Comparison of the Clinical Effect of Simple Nucleotomy for the Treatment of Single-segment Lumbar Disc Herniation Using a Microscope and Percutaneous Transforaminal Endoscope


 Objective: To compare the clinical effect of single-segment lumbar intervertebral herniation with simple nucleotomy using a microscope and percutaneous transforaminal endoscope. Methods: From May 2016 to October 2018, a total of 120 patients who underwent simple nucleotomy in our hospital for single-segment lumbar disc herniation were selected. According to the surgical methods, they were randomly divided into 2 groups: the microscopical treatment group included 60 cases, aged 28-65 years, with an average of 48.73 ± 12.35 years; the percutaneous transforaminal endoscopic treatment group included 60 cases, aged 29-67 years, with an average of 49.36 ± 11.76 years. The differences in the JOA score, ODI index, VAS score, serum CPK content, operation time, intraoperative bleeding, incision length, intraoperative X-ray fluoroscopy, hospital stay, and 1-year recurrence (secondary revision surgery) between the two groups were analysed. Results: On the second day after surgery, the serum CPK contents were higher than before surgery in both groups (P<0.01), and the CPK content was higher in the microscopical treatment group than in the percutaneous endoscopic treatment group (P<0.01). The JOA score at 1 year after surgery was significantly higher than before surgery, and the ODI index and VAS score at 1 year after surgery were significantly lower than before surgery in each group (P<0.01). Compared with the percutaneous endoscopic treatment group, the intraoperative bleeding and the lengths of incision and hospital stay were significantly increased (P<0.01) and the operation time (P<0.05) and number of X-ray fluoroscopies during the operation (P<0.01) were significantly reduced in the microscopic treatment group. At 1 year after surgery, compared with the microscopic treatment group, 2 cases of complications were found in the percutaneous endoscopic surgery group. One case was a postoperative recurrence, and the other one case was endoscopic operative failure, which received a second revision surgery using a microscope. Conclusion: Simple nucleotomy for the treatment of single-segment lumbar intervertebral herniation has good clinical effects using a microscope and percutaneous transforaminal endoscope. The percutaneous transforaminal endoscope has the advantages of less trauma, less bleeding, and shorter hospital stay, while the microscope has the advantages of shorter operation time and less intraoperative X-ray fluoroscopy.

at 1 year after surgery was significantly higher than before surgery, and the ODI index and VAS score at 1 year after surgery were significantly lower than before surgery in each group (P<0.01). Compared with the percutaneous endoscopic treatment group, the intraoperative bleeding and the lengths of incision and hospital stay were significantly increased (P<0.01) and the operation time (P<0.05) and number of X-ray fluoroscopies during the operation (P<0.01) were significantly reduced in the microscopic treatment group. At 1 year after surgery, compared with the microscopic treatment group, 2 cases of complications were found in the percutaneous endoscopic surgery group. One case was a postoperative recurrence, and the other one case was endoscopic operative failure, which received a second revision surgery using a microscope. Conclusion: Simple nucleotomy for the treatment of single-segment lumbar intervertebral herniation has good clinical effects using a microscope and percutaneous transforaminal endoscope. The percutaneous transforaminal endoscope has the advantages of less trauma, less bleeding, and shorter hospital stay, while the microscope has the advantages of shorter operation time and less intraoperative X-ray fluoroscopy.
[Key words] Lumbar disc herniation; Microscope; percutaneous transforaminal endoscope; Simple nucleotomy; Single-segment Lumbar disc herniation is one of the most common degenerative diseases of the spine, often causing low back pain and corresponding neurological symptoms in the innervation area [1] . Generally, surgical treatment is required if regular conservative treatment for 3-6 months is invalid [2] . In 1977, Yasargil [3] and Caspar [4] reported that the nucleus pulposus was removed under the microscope. Although it is still regarded as the gold standard for surgical treatment of lumbar disc herniation [5] , there may still be some complications, such as instability caused by excision of the articular joint and extensive epidural fibrosis [6] . Since the application of percutaneous transforaminal endoscopic technology in recent years [7][8] , it has become more mature, with the characteristics of local anaesthesia surgery, less trauma, less bleeding, fast recovery, and shorter hospital stay [9] , but there may still be risks of nerve root injury, dural tear and postoperative recurrence [2] . To further explore the efficacy of two surgical methods for the treatment of lumbar disc herniation, this article analysed retrospective studies from May 2016 to October 2018 in our department. A total of 120 patients with single-segment lumbar disc herniation were treated by simple nucleus pulposus removal, and the clinical effects of two surgical methods for the treatment of singlesegment lumbar disc herniation were compared.

Materials and Methods
From May 2016 to October 2018, a total of 120 patients were treated in the orthopaedics department of Pudong New Area Gongli Hospital due to single-segment lumbar disc herniation. All the cases were diagnosed with single-segment lumbar disc herniation with clinical symptoms, signs, and imaging examinations and regular conservative treatment for 3-6 months was ineffective. The cases were randomly divided into 2 groups according to the operational method: a microscopic group, aged 28-65 years, with an average of 48.73±12.35 years; and a percutaneous transforaminal endoscopic group, ages 29-67 years, with an average of 49.36±11.76 years; there were 60 patients in each group.

Inclusion and exclusion criteria
Inclusion criteria (1) Patients with single-segment lumbar disc herniation; (2) All the patients signed an informed consent to the surgical treatment plan.
Exclusion criteria (1) Patients with lumbar disc herniation with two or more segments; (2) Patients with lumbar spondylolisthesis and unstable segments.
The implementation of the research plan complies with the relevant ethical requirements of Shanghai Pudong New Area Gongli Hospital.

Surgical methods
At the time of admission, all the relevant examinations were completed. Routine Xray radiography, three-dimensional reconstruction CT and MRI examination of the lumbar spine were performed. After a joint consultation with three senior spine surgeons, the segment, type, and location of lumbar disc herniation were identified. a bevel-ended working cannula was inserted into the disc along the cannulated obturator, and the obturator was removed; (6) an endoscope was then inserted into the bevel-ended working cannula to explore the surrounding situation of the target disc;

Microscopic nucleotomy
(7) the prominent nucleus pulposus was removed with endoscopic forceps; (8) haemostasis was attempted by bipolar radiofrequency to repair the fibrous annulus; (9) the endoscope was withdrawn after the herniated fragment was removed; (10) the incision was closed with a sterile suture; and (11) off-bed activities could be performed on the second day after the surgery under the protection of waist support.
Postoperative treatment After the operation, the patient was asked to rest in bed and was treated symptomatically, such as swelling and neurotrophic symptoms. On the third day after surgery, the patient began to practice walking with waist protection and increased the amount of daily activities in a gradual manner. It was suggested that the patient should avoid weight-bearing for the waist and back and engaging in vigorous physical exercise within 3 months after surgery.
Creatine phosphokinase The content of serum CPK [10] was detected on the second postoperative day. The differences in perioperative indexes, such as operation time, intraoperative bleeding, incision length, number of X-ray fluoroscopies during surgery, length of hospital stay, and recurrence after 1 year (secondary operation) were observed.

Efficacy evaluation
Japanese Orthopedic Association (JOA) score [11] Low back pain, including subjective symptoms, objective findings, daily life limitations and bladder function assessment, was evaluated. The highest score is 29 points, and the lowest score is 0 points. The lower the score, the more obvious the dysfunction.
Oswestry Disability Index (ODI) [12] The lumbar function and short-term postoperative efficacy were evaluated. A total of 10 items were assessed, each with a score of 0 to 5 points; the highest score is 50 points; ODI = actual score / 50*100%.
The higher the score, the more obvious the dysfunction. [13] The pain levels in the waist, leg and wound were assessed. Ten points represents the most severe pain, and 0 points represents no pain.

Statistical method
The data are expressed as x±s. The comparison between the 2 groups was performed by independent sample t test, and the comparison between before and after operation was performed by paired t test. At the test level of α=0.05, P<0.05 was considered statistically significant.

General information
There was no significant differences in gender, age or surgical segment between the 2 groups (P>0.05) ( Table 1).

Serum CPK test
On the second day after surgery, the serum CPK contents in both groups were significantly higher than those before surgery (P<0.01), and the content in the microscopic group was significantly higher than that in the percutaneous transforaminal endoscopic group (P<0.01) ( Table 2).    Table 4).

Typical cases
At the 1 year postoperative follow-up, in the percutaneous transforaminal endoscopic group, 1 patient had relapsed and was discharged after conservative treatment (Fig 1); 1 patient failed surgery and underwent a second revision using a microscope (Fig 2). There was no postoperative recurrence or secondary revision surgery in the microscopic group (Table 4).

Microscope and percutaneous transforaminal endoscope are safe and effective treatments for lumbar disc herniation
The microscope was first applied to lumbar discectomy surgery in the 1970s [3][4] . Compared with open surgery under the naked eye, the microscope had obvious advantages in spinal surgery [14] , and it is still the gold standard for surgical treatment of lumbar disc herniation [5] . The percutaneous transforaminal endoscopic technology has been applied to lumbar discectomy since the beginning of the 21st century [7][8] . It has the advantages of less trauma, less bleeding, and shorter hospital stay [9] . The two surgical techniques work differently, and there are many differences in the specific operational processes. The main differences between the microscope and percutaneous transforaminal endoscope [15][16] are as follows: (1) Imaging: the former is three-dimensional imaging, and the latter is a two-dimensional plane; (2) Operational mode: the former is direct vision, and the latter is reverse video; (3) Surgical field of view: the former is large, and the latter is small; (4) Operational space: the former is sufficient, and the latter is limited; (5) Operational cooperation: the former can cooperate tacitly in the same field of view by two surgeons, and the latter is completed independently; (6) The indications for surgery of the former are broader than the latter. In this study, at the 1-year follow-up, the JOA scores, ODI indexes and VAS score of the two groups were significantly improved compared with those before surgery, and the difference was statistically significant. There were no significant differences in the JOA scores, ODI indexes and VAS scores between the two groups, whether before or after surgery. There were no complications, such as nerve root injury, dural tear, infection, and lumbar spine instability in both groups, suggesting that both microscope and percutaneous transforaminal endoscope are safe and effective treatments for lumbar disc herniation.

Serum Creatine phosphokinase (CPK) content is a sensitive indicator for evaluating the degree of paravertebral muscle injury after spinal surgery
Previous studies have shown that serum CPK levels increased most significantly during lumbar spine fusion surgery but also increased to varying degrees during minimally invasive lumbar spine surgery [17] and generally return to normal levels within a week after surgery [10] . This study showed that on the second day after surgery, the serum CPK contents of the 2 groups were significantly higher than before.
The increased value of the microscopic group was significantly higher than that of the percutaneous transforaminal endoscopic group, and the difference was statistically significant, which was essentially consistent with the previous research results. In addition, some scholars have found that the postoperative serum CPK content of male patients is much higher than that of females due to their higher muscle tissue content [18] ; however, in this study, there was no significant difference between the serum CPK content of males and females, whether before or after surgery. For patients with high risk of lumbar spine surgery, some scholars suggest taking dynamic and systematic measurements of CPK contents and establishing a standard measurement interval to assess the degree of muscle injury more effectively [19] . Further research is needed in future work.

Postoperative recurrence and failure of endoscopic surgery often occur in the treatment of lumbar disc herniation with percutaneous transforaminal
endoscope Percutaneous transforaminal endoscopic surgery is excellent for the treatment of lumbar disc herniation [20] , but recurrence after surgery and failure of endoscopic surgery have occurred [21] . Postoperative recurrence is one of the most common complications of percutaneous transforaminal endoscopic surgery, which is generally defined as the protrusion of the same area of the intervertebral disc that was last surgically removed after a period of improvement of the postoperative symptoms, with an incidence of approximately 5.8-6.2% [22][23][24] . As the most heavily loaded segment, the recurrence rate of the L4/5 intervertebral disc after percutaneous transforaminal endoscopic nucleotomy is the highest, but it may also be related to the fact that most surgical segments of percutaneous transforaminal endoscopic nucleotomy are at the L4/5 level [25] . In this study, there was 1 case of recurrence in the percutaneous transforaminal endoscopic group. An elderly man after simple nucleotomy of L4/5 intervertebral disc herniation accidentally sprained his waist more than one month after the operation and appeared to have symptoms similar to his preoperative neurological symptoms. He refused the second revision and was discharged after conservative treatment. The definition of endoscopic surgery failure [26] is as follows: (1) persistent neurostimulation symptoms within 2 weeks after surgery that require a second revision surgery; (2) no significant improvement in postoperative pain symptoms; and (3) imaging confirmed residual nucleus pulposus fragments. In this study, an elderly obese woman with L5/S1 intervertebral disc herniation (BMI of 28.62 kg/m 2 ) in the percutaneous transforaminal endoscopic group experienced pain and numbness in the left lower limb from the first day after surgery.
Postoperative MRI showed that the residual nucleus pulposus fragments remained on the left side of the L5S1 intervertebral space, which met the diagnostic criteria for endoscopic surgery failure. The second revision surgery using the microscope was performed on the 13th postoperative day, and the symptoms of pain and numbness in the left lower limb disappeared. In addition to the obesity factor [25] , the patient may have a greater relationship with the L5/S1 intervertebral space. Although the percutaneous transforaminal endoscopic technique has made great progress in the treatment of lumbar disc herniation, it is still very challenging to perform in the L5/S1 intervertebral space, mainly due to its unique anatomy, including the blocking of the iliac crest, huge facet joints and inclined intervertebral spaces; sometimes, the establishment of a bone tunnel on the iliac crest was required, resulting in increased difficulty and failure of the operation [27] . In this study, there were fewer cases of L5/S1 intervertebral space in the percutaneous transforaminal endoscopic group than in the microscopic group, which was also related to the above reasons. The author recommends that for patients with L5/S1 disc herniation, the imaging data should be fully evaluated before surgery, and percutaneous transforaminal endoscopic surgery should be carefully selected.

Limitations and deficiencies of this study
In this study, due to many shortcomings, such as the design of the experimental study and the number of samples, it is necessary to use multi-centre, large-sample, prospective cohort studies and other methods in future work to further confirm the clinical efficacy of simple nucleotomy for the treatment of single-segment lumbar disc herniation a using microscope and percutaneous transforaminal endoscope.

Conclusion
In summary, both the microscope and percutaneous transforaminal endoscope are effective treatments for lumbar disc herniation, and each has its own advantages.
The percutaneous transforaminal endoscope was superior in intraoperative bleeding, incision length, and hospital stay, while the microscope was slightly stronger in terms of operation time, intraoperative X-ray fluoroscopy, postoperative recurrence, and second revision.