has several advantages over OLM, including preservation of bony and muscular structure, shorter hospital stay (HS), and a smaller incision [ 5 &#; 7 ]. A new endoscopic technique that uses a unilateral biportal endoscopic (UBE) approach has been applied to conventional arthroscopic systems for spinal disease [ 8 , 9 ]. The arthroscopic discectomy technique, as described by Kambin [ 10 ], is different from the other MISS procedures because it allows for extraction of the offending herniated fragments from the posterior intervertebral disc. Patient satisfaction was rated at 87% [ 11 , 12 ], and the radiologic success rate was 16 out of 18 case series [ 11 &#; 13 ]. However, these reports were published before , and a detailed analysis on pain and patient satisfaction over time is yet to be performed. High-definition (HD) endoscopic visualization has been available since , allowing for better illumination and tissue identification compared with previous standard definition visualization [ 14 , 15 ]. The clinical results of these techniques with respect to comparisons of various parameters have not been analyzed to date. To the best of our knowledge, this is the first report on the evaluation of the clinical results of these techniques since they were introduced.
Statistical analyses were performed using SPSS for Windows (version 22.0; SPSS, Inc., Chicago, IL, USA). An independent sample t test (two sided) and Mann-Whitney test were used to compare numerical data between groups, such as VAS, ODI, OT, EBL, HS, postoperative complication, and follow-up duration. Fisher exact test and χ 2 test were used to compare categorical variables including sex, disc location, operation level, modified MacNab score, motor weakness, complication, and surgery conversion between groups. Changes in periodical variables from the preoperative period to each postoperative time were measured using Wilcoxon signed rank test and paired sample t test. A P value less than 0.05 was considered statistically significant.
OLM was performed under general or spinal anesthesia. The surgical procedure followed the standard method using a tube or Caspar retractor system [ 16 , 17 ]. The procedure was performed with the patient in a prone position on a radiolucent table. The incision point was at the inferior edge of the superior lamina of the lesion side in the AP view and parallel to the disc space in the lateral view. After creating a 3-cm incision in the midline, the fascia was dissected to the lateral edge of the inferior articular facet. Soft tissues, including the paraspinal muscles, were cleaned using a monopolar cautery system (Bovie® Medical, Inc., Purchase, NY, USA) to expose the ligamentum flavum. After partial laminotomy of the lower lamina of the upper lumbar spine and upper lamina of the lower lumbar spine, the ligamentum flavum was removed for disc discrimination. Then, the instruments were advanced to the epidural space and the dura margin, and the nerve roots were exposed. The root was retracted, and epidural dissection was performed. The protruded disc particles were found and removed with pituitary forceps and Kerrison punches. The mobility of the root was checked using a hook dissector after the pathologic disc particles were removed. Wound closure was performed using 1:0, 2:0, and 4:0 absorbable sutures (Vycryl®) and a skin stapler.
First, the two portal skin entry points were confirmed using preoperative axial MR images or plain anteroposterior (AP) radiographs to determine the optimal operation route. Then, the target disc was identified under the discographic images. In the left side approach, the insertion point for the endoscope (endoscopic portal) was 1&#;1.5 cm lateral to the midline in the lower margin of the upper lamina, while the upper margin of the lower lamina was the insertion point for surgical instruments (instrumental portal). The endoscopic portal was used for continuous irrigation and for viewing of the surgical procedure, while the instrumental portal was used for instrument manipulation and removal of the ruptured disc. After a serial dilator was inserted through the caudal portal, the muscle was dissected with an RF probe through the instrumental portal. The lower lamina of the upper lumbar spine and upper lamina of the lower lumbar spine were partially removed via an automated drill and Kerrison punches (partial laminotomy). The interlaminar ligament was then dissected using an RF probe and removed using rotating Kerrison punches. Annulotomy, disc fragment dissection, and ruptured fragment removal were performed using pituitary forceps and Kerrison punches. Decompressed root confirmation and disc space exploration were performed using a 90 ° hook dissector. The muscle and skin were sutured using a 2:0 absorbable suture (Vycryl®) and reinforced skin closure (Steri-Strip®, 3M, Inc.), Maplewood, MN, USA).
The supplementary video clip demonstrates the full process for the endoscopic unilateral biportal endoscopic (UBE) technique. (1) We performed unilateral partial laminotomy with automated drill. (2) Using a small laminotomy window, the interlamina was dissected with a radiofrequency probe. (3) Partial removal of the yellow ligament was performed with Kerrison punches. (4) Adhesion removal and disc dissection were done with hook dissector. (5) Ruptured disc removal and (6) disc space exploration and confirming the nerve root exposure were performed using a pituitary forcep and hook dissector (MP4 kb).
The surgery proceeded as follows (see Additional file 1 ). Additional file 1: Supplementary video clip. video file. (102M, mp4) The supplementary video clip demonstrates the full process for the endoscopic unilateral biportal endoscopic (UBE) technique. (1) We performed unilateral partial laminotomy with automated drill. (2) Using a small laminotomy window, the interlamina was dissected with a radiofrequency probe. (3) Partial removal of the yellow ligament was performed with Kerrison punches. (4) Adhesion removal and disc dissection were done with hook dissector. (5) Ruptured disc removal and (6) disc space exploration and confirming the nerve root exposure were performed using a pituitary forcep and hook dissector (MP4 kb).
Clinical outcomes were evaluated using the back and leg VAS (0&#;10) and the ODI (0&#;100%). Patient satisfaction was assessed via modified MacNab criteria (excellent, good, fair, and poor). Perioperative data (length of operation time (OT) and HS, estimated blood loss (EBL), and complications) were assessed via video records of the endoscopic and microscopic operation and clinical charts. Radiologic outcomes were evaluated using the pre- and 3-day postoperative MR images.
This study aims to compare the differences in the 1-year postoperative clinical course in terms of perioperative parameters, such as pain control, quality of life modification, and patient satisfaction between biportal endoscopic and traditional microscopic techniques. This is a case control study conducted at Himchan Hospital, Incheon, Korea; Leaders Hospital, Seoul, Korea; and Bareun-Sesang Hospital, Kyoungki, Korea. We enrolled 141 patients who underwent surgery for the treatment of LDH between May and October ; 60 consecutive patients were treated with UBE by three surgeons (Dr. S. Kim, Dr. S. Kang, and Dr. Y. Hong), while 81 consecutive patients were treated with OLM by two surgeons (Dr. S. Kim and Dr. Y. Hong). The inclusion criteria were (1) back or radiating pain related to LDH, (2) symptom persistence of more than 4 weeks, and (3) magnetic resonance (MR) images correlated to the symptoms. The exclusion criteria were as follows: (1) foraminal or extraforaminal disc involvement, (2) recurred LDH, (3) motion instability (defined as > 3 mm translation or > 5° angulation), (4) spondylolisthesis more than Meyerding grade II, (5) cauda equine syndrome, and (6) comorbid tumorous or infectious conditions. All participating institutions received approval from their respective institutional review board (KNU07-), and all patients provided written informed consent. The data were collected starting from the preoperative period until 12 months postoperative. Pain intensity, patient satisfaction, and quality of life as analyzed using the Visual Analogue Scale (VAS), modified MacNab score, and Oswestry Disability Index (ODI), respectively, were investigated at 1-week, 3-month, and 12-month postoperative follow-ups.
The clinical outcomes and operative findings are shown in Table . In both groups, postoperative back and leg pain and ODI were significantly improved (p < 0.001, Fig. a&#;c). Improvements in back pain 1 week after operation were significantly different between the UBE and OLM groups (4.05 ± 1.6 vs. 1.25 ± 1.7, p < 0.001). The mean OT was significantly longer in the UBE group (70.15 ± 22.0 min, p = 0.002) than in the OLM group (60.38 ± 15.5 min, Fig. d). The mean blood loss in the UBE group was significantly less than in the OLM group (34.67 ± 16.9 ml vs. 140 ± 57.8 ml, p < 0.001, Fig. e). The mean HS was significantly shorter in the UBE group than in the OLM group (2.77 ± 1.2 d vs. 6.37 ± 1.4 d, p = 0.005, Fig. f). After the ruptured or protruded disc was dissected, the compressing materials were removed (Fig. a). A decompressed traversing root and thecal sac indicated completion of operation (Fig. b). Compared with preoperative MRI (Fig. c), postoperative (Fig. d) MRI indicated relieved pathologic condition (Fig. e) with limited muscle injury radiologically (Fig. f). The ruptured disc fragment was completely removed in all cases except in three cases of UBE that required conversion to OLM. The surgery was modified due to blurred field of view from the bone and epidural bleeding. Controlling bleeding in the microscopic view is important because the RF probe and bone can be difficult to manipulate due to vision disturbance. No serious complications, including cauda equine syndrome, were observed. Two cases of cerebrospinal fluid leakage occurred, which were treated with conservative treatment including bed rest and fluid replacement. Only one case of operative site infection occurred in the OLM group, which was controlled using 3rd-generation antibiotics, such as cefotaxime.
A total of 146 patients who underwent spinal surgery were enrolled in the present study. Two of the 62 patients who underwent UBE and three of the 84 who underwent OLM were excluded because they were lost to follow-up. Consequently, we enrolled 60 and 81 patients who underwent UBE and OLM, respectively. The patients&#; demographic and preoperative characteristics (Table ) were not statistically different. The schematic differences between the two procedures are depicted in Fig. a, b.
As a form of MISS, UBE demonstrated several advantages and one disadvantage in the present study. First, it showed superiority in terms of short-term back pain recovery, a small volume of intraoperative blood loss, and less HS. Second, improvements in short-term leg pain and long-term back and leg pain, modification of the quality of life (ODI), patient satisfaction (modified MacNab score), and complication rate were similar to that of OLM. However, OT was longer in UBE than in OLM, but this is its only disadvantage in the present study. These results indicate that UBE can be used to minimize tissue damage, although several limitations, such as controlling bleeding, need to be overcome.
Although conventional open laminotomy and discectomy is an effective way for symptomatic herniation, muscle and ligament injury from surgery can lead to postoperative back pain and muscle atrophy [18]. Therefore, more time may be required for functional recovery and pain control after OLM. Postoperative back pain following mechanical trauma due to OLM has already been reported. Dvorak et al. reported that 70% of patients experienced back pain after conventional discectomy during long-term follow-up [19]. Parker et al. also reported that 32% of patients suffered back pain after conventional discectomy, and 9% of cases underwent fusion surgery for pain control [20]. Vodicar et al. reported that invasive procedures, including endplate perforation, decrease vertebral height and worsen back pain in the postoperative period [21]. Scarring of the epidural space can be problematic [22&#;24]. It may become clinically symptomatic and make revision surgery more difficult because of the connection of the thecal sac to the paravertebral muscle structures [25, 26]. As such, MISS techniques, such as transforaminal and interlaminar approach percutaneous endoscopic lumbar discectomy (PELD), have been developed to minimize injury to the posterior musculo-ligamentous structures [27, 28].
Uniportal transforaminal and interlaminar PELD are both good surgical methods. They can protect the posterior structures, such as the upper and lower laminas, ligamentous structure, and muscles, better than OLM. Although these procedures can remove soft disc herniation and ruptured LDH without foraminal obstruction, they have limited indications due to the restricted movements of the instruments and obstructed intervertebral foramen following degenerative changes. Microendoscopic discectomy is regarded as an alternative to OLM because it produces few traumas to soft tissues and results in rapid recovery and less intraoperative blood loss [29]. However, this technique requires the same exposure of muscle and bone and basic skills with that of conventional OLM, such as the use of a dilator and tubular retractor [29]. By contrast, UBE can achieve high-resolution visualization at only a small muscle dissection and use almost all laminectomy instruments without restriction. HD endoscopic vision makes disc dissection easier, and ruptured fragment removal and manipulation is possible as in the conventional technique. Because the same instruments are used while allowing for a more detailed view than in microscopic surgery, favorable radiologic outcomes can be achieved. UBE is a new method that combines the advantages of interlaminar endoscopy and microscopic surgery. The use of the uniportal system is limited because of the combined channel (viewing and instrumental) that limits the independent movement of instruments. By contrast, the UBE system uses independent channels for instruments; thus, movements are not restricted. Furthermore, instruments for both 0° or 30° arthroscopy for the knees and shoulders and standard laminectomy are used and additional devices are no longer needed. Moreover, the endoscopic trajectory is the same as that in conventional operation; thus, an experienced microscopic spine surgeon can achieve the necessary surgical skills without a steep learning curve [30].
Kambin et al. reported a high rate of 87% patient satisfaction for arthroscopic disc surgery [12]. The rating was based on pain reduction, medication changes, and lifestyle modifications. However, this study did not use universally accepted assessment scales such as VAS, ODI, and modified MacNab score. Casey et al. assessed the radiologic outcomes of arthroscopic discectomy and found that the success rates based on CT and MRI were 88.9% (n&#;=&#;18) and 85.7% (n&#;=&#;12), respectively [13]. However, this study did not perform a control analysis, and only radiologic outcomes were assessed. A recent study by Um et al. reported the outcomes of UBE after development of HD endoscopic vision [8]. The study showed that the ODI score decreased from 67.2&#;±&#;1.7 to 24.3&#;±&#;8.5, and the VAS for leg pain decreased from 8.3&#;±&#;1.1 to 2.4&#;±&#;1.1. This study showed favorable outcomes from UBE, which are consistent with our study. However, control group analysis was not performed, and the operation detail was not discussed. The present study is characterized by a detailed evaluation of the operation, analysis of controls, and evaluation according to the perioperative period. We also described the drawback of this surgery, which was prolonged OT.
Technical advances in the surgical techniques of LDH now permit a fully endoscopic procedure under continuous irrigation. This can provide optimal advantages for a MISS procedure [14] that became possible with more tissue-sparing techniques, which are being applied increasingly [31]. Compared with conventional OLM, UBE has the advantage of less intraoperative blood loss and postoperative back pain and relatively shorter HS due to the preservation of the back muscle and a smaller incision. These advantages extend the scope of lumbar spinal stenosis [30], degenerative diseases of the cervical spine, and even short-level fusion surgeries [8]. Through high-resolution video equipment, preserving the facet joint and ligament complex and lessening nerve traction is now possible. Another advantage is that UBE preserves the epidural vessel and discal tissues, avoiding annular incision with the knife. The combination of these advantages results in improved quality of life (ODI score). In terms of patient satisfaction, the modified MacNab score in UBE was equivalent to that in conventional OLM despite prolonged OT. This result may be due to the tissue-sparing nature of the procedure, rapid pain recovery, short HS, favorable pain outcomes, and improved quality of life.
Our results show that OT is longer in UBE than OLM primarily because most surgeons have been used to microscopic procedures for a long time. In UBE, only the right hand is in the instrument portal because the working portal is used only for the instruments; thus, the surgeon cannot use both hands, making it difficult to control bleeding and prolonging the OT. However, more surgical experience will reduce the OT.
The limitations of this study are its retrospective nature, small sample size, and short follow-up period. In addition, because of the nature of retrospective studies, selection bias seems to be intrinsic by patients&#; preferences and the surgeon&#;s experience may be influenced the outcomes. However, the results show that UBE can be an alternative surgery to OLM based on the favorable clinical results and the convenience from the new endoscopic instruments. Adequate randomized prospective studies for UBE are required to verify the present results.
The original contributions presented in the study are included in the article/Suplementary Material, further inquiries can be directed to the corresponding author/s.
This study aimed to evaluate the efficacy and safety of unilateral biportal endoscopy (UBE) versus other forms of spine surgery.
Electronic databases were systematically searched up to February . The authors used Review Manager 5.3 to manage the data and perform the review.
After the preliminary selection of 239 studies from electronic databases, the full inclusion criteria were applied; 16 studies were found to be eligible for inclusion. These 16 studies enrolled 1,488 patients: 653 patients in the UBE group, 570 in the microendoscopic discectomy group, 153 in the percutaneous endoscopic lumbar discectomy group, and 70 in the posterior lumbar interbody fusion group. UBE was superior to microendoscopic discectomy regarding 1-day Visual Analog Scale(VAS) back pain scores (P&#;<&#;0.). No difference was found between UBE and microendoscopic discectomy regarding 1-day Visual Analog Scale leg pain scores (P&#;=&#;0.25), long-term VAS back pain scores (P&#;=&#;0.06), long-term VAS leg pain scores (P&#;=&#;0.05), Oswestry Disability Index scores (P&#;=&#;0.09) or complications (P&#;=&#;0.19). Pooled analysis indicated that UBE was similar to percutaneous endoscopic lumbar discectomy regarding 1-day VAS back pain scores (P&#;=&#;0.71), 1-day VAS leg pain scores (P&#;=&#;0.37), long-term VAS back pain scores (P&#;=&#;0.75), long-term VAS leg pain scores (P&#;=&#;0.41), Oswestry Disability Index scores (P&#;=&#;0.07) and complications (P&#;=&#;0.88). One study reported no difference between UBE and posterior lumbar interbody fusion regarding long-term VAS back pain, long-term VAS leg pain, or Oswestry Disability Index scores.
UBE is superior to microendoscopic discectomy to relieve back pain 1 day postoperatively. However, these two procedures are similar regarding 1-day leg pain relief, long-term effects, and safety. UBE and percutaneous endoscopic lumbar discectomy are similar regarding 1-day pain relief, long-term effects and safety. More evidence is needed to evaluate the efficacy and safety of UBE versus posterior lumbar interbody fusion.
Keywords:
unilateral biportal endoscopic, percutaneous endoscopic lumbar discectomy (PELD), microendoscopic discectomy (MED), spine, minimally invasive surgery
The prevalence of spinal diseases has increased rapidly in all populations because of occupational ergonomic factors and extended life spans (1, 2). Among spinal disorders, lumbar spinal stenosis and lumbar disc herniation are the most common. Therefore, increasing attention is being focused on the search for appropriate treatment (3, 4). With the evolution of surgical techniques, minimally invasive spine surgery has emerged in recent decades as an alternative to conventional open surgery.
Unilateral biportal endoscopy (UBE) is a novel form of minimally invasive spine surgery. The roots of UBE date back to the s, when Kambin tried to apply arthroscopy to lumbar discectomy (5). Unlike other endoscopic procedures that have evolved, spine endoscopy procedures that are currently mature&#;namely, percutaneous endoscopic lumbar discectomy (PELD) and microendoscopic discectomy (MED)&#;rely on one portal. By contrast, UBE involves two portals on one side. One portal is for optical instruments and the saline irrigation system; the other is for surgical instruments. UBE allows adequate decompression control and wider surgical vision than one-portal spine endoscopy, leading to satisfactory safety and effectiveness (6).
Compared with traditional open surgery, the minimally invasive surgical technique provides the benefits of less trauma, reduced pain, and faster healing. MED and PELD are two common and mature minimally invasive spinal surgeries. According to the surgical approach, PELD can be divided into percutaneous endoscopic interlaminar discectomy (PEID) and percutaneous transforaminal endoscopic discectomy (PTED). However, conventional open surgery remains the gold standard for degenerative spine disorders. UBE has been introduced as a novel treatment option for spine disease in recent years. Although this procedure has been used for a relatively short time, previous studies have reported satisfactory outcomes compared with baseline. As a novel technique, UBE requires comparison to other, more mature surgical procedures to verify its efficacy and safety.
The body of research on UBE is growing (6), but some comparisons between this procedure and other forms of spine surgery have been inconsistent. Meta-analysis is defined as first-level evidence, which is the highest level of evidence. High-quality systematic reviews and meta-analyses of UBE versus other forms of spine surgery are lacking. Therefore, we conducted this systematic review and meta-analysis of the published literature to evaluate the efficacy and safety of UBE versus other forms of spine surgery.
Link to Lingchuang Yihui
The present systematic review and meta-analysis was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines.
The authors searched PubMed, the Cochrane Library, Scopus, Embase, Ovid, and Web of Science up to February using the following search terms: &#;unilateral biportal endoscopy&#; or &#;biportal endoscopy spine surgery&#;. The reference lists of included articles were also screened to avoid missing relevant studies. The full text was obtained from Peking University Library.
The inclusion criteria, specified according to the PICOS framework, were as follows.
P (patients): Patients diagnosed with lumbar disc herniation or spinal stenosis.
I (intervention): Patients who underwent UBE surgery.
C (comparison): Patients who underwent other spine surgery, specifically PELD, MED or posterior lumbar interbody fusion (PLIF).
O (outcomes): The primary outcomes included 1-day VAS leg pain, 1-day VAS back pain, long-term VAS leg pain, long-term VAS back pain, and Oswestry Disability Index (ODI) scores. Complication events were included as secondary outcomes to evaluate the safety of UBE. To be included, studies were required to report at least one of the above outcomes.
S (study design): All comparative studies: case&#;control studies; cohort studies, randomized clinical trials. The included studies were required to report at least one of the above outcomes. Only studies published in peer-reviewed journals were considered for inclusion. Only literature published in English was eligible for inclusion.
I. Patients diagnosed with tuberculosis, infection, scoliosis, fractures, tumors or rheumatoid arthritis.
II. Studies or patients presented by other included articles; review studies; case reports; technical notes.
III. Cervical surgeries.
Two authors independently screened the literature by reading the titles, abstracts, and full texts and applying the inclusion and exclusion criteria. The corresponding author, Liu, supervised the whole process and resolved all discrepancies.
Two authors worked independently to extract the following information: (1) general information: first author, publication year, and type of study; (2) participant characteristics: sample size, age, and baseline characteristics; (3) surgical procedure; (4) primary outcomes: 1-day VAS leg pain, 1-day VAS back pain, long-term VAS leg pain, long-term VAS back pain and ODI scores; and (5) secondary outcome: number of complications.
Only randomized controlled trials (RCTs) were eligible for risk-of-bias assessment. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) and Cochrane Collaboration criteria, two authors independently assessed the risk of bias in the included studies in the following areas: (1) random sequence generation; (2) allocation concealment; (3) blinding of participants and personnel; (4) blinding of outcome assessment; (5) incomplete outcome data; (6) selective reporting; and (7) other bias. The Newcastle&#;Ottawa Scale was applied to evaluate observational studies.
The authors performed the analysis using Review Manager 5.3. For continuous variables, mean differences (MDs) with 95% confidence intervals (CIs) were used to calculate pooled effects. For dichotomous outcomes, odds ratios (ORs) with 95% CIs were used to calculate pooled effects. Heterogeneity was represented using Higgins&#; I-squared statistic (I2). A fixed- or random-effects model was used according to the degree of heterogeneity. A random-effects model was applied when heterogeneity was low (I2&#;>&#;50%); otherwise, a fixed-effects model was applied. Funnel plots were generated and examined to detect publication bias. Visual estimation was performed to examine the asymmetry of the funnel plot. The corresponding author supervised the whole process.
The rapid development of minimally invasive surgery has resulted in novel techniques for treating spinal diseases. Minimally invasive surgery is defined by more than the small size of the skin incision. A procedure that addresses damage to vertebrae and muscles under a small incision cannot be considered minimally invasive. The aim of minimally invasive surgery is to achieve adequate decompression while minimizing surgery-related trauma and postoperative spinal instability.
UBE is a novel endoscopic procedure for treating spinal disorders. In UBE, two portals are created on the same side; one is for the optical instrument and irrigation system, and the other is for the surgical instrument used to perform decompression or discectomy. The clear surgical field allows safe and adequate decompression. Unlike PELD, UBE is procedurally and anatomically similar to the traditional surgical process. Experienced surgeons can combine their knowledge of classic spine anatomy with the skill of spine endoscopy. UBE utilizes the natural gap between muscles to avoid unnecessary damage to the spine and associated structures. The advantages of UBE include less damage to the paraspinal musculature, smaller wounds, and better surgical vision. (23, 24) The major challenges in UBE are establishing suitable saline irrigation, minimizing complications, and properly localizing the surgical region (25, 26).
PELD and MED, two commonly applied forms of minimally invasive spinal surgery, have been widely reported to have satisfactory effectiveness and safety. However, conventional open surgery remains the most common treatment for spinal canal stenosis and disc herniation. UBE, as a novel form of minimally invasive spine surgery, requires comparison to mature spine surgery to verify its efficacy and safety.
Pain is the most common chief complaint leading to spine surgery. Therefore, effective pain relief is the goal of most spine surgeries. (27) In most common spine diseases, pain results from compression of the spinal cord or nerve roots. Adequate nerve decompression is the key to achieving a good clinical prognosis. All included studies reported a rapid decrease in pain immediately after UBE surgery, with improvement in VAS scores. UBE also has satisfactory long-term efficacy compared with the perioperative baseline.
In the long-term pain evaluation, no difference was found between UBE and other forms of spinal surgery, such as PELD, MED, and PLIF. UBE, as well as other surgeries, can provide satisfactory pain improvement and quality of life. No difference was observed in long-term pain scores, indicating similar degrees of efficacy between UBE and other surgical procedures. The long-term effects depend on complete decompression around the compressed nerve roots or spinal cord to prevent recurrence. Thus, all the procedures provided sufficient decompression to achieve long-term efficacy.
Regarding ODI outcomes, the pooled analysis indicated no difference between UBE and MED or PELD. The ODI evaluation reflects quality of life after surgery. Pain and other symptoms caused by nerve compression are the major influential factors. In each group, long-term pain improved compared with the perioperative baseline, and the meta-analysis indicated no difference between groups. The similar efficacy of these procedures for pain relief can explain the similar quality of life between groups after surgery.
No difference was found between UBE and PELD or MED regarding instant leg pain relief. Because long-term leg pain was similar between the groups, all procedures provided sufficient relief from nerve compression. Radiating leg pain originates from nerve root compression. Therefore, UBE results in similar leg scores to PELD and MED because of adequate decompression.
All three groups achieved an immediate reduction in back pain compared with the perioperative baseline. For intergroup comparisons, UBE was as effective as PELD and superior to MED. Patients who had undergone UBE had lower VAS back pain scores than those who had undergone MED. Pain scores were not significantly different between the UBE and PELD groups. Long-term back pain analysis indicated that the efficacy of UBE was similar to that of PELD and MED, indicating an adequate degree of nerve decompression in all three groups. Therefore, the difference in VAS back pain scores at 1 day can be attributed to iatrogenic posterior musculoligamentous damage by surgical equipment. The muscle-stripping technique is applied in MED, and the muscle-splitting technique with sequential dilators and a blunt obturator is applied in PELD. UBE combines the muscle splitting and muscle stripping techniques. Splitting, stripping, dissection, retraction and cauterization of ligaments and muscles during surgery lead to iatrogenic pain postoperatively. Ito reported less bone resection in the UBE group than in the MED group. Therefore, regarding surgical damage, UBE is similar to PELD and more favorable than MED. Park did not compare short-term pain scores between UBE and PLIF. In theory, UBE is less invasive than PLIF, but more evidence is needed.
Because UBE is a novel procedure, safety should not be ignored. A pooled analysis reported no difference between UBE and MED or PELD regarding complications. Park reported similar results between UBE and PLIF. However, more evidence is needed to evaluate the comparative safety of UBE and PLIF. In addition to complications, surgeons and patients cannot ignore cumulative radiation exposure. Among PELD, UBE, and MED, Meter reported that PELD entailed the most radiation exposure, followed by UBE and MED. (28) However, high-quality RCTs comparing radiation exposure procedures are lacking.
This study is the first comprehensive summary and meta-analysis of published studies comparing UBE to other forms of spine surgery regarding efficacy and safety. However, several limitations exist as follows: (1) Only papers published in English were included; therefore, studies published in other languages might have been neglected. (2) Because of the limited number of RCTs, both prospective and retrospective studies were included. In contrast to RCTs, prospective and case&#;control studies do not constitute high-grade evidence according to the Cochrane criteria. (3) The follow-up schedules of the included studies were not always adequate. Some studies failed to evaluate 1-day VAS scores. Additionally, the length of follow-up varied from one month to one year after surgery; a follow-up period of one month (Choi ) is not sufficient to evaluate the long-term effects. Hao reported a 6-month follow-up. (4) Traditional open surgeries are important parts of spine surgery. However, only one study in Park reports a comparison between UBE and PLIF, and more clinical trials are needed for further analysis. Additionally, comparison between UBE and traditional open surgery, such as TILF or OLIF, is lacking. This study lacks analysis between UBE and traditional open surgery.
More multicenter RCTs comparing UBE to other forms of spinal surgery, including traditional open surgery and spinal endoscopy, are needed to evaluate the efficacy and safety of UBE.
Spinal endoscopy is increasingly common worldwide. Guidelines should identify major indications and counterindications for UBE and other spinal endoscopic procedures. Minimally invasive surgery aims to minimize damage while maximizing efficacy and safety rather than minimizing the size of the skin incision.
Unilateral biportal endoscopy is superior to MED in the relief of back pain at 1 day postoperatively. One-day leg pain relief, long-term effects and safety are similar between UBE and MED. UBE and PELD are similar regarding 1-day pain relief, long-term effects and safety. More evidence is needed to evaluate the efficacy and safety of UBE compared to PLIF.
The original contributions presented in the study are included in the article/Suplementary Material, further inquiries can be directed to the corresponding author/s.
BZ and SX: These two authors contributed equally to raising the conception of the study, searching and screening articles, processing data of the study, and drafting and reviewing the manuscript. LJ and CG: These authors contributed to the edited manuscript. CL: This author helped reviewed the manuscript. HL: Liu is the correspondence author. Liu supervised whole procession and solved discrepancy. All authors contributed to the article and approved the submitted version.
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.
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