Treatment for lumbar disc herniation with spinal stenosisto using unilateral biportal endoscopy technique:a retrospective study

Result: The operation time of the UBE group was better than that of the PEID group (P<0.05). Based on the comparative analysis between the two groups, both the ODI score and the pain index were not statistically significant (P>0.05) but the intra-group comparison before and after the treatment was statistically significant (P<0.05). No marked intraoperative and postoperative complications occurred in the UBE group. In the PEID group, one patient developed transient pain in the lower extremities 3 days after surgery, while another patient developed numbness and discomfort in the lower extremities. Both groups were treated conservatively and recovered. During the follow-up, there were no serious adverse events that required another operation.


Introduction
Lumbar disc herniation (LDH) clinically manifests with waist and leg pain due to the compression and stimulation of the surrounding tissues or nerve roots due to the lumbar disc degeneration, backward protrusion of nucleus pulposus or the emergence of nucleus pulposus after the rupture of intervertebral disc annulus fibrosus [1].
Meanwhile, due to the posterior protrusion of the nucleus pulposus, thickening of the ligamentum flavum and bone hyperplasia of the articular process, the space of the spinal canal is further reduced, which causes spinal stenosis to further aggravate waist and leg pain and even intermittent claudication [2]. Most scholars believe that a strict and rigorous systematic treatment plan from conservative treatment to final surgical treatment is required for LDH [3]. Patients with persistent pain after strict conservative treatment require surgical treatment [4][5]. Percutaneous endoscopic lumbar discectomy (PELD) is a rapidly developing new type of minimally invasive spinal surgery (MISS). Due to its advantages of a small incision, low blood loss, short hospital stay and exact curative effect, it has been affirmed and favored by a wide range of clinical surgeons in the treatment of LDH, spinal canal stenosis and even spinal fusion [6][7][8]. There are several surgical methods for percutaneous endoscopic technique, which are becoming more mature. However, each surgical method has its limitations. Regardless of the type of surgical approach of PELD, it is a single entrance (the observation and the operation ports are the same entrance).It is the same entrance in a tubular working sheath, and the co-axial relationship makes the visualization of the operation greatly restricted. Although the surgical field is microscopically enlarged, part of the field remains blocked, especially when a huge nucleus pulposus prolapses; the prolapsed nucleus pulposus is free to the posterior edge of the upper or lower vertebral body. Especially severe spinal canal stenosis and bilateral stenosis require decompression, it is difficult and challenging for surgeons [9][10][11] [12][13][14]. Although UBE has gradually attracted the attention of most scholars, large-scale multi-center studies that strongly ratify the long-term efficacy of the operation are scarce. Additionally, comparative studies on UBE and Percutaneous endoscopic interlaminar discectomy (PEID) in the treatment of LDH are extremely rare. Herein, we explore and analyze the effectiveness and safety of UBE and PEID in the treatment of LDH with spinal stenosis to provide a reference for the application of UBE in the treatment of such diseases.   Meanwhile, the protruding intervertebral disc tissue was shrunk, and the intervertebral foramen was explored. If the stenosis was still persistent, the upper and the lower articular processes of the excised part were enlarged by the isthmus. If a patient had bilateral spinal canal stenosis, the working sheath was withdrawn from the spinal canal, part of the spinous process was removed, the working sheath was pushed into the opposite spinal canal from under the spinous process, the yellow ligament and prominent nucleus pulposus were removed and the intervertebral foramen was explored. Additionally, the patient was carefully examined for any sign of active bleeding after removing part of the upper and the lower articular processes. When the nerve root was loose and active and the dural sac was pulsatile, the patient withdrew corresponding author: Zhichao Gao Email: leadyourdream@163.com from the endoscope and the working channel. The incision was then sutured. sheath and the inner core were placed through the observation channel and the inner core was pulled out and placed into the arthroscope (Fig.2). The dilator was gradually inserted through the working incision to expand the soft tissue, form a working channel, open the perfusion system and continue the normal saline irrigation. The soft tissue structures obstructing the line of sight were cleaned and bleeding was stopped using a plasma radiofrequency knife to expose the bony tissue structure of the first field of view under the microscope, i.e., the junction of the spinous process and the lower edge of the upper vertebral body. This structure was also the initial target point for endoscopes and decompression devices. The operator operated with both hands and the left hand held the arthroscope. The arthroscope direction was adjusted to fully expose the surgical field. The instrument was operated with the right hand under the direct view of an endoscope. The bony laminae and the soft tissues on the surface of the ligamentum flavum were separated using a plasma radiofrequency knife and the inner edge of the articular process joint was exposed to the outside and the underside (Fig.3). The arthroscope was adjusted to expose the bony structure at the was carefully stopped using a plasma radiofrequency knife to fully expose the intervertebral disc and remove the nucleus pulposus tissue (Fig.3). Observation under the microscope showed that the intraspinal dural sac had normal pulsation and external blood vessels were full, the nerve roots recovered to the normal shape and path, and there was no significant compression at the outlet (Fig.3). There was also no significant hemorrhage. After the instruments and the arthroscope were removed, residual lavage fluid was removed, the incision was sutured and the drainage tube was retained.

Postoperative treatment and rehabilitation management
All patients were treated with postoperative neurotrophic therapy and patients corresponding author: Zhichao Gao Email: leadyourdream@163.com with postoperative acute pain were treated with non-steroidal anti-inflammatory drugs (NSAIDs). The patient was advised to get out of bed with waist circumference for 1~3 days after the operation. Strenuous exercise was not recommended, and bed rest was still advocated. Bed rest was still advocated. Additionally, the patient was required to avoid weight-bearing bending and twisting of the waist, as well as the moderate exercise of the lower back muscle.

Outcome measures
All patients underwent magnetic resonance imaging (MRI) and computed tomography (CT) examinations on the second postoperative day (Fig.1) The VAS and ODI scores at different time points before and after the operation were compared using one-way repeated measures analysis of variance (ANOVA). The t-test was used for comparison between the two groups. A p-value of <0.05 was considered significant, and all tests were 2 sided.

Patient demographic features
In the UBE group, there were 20 patients (14 males and 6 females) aged 55.80 ± 17.99 years old, including 7 and 13 cases at the L4/L5 and L5/S1 surgical segments, respectively. In the PEID group, there were 20 patients (15 males and 5 females) aged 39.89 ± 12.81 years old, including 8 and 12 cases at the L4/L5 and L5/S1 operation segments, respectively. There was no significant difference in basic information between the two groups. Demographic features of the patients are shown in Table 1. L5-S1 (n) 12 13

Comparison of surgical indexes between two groups
In the UBE group, the operation time and the hospital stay were 54.5 ± 13.67 minutes and 5.15 ± 2.01 days, respectively. In the PEID group, the operation time and the hospital stay were 64.8 ± 15.51 minutes and 5.8 ± 3.37 days, respectively.
The operation time in the UBE group was better than that in the PEID group (P<0.05) (Fig.4), and the hospitalization days between the two groups had no significant corresponding author: Zhichao Gao Email: leadyourdream@163.com difference (P>0.05).

Comparison of VAS scores of back pain between the two groups
The preoperative back pain scores in the UBE and the PEID groups were 5.75 ± 0.91 and 5.35 ± 0.99, respectively but there was no significant difference between the two groups (P>0.05). The back pain scores of patients in the two groups after the operation were significantly improved as compared with those before the operation. The 1-day, 3-month and last follow-up scores in the UBE group were 3.35 ± 0.90, 2.45 ± 0.61 and 1.25 ± 0.55, respectively, while scores in the PEID group were 3.3 ± 0.57, 2.45 ± 0.51 and 1.45 ± 0.51, respectively. The postoperative pain in both groups was significantly lower than that before surgery (P<0.05) but there was no significant difference between the two groups (P>0.05) (Fig.4).

Comparison of VAS scores of leg pain between the two groups
The preoperative leg pain scores in the UBE and the PEID groups were 7.15 ± 0.99 and 7.15 ± 0.99, respectively, with no significant difference between the two groups (P>0.05). The leg pain scores of the two groups after the operation were also significantly improved as compared with those before the operation. The 1-day, 3-months and last follow-up scores in the UBE group were 3.15 ± 0.59, 2.3 ± 0.47 and 1.35 ± 0.59, respectively, while scores in the PEID group were 3.35 ± 0.59, 2.55 ± 0.51 and 1.5 ± 0.51, respectively. Postoperative pain in both groups was significantly lower than that before surgery (P<0.05) but there was no significant difference between the two groups (P>0.05) (Fig.4) .

Comparison of ODI dysfunction index between the two groups
The ODI score of the preoperative UBE group was 69.6 ± 4.88, while that of the PEID group was 69.6 ± 4.88 but there was no significant difference between the two groups (P>0.05). The scores in the UBE group at 3 months after surgery and the improved as compared with those before surgery (P<0.05) but there was no significant difference between the two groups (P>0.05) (Fig.4).
There was no significant difference between the two groups (P>0.05).   [17]. However, the transforaminal technique exposed its shortcomings in the presence of a narrow foramen at the L5/S1 segment, hypertrophy of the transverse process of the lumbar 5 vertebral body and high iliac crest obstruction. Therefore, in 2006, Professor Ruetten [18] proposed the intervertebral approach based on the limitations of the transforaminal technique, making the endoscopic technology mature.

Complications
It is undeniable that percutaneous endoscopy has its unique advantages in MISS invasive spinal surgery, but some problems still remain exposed in daily surgery. First, the safe and effective puncture positioning technology enables most surgeons to learn a steep rise in the curve [19,20].  [11,21,22] days and 80%, respectively, which are similar to our current study [12]. However, the incidence of surgical complications in our patients was 0%, which was superior to the current average incidence of surgical complications. The lack of surgical complications could be attributed to the small sample size of our previous study, which was also a major defect in the study. The average operation time in the present study was 54.5 ± 13.67 minutes, which was shorter than the 79.2 minutes in our previous study [12]. This may be due to our rich previous The UBE technology can be used not only in the treatment of LDH and spinal canal stenosis [14,25] but also in the treatment of lumbar spine fusion [26], distal syndrome [27] and cervical disc herniation [28]. Although its minimally invasive advantages are gradually accepted by most scholars, its disadvantages cannot be overlooked. surgery and could bring a series of conveniences, more blood oozing from the bone surface is inevitable. Although radio frequency technology can be utilized to stop bleeding and bone wax, gelatin sponge and brain cotton applied in compression hemostasis, hemostasis may not be completely achieved; the water medium mixed with blood is more turbid than the air medium, thus blurring the surgical field of view.
Moreover, if there is more bleeding after surgery, the spinal hematoma is likely to be formed, hence the need to place an incision drainage tube after routine surgery.
Our insights into the UBE technology are focused on the following: (1) Arthroscopic radiofrequency can be used at the junction of the spinous process and should be performed on the cephalic side using a 30-degree arthroscope to operate after clear tissue identification is ensured. When treating the ipsilateral intervertebral foramen, the arthroscope can be erected to vividly observe the condition of the ipsilateral intervertebral foramen and perform the treatment according to needs. For scholars who are not familiar with the 30-degree arthroscope, the 0-degree arthroscope can still be used but the scope of the operation field is smaller than that of the 30-degree arthroscope.