Comparison of lumbar microdiscectomy and unilateral biportal endoscopic discectomy outcomes: a single-center experience

Mehmet İlker Özer Neurosurgery Department, Sincan Training and Research Hospital, Ankara, Turkey

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Oğuz Kağan Demirtaş Neurosurgery Department, Sincan Training and Research Hospital, Ankara, Turkey

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OBJECTIVE

Lumbar microdiscectomy (LMD) is still the gold-standard treatment for lumbar disc herniations with progressive neurological deficits that are refractory to conservative treatment. With improvement of endoscopic systems in recent years, endoscopic discectomy techniques have been developed as an alternative to LMD. The unilateral biportal endoscopic discectomy (UBE) technique is one of these endoscopic techniques, and its popularity has increased in recent years because it does not require high-cost specialized endoscopes, many microsurgical instruments are compatible with this system, and it is similar to LMD in terms of anatomical orientation. This study compared results between LMD and UBE techniques in patients with lumbar disc herniations performed by the same spine surgeons at a single center.

METHODS

The data of patients with lumbar disc herniation who were operated on with LMD and UBE techniques were retrospectively reviewed. The data obtained were statistically evaluated. The operative video of one of the patients who underwent UBE was edited for demonstration.

RESULTS

Between January 2021 and June 2022, 93 patients were operated on for lumbar disc herniation. LMD was performed in 39 patients, and UBE was performed in 54 patients. There were no significant differences in the complications, recurrence, postoperative back and leg pain, patient satisfaction rates, and quality of life index results of the patients in the two groups. The operation time was shorter in the LMD group. In the UBE group, estimated blood loss was lower and postoperative hospitalization was shorter.

CONCLUSIONS

Although LMD is still the gold-standard treatment for lumbar disc herniation, the results of UBE are comparable to those of LMD, and it may be a good alternative for spine surgeons who prefer minimally invasive surgery.

ABBREVIATIONS

LMD = lumbar microdiscectomy; ODI = Oswestry Disability Index; RF = radiofrequency; UBE = unilateral biportal endoscopic discectomy; VAS = visual analog scale.

OBJECTIVE

Lumbar microdiscectomy (LMD) is still the gold-standard treatment for lumbar disc herniations with progressive neurological deficits that are refractory to conservative treatment. With improvement of endoscopic systems in recent years, endoscopic discectomy techniques have been developed as an alternative to LMD. The unilateral biportal endoscopic discectomy (UBE) technique is one of these endoscopic techniques, and its popularity has increased in recent years because it does not require high-cost specialized endoscopes, many microsurgical instruments are compatible with this system, and it is similar to LMD in terms of anatomical orientation. This study compared results between LMD and UBE techniques in patients with lumbar disc herniations performed by the same spine surgeons at a single center.

METHODS

The data of patients with lumbar disc herniation who were operated on with LMD and UBE techniques were retrospectively reviewed. The data obtained were statistically evaluated. The operative video of one of the patients who underwent UBE was edited for demonstration.

RESULTS

Between January 2021 and June 2022, 93 patients were operated on for lumbar disc herniation. LMD was performed in 39 patients, and UBE was performed in 54 patients. There were no significant differences in the complications, recurrence, postoperative back and leg pain, patient satisfaction rates, and quality of life index results of the patients in the two groups. The operation time was shorter in the LMD group. In the UBE group, estimated blood loss was lower and postoperative hospitalization was shorter.

CONCLUSIONS

Although LMD is still the gold-standard treatment for lumbar disc herniation, the results of UBE are comparable to those of LMD, and it may be a good alternative for spine surgeons who prefer minimally invasive surgery.

In Brief

This study demonstrates that unilateral biportal endoscopic discectomy (UBE) is a safe and effective alternative to traditional lumbar microscopic discectomy (LMD) for treating lumbar disc herniation. UBE offers benefits such as shorter hospital stay and reduced postoperative pain while maintaining high patient satisfaction. This research contributes valuable insights into minimally invasive spine surgery techniques, aiding clinicians in making informed treatment decisions.

Lumbar disc herniation is a common disease with symptoms such as low-back and leg pain, numbness, weakness, and claudication that occur after the herniated disc material compresses the spinal nerve roots. Its prevalence varies between 12.2% and 43%.1 Conservative treatments should be applied to patients with mild symptoms and who do not progressively worsen. However, surgical treatment is required for cases where medical treatment is not sufficient and neurological deficits (e.g., motor, sensory) are progressive. Currently, the gold-standard technique is lumbar microscopic discectomy (LMD) with partial laminectomy. The LMD technique may require bone excision, manipulation of neurovascular tissues, and a large defect in the annulus fibrosus. Spinal instability and chronic low-back pain may occur after LMD.2 Unilateral biportal endoscopic discectomy (UBE) is a minimally invasive spinal surgery technique that is increasing in popularity because it can be performed with less damage to bone and muscle tissue, shorter hospital stay, less bleeding, and smaller incisions.3 UBE is the adaptation of conventional arthroscopic systems to spinal diseases.4 Although the arthroscopic discectomy technique was described by Kambin in 1987,12 it took on its modern form after 2010 owing to the advent of high-quality endoscopes in 2007 and more satisfactory results have been obtained. In this study, the results of the gold-standard microscopic surgery technique and the UBE technique, such as pain control, change in quality of life including patient satisfaction, recurrence, and early/late complication at 1 year postoperatively, were compared retrospectively.

Methods

Patient data were collected independently from participants with written informed consent, and the results were analyzed anonymously. The Clinical Research Ethics Committee allowed retrospective data collection by the Ankara Bilkent City Hospital board. The data were obtained from the historical records of the patients. The inclusion criteria were 1) back pain or radiating pain associated with LDH, 2) persistence of symptoms for more than 6 weeks, and 3) availability of MR images that correlated with symptoms. The exclusion criteria were as follows: 1) extraforaminal disc involvement, 2) recurrent LDH, 3) degenerative spinal stenosis, 4) motion instability (defined as > 3 mm translation or > 5° angulation), 5) spondylolisthesis greater than Meyerding grade II, 6) cauda equine syndrome, and 7) comorbid tumorous or infectious disease. The final choice between the two different techniques (LMD or UBE) was made by the patients after they were well informed about the surgical procedures, complications, recurrences, and experiences. Data were collected from the preoperative period to 1 year postoperatively. Pain intensity, patient satisfaction, and quality of life were analyzed using the visual analog scale (VAS), the modified Macnab score, and the Oswestry Disability Index (ODI) at the 6-hour and 3-month postoperative follow-up evaluations. Clinical outcomes were assessed using back and leg scores on VAS (range 0–10) and ODI (0%–100%). Patient satisfaction was assessed using the modified Macnab criteria (excellent, good, fair, and poor). Perioperative data such as operative time (OT), hospital stay after surgery, estimated blood loss, and complications were assessed using video recordings of the endoscopic and microscopic surgical procedures and clinical charts.

Technique

Unilateral Biportal Endoscopic Discectomy

Procedures were performed using with a 30°, 4-mm rigid arthroscope, a 4-mm spherical burr (Stryker), a 3.5-mm radiofrequency (RF) ablation probe (Stryker) and standard open laminectomy tools such as hook dissectors, Kerrison punches, rotating Kerrison punches, and pituitary forceps.

The patient underwent general anesthesia and was placed in the prone position. For C-arm fluoroscopy, the surgical bed was adjusted so that the target intervertebral space was as perpendicular to the floor as possible. A 5-mm transverse incision is made in the cranial pedicle (viewing portal) and a 9-mm transverse incision (working portal) is made in the caudal pedicle, targeting the lower endplate of the vertebra cranial to the herniated disc space. During both incisions, the scalpel is tilted slightly toward the target lamina so that the water can drain well. Both incisions are made approximately 1–1.5 cm lateral to the midline. It is planned to coincide with the midline or inner edge of the pedicle. The bilateral channels were dilated with a step-by-step dilator, allowing the inferior edge of the superior lamina and the interlaminar space to be touched by the dilator (Fig. 1A–C). The surgeon held the arthroscope with their left hand and the instrument with their right hand. For right-sided disc herniations, the surgeon is positioned on the right side of the patient and makes incisions with the viewing portal caudal and the working portal cranial so that they can use their dominant hand (Fig. 1D–E). Through the two channels, the camera lens and the instrument meet in the space around the interlaminar window in a continuous perfusion water environment. After initiating water flow, the surgical teams should place the operating table in the reverse Trendelenburg position to prevent increased intracranial pressure and retinal hemorrhage.

FIG. 1.
FIG. 1.

Demonstration of the triangulation phase. A: Demonstration of left-sided L4–5 triangulation on anteroposterior fluoroscopy. B: Demonstration of L4–5 triangulation on lateral fluoroscopy imaging. C: Photograph of triangulation of the left L4–5 disc. The cranial side has a viewing port, whereas the caudal side has a working port. D: Photograph of triangulation in right-sided disc herniation. There is a working port on the cranial side and a viewing port on the caudal side. E: Demonstration of a right-sided lumbar disc herniation after triangulation. There is a caudal viewing port and a cranial working port. Water flows in through the viewing port and flows out through the working port without any fixed retractor. Irrigation is achieved with the help of gravity by hanging the solution 30–50 cm above the working field. The water outflow is achieved with well-executed triangulation from the viewing port into the low-pressure working port mouth. No fixed retractor is used here. This port’s mouth remains open only with water pressure and muscle relaxation due to anesthesia. Figure is available in color online only.

Structures such as the inferior border of the superior lamina, the root of the spinous process, the superior border of the inferior lamina, the inner border of the facet joint, and the interlaminar ligamentum flavum were exposed with a plasma RF knife (Fig. 2A). The inferior margin of the superior lamina, the superior margin of the inferior lamina, and the medial aspect of the facet joint may be removed with a high-speed spherical drill (Fig. 2B–C). If discectomy is planned without laminectomy at the L5–S1 level, the cranial observation portal can be positioned more caudal to the superior pedicle level to prevent the telescope from getting caught in the superior lamina. Then, the ligamentum flavum was removed (Fig. 2D). The neural structures were slightly retracted with blunt instruments (Fig. 2E) and the intervertebral disc fragment was removed (Fig. 2F). Once appropriate decompression has been confirmed with a blunt probe and there is no visible bleeding, the procedure is complete. Representative cases are shown in Video 1.

FIG. 2.
FIG. 2.

Operative stages of a patient with left-sided L4–5 disc herniation who underwent UBE discectomy. A: Anatomical orientation and recognition of structures after triangulation. B: Inferior partial laminectomy of the L4 lamina with spherical burr. C: Visualization of the ligamentum flavum after successful partial laminectomy. D: Dissection and removal of the ligamentum flavum from medial to lateral and from cranial to caudal. E: Identification of the L5 traversing nerve root and thecal sac, as well as retraction of the neural structures with blunt instruments. F: Mobilization and removal of the intervertebral disc fragment located deep within the neural structures. Figure is available in color online only.

VIDEO 1. UBE discectomy video of a patient with left-sided L4–5 disc herniation. © Oğuz Kağan Demirtaş, published with permission. Click here to view.

Lumbar Microdiscectomy

The patients in the LMD group had a normal 3- to 4-cm-long midline incision placed on the side of the disc herniation, as well as application of the muscle-stripping technique. Then, a Markham-Meyerding retractor was placed. With the use of microscope magnification, the herniated disc was removed after partial laminectomy and flavectomy.

Statistical Analysis

The conformity of the continuous variables to their normal distributions was tested with the Shapiro-Wilk test. Descriptive statistics were used to describe continuous variables (mean ± SD, minimum and maximum, and median). The Mann-Whitney U-test was used to compare two independent and nonnormally distributed variables. The comparison of two independent variables that conformed to a normal distribution was made with Student t-test. The Wilcoxon test was used to compare two dependent and normally distributed variables. The chi-square (or Fisher exact test where appropriate) was used to examine the relationship between categorical variables. The statistical significance level was set at 0.05. Analyses were performed using MedCalc Statistical Software version 12.7.7 (MedCalc Software bvba; http://www.medcalc.org).

Results

In total, 93 patients underwent operations for lumbar disc herniation at Sincan State Hospital between January 2021 and June 2022. Thirty-nine patients (41.9%) underwent microsurgery, while 54 underwent UBE. Forty-two patients (45.2%) were female. Thirty-six patients (38.7%) had right-sided symptoms and disc herniation, while 57 patients (61.29%) had left-sided symptoms. Discectomy was performed in 2 (2.1%) patients at the L2–3 level, 9 (9.6%) patients at the L3–4 level, 50 (53.7%) patients at the L4–5 level, and 32 (34.4%) patients at the L5–S1 level (Table 1). Eight-nine patients had no complications in the early or late postoperative period, whereas 4 patients experienced complications. One patient had temporary blindness in one eye due to retinal hemorrhage (UBE group), 2 had a dural tear (1 UBE and 1 LMD patient), and 1 had thermal damage of the root (LMD patients) that were experienced as complications. Two of the patients operated on with the UBE method and 2 of the patients operated on with the LMD technique underwent reoperations due to recurrence. At the end of the 3rd month, the Macnab score was measured as excellent in 67 (72.04%) patients, fair in 12 (12.9%) patients, good in 11 (11.82%), and poor in 3 (3.22%).

TABLE 1.

General characteristics of the patients and operations

Op CharacteristicNo. (%) of Patients
GroupMicrosurgery39 (41.9)
UBE54 (58.1)
SexMale51 (54.8)
Female42 (45.2)
Level of pathologyL5–S132 (34.4)
L4–550 (53.7)
L3–49 (9.6)
L2–32 (2.1)
SideRt36 (38.7)
Lt57 (61.29)

The mean ± SD age was 43.28 ± 11.38 years in LMD group and 46.04 ± 9.75 years in UBE group, with no difference observed (p = 0.213). The mean OT was 84.69 ± 19.92 minutes for LMD and 109.94 ± 67.4 minutes for UBE, indicating that microsurgery was faster than UBE (p = 0.043). The VAS score for low-back pain at the 6th postoperative hour was 2.76 ± 1.08 in the LMD group and 2.63 ± 1.83 in the UBE group, with no difference observed (p = 0.11). The VAS score for low-back pain at the 3rd postoperative month was 1.67 ± 1.34 in the LMD group and 1.28 ± 1.28 in the UBE group, with no difference observed (p = 0.072). Decrease in low-back pain after surgery was observed within 3 months in both groups (p < 0.001). The mean ± SD preoperative VAS score for leg pain was 7.87 ± 1.1 in the LMD group and 7.54 ± 1.51 in the UBE group (p = 0.321). The VAS score for leg pain at 6 hours postoperatively was 1.46 ± 0.88 in the LMD group and 1.5 ± 1.85 in the UBE group (p = 0.097). The change in VAS score for postoperative leg pain was 6.41 ± 1.16 in the LMD group and 6.037 ± 2.136 in the UBE group, and no difference was observed (p = 0.513). Decrease in radicular leg pain after surgery was observed within 3 months in both groups (p < 0.001). Preoperative ODI score was 73.9 ± 6.71 in the LMD group and 62.5 ± 14.36 in the UBE group (p < 0.001). The ODI score at the 3rd postoperative month was 18.05 ± 17.22 in the microsurgery group and 17.41 ± 13.93 in the UBE group (p = 0.876). ODI change at 3 months postoperatively was 55.84 ± 16.55 in the microsurgery group and 45.09 ± 17.26 in the UBE group (p < 0.001). The preoperative hemoglobin value was 14.16 ± 1.32 g/dl in the LMD group and 14.07 ± 1.69 g/dl in the UBE group (p = 0.635). The hemoglobin value measured at the 2nd postoperative hour was 12.93 ± 1.39 g/dl in the LMD group and 13.03 ± 1.69 g/dl in the UBE group (p = 0.346). The difference between the preoperative and postoperative hemoglobin levels was greater in the microsurgery group (1.22 ± 0.56 g/dl) than in the UBE group (1.03 ± 0.69) (p = 0.003). Postoperative discharge time was longer in the LMD group (23.44 ± 8.26 hours) than in the UBE group (21.5 ± 33.24 hours) (p = 0.003) (Table 2).

TABLE 2.

Comparisons between groups

LMDUBEp Value
Age, yrs43.28 ± 11.38/44 (22–68)46.04 ± 9.75/45 (25–68)0.213*
OT, mins84.69 ± 19.92/80 (60–150)109.94 ± 67.4/95 (20–360)0.043
Back pain
 Preop VAS6.54 ± 1.6/7 (4–10)
 Postop 6th hr2.76 ± 1.08/3 (1–5)2.63 ± 1.83/2 (0–8)0.118
 Postop 3rd mo1.67 ± 1.34/1 (0–6)1.28 ± 1.28/1 (0–5)0.072
 p value<0.001<0.001
Leg pain
 Preop VAS7.87 ± 1.1/8 (6–10)7.54 ± 1.51/8 (4–10)0.321
 Postop 6th hr1.46 ± 0.88/1 (1–4)1.5 ± 1.85/1 (0–7)0.097
 Postop 3rd mo1.14 ± 1.15/1 (0–5)1.10 ± 0.71/1 (0–3)0.61
 p value<0.001<0.001
ODI
 Preop73.9 ± 6.71/74 (60–90)62.5 ± 14.36/63.5 (34–85)<0.001
 Postop 3rd mo18.05 ± 17.22/12 (4–78)17.41 ± 13.93/12 (4–66)0.876
 p value<0.001<0.001
Hemoglobin, g/dl
 Preop14.16 ± 1.32/14.1 (11.6–17)14.07 ± 1.69/14.35 (9.1–17.3)0.635
 Postop12.93 ± 1.39/12.9 (9.1–16.4)13.03 ± 1.69/13.15 (8.2–15.6)0.346
 p value<0.001<0.001
Discharge time, hrs after op23.44 ± 8.26/22 (15–50)21.5 ± 33.24/12.5 (6–240)<0.001

Values are shown as mean ± SD/median (range) unless indicated otherwise. Boldface type indicates statistical significance (p < 0.05).

Determined with the Student t-test.

Determined with the Mann-Whitney U-test.

Determined with the Wilcoxon test.

There was no difference between the proportions of sexes in both groups (p = 0.870). Complications occurred in 2/39 (5.1%) patients in the LMD group and 2/54 (3.7%) patients in the UBE group (p = 0.138) No significant difference was observed in the 3rd postoperative month in terms of the Macnab scores between groups (Table 3).

TABLE 3.

Comparisons of sex, complications, recurrence, and Macnab score between the LMD and UBE Groups

LMDUBEp Value
Sex
 Male21 (53.8)30 (55.6)0.870*
 Female18 (46.2)24 (44.4)
Complication
 No2 (5.1)2 (3.7)0.138
 Yes37 (94.8)52 (96.2)
Recurrence
 Yes2 (5.1)2 (3.7)0.138
 No37 (94.8)52 (96.2)
Macnab score at 3rd mo
 Excellent31 (79.5)36 (66.7)0.623
 Fair4 (10.3)8 (14.8)
 Good3 (7.7)8 (14.8)
 Poor1 (2.6)2 (3.7)

Values are shown as number (%) unless indicated otherwise.

Determined with the Fisher exact test.

Determined with the chi-square test.

Discussion

In recent years, minimally invasive surgical procedures have come to the forefront not only in neurosurgery but also in all surgical branches. Its popularity is increasing due to less postoperative pain, less bleeding, and early discharge times. As awareness increases, the expectation and demand for endoscopic surgery has increased in patients diagnosed with herniated lumbar disc. In this study, we analyzed the advantages and disadvantages of LMD and UBE, a type of minimally invasive spine surgery technique.

Since 2007, the quality of the equipment has significantly increased, especially with regard to the arthroscopic instrumentation systems that are now connected to high-definition TV displays.5 The most striking advantage of the endoscopic technique is the magnified view and image clarity.6 Therefore, neurovascular structures and compression of the herniated disc are better visualized. Decompressing the nerve is easier and has less root extraction. This makes it possible to peel the nerve root from the herniated disc more easily and to perform adequate discectomy without enlarging the posterior longitudinal ligament defect. In addition, epidural adipose tissue excision, which accelerates the development of postoperative scar tissue, is minimized.7

Of course, image quality–enhancing systems, in addition to 30° telescopes, arthroscopic osteotomes, and angled surgical instruments suitable for the endoscopic technique, have been developed.5 Only 30° telescope were used in our operations. Recognizing anatomical structures such as the lamina and medial facet, ligamentum flavum, and spinous process with the 30° telescope was difficult in the first cases. However, after the learning curve is completed, it is possible to complete the surgery with less laminectomy, facetectomy, and flavectomy with the help of angled instruments.8

Because the paravertebral muscles are not stripped from the bone with the UBE technique, but instead passed between the muscle fibers with the help of dilators, muscle damage and long-term muscle atrophy are less common.9 In our study, no significant differences were observed in terms of the early postoperative (6th hour) and late postoperative (3rd month) low-back pain VAS scores between LMD and UBE groups. Although we observed that patients who underwent UBE had less low-back pain during the early postoperative period, we did not find a statistical difference between the two groups. Nevertheless, 3 of 54 UBE patients did not receive any analgesics in early postoperative period, whereas 6 of 39 LMD patients received narcotic analgesics in addition to nonsteroidal anti-inflammatory drugs for low-back pain. Kim et al. announced that they found no significant difference in the low-back pain VAS scores between the two groups in the late period (12 months postoperatively), but they found a significant difference in favor of UBE patients in the early period (1–12 weeks postoperatively).10 There was no difference in postoperative ODI scores between the microdiscectomy and UBE group. Because this study was performed on a relatively small group, it needs to be validated with series with higher patient numbers.

Continuous saline irrigation during surgery helps to establish a possible working space, prevents infection, and also serves as a tamponade against epidural bleeding.4 With the help of high-definition image quality and a closer view, bleeding foci can be quickly detected and hemostasis is ensured with RF ablation. Due to the preservation of the back muscle and a smaller incision, UBE has the advantages over standard LMD in terms of decreased intraoperative blood loss, postoperative back pain, and relatively shorter hospital stay.10 Indeed, in our study, it was observed that the decrease in the hemoglobin values of the UBE patients was less and the discharge time was shorter. Although the discharge time of the 1 patient in the endoscopic group with complications (retinal hemorrhage) was 10 days, we found that the length of hospitalization was significantly shorter in the endoscopic group.

The benefits of UBE include enhanced surgical tool mobility with separate visualization and working portals, a good and wide field of vision, and unrestricted access to the contralateral and foraminal regions.11 High-definition vision makes disc dissection easier, and ruptured fragment excision and manipulation is possible as with the conventional technique. The benefits of interlaminar endoscopy and microscopic surgery are combined in UBE.10 UBE can be defined as hybrid surgery with these characteristics. Because UBE does not require a fixed retractor in the working port, the range of motion is close to the level of lumbar microdiscectomy. This is an advantage of UBE compared with tubular endoscopy and other monoportal techniques that have to work in a fixed working port. The biportal technique is compatible with fusion surgery in the presence of instability after decompression, especially in patients with degenerative stenosis, as it is possible to place interbody cages such as those for transforaminal interbody fusion and extreme lateral interbody fusion. The disadvantages of UBE compared with monoportal techniques are that two different skin incisions are made and the muscles are dilated in two different ports. This may theoretically cause more back pain and muscle damage than monoportal endoscopic systems.

Additionally, tools are utilized for routine laminectomy/microdiscectomy, routine 0° or 30° arthroscopy are utilized for the shoulders and knee cases, and dilatators are the only extra equipment required. Due to the lower cost, UBE is more likely to be widely accepted in limited-resource hospitals because it can be employed with open spinal surgical equipment and general arthroscopic lenses.4,10,11

In our study, we observed that the most important disadvantage in the UBE group was the length of the surgical time. Especially in the first 20 cases (the period when we had not completed our learning curve), we observed that the factors that prolonged the surgical time were as follows: 1) table setup (a waterproof cover is used to prevent the patient from getting wet, and sterile sheathing of the endoscope and arthroscopic burr device are used because there is no low-temperature sterilization); 2) triangulation difficulty (in obese patients, as well as those with poor-quality images on the C-arm scope); 3) inadequate clearance of the spinolaminar junction with the dilator (subsequent attempts are needed to remove soft tissues with RF ablation and disc forceps, and new bleeding may be caused by these procedures); 4) difficulty achieving orientation in the first cases because we used a 30° telescope (i.e., inability to recognize the guiding anatomical structures); and 5) hemostasis.

Kim et al. also emphasized that OT is longer than open surgery and that the most important reason for this is bleeding control.10 Soliman, in his study describing the technique, stated that its OT is similar to that of open surgery, especially after completing the learning curve.4 In our series, we found that the OT was significantly shortened as our experience increased. We shortened the preparation time with the provision of an appropriate endoscopy drape and gas plasma sterilization system (low temperature sterilization of the plastic and electrical instruments). As experience increased, triangulation, perilaminar soft-tissue cleaning (multifidus muscle), and achieving anatomical orientation became faster. After good triangulation—when the viewing portal and working portal meet in the same working space at the spinolaminar junction and thus the inflow-outflow is perfect—the tamponade effect of the water pressure on the epidural vascular structures solves the bleeding problem to a great extent. Of course, knowing the vascular anatomy of the region (superior and inferior articular artery, interarticular artery, and radicular artery) also facilitates hemostasis. Considering these suggestions, we believe that the OT is not a disadvantage and that the UBE technique may even be faster than open surgery.

In our study, we found no significant difference between the two techniques in terms of complications. Recurrence developed in 2 patients who underwent operations endoscopically and recurrence surgery was performed with the endoscopic technique. No CSF leakage or infection was observed in patients with dural injury. The most serious complication of the UBE technique was transient visual impairment or retinal hemorrhage, which we observed in 1 patient due to increased intradural pressure owing to increased water pressure. During this case, the height of the water was increased due to the large amount of epidural bleeding and imperfect triangulation. With the increase in epidural pressure, the patient showed signs of increased intracranial pressure, including a sudden increase in blood pressure and bradycardia during the 20th minute of the operation. At this point, the water inflow was stopped, dilatators were reinserted, water outflow was restored, and the surgery was continued and terminated in a total of 45 minutes. When the patient woke up, he described severe nuchal pain and bilateral visual blurring. After ophthalmological examination, bilateral retinal hemorrhage was detected and laser photocoagulation was performed. During follow-up, the patient’s vision completely recovered. In order to prevent this situation, which we also experienced at the beginning of the learning curve, it is necessary to apply the reverse Trendelenburg position to the operating table in order to make sufficient dilatation while preparing the working portal in triangulation, as well as to work in a way that saline outflow is perfect. It is assumed that an automatic pump that measures pressure is more secure. When the operation exceeds 1 hour, saline infusion is turned off for a while10 and epidural pressure is briefly reduced. If pressure decrease cannot be achieved, switching to microsurgery should not be avoided. If the triangulation is not done well, the water inflow and outflow are separated by the small muscles. For this reason, two separate water cavities are formed at the viewing and working ports, and a small portion of the water exits through the skin while most of it is trapped inside. This results in serious complications due to increased epidural pressure. Therefore, good triangulation is the most critical point of this technique.

The retrospective nature, lack of a randomized control group, small sample size, and short follow-up period are the limitations of this study. In addition, biochemical values such as creatine kinase and C-reactive protein could have been used for biochemical proof of less muscle damage. Another limitation is that because we do not have a pump irrigation system in our clinic, saline irrigation was performed with the help of gravity; therefore, epidural pressure could not be measured. Due to the small number of cases, the surgical procedures performed before the learning curve were completed and included in the endoscopic group. A detailed examination of the advantages and disadvantages of the UBE technique against gold-standard LMD is an influential aspect of the study.

Conclusions

UBE may be an alternative to lumbar microdiscectomy for surgeons who want to perform minimally invasive spinal surgery. Naturally, adequate randomized prospective studies of UBE are needed to confirm the outcomes of the present study. We believe that minimally invasive spine surgery methods should be standardized in residency training.

Disclosures

The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

Author Contributions

Conception and design: both authors. Acquisition of data: both authors. Analysis and interpretation of data: both authors. Drafting the article: Demirtaş. Critically revising the article: Özer. Approved the final version of the manuscript on behalf of both authors: Demirtaş. Statistical analysis: Demirtaş. Study supervision: both authors.

Supplemental Information

Videos

Video 1. https://vimeo.com/871873632.

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    Alonge EO, Guo C, Wang Y, Zhang H. The mysterious role of epidural fat tissue in spine surgery: a comprehensive descriptive literature review. Clin Spine Surg. 2023;36(1):1-7.

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    • Export Citation
  • 8

    Heo DH, Lee DC, Park CK. Comparative analysis of three types of minimally invasive decompressive surgery for lumbar central stenosis: biportal endoscopy, uniportal endoscopy, and microsurgery. Neurosurg Focus. 2019;46(5):E9.

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    • Export Citation
  • 9

    Heo DH, Lee N, Park CW, Kim HS, Chung HJ. Endoscopic unilateral laminotomy with bilateral discectomy using biportal endoscopic approach: technical report and preliminary clinical results. World Neurosurg. 2020;137:3137.

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    • Export Citation
  • 10

    Kim SK, Kang SS, Hong YH, Park SW, Lee SC. Clinical comparison of unilateral biportal endoscopic technique versus open microdiscectomy for single-level lumbar discectomy: a multicenter, retrospective analysis. J Orthop Surg Res. 2018;13(1):22.

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  • 11

    Lin GX, Huang P, Kotheeranurak V, et al. A systematic review of unilateral biportal endoscopic spinal surgery: preliminary clinical results and complications. World Neurosurg. 2019;125:425432.

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    • Search Google Scholar
    • Export Citation
  • 12

    Kambin P, Brager MD. Percutaneous posterolateral discectomy. Anatomy and mechanism. Clin Orthop Relat Res. 1987;223:145154.

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Images from Özer and Demirtaş (pp 351–358).
  • FIG. 1.

    Demonstration of the triangulation phase. A: Demonstration of left-sided L4–5 triangulation on anteroposterior fluoroscopy. B: Demonstration of L4–5 triangulation on lateral fluoroscopy imaging. C: Photograph of triangulation of the left L4–5 disc. The cranial side has a viewing port, whereas the caudal side has a working port. D: Photograph of triangulation in right-sided disc herniation. There is a working port on the cranial side and a viewing port on the caudal side. E: Demonstration of a right-sided lumbar disc herniation after triangulation. There is a caudal viewing port and a cranial working port. Water flows in through the viewing port and flows out through the working port without any fixed retractor. Irrigation is achieved with the help of gravity by hanging the solution 30–50 cm above the working field. The water outflow is achieved with well-executed triangulation from the viewing port into the low-pressure working port mouth. No fixed retractor is used here. This port’s mouth remains open only with water pressure and muscle relaxation due to anesthesia. Figure is available in color online only.

  • FIG. 2.

    Operative stages of a patient with left-sided L4–5 disc herniation who underwent UBE discectomy. A: Anatomical orientation and recognition of structures after triangulation. B: Inferior partial laminectomy of the L4 lamina with spherical burr. C: Visualization of the ligamentum flavum after successful partial laminectomy. D: Dissection and removal of the ligamentum flavum from medial to lateral and from cranial to caudal. E: Identification of the L5 traversing nerve root and thecal sac, as well as retraction of the neural structures with blunt instruments. F: Mobilization and removal of the intervertebral disc fragment located deep within the neural structures. Figure is available in color online only.

  • 1

    Konstantinou K, Dunn KM. Sciatica: review of epidemiological studies and prevalence estimates. Spine (Phila Pa 1976). 2008;33(22):2464-2472.

  • 2

    Carragee EJ, Han MY, Suen PW, Kim D. Clinical outcomes after lumbar discectomy for sciatica: the effects of fragment type and anular competence. J Bone Joint Surg Am. 2003;85(1):102-108.

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  • 3

    Ahn Y, Lee SH, Park WM, Lee HY, Shin SW, Kang HY. Percutaneous endoscopic lumbar discectomy for recurrent disc herniation: surgical technique, outcome, and prognostic factors of 43 consecutive cases. Spine (Phila Pa 1976). 2004;29(16):E326-E332.

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  • 4

    Soliman HM. Irrigation endoscopic discectomy: a novel percutaneous approach for lumbar disc prolapse. Eur Spine J. 2013;22(5):1037-1044.

  • 5

    Gibson JNA, Cowie JG, Iprenburg M. Transforaminal endoscopic spinal surgery: the future ‘gold standard’ for discectomy? A review. Surgeon. 2012;10(5):290-296.

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  • 6

    Heo DH, Quillo-Olvera J, Park CK. Can percutaneous biportal endoscopic surgery achieve enough canal decompression for degenerative lumbar stenosis? Prospective case-control study. World Neurosurg. 2018;120:e684e689.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 7

    Alonge EO, Guo C, Wang Y, Zhang H. The mysterious role of epidural fat tissue in spine surgery: a comprehensive descriptive literature review. Clin Spine Surg. 2023;36(1):1-7.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 8

    Heo DH, Lee DC, Park CK. Comparative analysis of three types of minimally invasive decompressive surgery for lumbar central stenosis: biportal endoscopy, uniportal endoscopy, and microsurgery. Neurosurg Focus. 2019;46(5):E9.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 9

    Heo DH, Lee N, Park CW, Kim HS, Chung HJ. Endoscopic unilateral laminotomy with bilateral discectomy using biportal endoscopic approach: technical report and preliminary clinical results. World Neurosurg. 2020;137:3137.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 10

    Kim SK, Kang SS, Hong YH, Park SW, Lee SC. Clinical comparison of unilateral biportal endoscopic technique versus open microdiscectomy for single-level lumbar discectomy: a multicenter, retrospective analysis. J Orthop Surg Res. 2018;13(1):22.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 11

    Lin GX, Huang P, Kotheeranurak V, et al. A systematic review of unilateral biportal endoscopic spinal surgery: preliminary clinical results and complications. World Neurosurg. 2019;125:425432.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 12

    Kambin P, Brager MD. Percutaneous posterolateral discectomy. Anatomy and mechanism. Clin Orthop Relat Res. 1987;223:145154.

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