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Comparison of the clinical efficacy of full-endoscopic large-channel interbody decompression and fusion with unilateral versus bilateral pedicle-screw fixation in the treatment of lumbar degenerative disease
⁎Corresponding author: Wei Jiao. 0558jw@163.com
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Received: ,
Accepted: ,
This article was originally published by Reed Elsevier India Pvt. Ltd. and was migrated to Scientific Scholar after the change of Publisher.
Abstract
Abstract
Comparison of the clinical efficacy of full-endoscopic large-channel interbody decompression and fusion combined with unilateral versus bilateral pedicle-screw fixation in the treatment of single-level lumbar degenerative disease.
We conducted a retrospective analysis of the clinical data of 56 patients with single-level lumbar degenerative disease who underwent full-endoscopic large-channel interbody decompression, fusion, and internal fixation surgery at our hospital. Among them, 26 patients underwent unilateral pedicle screw fixation (UPSF), and 30 patients underwent bilateral pedicle screw fixation (BPSF).The comparison included the following parameters: surgical time, intraoperative fluoroscopy frequency, hospitalization costs, length of hospital stay, changes in hemoglobin levels before and after surgery, and complication rates. Preoperative and postoperative pain were assessed using the Visual Analog Scale (VAS) at 3 days, 3 months, and 1 year. Functional disability was evaluated using the Oswestry Disability Index (ODI) at preoperative, 3-month, and 1-year follow-ups. One year post-surgery, interbody fusion was evaluated by CT, and clinical outcomes were assessed using the modified MacNab criteria.
The surgical time, intraoperative fluoroscopy frequency, hospitalization costs, and length of hospital stay were significantly higher in the BPSF group compared to the UPSF group (P < 0.05). There was no statistical difference in the changes in hemoglobin levels between the two groups postoperatively (P > 0.05). The VAS scores at 3 days, 3 months, and 1 year, as well as the ODI scores at 3 months and 1 year, were significantly lower than preoperative values in both groups (P < 0.05). However, there were no significant differences in the VAS and ODI scores at the same time points between the two groups (P > 0.05). The complication rates, fusion rates at 1 year, and the excellent rate according to the modified MacNab criteria were not significantly different between the two groups (P > 0.05).
The treatment of single-segment lumbar degenerative disease using a large-channel full-endoscopic intervertebral decompression and fusion combined with UPSF is safe and effective. Compared with BPSF group, UPSF group has advantages in terms of fewer fluoroscopy times, shorter surgical duration, lower hospitalization costs, and shorter hospital stays.
Keywords
Unilateral pedicle screw fixation
Bilateral pedicle screw fixation
Lumbar degenerative disease
Intervertebral fusion
Full-endoscopic large-channel interbody decompression
1 Introduction
Lumbar degenerative disease (LDD) is the most common cause of chronic low back and leg pain, with its incidence steadily increasing.1,2 Pedicle screw fixation combined with interbody fusion is a classic and standardized surgical treatment for LDD. This method effectively reconstructs spinal stability, restores the height of the intervertebral disc and foramen, and achieves nerve root decompression, thereby significantly alleviating the patient's clinical symptoms.3 The traditional bilateral pedicle screw fixation (BPSF) method requires the dissection of bilateral paraspinal soft tissues, resulting in longer surgery time, more blood loss, and a higher risk associated with pedicle screw placement. In 1992, Kabins4 first introduced unilateral pedicle screw fixation (UPSF), achieving clinical results similar to those of bilateral pedicle screw fixation. Existing evidence indicates that unilateral pedicle screw fixation not only provides the same biomechanical stability as bilateral fixation but also offers advantages in terms of shorter surgery time and reduced surgical trauma.5
Currently, there are few comparative studies on the efficacy of large-channel full-endoscopic intervertebral decompression and fusion combined with UPSF versus BPSF for the treatment of single-segment LDD. This study retrospectively analyzes LDD patients with single-segment involvement treated at our hospital, comparing the efficacy of large-channel full-endoscopic intervertebral decompression and fusion combined with UPSF versus BPSF.
2 Methods
2.1 Patients
We retrospectively analyzed clinical data from 56 patients with single-segment LDD who underwent endoscopic lumbar decompression, fusion, and fixation surgery through a large channel at our hospital. All surgeons involved in the procedures are specialists in spinal surgery, each with over 10 years of extensive clinical experience. Data regarding diagnosis, age, sex, height, and weight surgical segment were collected. All patients signed informed consent forms, and the study was approved by the ethics committee of our hospital.
2.2 Inclusion and exclusion criteria
Inclusion criteria: (1)Lumbar disc herniation with lumbar instability or Modic changes, lumbar spinal stenosis with lumbar instability, or grade I lumbar spondylolisthesis (Meyerding classification); (2)Persistent or recurrent low back pain, leg pain, or intermittent claudication, unresponsive to strict conservative treatment for more than six months; (3)The radiological results were consistent with the symptoms.
Exclusion criteria: (1)Grade II or higher lumbar spondylolisthesis, multi-segment lumbar instability, lumbar spondylolisthesis, or spondylolytic spondylolisthesis; (2)Patients with infections, tumors, abnormal laboratory results, or poor local skin conditions; (3)Patients with multiple underlying conditions who cannot tolerate anesthesia or surgery; (4)Patients with severe substance abuse or psychiatric disorders.
2.3 Surgical techniques
The patient was intubated under general anesthesia and placed in the prone position. Fluoroscopy was performed using a C-arm X-ray machine, with the symptomatic side or the more symptomatic side as the surgical side. The responsible segment was located, and the interlaminar space and bilateral pedicles of the vertebrae were marked. Routine disinfection of the surgical area was performed, and drapes were applied.After puncturing the marked area, fluoroscopic guidance with the C-arm was used to locate the puncture site and direction. A scalpel was used to make a 1 cm incision through the skin to the deep fascia. Gradual soft tissue dilators were inserted until reaching the interlaminar space, and a working cannula was placed. The position of the channel was confirmed with fluoroscopy, and the spinal large-channel endoscope system was connected. The joint soft tissue was cleaned under endoscopic view, and the bony structures were exposed. The lamina was treated first, followed by partial excision of the facet joints (bone particles were trimmed for use in intervertebral bone grafting). The endoscopic forceps were used to enlarge the lateral recess and excise the yellow ligament. The nerve roots were fully decompressed and visible.A working channel was established through the opposite side of the spinous process and lamina. Similarly, bony decompression was performed on the contralateral side, and the yellow ligament was excised. Under fluoroscopy, complete decompression of both the bilateral nerve roots and the dura mater was confirmed. The spinal large-channel endoscope was removed, and intervertebral fusion instruments were placed. The intervertebral nucleus pulposus and adjacent endplates were scraped, and the nucleus pulposus was sent for examination. The disc soft tissue was cleaned under the endoscope, and bone graft material consisting of allograft bone mixed with autograft bone granules was implanted through a graft funnel channel.Under fluoroscopy with the C-arm, an intervertebral cage was inserted through the fusion channel. The spinal endoscope system was reinserted to confirm the cage position and ensure good nerve root decompression.
For the UPSF group, a 1 cm longitudinal incision was made at the surface projection of the pedicle on the surgical side. The incision was made layer by layer, and a guidewire was inserted. After confirming the position with fluoroscopy, two pedicle screws were placed along the guidewire. The connecting rod was installed, and the screw caps were tightened.
For the BPSF group, two pedicle screws were similarly placed on the contralateral side, followed by installation of the connecting rods and tightening of the screw caps. After confirming that all instruments and gauze were accounted for, the wound was closed layer by layer and dressed.
2.4 Postoperative treatment
Both groups of patients received second-generation cephalosporin antibiotics for infection prevention both preoperatively and postoperatively. Patients with nerve root irritation were treated with mannitol for dehydration and neurotrophic drugs. Strict bed rest was required for 48 h postoperatively, with instructions for the patient to perform isometric exercises of both lower limbs while in bed. On the third postoperative day, patients were allowed to wear a lumbar brace and engage in mild activities outside of bed. The lumbar brace should be worn for one month, with the primary focus on bed rest. Patients were advised to avoid bending, heavy lifting, and strenuous physical labor, while gradually engaging in exercises to strengthen the lumbar and back muscles.
2.5 Evaluation criteria and observational indicators
The intraoperative fluoroscopy times, preoperative and postoperative hemoglobin changes, surgical time, hospital stay duration, hospitalization costs, and complications were recorded for both groups. Visual analog scales (VAS) for back pain and leg pain were assessed preoperatively, at 3 days postoperatively, at 3 months, and at 1 year. The Oswestry Disability Index (ODI) was evaluated preoperatively, at 3 months, and at 1 year. At 1 year postoperatively, CT assessments of intervertebral fusion were conducted using the modified Brantigan6 grading system: Grade I: No connection between the upper and lower parts, with height loss and bone graft resorption. Grade II: No connection between the upper and lower parts, but bone volume has increased compared to the immediate postoperative bone graft volume. Grade III: 50% connection between the upper and lower parts, but with significant radiolucent lines. Grade IV: Good fusion with minimal radiolucent lines. Grade V: Complete fusion with good shaping. Grade ≥ IV was considered successful fusion.
2.6 Statistical analysis
Statistical analysis of baseline data, clinical efficacy-related indicators, and other variables was performed using SPSS 27.0 software. The K-S test was used to analyze whether the data followed a normal distribution. Measurement data were expressed as mean ± standard deviation (x ± s). Independent t-tests were used to compare means between the two groups, and analysis of variance (ANOVA) was used to compare data at different time points within the same group. Post-hoc tests were conducted using the LSD method. Fisher's exact probability method and chi-square tests were used to compare categorical and count data between groups. A P-value of <0.05 was considered statistically significant.
3 Results
A total of 56 patients were included in this study, consisting of 20 males and 36 females, with ages ranging from 40 to 71 years. Among them, 26 patients underwent large-channel full-endoscopic intervertebral decompression and fusion combined with UPSF, and 30 patients underwent the same procedure combined with BPSF. There were no statistically significant differences between the two groups in terms of age, BMI, gender, disease type, or surgical segment(P > 0.05) (Table 1), indicating that the groups were comparable.
| UPSF(n = 26) | BPSF(n = 30) | t | P | |
| Age (yrs) | 53.9 ± 8.7 | 57.4 ± 9.2 | −1.434 | 0.157 |
| BMI(kg/m2) | 24.9 ± 3.3 | 25.0 ± 3.3 | −0.030 | 0.976 |
| Sex | 0.157 | 0.876 | ||
| Male | 9 | 11 | ||
| Female | 17 | 19 | ||
| Preoperative diagnosis | 0.721 | 0.474 | ||
| LDH | 10 | 13 | ||
| LSS | 7 | 10 | ||
| Lumbar spondylolisthesis | 9 | 7 | ||
| Operative segment | −0.105 | 0.917 | ||
| L3/4 | 4 | 4 | ||
| L4/5 | 15 | 18 | ||
| L5/S1 | 7 | 8 |
All surgeries were successfully performed, and all patients were regularly followed up. Compared with the BPSF group, the UPSF group had fewer intraoperative fluoroscopy times, shorter surgical duration, lower hospitalization costs, and shorter hospital stays, all of which showed statistically significant differences (P < 0.05). There was no statistically significant difference in the change in hemoglobin levels between the two groups postoperatively (P > 0.05).Both groups experienced 1 case of dural tear, resulting in cerebrospinal fluid leakage, which was successfully treated with conservative management. In the BPSF group, 1 case of upper endplate fracture occurred during cage insertion, which was treated symptomatically. At the last follow-up, 1 case of cage displacement occurred in the UPSF group, and 1 case of cage subsidence occurred in the bilateral fixation group. There was no statistically significant difference in the complication rates between the two groups (P > 0.05) (Table 2).
| UPSF(n = 26) | BPSF(n = 30) | t | P | |
| Number of fluoroscopy times | 8.4 ± 2.0 | 12.4 ± 3.3 | −5.549 | <0.001 |
| Operation duration (min) | 146.2 ± 24.9 | 189.7 ± 35.2 | −5.269 | <0.001 |
| Hospital stay duration(d) | 9.2 ± 2.2 | 11.9 ± 3.2 | −3.603 | <0.001 |
| Hospitalization costs(yuan) | 36553.7 ± 2187.1 | 42796.0 ± 5233.8 | −5.663 | <0.001 |
| Change in Hb(g/L) | 11.5 ± 7.0 | 14.5 ± 8.7 | −1.434 | 0.157 |
| Postoperative complications | 2 | 3 | −0.297 | 0.768 |
| Cage displacement | 1 | 0 | ||
| Cage subsidence | 0 | 1 | ||
| Upper endplate fracture | 0 | 1 | ||
| Dural tear | 1 | 1 |
Compared with preoperative values, the VAS scores and ODI at each postoperative time point were significantly decreased in both groups (P < 0.05). There were no statistically significant differences in VAS scores and ODI between the two groups at the same time points (P > 0.05) (Table 3). The interbody fusion rate at 1 year postoperatively was 92.3% in the unilateral fixation group and 90.0% in the bilateral fixation group. There was no statistically significant difference between the two groups (P > 0.05) (Table 4 and Figs. 1 and 2). At 1 year postoperatively, the UPSF group had 19 excellent cases, 5 good cases, 2 fair cases, and 0 poor cases, with an excellent-good rate of 90%. The BPSF group had 21 excellent cases, 6 good cases, 3 fair cases, and 0 poor cases, with an excellent-good rate of 88.9%. There was no statistically significant difference in the excellent-good rate between the two groups at 1 year postoperatively (P > 0.05).
| UPSF(n = 26) | BPSF(n = 30) | t | P | |
| Low back pain VAS score | ||||
| Before operation | 7.0 ± 1.0 | 7.0 ± 1.1 | −0.317 | 0.891 |
| Postoperative 3 days | 2.0 ± 0.9 | 2.2 ± 0.9 | −0.670 | 0.506 |
| 3 months post-operation | 1.58 ± 0.58 | 1.67 ± 0.61 | −0.564 | 0.575 |
| Postoperative 1 year | 1.38 ± 0.50 | 1.37 ± 0.49 | 0.136 | 0.892 |
| Leg pain VAS score | ||||
| Before operation | 6.96 ± 1.00 | 6.87 ± 1.11 | 0.335 | 0.739 |
| Postoperative 3 days | 2.15 ± 0.83 | 2.27 ± 0.87 | −0.494 | 0.623 |
| 3 months post-operation | 1.62 ± 0.64 | 1.73 ± 0.64 | −0.689 | 0.494 |
| Postoperative 1 year | 1.31 ± 0.47 | 1.40 ± 0.50 | −0.709 | 0.481 |
| ODI | ||||
| Before operation | 44.04 ± 4.17 | 41.83 ± 5.36 | 1.698 | 0.095 |
| 3 months post-operation | 10.00 ± 1.65 | 9.80 ± 1.13 | 0.536 | 0.594 |
| Postoperative 1 year | 9.35 ± 1.50 | 9.27 ± 1.05 | 0.233 | 0.817 |
| UPSF(n = 26) | BPSF(n = 30) | |
| Grade 1 | 0 | 0 |
| Grade 2 | 1 | 1 |
| Grade 3 | 1 | 2 |
| Grade 4 | 19 | 19 |
| Grade 5 | 5 | 8 |
4 Discussion
Pedicle screw fixation combined with interbody fusion is a well-established technique for treating degenerative lumbar spine diseases. It provides immediate and stable stability to the lumbar spine through pedicle screw fixation while preserving the posterior ligamentous complex. However, whether to choose UPSF or BPSF remains a controversial topic. This study evaluated 56 patients with single-segment degenerative lumbar disease who underwent full-endoscopic interbody decompression and fusion fixation. The comparison between UPSF and BPSF showed that unilateral fixation achieved similar clinical outcomes. However, it offers advantages such as smaller surgical trauma, lower hospitalization costs, avoidance of contralateral soft tissue damage, shorter operation time, and reduced risk of potential surgical complications.
In terms of clinical efficacy, Wang et al.7 conducted a study on 58 patients with LDD who underwent minimally invasive transforaminal lumbar interbody fusion combined with UPSF. The results showed that all surgeries were successfully completed without nerve root damage or dural tears. The average follow-up was 6 months, and both ODI and VAS scores significantly improved postoperatively compared to preoperative levels. The MacNab excellent-good rate was 96.6%, and the fusion rate based on the Brantigan evaluation standard was 94.8%. A related meta-analysis pointed out that there were no significant differences between UPSF and BPSF in LDD patients regarding fusion rate, hospital stay, VAS scores, ODI, and physical function at 3 and 6 months postoperatively.8 These clinical studies suggest that minimally invasive transforaminal lumbar fusion combined with UPSF can achieve satisfactory clinical outcomes. Although MIS-TLIF utilizes tubular retractors and a microscope to minimize trauma, reduce blood loss, and accelerate postoperative recovery, it has a significant drawback. The use of air as the medium during endoscopy can lead to limited visibility due to intraoperative bleeding, making the procedure more complex.9
This study employed a spinal large-channel endoscopic system, where the use of water as the medium for endoscopic imaging made the procedure simpler and clearer. The entire decompression surgery was performed through a working channel with a diameter of only about 1 cm, eliminating the need for excessive tissue retraction and minimizing skin incision length and deep soft tissue damage. In this study, both groups of patients showed a significant decrease in ODI and VAS scores at each postoperative time point compared to preoperative values (P < 0.05). However, there were no statistically significant differences in ODI and VAS scores at the same postoperative time points between the two groups. This suggests that endoscopic large-channel decompression fusion combined with UPSF and BPSF for the treatment of degenerative lumbar diseases yield similar outcomes, both helping patients achieve good spinal function recovery and stability.
Gu et al.10 conducted a prospective cohort study on 74 patients treated with unilateral or bilateral two-level MIS-TLIF and found that the fusion rates for UPSF and BPSF were comparable. Similar to the results of this study, the UPSF in this study had a 1-year fusion rate of 92.3%, while the BPSF group had a 1-year fusion rate of 90.0%, with no statistically significant difference. In a biomechanical study, Chen et al.11 demonstrated that UPSF is sufficient to maintain spinal stability. It effectively reduces the stress shielding of the fused vertebrae and also minimizes the stress transmission to the adjacent vertebrae above and below the fused segment. Excessive stress can lead to a reduction in bone mass at the fused segment, which may decrease the fusion rate, while appropriate stress can promote bone graft fusion.12 McAfee et al.'s13 study pointed out that excessive internal fixation can induce stress shielding, leading to the development of osteoporosis. Goel et al.12 also reported that unilateral pedicle screw systems can reduce stress shielding of the vertebrae and decrease peak stress in adjacent segments. Therefore, unilateral fixation provides sufficient biomechanical stability while preserving some physiological stress transmission, which helps promote bone integration in the grafted area.
Previous meta-analyses have shown that UPSF yields good clinical outcomes in single-segment interbody fusion. However, its application in multi-segment fusion remains controversial. Studies have pointed out that the effects of UPSF on subsidence of the interbody fusion device and adjacent segment degeneration are not yet clear. Furthermore, as the number of fused segments increases, the normal mobility of the lumbar spine may gradually decrease, potentially leading to postoperative functional impairment in patients.14 However, Yang et al.15 conducted a study on 106 patients with UPSF or BPSF for the treatment of two-level degenerative lumbar diseases. Both groups showed high fusion rates, with no significant difference in fusion outcomes. Therefore, the author believes that for patients with normal BMI and bone mass, UPSF can be used in multi-segment lumbar interbody fusion surgeries.
Related studies have pointed out that UPSF typically results in less intraoperative blood loss compared to bilateral pedicle fixation, as it does not require dissection of the contralateral soft tissues.16 Interestingly, the results of this study show no significant difference in blood loss between the two surgical approaches. The large-channel full-endoscopic interbody decompression surgery is performed under a water medium, making it difficult to directly measure the exact blood loss during the procedure. However, we indirectly assessed the difference in blood loss by comparing the preoperative and postoperative changes in hemoglobin levels. There was no statistically significant difference in the reduction of hemoglobin between the two groups. However, the number of fluoroscopic exposures in the BPSF group was significantly higher than that in the UPSF group. Related studies have shown a certain linear relationship between radiation exposure and the occurrence of diseases such as leukemia, neurological disorders, and malignant tumors.17 The amount of radiation received is closely related to factors such as fluoroscopy time (number of exposures), the age and location of the person being exposed, the presence or absence of protective measures, and the distance from the radiation source. The UPSF approach effectively reduces the number of fluoroscopic exposures, allowing the surgery to be performed under relatively safer conditions for the patient.
In terms of complications, a meta-analysis showed that the incidence of nerve root injury and dural tears in endoscopic fusion surgery was 2.5% and 10.2%, respectively.18 In this study, both groups had 1 case of dural tear, which resulted in cerebrospinal fluid leakage. Both cases were successfully treated with conservative management. In the UPSF group, there was 1 case of cage displacement, but no significant symptoms were observed. Conservative treatment and close follow-up were provided, and at the 1-year postoperative follow-up, interbody fusion had occurred. Related studies suggest that cage displacement is primarily associated with factors such as osteoporosis, the morphology of the intervertebral space, the handling of the intervertebral space and endplates, the type of cage used, and low BMI.19,20
Hiyama et al.21 reported that in lateral lumbar interbody fusion (LLIF), the cage subsidence rate in the UPSF group was significantly higher than that in the BPSF group. LLIF surgery achieves indirect neural decompression through the expansion mechanism of the cage. However, UPSF may not provide sufficient support, and with the worsening of cage subsidence, there is a risk of recurrent neurological symptoms in patients. This issue led to the premature termination of the study. Suk et al.22 conducted a prospective study on 87 patients who underwent single-segment or multi-segment lumbar fusion surgery. They pointed out that there was no significant difference in postoperative complications between UPSF and BPSF. In this study, only 1 patient in the BPSF group experienced an endplate fracture during cage insertion. The patient received symptomatic treatment, and during follow-up, cage subsidence was observed. However, no significant impact on the patient's quality of life was noted. A biomechanical study by Santoni et al.23 indicated that cases with endplate damage are more prone to cage subsidence. The occurrence of cage subsidence is related to various factors, primarily including patient-specific characteristics, the type and size of the cage, the shape of the intervertebral disc space, and surgical techniques.24 Therefore, long-term follow-up is crucial for evaluating the internal fixation, cage, spinal stability, neurological function, and the overall functional status of the patient.
Currently, there is no clear standard for the management of cage-related complications both domestically and internationally. The author believes that cage subsidence and displacement do not necessarily require surgical intervention. For patients without obvious neurological symptoms, conservative treatment and close follow-up may result in long-term satisfactory clinical outcomes. However, if symptoms of nerve compression appear and lead to serious consequences, conservative treatment becomes meaningless, and surgery should be performed as soon as possible. If a displaced cage undergoes bony fusion, the difficulty and risks of revision surgery will increase.
There are some limitations to our study. The number of cases selected in this study is relatively small, and the follow-up period is short. More clinical cases and long-term follow-up are needed for further validation. Additionally, this study focuses on patients with single-segment fusion fixation, without analyzing those who underwent multi-stage fusion fixation, and the differences between these groups have not been verified.
5 Conclusion
In the treatment of single-segment LDD with full-endoscopic large-channel interlaminar decompression and fusion with pedicle screw fixation, both UPSF and BPSF demonstrate good clinical outcomes. Compared with the BPSF group, the UPSF group shows advantages in terms of intraoperative fluoroscopy times, surgery duration, hospitalization costs, and length of hospital stay.
Ethical approval and consent to participate
This study received approval from the Institutional Review Board and the Ethics Committee of Fuyang People's Hospital Affiliated to Anhui Medical University (No.2022 - 33).This research adheres to the ethical standards for medical research involving human subjects as stipulated in the Declaration of Helsinki.All participants in this manuscript provided written informed consent.All procedures were carried out in accordance with the relevant guidelines stated in the manuscript.
Consent for publication
Patients signed informed consent regarding publishing their data in this study.
Author contributions
CYK and ZHR contributed equally to this work and share first authorship.
JW, CXL, and CYK designed the study and performed the experiments; YW, CYK, ZHR, SXH, and XJL collected the data; CYK, ZHR, SXH, and XJL analyzed the data; CYK, CXL, and JW prepared the manuscript. CYK and ZHR contributed equally to this work and share first authorship. All authors read and approved the final manuscript.
Funding
This work was supported by Health Commission of Anhui province (grant number. AHWJ2023A20443), Medical Innovation Foundation from Spinal deformity clinical and research center of Anhui province (grant number:AHJZJX-ZD-002).
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