Comparison of Short-Term Efficacy of Single-port Endoscopic Discectomy and Unilateral Biportal Endoscopic Discectomy in the Treatment of L5/S1 Lumbar Disc Herniation at Michigan State University Grade 2

Comparison of Short-Term Efficacy of Single-port Endoscopic Discectomy and Unilateral Biportal Endoscopic Discectomy in the Treatment of L5/S1 Lumbar Disc Herniation at Michigan State University Grade 2 | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Comparison of Short-Term Efficacy of Single-port Endoscopic Discectomy and Unilateral Biportal Endoscopic Discectomy in the Treatment of L5/S1 Lumbar Disc Herniation at Michigan State University Grade 2 Xianyi Zhang, Jie Shang, Tianci Fang, MUSTAFA ABBAS FARHOOD SULTANI, and 9 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8742945/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 12 You are reading this latest preprint version Abstract Background and Objective Single-port endoscopic (open surgical excision [OSE]) discectomy and unilateral biportal endoscopic (UBE) discectomy have demonstrated effective therapeutic outcomes in lumbar disc herniation (LDH) treatment. However, there is a lack of clear guidelines for selecting surgical techniques for LDH at Michigan State University (MSU) grade 2. This study aimed to compare the clinical efficacy and imaging data of OSE and UBE in treating L5/S1 LDH at MSU grade 2. Methods This retrospective cohort study enrolled patients with L5/S1 LDH who were admitted between September 2022 and July 2024. Patients were stratified into OSE (n = 97) and UBE (n = 119) groups according to the surgical technique performed. Each group was further stratified into two subgroups based on the MSU classification of LDH (types 2B and 2C). All patients were followed for a minimum of one year. Perioperative parameters, serum levels of prostaglandin E2 (PGE2) and transthyretin (TTR), visual analog scale (VAS) score, Oswestry Disability Index (ODI), postoperative complication rate, recurrence rate, and modified MacNab criteria at the final follow-up were recorded and compared between groups to assess clinical efficacy. Surgical outcomes were further evaluated using radiological parameters, including bone loss volume (BLV), disc height index (DHI), lumbar range of motion (ROM), sagittal translation (ST), and paraspinal muscle relative cross-sectional area (RCSA). Results No significant difference was observed in the operation time and hospital stay between the two groups (P > 0.05). Incision length, intraoperative blood loss, and number of intraoperative fluoroscopy exposures were significantly lower in the OSE group than in the UBE group (P < 0.05). During a minimum of 1 year of postoperative follow-up, no statistically significant difference was observed in the VAS scores of the waist and legs and ODI at any assessed time point between the two groups (P > 0.05). However, the VAS scores of incision-related pain in the OSE group were lower than those in the UBE group on days 1 and 3 postoperatively (P < 0.05). No significant difference was observed between the two groups in complication rates, recurrence rates, modified MacNab scores, DHI, ROM, ST, erector spinae RCSA, or psoas major RCSA within 1 year postoperatively (P > 0.05). However, the OSE group demonstrated significantly better outcomes than the UBE group with respect to bone loss, serum PGE2, TTR levels, and multifidus RCSA (P < 0.05). Conclusion OSE and UBE can achieve good therapeutic effects in the treatment of grade 2 LDH at the L5/S1 segment in patients with MSU. Compared with UBE, OSE demonstrated advantages, including reduced surgical trauma, less early postoperative incision pain, a lower perioperative inflammatory response, improved preservation of bone structure, and enhanced protection of the multifidus muscle, reflecting higher surgical precision and a more minimally invasive profile. In clinical practice, treatment should be individualized based on the specific conditions of each patient. Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction Lumbar disc herniation (LDH) is a common orthopedic disorder, affecting tens of millions of individuals worldwide each year. Its clinical symptoms primarily include low back pain, radicular leg pain, and lower extremity numbness; in severe cases, LDH may result in gait disturbances or even bladder and bowel dysfunction [1, 2]. For patients who failed to respond adequately to conservative treatment, surgical intervention represents an important therapeutic option. Selection of an appropriate surgical approach based on specific LDH subtypes is essential for optimizing postoperative outcomes. The Michigan State University (MSU) classification is widely used in clinical practice for classifying LDH. This system classifies lumbar intervertebral disc protrusions based on their location and extent on axial magnetic resonance imaging (MRI) using the superior and inferior margins of the lumbar facet joints as anatomical boundaries. The degree of disc protrusion is graded as 1, 2, or 3, with higher grades indicating more severe herniation. Additionally, the protrusion area is divided into the central zone (Zone A), the lateral zone (Zone B), and the far lateral zone (Zone C) according to the medial edge of the facet joint [3, 4]. Among them, MSU grade 2 herniation is characterized by intervertebral disc protrusion extending to the level of the pedicle, with clinical severity intermediate between mild grade 1 and severe grade 3, but still capable of causing significant radicular symptoms [5]. With advances in minimally invasive spinal surgery, endoscopic surgery has become the predominant surgical approach for treating LDH. Among these, unilateral biportal endoscopy (UBE) and single-port endoscopy (OSE) are two commonly used minimally invasive surgical techniques [6, 7]. UBE utilizes an observation channel and an operation channel through two independent incisions during the operation, providing a broad surgical field and flexible instrument operation [8, 9]. Conversely, OSE integrates visualization and instrumentation through a single incision, and the endoscope and surgical instruments are not restricted by a fixed working channel, offering potential advantages regarding operation coordination and flexibility. However, OSE is generally associated with a steeper learning curve compared with UBE [10]. Previous studies have demonstrated that UBE and OSE have good short-term efficacy in treating non-specific subtypes of LDH [11, 12]. However, for specific LDH subtypes, particularly MSU grade 2 herniations, especially protrusions located in the foraminal and extraforaminal stenosis regions (types 2B and 2C), high-level evidence comparing the relative advantages of OSE and UBE remains limited. These regions are characterized by complex anatomy and proximity to the nerve roots, placing greater demand on surgical precision and minimally invasive techniques. Therefore, this retrospective study aimed to compare the clinical and radiological outcomes of OSE and UBE in the treatment of patients with MSU grade 2 LDH at the L5/S1 level, aiming to provide evidence-based guidance for surgical technique selection for specific subtypes of LDH and facilitate individualized treatment strategies in clinical practice. Materials and Methods Patient Data This study was conducted in accordance with the ethical principles of the Declaration of Helsinki (2013 revision) and was approved by the Ethics Committee of Xuzhou Central Hospital (No.: XZXY-LK-20210810-0121). The requirement for informed consent was waived due to the retrospective nature of the study. This study included 216 patients with L5/S1 segment LDH who underwent surgery at our hospital between September 2022 and July 2024. Among them, 97 patients underwent OSE surgery, and 119 patients underwent UBE surgery. All procedures were performed by the same experienced spinal surgeons. The inclusion criteria were as follows: (1) Patients with complete clinical data; (2) patients who met the diagnostic criteria for LDH with corresponding symptoms and signs; (3) patients with lumbar intervertebral disc protrusion at the L5/S1 segment confirmed using computed tomography (CT) or MRI; (4) patients with MSU classification of type 2B or 2C; (5) patients who met surgical indications and ineffective conservative treatment; (6) patients with postoperative follow-up time of at least 1 year. The exclusion criteria were as follows: (1) Patients with incomplete clinical data; (2) patients with comorbidities such as lumbar spondylolisthesis, lumbar deformity, lumbar instability, scoliosis, or spinal tumors; (3) patients with multilevel LDH or severe spinal canal stenosis; (4) patients with a history of lumbar spine surgery, fracture, infection, or tumor; (5) patients with severe heart and lung insufficiency or coagulation dysfunction, who cannot tolerate the surgery. Surgical techniques Single-port endoscopic technique The patients were placed in the prone position under general anesthesia. The target intervertebral levels were identified using a C-arm X-ray machine. After routine skin disinfection and draping, a skin protective film was applied. A longitudinal incision was made at the intersection of the target intervertebral space and the spinous process of the corresponding vertebra. The skin, subcutaneous fascia, and deep fascia were incised sequentially, and the soft tissues were bluntly dissected to expose the lamina. The OSE endoscopic system was inserted, and the ligamentum flavum was carefully dissected and partially resected along the inferior margin of the upper lamina and superior margin of the lower lamina. The lower 1/3 of the upper lamina and the superior edge of the lower lamina were removed using a nucleus pulposus forceps to enlarge the operative window. After adequate exposure, the nerve root was gently retracted with a nerve retractor to expose and remove the free nucleus pulposus tissue. After confirmation of adequate nerve root decompression and hemostasis, the instruments were withdrawn, and the incision was closed in layers. Single-channel dual-port endoscopic technique Patients were placed in the prone position under general anesthesia. The surgical segment was located and marked under fluoroscopic guidance. Two small surgical incisions were made adjacent to the spinous process. After bluntly dissecting the subcutaneous fascia, a soft tissue dilator was inserted to establish the observation and operation channels. The endoscope and instruments were inserted, and normal saline was continuously perfused to maintain a clear surgical field. The soft tissues were dissected to expose the ipsilateral facet joint and the superior and inferior lamina margins of the target intervertebral space. A bone window was created using a burr and osteotome, followed by resection of the ligamentum flavum for decompression. The dural sac and nerve root were exposed and gently retracted to expose the intervertebral disc. The nucleus pulposus tissue was removed. The dural sac and nerve root were re-examined to confirm adequate decompression and hemostasis. A negative pressure drainage tube was placed, and the incisions were closed. Observation indicators Demographic and perioperative parameters were recorded and analyzed, including age, sex, body mass index (BMI), type of intervertebral disc protrusion (MSU classification), operation time, incision length, intraoperative blood loss, number of intraoperative fluoroscopy exposures, and length of hospital stay. Serum levels of prostaglandin E2 (PGE2) and transthyretin (TTR) were measured preoperatively and on postoperative days 1 and 3. Clinical outcome assessment Incision-related pain was assessed using the visual analog scale (VAS) on preoperative days 1 and 3. The VAS score for low back pain (VAS-b), leg pain (VAS-l), Oswestry Disability Index (ODI), modified MacNab criteria, postoperative complications (including dural tear, nerve root injury, and wound infection), and recurrence rate (defined as the recurrence of symptomatic protrusion at the same segment and side) were recorded on postoperative day 1 and at 1 month, 6 months, and 1 year. Imaging assessment Bone loss volume Bone loss volume (BLV) was calculated utilizing three-dimensional CT reconstruction software. Three-dimensional models of L5 and S1 vertebrae were generated preoperatively and postoperatively (Fig. 3 ). BLV was defined as the difference between the combined preoperative and postoperative volumes of the L5 and S1 vertebrae. Intervertebral DHI The intervertebral DHI was measured on the sagittal lumbar spine images. The sum of the anterior height (a) and posterior height (b) of the intervertebral space was divided by the sum of the superior lamina length (c) and inferior lamina length (d) of the responsible segment. DHI = (a + b) / (c + d) (Fig. 3 ). Lumbar range of motion and sagittal translation The changes in the range of motion (ROM) and sagittal translation (ST) of the operated segment of the lumbar spine were assessed preoperatively and postoperatively to evaluate the effects of the two surgical techniques on lumbar stability (L5/S1 ROM ≥ 20° or ST ≥ 3 mm indicated lumbar instability) (Fig. 3 ). Paraspinal muscle relative cross-sectional area Patients underwent lumbar magnetic resonance imaging (MRI) examination. MRI images were obtained through the Picture Archiving and Communication System. The T2-weighted images at the middle level of L5 and S1 were selected (five consecutive slices per level). The relative cross-sectional area of the paraspinal muscles was measured using ImageJ software and calculated as the ratio of the cross-sectional area to the corresponding vertebral body area. Measurements were independently completed by two trained physicians, and the average value was taken. Statistical analysis The Statistical Package for the Social Sciences software (version 27.0) was utilized for data analysis. Measurement data that conformed to a normal distribution are represented as mean ± standard deviation (x ± s). Independent sample t-tests were utilized for comparisons between groups, and repeated measures analysis of variance was utilized for comparisons at different time points within groups. Count data are represented as cases (n) and percentages (%), and chi-square tests or Fisher's exact tests were utilized for comparisons between groups. A P < 0.05 was considered statistically significant. Results Baseline data and perioperative outcomes of patients This study included 216 patients, with 97 in the OSE group (56 type 2B and 41 type 2C) and 119 in the UBE group (62 type 2B and 57 type 2C). No statistically significant differences were observed in baseline data such as sex, age, BMI, and MSU subtype distribution between the two groups (P > 0.05), making them comparable (Table 1). The operation time and length of hospital stay were similar in both groups (P > 0.05). The OSE group exhibited shorter incision length (2.55 ± 0.88 cm versus 4.10 ± 1.05 cm, P < 0.001), less intraoperative blood loss (58.95 ± 4.98 mL versus 65.21 ± 5.68 mL, P < 0.001), and fewer intraoperative fluoroscopy times (2.97 ± 0.62 versus 4.11 ± 0.84, P 0.05). However, on postoperative days 1 and 3, the PGE2 level in the OSE group was significantly lower than that in the UBE group, whereas the TTR level was significantly higher (P 0.05). VAS-B, VAS-L scores, and ODI in both groups were significantly improved at all postoperative time points compared with preoperative levels (P 0.05). However, the VAS score for incision pain in the OSE group was lower than that in the UBE group on days 1 and 3 postoperatively (P < 0.001). According to the modified MacNab criteria, the excellent and good rate was 87.62% in the OSE group and 84.87% in the UBE group, with no statistically significant difference between the two groups (P > 0.05). Complications and recurrence During the postoperative follow-up period, there were three cases of dural tear and two cases of wound infection that occurred in the OSE group, with no cases of nerve root injury, resulting in an overall complication rate of 5.15%. Two patients in the OSE group experienced recurrence (2.06%). In the UBE group, four cases of dural tear, one case of nerve root injury, and two cases of wound infection were recorded, yielding a complication rate of 5.88% and two cases of recurrence (1.68%). All complications and recurrence cases were resolved satisfactorily following targeted treatment. No statistically significant differences were observed between the two groups in terms of complication and recurrence rates (P > 0.05). Comparison of imaging data between the two groups Imaging results The BLV was significantly greater in the UBE group than in the OSE group (P 0.05). In both groups, DHI decreased significantly at 6 months postoperatively compared with preoperative values (P 0.05). At 6 months postoperatively, ROM and ST in both groups remained within normal limits, with no evidence of lumbar instability. No statistically significant differences were observed in ROM and ST between the two groups at any time points (P > 0.05). No statistically significant differences were observed in preoperative multifidus (MF) RCSA, erector spinae (ES) RCSA, and psoas major (PS) RCSA between the two groups (P > 0.05). At 1 year postoperatively, MF RCSA was significantly reduced in both groups compared with preoperative levels (P 0.05). MF RCSA in the OSE group was significantly higher than that in the UBE group at 1-year follow-up (P 0.05). Discussion Lumbar disc herniation (LDH) is a common degenerative spinal disorder and a major cause of low back and leg pain [13–15]. With the rapid advancement of minimally invasive spinal surgery techniques, endoscopic surgery has gradually become a mainstream treatment modality for LDH. Among these approaches, OSE and UBE have recently emerged as effective techniques for the management of non-specific LDH. However, LDH involving the intervertebral foramen and extraforaminal regions remains technically challenging. Given the limited research on specific types of LDH at MSU grade 2, this study compared the efficacy of OSE and UBE in treating MSU grade 2 LDH at the L5/S1 segment and found that both methods were comparable regarding mid- to long-term pain relief and functional recovery. However, OSE demonstrated significant advantages in multiple indicators, indicating the minimally invasive nature and tissue protection of the surgery. Regarding clinical efficacy, this study demonstrated that the OSE group exhibited better outcomes regarding surgical incision length, reduced intraoperative blood loss, and fewer intraoperative fluoroscopies compared with the UBE group, consistent with the reports of Feng Y et al. [16, 17]. These differences may be attributed to the physical structure of the two surgical methods. UBE establishes observation and operation channels through two incisions. Although the individual operation channels have a relatively flexible angle, soft tissue dissection should be performed under indirect endoscopic visualization, which may result in sustained traction, compression, and partial damage to the muscles and fascia. However, OSE performs observation and operation through a single incision, similar to percutaneous endoscopic lumbar discectomy, allowing clearer identification of anatomical structures under direct vision and reducing damage to muscles and fascia. Furthermore, this study observed that the VAS score for early postoperative incision pain in the OSE group was lower than that in the UBE group, indicating that UBE is more invasive and may result in delayed short-term recovery after surgery. This hypothesis was validated by biochemical indicators. This study presented novel inflammatory indicators, serum PGE2 and TTR, and compared the short-term changes in these indicators after surgery. The results revealed that the PGE2 level in the OSE group was lower than that in the UBE group on postoperative day 1, but the TTR level was higher. PGE2 is an inflammatory mediator released in localized inflammatory tissues and functions as a neuromodulator that modifies neuronal excitability, primarily serving as a pain mediator in mediating pain responses [18, 19]. TTR is a highly amyloidogenic protein that, under inflammatory conditions, experiences amyloidosis, resulting in a decrease in its level [20, 21]. Comparative analysis of these inflammatory indicators revealed that OSE causes less damage to the lumbar fascia and muscles, diminishes postoperative local inflammatory responses and tissue edema, and thus alleviates pain stimulation. This is consistent with the findings of Ahn Y et al. [7, 11], who reported that OSE is less invasive and results in reduced tissue damage than UBE. This study indicated that VAS-B, VAS-L scores, and ODI of the two groups of patients improved at different postoperative time points compared with those before the operation. Second, during the 1-year postoperative follow-up, no statistically significant differences were observed in VAS-B, VAS-L scores, and ODI between the two groups. This is consistent with the findings of Liu C et al. [22, 23], who reported that the enhancement rates of VAS scores and ODI at the last follow-up were highly consistent between OSE and UBE. This suggests that both surgical methods can accomplish comprehensive nerve root decompression, alleviate the clinical symptoms of patients, and achieve similar functional rehabilitation levels. Additionally, regarding the modified MacNab criteria, the excellent and good rates of both groups exceeded 80%, signifying that both surgical techniques were recognized by patients as satisfactory. With the increasing adoption of spinal endoscopic techniques, greater attention has been directed toward postoperative complications. Dural tear, nerve root injury, and surgical site infection are common complications of spinal endoscopy. Chu PL et al. [24] reported that the complication rate of UBE was 5.4%, whereas Lyu Y et al. [25] reported that the complication rate of OSE was 5.2%. In this study, which focused on MSU grade 2 LDH, the UBE group experienced four cases of dural tear, one case of nerve root injury, and two cases of postoperative wound infection, whereas the OSE group experienced three cases of dural tear, no nerve root injury, and two cases of postoperative wound infection. The overall complication rates in both groups were not significantly different from those of previous research results, and no statistically significant differences were observed in the complication rates between the two groups, indicating that both techniques have good safety. Regarding the recurrence rate, the recurrence of LDH after discectomy remains a clinical concern. A previous study reported postoperative recurrence rates ranging from 5% to 12% [26]. In this study, the recurrence rates in both groups were lower than the reported rates, indicating that spinal endoscopy techniques have a relatively low risk of short-term recurrence for foraminal and extra-foraminal disc herniations. However, long-term follow-up is required to confirm the accuracy of the experiment. Although no statistically significant differences were observed between the two groups regarding long-term VAS scores, ODI, and the modified MacNab criteria, this does not imply equivalent effects on the local spinal environment. The protection of the bony structure and muscle tissue of the spine after surgery is associated with the patient's long-term biomechanical stability and postoperative quality of life. Regarding bony structure preservation, previous studies have demonstrated [10] that through finite element analysis, the removal of over 30% of the superior articular process can reduce the lumbar spine range of motion, increase facet joint loading, and elevate intervertebral disc pressure, thereby adversely affecting spinal stability. To quantify the bone loss volume more intuitively and accurately, this study utilized 3D Slicer software to precisely calculate the BLV during the operation and found that the bone loss in the UBE group was significantly more than that in the OSE group. This finding is consistent with the results of Zhang J et al. [27, 28]. UBE frequently requires extensive bony resection of the lamina and the medial aspect of the facet joint to provide an adequate surgical field and instrument operation space when dealing with protrusions located in the foramen and extra-foraminal regions, such as MSU 2B/2C type. Excessive resection of the facet joint is typically a risk factor for postoperative lumbar instability and accelerated adjacent segment disease in the long term [29]. The OSE technique, owing to its precisely targeted decompression characteristics, facilitates effective nerve decompression through a smaller bone window, thereby enhancing spinal stability. Although no significant differences were observed in DHI, ROM, and ST between the two groups during the 1-year postoperative follow-up period, suggesting that both surgical methods can effectively preserve lumbar stability, the increased bone loss in the UBE group may indicate a potential loss of biomechanical advantages. The risk of adjacent segment degeneration in the future may increase in young, physically active patients. Therefore, long-term follow-up is needed to observe the long-term effects. Regarding muscle tissue protection, the MF RCSA of both groups decreased significantly at 6 months postoperatively compared to preoperative levels; however, the decrease in the OSE group was significantly smaller than that in the UBE group. The multifidus muscle, a deep paraspinal muscle, is essential for maintaining lumbar segmental stability. The atrophy and fat infiltration are significantly associated with chronic low back pain and poor functional recovery post-surgery [30, 31]. The establishment of two channels and soft tissue dissection and retraction in the UBE procedure may compromise the nerve and blood supply of the multifidus muscle, resulting in denervation atrophy. Concurrently, postoperative pain and inflammation may hinder rehabilitation exercises, exacerbating disuse atrophy. Conversely, the OSE operation through a single channel maximally preserves the nerve supply and structural integrity of the multifidus muscle. This is consistent with the superior muscle imaging outcomes in the OSE group post-surgery as reported by Li T et al. [10, 16]. No significant difference was observed in the relative cross-sectional area of the erector spinae and psoas major muscles pre- and post-surgery between the two groups. This may be attributable to the fact that these muscles, functioning as stabilizers, are less directly affected by single-segment surgery and possess a greater compensatory ability than the multifidus muscle. Additionally, the milder pain and inflammatory response in the OSE group after surgery allow patients to commence lumbar muscle function exercises earlier, thereby reducing the risk of disuse atrophy of the lumbar muscles. Furthermore, enhanced preservation of the multifidus muscle aids in sustaining the dynamic stability of the surgical segment, mitigating the risk of long-term adjacent segment disease and chronic low back pain. Limitations This study has the following limitations: The retrospective study design had inherent selection bias; the sample size was relatively small, especially the number of cases in each MSU subgroup. Furthermore, the follow-up period was relatively short (≥ 1 year), and it is impossible to evaluate the effects of the two surgical methods on long-term outcomes (5–10 years or more), such as adjacent segment disease and reoperation rate. Future large-scale, prospective, long-term follow-up, and multi-center studies are required to provide higher-level evidence. Conclusion OSE and UBE are efficacious, minimally invasive techniques for treating grade 2 lumbar disc herniation at the L5/S1 segment. They are comparable with mid- to long-term neurological function recovery and patient satisfaction. However, OSE, characterized by its single-channel and coaxial visualization capabilities, offers significant advantages in minimizing surgical trauma, mitigating early postoperative pain, decreasing inflammatory responses, enhancing the preservation of bony structures, and protecting the core stabilizing muscle group (multifidus muscle), thereby demonstrating a superior minimally invasive approach. In clinical practice, it is recommended to personalize surgical approaches based on the specific anatomical characteristics of the patient, protrusion type, and the surgeon's expertise to optimize patient outcomes. Abbreviations OSE – Single-port endoscopic (open surgical excision) UBE – Unilateral biportal endoscopic LDH – Lumbar disc herniation MSU – Michigan State University PGE2 – Prostaglandin E2 TTR – Transthyretin VAS – Visual analog scale ODI – Oswestry Disability Index BLV – Bone loss volume DHI – Disc height index ROM – Range of motion ST – Sagittal translation RCSA – Relative cross-sectional area MRI – Magnetic resonance imaging CT – Computed tomography BMI – Body mass index MF – Multifidus ES – Erector spinae PS – Psoas major Declarations Author contributions Tianci Fang、Lei Liu、MUSTAFA ABBAS FARHOOD SULTANI、Liang Guo、Ziwei Xia and Meng Han designed the study and gave us several meaningful suggestions. Jie Shang、Yue Zhang and Chao Ma reviewed and collected the medical records. Guizhu Ji、Youdi Xue and Hengcai Zhou analyzed and interpreted the patient data. Xianyi Zhang was a contributor in writing the manuscript. Data availability The datasets used and analyzed in this study can be obtained from the corresponding author upon reasonable request. Ethics approval and consent to participate This study strictly adhered to the ethical principles of the Declaration of Helsinki (World Medical Association, 2024). The research protocol was reviewed and approved by the Biomedical Research Ethics Committee of Xuzhou Central Hospital (Approval Number: XZXY-LK-20210810-0121). All participants signed written informed consent forms after fully understanding the purpose, procedures, and their rights of the study. Throughout the study, the privacy rights, data confidentiality, and the right to withdraw at any time of the participants were strictly protected. No personal identity information was used in this study. As this study was a retrospective one, the requirement for informed consent was waived. Consent for publication Not applicable. Competing interests The authors declare no competing interests. Funding statement This study was supported by the Project of Xuzhou Municipal Health Commission (Grant No.KC21206), Contract for Science and Technology Projects of Xuzhou Health Commission (Grant No.XWKYHT20230054), Jiangsu Provincial Medical Center (Grant No. QNRC2016392), Pengcheng Talents - Medical Young Reserve Talents Training Project (Grant No.XWRCHT20220020), Xuzhou Science and Technology Project Contract(Grant No.KC23177). Acknowledgement No acknowledgements to declare. References Yu P, Mao F, Chen J, Ma X, Dai Y, Liu G, Dai F, Liu J. Characteristics and mechanisms of resorption in lumbar disc herniation. Arthritis Res Ther. 2022 Aug 23;24(1):205. doi: 10.1186/s13075-022-02894-8. PMID: 35999644; PMCID: PMC9396855. La Rosa C, Morabito S, Carloni A, Davini T, Remelli C, Specchi S, Bernardini M. Prevalence, MRI findings, and clinical features of lumbosacral intervertebral disc protrusion in French Bulldogs diagnosed with acute thoracic or lumbar intervertebral disc extrusion. Front Vet Sci. 2023 Nov 23;10:1302418. doi: 10.3389/fvets.2023.1302418. PMID: 38076554; PMCID: PMC10702215. Cristiani-Winer M, Ortiz P, Orosco-Falcone D, Guimbard-Pérez J, Carabajal J, Eluani M. ¿Es confiable la clasificación de la hernia de disco lumbar de la Universidad Estatal de Míchigan entre cirujanos de columna? [Is the Michigan State University lumbar disc herniation classification reliable among spine surgeons?]. Acta Ortop Mex. 2022 Mar-Apr;36(2):104-109. Spanish. PMID: 36481551. Du PY, Zhang YW, Cao XH, Liu YL, Yan YT, Liu L, Du SQ. Paravertebral Muscle Morphology in L4-L5 Disc Herniation: Insights from the Michigan State University Classification. Med Sci Monit. 2023 Oct 21;29:e941937. doi: 10.12659/MSM.941937. PMID: 37864329; PMCID: PMC10595040. Tan F, Zhang F, Han S, Song X, Yuan Y, Wang J. [Analysis of effectiveness of one-hole split endoscopy technique in treatment of lumbar spinal stenosis]. Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi. 2024 Mar 15;38(3):337-341. Chinese. doi: 10.7507/1002-1892.202401042. PMID: 38500428; PMCID: PMC10982041. Ju CI, Kim P, Seo JH, Kim SW, Lee SM. Complications of Cervical Endoscopic Spinal Surgery: A Systematic Review and Narrative Analysis. World Neurosurg. 2023 Oct;178:330-339. doi: 10.1016/j.wneu.2023.07.058. Epub 2023 Jul 20. PMID: 37479028. Ahn Y, Lee S. Uniportal versus biportal endoscopic spine surgery: a comprehensive review. Expert Rev Med Devices. 2023 Jul;20(7):549-556. doi: 10.1080/17434440.2023.2214678. Epub 2023 May 15. PMID: 37183715. Reis JPG, Pinto EM, Teixeira A, Frada R, Rodrigues D, Cunha R, Miranda A. Unilateral biportal endoscopy: review and detailed surgical approach to extraforaminal approach. EFORT Open Rev. 2025 Mar 3;10(3):151-155. doi: 10.1530/EOR-24-0137. PMID: 40071975; PMCID: PMC11896681. Meng H, Su N, Lin J, Fei Q. Comparative efficacy of unilateral biportal endoscopy and micro-endoscopic discectomy in the treatment of degenerative lumbar spinal stenosis: a systematic review and meta-analysis. J Orthop Surg Res. 2023 Oct 31;18(1):814. doi: 10.1186/s13018-023-04322-2. PMID: 37907922; PMCID: PMC10619222. Li T, Jiang Q, Zhong W, Zhu T, Lu Z, Ding Y. One-hole split endoscope versus unilateral biportal endoscopy for lumbar spinal stenosis: a retrospective propensity score study. J Orthop Surg Res. 2024 Apr 22;19(1):254. doi: 10.1186/s13018-024-04743-7. PMID: 38649974; PMCID: PMC11034078. Deng C, Li X, Wu C, Xie W, Chen M. One-hole split endoscopy versus unilateral biportal endoscopy for lumbar degenerative disease: a systematic review and meta-analysis of clinical outcomes and complications. J Orthop Surg Res. 2025 Feb 21;20(1):187. doi: 10.1186/s13018-025-05591-9. PMID: 39985036; PMCID: PMC11844110. Zhang Y, Feng B, Hu P, Dai G, Su W. One-hole split endoscopy technique versus unilateral biportal endoscopy technique for L5-S1 lumbar disk herniation: analysis of clinical and radiologic outcomes. J Orthop Surg Res. 2023 Sep 9;18(1):668. doi: 10.1186/s13018-023-04159-9. PMID: 37689668; PMCID: PMC10492266. Fardon DF, Williams AL, Dohring EJ, Murtagh FR, Gabriel Rothman SL, Sze GK. Lumbar disc nomenclature: version 2.0: Recommendations of the combined task forces of the North American Spine Society, the American Society of Spine Radiology and the American Society of Neuroradiology. Spine J. 2014 Nov 1;14(11):2525-45. doi: 10.1016/j.spinee.2014.04.022. Epub 2014 Apr 24. PMID: 24768732. La Rosa C, Morabito S, Carloni A, Davini T, Remelli C, Specchi S, Bernardini M. Prevalence, MRI findings, and clinical features of lumbosacral intervertebral disc protrusion in French Bulldogs diagnosed with acute thoracic or lumbar intervertebral disc extrusion. Front Vet Sci. 2023 Nov 23;10:1302418. doi: 10.3389/fvets.2023.1302418. PMID: 38076554; PMCID: PMC10702215. Radoš I, Lončarić Katušin M, Budrovac D, Dimitrijević I, Hnatešen D, Omrčen I. PERCUTANEOUS LASER DISC DECOMPRESSION FOR LUMBAR RADICULAR PAIN: A SYSTEMATIC REVIEW OF PUBMED IN THE LAST FIVE YEARS. Acta Clin Croat. 2023 Nov;62(Suppl4):63-67. doi: 10.20471/acc.2023.62.s4.9. PMID: 40463453; PMCID: PMC12128808. Qing P, Guo W, Xie S, Zhao S, Cui L, Li M, Gong S, Hu Y. Clinical efficacy of one-hole split endoscopy vs. unilateral biportal endoscopy for the treatment of single-segment lumbar spinal stenosis: a retrospective study with 2-year follow-up. Front Surg. 2025 Feb 18;12:1495741. doi: 10.3389/fsurg.2025.1495741. PMID: 40040816; PMCID: PMC11876375. Feng Y, Zhang W, Li K, Lin X, Liu C, Wang C, Hu B, Wang K, Xu W, Si H. Evaluation of the Effectiveness of Cervical One-Hole Split Endoscopic Keyhole Surgery for Cervical Radiculopathy. J Pain Res. 2024 Sep 19;17:3093-3099. doi: 10.2147/JPR.S451943. PMID: 39318547; PMCID: PMC11420887. Cheng H, Huang H, Guo Z, Chang Y, Li Z. Role of prostaglandin E2 in tissue repair and regeneration. Theranostics. 2021 Aug 13;11(18):8836-8854. doi: 10.7150/thno.63396. PMID: 34522214; PMCID: PMC8419039. Bryson TD, Harding P. Prostaglandin E2 EP receptors in cardiovascular disease: An update. Biochem Pharmacol. 2022 Jan;195:114858. doi: 10.1016/j.bcp.2021.114858. Epub 2021 Nov 22. PMID: 34822808. Fontana M, Berk JL, Gillmore JD, Witteles RM, Grogan M, Drachman B, Damy T, Garcia-Pavia P, Taubel J, Solomon SD, Sheikh FH, Tahara N, González-Costello J, Tsujita K, Morbach C, Pozsonyi Z, Petrie MC, Delgado D, Van der Meer P, Jabbour A, Bondue A, Kim D, Azevedo O, Hvitfeldt Poulsen S, Yilmaz A, Jankowska EA, Algalarrondo V, Slugg A, Garg PP, Boyle KL, Yureneva E, Silliman N, Yang L, Chen J, Eraly SA, Vest J, Maurer MS; HELIOS-B Trial Investigators. Vutrisiran in Patients with Transthyretin Amyloidosis with Cardiomyopathy. N Engl J Med. 2025 Jan 2;392(1):33-44. doi: 10.1056/NEJMoa2409134. Epub 2024 Aug 30. PMID: 39213194. Gentile L, Coelho T, Dispenzieri A, Conceição I, Waddington-Cruz M, Kristen A, Wixner J, Diemberger I, Gonzalez-Moreno J, Cariou E, Maurer MS, Planté-Bordeneuve V, Garcia-Pavia P, Tournev I, Gonzalez-Costello J, Duarte AG, Grogan M, Mazzeo A, Chapman D, Gupta P, Glass O, Amass L; THAOS investigators. A 15-year consolidated overview of data in over 6000 patients from the Transthyretin Amyloidosis Outcomes Survey (THAOS). Orphanet J Rare Dis. 2023 Nov 10;18(1):350. doi: 10.1186/s13023-023-02962-5. PMID: 37946256; PMCID: PMC10636983. Liu C, Zhang W, Wang C, Hu B, Wang K, Feng Y, Li L, Xu W, Si H. Comparison of one-hole split endoscopic discectomy and microendoscopic discectomy in the treatment of lumbar disk herniation: a one-year retrospective cohort study. J Orthop Surg Res. 2024 Feb 6;19(1):123. doi: 10.1186/s13018-024-04574-6. PMID: 38317253; PMCID: PMC10845564. Zhang Y, Feng B, Ning H, Dai G, Su W, Lu H, Hu P. One-hole split endoscope technique for migrated lumbar disc herniation: a single-centre, retrospective study of a novel technique. J Orthop Surg Res. 2023 Jul 5;18(1):483. doi: 10.1186/s13018-023-03967-3. PMID: 37408054; PMCID: PMC10324176. Chu PL, Wang T, Zheng JL, Xu CQ, Yan YJ, Ma QS, Meng-Chen Y, Da-Sheng T. Global and Current Research Trends of Unilateral Biportal Endoscopy/Biportal Endoscopic Spinal Surgery in the Treatment of Lumbar Degenerative Diseases: A Bibliometric and Visualization Study. Orthop Surg. 2022 Apr;14(4):635-643. doi: 10.1111/os.13216. Epub 2022 Mar 16. PMID: 35293686; PMCID: PMC9002063. Lyu Y, Liu GG, Li FL. [One-hole split endoscope-assisted transforaminal lumbar interbody fusion for the treatment of lumbar degenerative diseases:an early efficacy observation]. Zhongguo Gu Shang. 2025 Nov 25;38(11):1106-11. Chinese. doi: 10.12200/j.issn.1003-0034.20250208. PMID: 41340298. Shen SC, Chen HC, Tsou HK, Lin RH, Shih YT, Huang CW, Tang CL, Chen HT, Chang CC, Tzeng CY. Percutaneous endoscopic lumbar discectomy for L5-S1 disc herniation based on image analysis and clinical findings: A retrospective review of 345 cases. Medicine (Baltimore). 2023 Feb 3;102(5):e32832. doi: 10.1097/MD.0000000000032832. PMID: 36749265; PMCID: PMC9901959. Zhang J, Yan R, Xu S, Shao B, Dou Y. Short-term lumbar disc and lumbar stability changes of one-hole split endoscope technique treatment of spinal stenosis. BMC Musculoskelet Disord. 2024 Apr 24;25(1):325. doi: 10.1186/s12891-024-07443-9. PMID: 38659005; PMCID: PMC11040931. Lyu Y, Liu GG, Li FL. [One-hole split endoscope-assisted transforaminal lumbar interbody fusion for the treatment of lumbar degenerative diseases:an early efficacy observation]. Zhongguo Gu Shang. 2025 Nov 25;38(11):1106-11. Chinese. doi: 10.12200/j.issn.1003-0034.20250208. PMID: 41340298. Fang N, Yan S, Yang A. Research advances in unilateral endoscopic spinal surgery for the treatment of lumbar disc herniation: a review. J Orthop Surg Res. 2025 Jul 11;20(1):643. doi: 10.1186/s13018-025-06071-w. PMID: 40646647; PMCID: PMC12255086. Abd-Elsayed A, Kurt E, Kollenburg L, Hasoon J, Wahezi SE, Storlie NR. Lumbar Multifidus Dysfunction and Chronic Low Back Pain: Overview, Therapies, and an Update on the Evidence. Pain Pract. 2025 Jun;25(5):e70044. doi: 10.1111/papr.70044. PMID: 40361257. Stevens S, Agten A, Timmermans A, Vandenabeele F. Unilateral changes of the multifidus in persons with lumbar disc herniation: a systematic review and meta-analysis. Spine J. 2020 Oct;20(10):1573-1585. doi: 10.1016/j.spinee.2020.04.007. Epub 2020 Apr 20. PMID: 32325246. Tables Tables 1 to 4 are available in the Supplementary Files section. Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8742945","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":601471962,"identity":"928f884e-b1ab-4b73-b4d5-a40231dd027b","order_by":0,"name":"Xianyi Zhang","email":"","orcid":"","institution":"Xuzhou Clinical School of Xuzhou Medical University","correspondingAuthor":false,"prefix":"","firstName":"Xianyi","middleName":"","lastName":"Zhang","suffix":""},{"id":601471963,"identity":"1380e313-0615-47e9-92c5-023906c2552b","order_by":1,"name":"Jie Shang","email":"","orcid":"","institution":"Xuzhou Central 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Han","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABBElEQVRIiWNgGAWjYBACAygtx8bM2MAM4vIzMx9+QIwWY3525gNgLZLtbGkGxGhJnNnPlsAMFjnPoyCBT4s5+9mjGz7uqGXccJjH8HNBwR1548M8QINqbKJxabHsyUu7OfPMcWaDwzzG0jMMnhluO8x74AHDsbTcBlwOO5Bjdpu37RgbUIsZM4/BYcZth/kSDBgbDuPWcv6N2e2/bcd4YFrsNzfzGEjg1XIDaAtjW42EZDNbGkhL4gZmglremN3sbTtgAIoOaaCW5BmHgYGcgM8v53PMbvxsq6tv4z/Y+Jnnz2Hb/v7Dhx98qLHBqQUKDqPxE/ArB4E6wkpGwSgYBaNg5AIAU2tdp6EH44EAAAAASUVORK5CYII=","orcid":"","institution":"Xuzhou Clinical School of Xuzhou Medical University","correspondingAuthor":true,"prefix":"","firstName":"Meng","middleName":"","lastName":"Han","suffix":""}],"badges":[],"createdAt":"2026-01-30 15:54:40","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8742945/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8742945/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":104404562,"identity":"6b3f76f0-6fe6-42e2-9922-799dc3e1874b","added_by":"auto","created_at":"2026-03-11 12:20:31","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":415617,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic diagram of MSU grading and zoning.(A) \u003cstrong\u003eGrading (Horizontal Axis):\u003c/strong\u003e Herniation severity increases from Grade 1 to Grade 3, correlating with \u003cstrong\u003eworsening\u003c/strong\u003e nerve compression. (B) \u003cstrong\u003eZoning (Vertical Axis):\u003c/strong\u003eLines indicating the zoning of disc herniation are drawn along the vertical axis. Herniations within Zone-B and Zone-C imply a more significant clinical consequence.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-8742945/v1/2d3984c47811e5e69ff710d2.png"},{"id":104405157,"identity":"f78eb79d-1e61-4ef4-a744-456b998f950a","added_by":"auto","created_at":"2026-03-11 12:21:57","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":617852,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic diagram of the OSE and UBE technology endoscope. (A) During the OSE surgery, the surgical operation scene shows that the working channel and the observation channel are located within the same soft tissue incision.(B, C) Photographs obtained during the surgery.(A1) During the UBE surgery, the surgical operation scene is shown where the working channel and the observation channel are located within two soft tissue incisions respectively.(B1, C1) Photographs obtained during the surgery.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-8742945/v1/80ec958137f7319c43ae23e8.png"},{"id":104405109,"identity":"51022797-c162-4525-83a2-762a08f439ba","added_by":"auto","created_at":"2026-03-11 12:21:48","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":297821,"visible":true,"origin":"","legend":"\u003cp\u003e(A, B) Dynamic position X-ray was used to measure ROM and ST before and after surgery, ROM=α−β, ST=|c–c’|. (C) Lateral lumbar X-ray was used to measure DH before and after surgery, DHI=a+b/c+d.(D,E)Measurement of the volume of bone loss during the operation. (D) Preoperative modeling of the L5 and S1 vertebrae and their total volume. (E) Postoperative modeling of the L5 and S1 vertebrae and their total volume.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-8742945/v1/0893d881483392bc2dc732ca.png"},{"id":104258219,"identity":"22a0ba48-ef79-46ea-818e-f9788642f9cc","added_by":"auto","created_at":"2026-03-09 17:36:23","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":407755,"visible":true,"origin":"","legend":"\u003cp\u003eThe patient experienced severe sciatic nerve pain and lower back pain on the left side, which persisted for 3 months. He received treatment with OSE. (A-C) The preoperative MRI and CT scan results showed a disc protrusion at the L5-S1 level (using the Michigan State University classification 2B). (D) The spine was preoperatively modeled and its total volume was calculated. (A1-C1) Postoperative MRI and CT scans showed that the protruding nucleus pulposus tissue had been removed.(D1) Perform postoperative modeling of the spine and calculate its total volume.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-8742945/v1/32f92ece5ffa85b8c54f9463.png"},{"id":104405209,"identity":"122523e3-4961-4a21-a764-4a99fc1ef9a9","added_by":"auto","created_at":"2026-03-11 12:22:07","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":436369,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eThe patient experienced severe sciatic nerve pain and low back pain on the right side, which persisted for 5 months. The patient received treatment with UBE. \u003c/strong\u003e(A-C) The preoperative MRI and CT scan results showed a disc protrusion at the L5-S1 level (using the Michigan State University classification 2B). (D) The spine was preoperatively modeled and its total volume was calculated. (A1-C1) Postoperative MRI and CT scans showed that the protruding nucleus pulposus tissue had been removed.(D1) Perform postoperative modeling of the spine and calculate its total volume.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-8742945/v1/226cdc842bb23e63d4b3a62d.png"},{"id":104408787,"identity":"c0f071e5-025d-4b62-8102-1e83ccca59c4","added_by":"auto","created_at":"2026-03-11 12:43:24","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3292701,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8742945/v1/f343809d-1370-4b4b-9b3a-39be1e93bd26.pdf"},{"id":104258221,"identity":"045ab6b6-4105-48d0-a06d-a27529628c4a","added_by":"auto","created_at":"2026-03-09 17:36:23","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":132282,"visible":true,"origin":"","legend":"","description":"","filename":"TABLES.docx","url":"https://assets-eu.researchsquare.com/files/rs-8742945/v1/d588ef1193ad58d78e91a235.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Comparison of Short-Term Efficacy of Single-port Endoscopic Discectomy and Unilateral Biportal Endoscopic Discectomy in the Treatment of L5/S1 Lumbar Disc Herniation at Michigan State University Grade 2","fulltext":[{"header":"Introduction","content":"\u003cp\u003eLumbar disc herniation (LDH) is a common orthopedic disorder, affecting tens of millions of individuals worldwide each year. Its clinical symptoms primarily include low back pain, radicular leg pain, and lower extremity numbness; in severe cases, LDH may result in gait disturbances or even bladder and bowel dysfunction [1, 2]. For patients who failed to respond adequately to conservative treatment, surgical intervention represents an important therapeutic option. Selection of an appropriate surgical approach based on specific LDH subtypes is essential for optimizing postoperative outcomes. The Michigan State University (MSU) classification is widely used in clinical practice for classifying LDH. This system classifies lumbar intervertebral disc protrusions based on their location and extent on axial magnetic resonance imaging (MRI) using the superior and inferior margins of the lumbar facet joints as anatomical boundaries. The degree of disc protrusion is graded as 1, 2, or 3, with higher grades indicating more severe herniation. Additionally, the protrusion area is divided into the central zone (Zone A), the lateral zone (Zone B), and the far lateral zone (Zone C) according to the medial edge of the facet joint [3, 4]. Among them, MSU grade 2 herniation is characterized by intervertebral disc protrusion extending to the level of the pedicle, with clinical severity intermediate between mild grade 1 and severe grade 3, but still capable of causing significant radicular symptoms [5].\u003c/p\u003e \u003cp\u003eWith advances in minimally invasive spinal surgery, endoscopic surgery has become the predominant surgical approach for treating LDH. Among these, unilateral biportal endoscopy (UBE) and single-port endoscopy (OSE) are two commonly used minimally invasive surgical techniques [6, 7]. UBE utilizes an observation channel and an operation channel through two independent incisions during the operation, providing a broad surgical field and flexible instrument operation [8, 9]. Conversely, OSE integrates visualization and instrumentation through a single incision, and the endoscope and surgical instruments are not restricted by a fixed working channel, offering potential advantages regarding operation coordination and flexibility. However, OSE is generally associated with a steeper learning curve compared with UBE [10]. Previous studies have demonstrated that UBE and OSE have good short-term efficacy in treating non-specific subtypes of LDH [11, 12].\u003c/p\u003e \u003cp\u003eHowever, for specific LDH subtypes, particularly MSU grade 2 herniations, especially protrusions located in the foraminal and extraforaminal stenosis regions (types 2B and 2C), high-level evidence comparing the relative advantages of OSE and UBE remains limited. These regions are characterized by complex anatomy and proximity to the nerve roots, placing greater demand on surgical precision and minimally invasive techniques. Therefore, this retrospective study aimed to compare the clinical and radiological outcomes of OSE and UBE in the treatment of patients with MSU grade 2 LDH at the L5/S1 level, aiming to provide evidence-based guidance for surgical technique selection for specific subtypes of LDH and facilitate individualized treatment strategies in clinical practice.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003ePatient Data\u003c/p\u003e \u003cp\u003e This study was conducted in accordance with the ethical principles of the Declaration of Helsinki (2013 revision) and was approved by the Ethics Committee of Xuzhou Central Hospital (No.: XZXY-LK-20210810-0121). The requirement for informed consent was waived due to the retrospective nature of the study.\u003c/p\u003e \u003cp\u003eThis study included 216 patients with L5/S1 segment LDH who underwent surgery at our hospital between September 2022 and July 2024. Among them, 97 patients underwent OSE surgery, and 119 patients underwent UBE surgery. All procedures were performed by the same experienced spinal surgeons.\u003c/p\u003e \u003cp\u003eThe inclusion criteria were as follows: (1) Patients with complete clinical data; (2) patients who met the diagnostic criteria for LDH with corresponding symptoms and signs; (3) patients with lumbar intervertebral disc protrusion at the L5/S1 segment confirmed using computed tomography (CT) or MRI; (4) patients with MSU classification of type 2B or 2C; (5) patients who met surgical indications and ineffective conservative treatment; (6) patients with postoperative follow-up time of at least 1 year. The exclusion criteria were as follows: (1) Patients with incomplete clinical data; (2) patients with comorbidities such as lumbar spondylolisthesis, lumbar deformity, lumbar instability, scoliosis, or spinal tumors; (3) patients with multilevel LDH or severe spinal canal stenosis; (4) patients with a history of lumbar spine surgery, fracture, infection, or tumor; (5) patients with severe heart and lung insufficiency or coagulation dysfunction, who cannot tolerate the surgery.\u003c/p\u003e \u003cp\u003eSurgical techniques\u003c/p\u003e \u003cp\u003eSingle-port endoscopic technique\u003c/p\u003e \u003cp\u003eThe patients were placed in the prone position under general anesthesia. The target intervertebral levels were identified using a C-arm X-ray machine. After routine skin disinfection and draping, a skin protective film was applied. A longitudinal incision was made at the intersection of the target intervertebral space and the spinous process of the corresponding vertebra. The skin, subcutaneous fascia, and deep fascia were incised sequentially, and the soft tissues were bluntly dissected to expose the lamina. The OSE endoscopic system was inserted, and the ligamentum flavum was carefully dissected and partially resected along the inferior margin of the upper lamina and superior margin of the lower lamina. The lower 1/3 of the upper lamina and the superior edge of the lower lamina were removed using a nucleus pulposus forceps to enlarge the operative window. After adequate exposure, the nerve root was gently retracted with a nerve retractor to expose and remove the free nucleus pulposus tissue. After confirmation of adequate nerve root decompression and hemostasis, the instruments were withdrawn, and the incision was closed in layers.\u003c/p\u003e \u003cp\u003eSingle-channel dual-port endoscopic technique\u003c/p\u003e \u003cp\u003ePatients were placed in the prone position under general anesthesia. The surgical segment was located and marked under fluoroscopic guidance. Two small surgical incisions were made adjacent to the spinous process. After bluntly dissecting the subcutaneous fascia, a soft tissue dilator was inserted to establish the observation and operation channels. The endoscope and instruments were inserted, and normal saline was continuously perfused to maintain a clear surgical field. The soft tissues were dissected to expose the ipsilateral facet joint and the superior and inferior lamina margins of the target intervertebral space. A bone window was created using a burr and osteotome, followed by resection of the ligamentum flavum for decompression. The dural sac and nerve root were exposed and gently retracted to expose the intervertebral disc. The nucleus pulposus tissue was removed. The dural sac and nerve root were re-examined to confirm adequate decompression and hemostasis. A negative pressure drainage tube was placed, and the incisions were closed.\u003c/p\u003e \u003cp\u003eObservation indicators\u003c/p\u003e \u003cp\u003eDemographic and perioperative parameters were recorded and analyzed, including age, sex, body mass index (BMI), type of intervertebral disc protrusion (MSU classification), operation time, incision length, intraoperative blood loss, number of intraoperative fluoroscopy exposures, and length of hospital stay. Serum levels of prostaglandin E2 (PGE2) and transthyretin (TTR) were measured preoperatively and on postoperative days 1 and 3.\u003c/p\u003e \u003cp\u003eClinical outcome assessment\u003c/p\u003e \u003cp\u003eIncision-related pain was assessed using the visual analog scale (VAS) on preoperative days 1 and 3. The VAS score for low back pain (VAS-b), leg pain (VAS-l), Oswestry Disability Index (ODI), modified MacNab criteria, postoperative complications (including dural tear, nerve root injury, and wound infection), and recurrence rate (defined as the recurrence of symptomatic protrusion at the same segment and side) were recorded on postoperative day 1 and at 1 month, 6 months, and 1 year.\u003c/p\u003e \u003cp\u003eImaging assessment\u003c/p\u003e \u003cp\u003eBone loss volume\u003c/p\u003e \u003cp\u003eBone loss volume (BLV) was calculated utilizing three-dimensional CT reconstruction software. Three-dimensional models of L5 and S1 vertebrae were generated preoperatively and postoperatively (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). BLV was defined as the difference between the combined preoperative and postoperative volumes of the L5 and S1 vertebrae.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIntervertebral DHI\u003c/p\u003e \u003cp\u003eThe intervertebral DHI was measured on the sagittal lumbar spine images. The sum of the anterior height (a) and posterior height (b) of the intervertebral space was divided by the sum of the superior lamina length (c) and inferior lamina length (d) of the responsible segment. DHI = (a\u0026thinsp;+\u0026thinsp;b) / (c\u0026thinsp;+\u0026thinsp;d) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eLumbar range of motion and sagittal translation\u003c/p\u003e \u003cp\u003eThe changes in the range of motion (ROM) and sagittal translation (ST) of the operated segment of the lumbar spine were assessed preoperatively and postoperatively to evaluate the effects of the two surgical techniques on lumbar stability (L5/S1 ROM\u0026thinsp;\u0026ge;\u0026thinsp;20\u0026deg; or ST\u0026thinsp;\u0026ge;\u0026thinsp;3 mm indicated lumbar instability) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eParaspinal muscle relative cross-sectional area\u003c/p\u003e \u003cp\u003ePatients underwent lumbar magnetic resonance imaging (MRI) examination. MRI images were obtained through the Picture Archiving and Communication System. The T2-weighted images at the middle level of L5 and S1 were selected (five consecutive slices per level). The relative cross-sectional area of the paraspinal muscles was measured using ImageJ software and calculated as the ratio of the cross-sectional area to the corresponding vertebral body area. Measurements were independently completed by two trained physicians, and the average value was taken.\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eThe Statistical Package for the Social Sciences software (version 27.0) was utilized for data analysis. Measurement data that conformed to a normal distribution are represented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (x\u0026thinsp;\u0026plusmn;\u0026thinsp;s). Independent sample t-tests were utilized for comparisons between groups, and repeated measures analysis of variance was utilized for comparisons at different time points within groups. Count data are represented as cases (n) and percentages (%), and chi-square tests or Fisher's exact tests were utilized for comparisons between groups. A P\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cstrong\u003eBaseline data and perioperative outcomes of patients\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study included 216 patients, with 97 in the OSE group (56 type 2B and 41 type 2C) and 119 in the UBE group (62 type 2B and 57 type 2C). No statistically significant differences were observed in baseline data such as sex, age, BMI, and MSU subtype distribution between the two groups (P \u0026gt; 0.05), making them comparable (Table 1).\u003c/p\u003e\n\u003cp\u003eThe operation time and length of hospital stay were similar in both groups (P \u0026gt; 0.05). The OSE group exhibited shorter incision length (2.55 \u0026plusmn; 0.88 cm versus 4.10 \u0026plusmn; 1.05 cm, P \u0026lt; 0.001), less intraoperative blood loss (58.95 \u0026plusmn; 4.98 mL versus 65.21 \u0026plusmn; 5.68 mL, P \u0026lt; 0.001), and fewer intraoperative fluoroscopy times (2.97 \u0026plusmn; 0.62 versus 4.11 \u0026plusmn; 0.84, P \u0026lt; 0.001) than the UBE group (Table 2). No differences were observed in preoperative serum PGE2 and TTR levels between the two groups (P \u0026gt; 0.05). However, on postoperative days 1 and 3, the PGE2 level in the OSE group was significantly lower than that in the UBE group, whereas the TTR level was significantly higher (P \u0026lt; 0.001) (Table 4).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClinical efficacy evaluation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo statistically significant differences in preoperative VAS-B, VAS-L scores, and ODI between the two groups (P \u0026gt; 0.05). VAS-B, VAS-L scores, and ODI in both groups were significantly improved at all postoperative time points compared with preoperative levels (P \u0026lt; 0.05). No statistically significant differences were observed in VAS-B, VAS-L scores, and ODI between the two groups at day 1, 1 month, 6 months, and 1 year postoperatively (P \u0026gt; 0.05). However, the VAS score for incision pain in the OSE group was lower than that in the UBE group on days 1 and 3 postoperatively (P \u0026lt; 0.001).\u003c/p\u003e\n\u003cp\u003eAccording to the modified MacNab criteria, the excellent and good rate was 87.62% in the OSE group and 84.87% in the UBE group, with no statistically significant difference between the two groups (P \u0026gt; 0.05).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eComplications and recurrence\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDuring the postoperative follow-up period, there were three cases of dural tear and two cases of wound infection that occurred in the OSE group, with no cases of nerve root injury, resulting in an overall complication rate of 5.15%. Two patients in the OSE group experienced recurrence (2.06%). In the UBE group, four cases of dural tear, one case of nerve root injury, and two cases of wound infection were recorded, yielding a complication rate of 5.88% and two cases of recurrence (1.68%). All complications and recurrence cases were resolved satisfactorily following targeted treatment. No statistically significant differences were observed between the two groups in terms of complication and recurrence rates (P \u0026gt; 0.05).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eComparison of imaging data between the two groups\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eImaging results\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe BLV was significantly greater in the UBE group than in the OSE group (P \u0026lt; 0.05). No statistically significant differences were observed in preoperative DHI between the two groups (P \u0026gt; 0.05). In both groups, DHI decreased significantly at 6 months postoperatively compared with preoperative values (P \u0026lt; 0.05); however, no statistically significant differences in DHI were observed between the two groups at the 1-year follow-up (P \u0026gt; 0.05). At 6 months postoperatively, ROM and ST in both groups remained within normal limits, with no evidence of lumbar instability. No statistically significant differences were observed in ROM and ST between the two groups at any time points (P \u0026gt; 0.05). No statistically significant differences were observed in preoperative multifidus (MF) RCSA, erector spinae (ES) RCSA, and psoas major (PS) RCSA between the two groups (P \u0026gt; 0.05). At 1 year postoperatively, MF RCSA was significantly reduced in both groups compared with preoperative levels (P \u0026lt; 0.05), whereas no statistically significant differences were observed in ES RCSA and PS RCSA compared with preoperative levels (P \u0026gt; 0.05). MF RCSA in the OSE group was significantly higher than that in the UBE group at 1-year follow-up (P \u0026lt; 0.001), and no statistically significant differences were observed in ES RCSA and PS RCSA between the two groups at 1-year postoperatively (P \u0026gt; 0.05).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eLumbar disc herniation (LDH) is a common degenerative spinal disorder and a major cause of low back and leg pain [13\u0026ndash;15]. With the rapid advancement of minimally invasive spinal surgery techniques, endoscopic surgery has gradually become a mainstream treatment modality for LDH. Among these approaches, OSE and UBE have recently emerged as effective techniques for the management of non-specific LDH. However, LDH involving the intervertebral foramen and extraforaminal regions remains technically challenging. Given the limited research on specific types of LDH at MSU grade 2, this study compared the efficacy of OSE and UBE in treating MSU grade 2 LDH at the L5/S1 segment and found that both methods were comparable regarding mid- to long-term pain relief and functional recovery. However, OSE demonstrated significant advantages in multiple indicators, indicating the minimally invasive nature and tissue protection of the surgery.\u003c/p\u003e \u003cp\u003eRegarding clinical efficacy, this study demonstrated that the OSE group exhibited better outcomes regarding surgical incision length, reduced intraoperative blood loss, and fewer intraoperative fluoroscopies compared with the UBE group, consistent with the reports of Feng Y et al. [16, 17]. These differences may be attributed to the physical structure of the two surgical methods. UBE establishes observation and operation channels through two incisions. Although the individual operation channels have a relatively flexible angle, soft tissue dissection should be performed under indirect endoscopic visualization, which may result in sustained traction, compression, and partial damage to the muscles and fascia. However, OSE performs observation and operation through a single incision, similar to percutaneous endoscopic lumbar discectomy, allowing clearer identification of anatomical structures under direct vision and reducing damage to muscles and fascia.\u003c/p\u003e \u003cp\u003eFurthermore, this study observed that the VAS score for early postoperative incision pain in the OSE group was lower than that in the UBE group, indicating that UBE is more invasive and may result in delayed short-term recovery after surgery. This hypothesis was validated by biochemical indicators. This study presented novel inflammatory indicators, serum PGE2 and TTR, and compared the short-term changes in these indicators after surgery. The results revealed that the PGE2 level in the OSE group was lower than that in the UBE group on postoperative day 1, but the TTR level was higher. PGE2 is an inflammatory mediator released in localized inflammatory tissues and functions as a neuromodulator that modifies neuronal excitability, primarily serving as a pain mediator in mediating pain responses [18, 19]. TTR is a highly amyloidogenic protein that, under inflammatory conditions, experiences amyloidosis, resulting in a decrease in its level [20, 21]. Comparative analysis of these inflammatory indicators revealed that OSE causes less damage to the lumbar fascia and muscles, diminishes postoperative local inflammatory responses and tissue edema, and thus alleviates pain stimulation. This is consistent with the findings of Ahn Y et al. [7, 11], who reported that OSE is less invasive and results in reduced tissue damage than UBE.\u003c/p\u003e \u003cp\u003eThis study indicated that VAS-B, VAS-L scores, and ODI of the two groups of patients improved at different postoperative time points compared with those before the operation. Second, during the 1-year postoperative follow-up, no statistically significant differences were observed in VAS-B, VAS-L scores, and ODI between the two groups. This is consistent with the findings of Liu C et al. [22, 23], who reported that the enhancement rates of VAS scores and ODI at the last follow-up were highly consistent between OSE and UBE. This suggests that both surgical methods can accomplish comprehensive nerve root decompression, alleviate the clinical symptoms of patients, and achieve similar functional rehabilitation levels. Additionally, regarding the modified MacNab criteria, the excellent and good rates of both groups exceeded 80%, signifying that both surgical techniques were recognized by patients as satisfactory.\u003c/p\u003e \u003cp\u003eWith the increasing adoption of spinal endoscopic techniques, greater attention has been directed toward postoperative complications. Dural tear, nerve root injury, and surgical site infection are common complications of spinal endoscopy. Chu PL et al. [24] reported that the complication rate of UBE was 5.4%, whereas Lyu Y et al. [25] reported that the complication rate of OSE was 5.2%. In this study, which focused on MSU grade 2 LDH, the UBE group experienced four cases of dural tear, one case of nerve root injury, and two cases of postoperative wound infection, whereas the OSE group experienced three cases of dural tear, no nerve root injury, and two cases of postoperative wound infection. The overall complication rates in both groups were not significantly different from those of previous research results, and no statistically significant differences were observed in the complication rates between the two groups, indicating that both techniques have good safety. Regarding the recurrence rate, the recurrence of LDH after discectomy remains a clinical concern. A previous study reported postoperative recurrence rates ranging from 5% to 12% [26]. In this study, the recurrence rates in both groups were lower than the reported rates, indicating that spinal endoscopy techniques have a relatively low risk of short-term recurrence for foraminal and extra-foraminal disc herniations. However, long-term follow-up is required to confirm the accuracy of the experiment.\u003c/p\u003e \u003cp\u003eAlthough no statistically significant differences were observed between the two groups regarding long-term VAS scores, ODI, and the modified MacNab criteria, this does not imply equivalent effects on the local spinal environment. The protection of the bony structure and muscle tissue of the spine after surgery is associated with the patient's long-term biomechanical stability and postoperative quality of life. Regarding bony structure preservation, previous studies have demonstrated [10] that through finite element analysis, the removal of over 30% of the superior articular process can reduce the lumbar spine range of motion, increase facet joint loading, and elevate intervertebral disc pressure, thereby adversely affecting spinal stability. To quantify the bone loss volume more intuitively and accurately, this study utilized 3D Slicer software to precisely calculate the BLV during the operation and found that the bone loss in the UBE group was significantly more than that in the OSE group. This finding is consistent with the results of Zhang J et al. [27, 28]. UBE frequently requires extensive bony resection of the lamina and the medial aspect of the facet joint to provide an adequate surgical field and instrument operation space when dealing with protrusions located in the foramen and extra-foraminal regions, such as MSU 2B/2C type. Excessive resection of the facet joint is typically a risk factor for postoperative lumbar instability and accelerated adjacent segment disease in the long term [29]. The OSE technique, owing to its precisely targeted decompression characteristics, facilitates effective nerve decompression through a smaller bone window, thereby enhancing spinal stability. Although no significant differences were observed in DHI, ROM, and ST between the two groups during the 1-year postoperative follow-up period, suggesting that both surgical methods can effectively preserve lumbar stability, the increased bone loss in the UBE group may indicate a potential loss of biomechanical advantages. The risk of adjacent segment degeneration in the future may increase in young, physically active patients. Therefore, long-term follow-up is needed to observe the long-term effects. Regarding muscle tissue protection, the MF RCSA of both groups decreased significantly at 6 months postoperatively compared to preoperative levels; however, the decrease in the OSE group was significantly smaller than that in the UBE group. The multifidus muscle, a deep paraspinal muscle, is essential for maintaining lumbar segmental stability. The atrophy and fat infiltration are significantly associated with chronic low back pain and poor functional recovery post-surgery [30, 31]. The establishment of two channels and soft tissue dissection and retraction in the UBE procedure may compromise the nerve and blood supply of the multifidus muscle, resulting in denervation atrophy. Concurrently, postoperative pain and inflammation may hinder rehabilitation exercises, exacerbating disuse atrophy. Conversely, the OSE operation through a single channel maximally preserves the nerve supply and structural integrity of the multifidus muscle. This is consistent with the superior muscle imaging outcomes in the OSE group post-surgery as reported by Li T et al. [10, 16]. No significant difference was observed in the relative cross-sectional area of the erector spinae and psoas major muscles pre- and post-surgery between the two groups. This may be attributable to the fact that these muscles, functioning as stabilizers, are less directly affected by single-segment surgery and possess a greater compensatory ability than the multifidus muscle. Additionally, the milder pain and inflammatory response in the OSE group after surgery allow patients to commence lumbar muscle function exercises earlier, thereby reducing the risk of disuse atrophy of the lumbar muscles. Furthermore, enhanced preservation of the multifidus muscle aids in sustaining the dynamic stability of the surgical segment, mitigating the risk of long-term adjacent segment disease and chronic low back pain.\u003c/p\u003e\n\u003ch3\u003eLimitations\u003c/h3\u003e\n\u003cp\u003e This study has the following limitations: The retrospective study design had inherent selection bias; the sample size was relatively small, especially the number of cases in each MSU subgroup. Furthermore, the follow-up period was relatively short (\u0026ge;\u0026thinsp;1 year), and it is impossible to evaluate the effects of the two surgical methods on long-term outcomes (5\u0026ndash;10 years or more), such as adjacent segment disease and reoperation rate. Future large-scale, prospective, long-term follow-up, and multi-center studies are required to provide higher-level evidence.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eOSE and UBE are efficacious, minimally invasive techniques for treating grade 2 lumbar disc herniation at the L5/S1 segment. They are comparable with mid- to long-term neurological function recovery and patient satisfaction. However, OSE, characterized by its single-channel and coaxial visualization capabilities, offers significant advantages in minimizing surgical trauma, mitigating early postoperative pain, decreasing inflammatory responses, enhancing the preservation of bony structures, and protecting the core stabilizing muscle group (multifidus muscle), thereby demonstrating a superior minimally invasive approach. In clinical practice, it is recommended to personalize surgical approaches based on the specific anatomical characteristics of the patient, protrusion type, and the surgeon's expertise to optimize patient outcomes.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eOSE \u0026ndash; Single-port endoscopic (open surgical excision) \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eUBE \u0026ndash; Unilateral biportal endoscopic \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eLDH \u0026ndash; Lumbar disc herniation \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eMSU \u0026ndash; Michigan State University \u0026nbsp;\u003c/p\u003e\n\u003cp\u003ePGE2 \u0026ndash; Prostaglandin E2 \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTTR \u0026ndash; Transthyretin \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eVAS \u0026ndash; Visual analog scale \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eODI \u0026ndash; Oswestry Disability Index \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eBLV \u0026ndash; Bone loss volume \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eDHI \u0026ndash; Disc height index \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eROM \u0026ndash; Range of motion \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eST \u0026ndash; Sagittal translation \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eRCSA \u0026ndash; Relative cross-sectional area \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eMRI \u0026ndash; Magnetic resonance imaging \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eCT \u0026ndash; Computed tomography \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eBMI \u0026ndash; Body mass index \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eMF \u0026ndash; Multifidus \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eES \u0026ndash; Erector spinae \u0026nbsp;\u003c/p\u003e\n\u003cp\u003ePS \u0026ndash; Psoas major \u0026nbsp;\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTianci Fang、Lei Liu、MUSTAFA ABBAS FARHOOD SULTANI、Liang Guo、Ziwei Xia and Meng Han designed the study and gave us several meaningful suggestions. Jie Shang、Yue Zhang and Chao Ma\u0026nbsp;reviewed and collected the medical records.\u0026nbsp;Guizhu Ji、Youdi Xue and Hengcai Zhou\u0026nbsp;analyzed and interpreted the patient data.\u0026nbsp;Xianyi Zhang\u0026nbsp;was a contributor in writing the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability \u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and analyzed in this study can be obtained from the corresponding author upon reasonable request.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study strictly adhered to the ethical principles of the Declaration of Helsinki (World Medical Association, 2024). The research protocol was reviewed and approved by the Biomedical Research Ethics Committee of Xuzhou Central Hospital (Approval Number: XZXY-LK-20210810-0121). All participants signed written informed consent forms after fully understanding the purpose, procedures, and their rights of the study. Throughout the study, the privacy rights, data confidentiality, and the right to withdraw at any time of the participants were strictly protected. No personal identity information was used in this study. As this study was a retrospective one, the requirement for informed consent was waived.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was supported by the \u003cstrong\u003eProject of Xuzhou Municipal Health Commission\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e(Grant No.KC21206), Contract for Science and Technology Projects of Xuzhou Health Commission (Grant No.XWKYHT20230054), \u003cstrong\u003eJiangsu Provincial Medical Center\u003c/strong\u003e (Grant No. QNRC2016392), Pengcheng Talents - Medical Young Reserve Talents Training Project (Grant No.XWRCHT20220020), \u0026nbsp;Xuzhou Science and Technology Project Contract(Grant No.KC23177).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo acknowledgements to declare.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eYu P, Mao F, Chen J, Ma X, Dai Y, Liu G, Dai F, Liu J. Characteristics and mechanisms of resorption in lumbar disc herniation. Arthritis Res Ther. 2022 Aug 23;24(1):205. doi: 10.1186/s13075-022-02894-8. PMID: 35999644; PMCID: PMC9396855.\u003c/li\u003e\n\u003cli\u003eLa Rosa C, Morabito S, Carloni A, Davini T, Remelli C, Specchi S, Bernardini M. Prevalence, MRI findings, and clinical features of lumbosacral intervertebral disc protrusion in French Bulldogs diagnosed with acute thoracic or lumbar intervertebral disc extrusion. Front Vet Sci. 2023 Nov 23;10:1302418. doi: 10.3389/fvets.2023.1302418. PMID: 38076554; PMCID: PMC10702215.\u003c/li\u003e\n\u003cli\u003eCristiani-Winer M, Ortiz P, Orosco-Falcone D, Guimbard-P\u0026eacute;rez J, Carabajal J, Eluani M. \u0026iquest;Es confiable la clasificaci\u0026oacute;n de la hernia de disco lumbar de la Universidad Estatal de M\u0026iacute;chigan entre cirujanos de columna? [Is the Michigan State University lumbar disc herniation classification reliable among spine surgeons?]. Acta Ortop Mex. 2022 Mar-Apr;36(2):104-109. Spanish. PMID: 36481551.\u003c/li\u003e\n\u003cli\u003eDu PY, Zhang YW, Cao XH, Liu YL, Yan YT, Liu L, Du SQ. Paravertebral Muscle Morphology in L4-L5 Disc Herniation: Insights from the Michigan State University Classification. Med Sci Monit. 2023 Oct 21;29:e941937. doi: 10.12659/MSM.941937. PMID: 37864329; PMCID: PMC10595040.\u003c/li\u003e\n\u003cli\u003eTan F, Zhang F, Han S, Song X, Yuan Y, Wang J. [Analysis of effectiveness of one-hole split endoscopy technique in treatment of lumbar spinal stenosis]. Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi. 2024 Mar 15;38(3):337-341. Chinese. doi: 10.7507/1002-1892.202401042. PMID: 38500428; PMCID: PMC10982041.\u003c/li\u003e\n\u003cli\u003eJu CI, Kim P, Seo JH, Kim SW, Lee SM. Complications of Cervical Endoscopic Spinal Surgery: A Systematic Review and Narrative Analysis. World Neurosurg. 2023 Oct;178:330-339. doi: 10.1016/j.wneu.2023.07.058. Epub 2023 Jul 20. PMID: 37479028.\u003c/li\u003e\n\u003cli\u003eAhn Y, Lee S. Uniportal versus biportal endoscopic spine surgery: a comprehensive review. Expert Rev Med Devices. 2023 Jul;20(7):549-556. doi: 10.1080/17434440.2023.2214678. Epub 2023 May 15. PMID: 37183715.\u003c/li\u003e\n\u003cli\u003eReis JPG, Pinto EM, Teixeira A, Frada R, Rodrigues D, Cunha R, Miranda A. Unilateral biportal endoscopy: review and detailed surgical approach to extraforaminal approach. EFORT Open Rev. 2025 Mar 3;10(3):151-155. doi: 10.1530/EOR-24-0137. PMID: 40071975; PMCID: PMC11896681.\u003c/li\u003e\n\u003cli\u003eMeng H, Su N, Lin J, Fei Q. Comparative efficacy of unilateral biportal endoscopy and micro-endoscopic discectomy in the treatment of degenerative lumbar spinal stenosis: a systematic review and meta-analysis. J Orthop Surg Res. 2023 Oct 31;18(1):814. doi: 10.1186/s13018-023-04322-2. PMID: 37907922; PMCID: PMC10619222.\u003c/li\u003e\n\u003cli\u003eLi T, Jiang Q, Zhong W, Zhu T, Lu Z, Ding Y. One-hole split endoscope versus unilateral biportal endoscopy for lumbar spinal stenosis: a retrospective propensity score study. J Orthop Surg Res. 2024 Apr 22;19(1):254. doi: 10.1186/s13018-024-04743-7. PMID: 38649974; PMCID: PMC11034078.\u003c/li\u003e\n\u003cli\u003eDeng C, Li X, Wu C, Xie W, Chen M. One-hole split endoscopy versus unilateral biportal endoscopy for lumbar degenerative disease: a systematic review and meta-analysis of clinical outcomes and complications. J Orthop Surg Res. 2025 Feb 21;20(1):187. doi: 10.1186/s13018-025-05591-9. PMID: 39985036; PMCID: PMC11844110.\u003c/li\u003e\n\u003cli\u003eZhang Y, Feng B, Hu P, Dai G, Su W. One-hole split endoscopy technique versus unilateral biportal endoscopy technique for L5-S1 lumbar disk herniation: analysis of clinical and radiologic outcomes. J Orthop Surg Res. 2023 Sep 9;18(1):668. doi: 10.1186/s13018-023-04159-9. PMID: 37689668; PMCID: PMC10492266.\u003c/li\u003e\n\u003cli\u003eFardon DF, Williams AL, Dohring EJ, Murtagh FR, Gabriel Rothman SL, Sze GK. Lumbar disc nomenclature: version 2.0: Recommendations of the combined task forces of the North American Spine Society, the American Society of Spine Radiology and the American Society of Neuroradiology. Spine J. 2014 Nov 1;14(11):2525-45. doi: 10.1016/j.spinee.2014.04.022. Epub 2014 Apr 24. PMID: 24768732.\u003c/li\u003e\n\u003cli\u003eLa Rosa C, Morabito S, Carloni A, Davini T, Remelli C, Specchi S, Bernardini M. Prevalence, MRI findings, and clinical features of lumbosacral intervertebral disc protrusion in French Bulldogs diagnosed with acute thoracic or lumbar intervertebral disc extrusion. Front Vet Sci. 2023 Nov 23;10:1302418. doi: 10.3389/fvets.2023.1302418. PMID: 38076554; PMCID: PMC10702215.\u003c/li\u003e\n\u003cli\u003eRado\u0026scaron; I, Lončarić Katu\u0026scaron;in M, Budrovac D, Dimitrijević I, Hnate\u0026scaron;en D, Omrčen I. PERCUTANEOUS LASER DISC DECOMPRESSION FOR LUMBAR RADICULAR PAIN: A SYSTEMATIC REVIEW OF PUBMED IN THE LAST FIVE YEARS. Acta Clin Croat. 2023 Nov;62(Suppl4):63-67. doi: 10.20471/acc.2023.62.s4.9. PMID: 40463453; PMCID: PMC12128808.\u003c/li\u003e\n\u003cli\u003eQing P, Guo W, Xie S, Zhao S, Cui L, Li M, Gong S, Hu Y. Clinical efficacy of one-hole split endoscopy vs. unilateral biportal endoscopy for the treatment of single-segment lumbar spinal stenosis: a retrospective study with 2-year follow-up. Front Surg. 2025 Feb 18;12:1495741. doi: 10.3389/fsurg.2025.1495741. PMID: 40040816; PMCID: PMC11876375.\u003c/li\u003e\n\u003cli\u003eFeng Y, Zhang W, Li K, Lin X, Liu C, Wang C, Hu B, Wang K, Xu W, Si H. Evaluation of the Effectiveness of Cervical One-Hole Split Endoscopic Keyhole Surgery for Cervical Radiculopathy. J Pain Res. 2024 Sep 19;17:3093-3099. doi: 10.2147/JPR.S451943. PMID: 39318547; PMCID: PMC11420887.\u003c/li\u003e\n\u003cli\u003eCheng H, Huang H, Guo Z, Chang Y, Li Z. Role of prostaglandin E2 in tissue repair and regeneration. Theranostics. 2021 Aug 13;11(18):8836-8854. doi: 10.7150/thno.63396. PMID: 34522214; PMCID: PMC8419039.\u003c/li\u003e\n\u003cli\u003eBryson TD, Harding P. Prostaglandin E2 EP receptors in cardiovascular disease: An update. Biochem Pharmacol. 2022 Jan;195:114858. doi: 10.1016/j.bcp.2021.114858. Epub 2021 Nov 22. PMID: 34822808.\u003c/li\u003e\n\u003cli\u003eFontana M, Berk JL, Gillmore JD, Witteles RM, Grogan M, Drachman B, Damy T, Garcia-Pavia P, Taubel J, Solomon SD, Sheikh FH, Tahara N, Gonz\u0026aacute;lez-Costello J, Tsujita K, Morbach C, Pozsonyi Z, Petrie MC, Delgado D, Van der Meer P, Jabbour A, Bondue A, Kim D, Azevedo O, Hvitfeldt Poulsen S, Yilmaz A, Jankowska EA, Algalarrondo V, Slugg A, Garg PP, Boyle KL, Yureneva E, Silliman N, Yang L, Chen J, Eraly SA, Vest J, Maurer MS; HELIOS-B Trial Investigators. Vutrisiran in Patients with Transthyretin Amyloidosis with Cardiomyopathy. N Engl J Med. 2025 Jan 2;392(1):33-44. doi: 10.1056/NEJMoa2409134. Epub 2024 Aug 30. PMID: 39213194.\u003c/li\u003e\n\u003cli\u003eGentile L, Coelho T, Dispenzieri A, Concei\u0026ccedil;\u0026atilde;o I, Waddington-Cruz M, Kristen A, Wixner J, Diemberger I, Gonzalez-Moreno J, Cariou E, Maurer MS, Plant\u0026eacute;-Bordeneuve V, Garcia-Pavia P, Tournev I, Gonzalez-Costello J, Duarte AG, Grogan M, Mazzeo A, Chapman D, Gupta P, Glass O, Amass L; THAOS investigators. A 15-year consolidated overview of data in over 6000 patients from the Transthyretin Amyloidosis Outcomes Survey (THAOS). Orphanet J Rare Dis. 2023 Nov 10;18(1):350. doi: 10.1186/s13023-023-02962-5. PMID: 37946256; PMCID: PMC10636983.\u003c/li\u003e\n\u003cli\u003eLiu C, Zhang W, Wang C, Hu B, Wang K, Feng Y, Li L, Xu W, Si H. Comparison of one-hole split endoscopic discectomy and microendoscopic discectomy in the treatment of lumbar disk herniation: a one-year retrospective cohort study. J Orthop Surg Res. 2024 Feb 6;19(1):123. doi: 10.1186/s13018-024-04574-6. PMID: 38317253; PMCID: PMC10845564.\u003c/li\u003e\n\u003cli\u003eZhang Y, Feng B, Ning H, Dai G, Su W, Lu H, Hu P. One-hole split endoscope technique for migrated lumbar disc herniation: a single-centre, retrospective study of a novel technique. J Orthop Surg Res. 2023 Jul 5;18(1):483. doi: 10.1186/s13018-023-03967-3. PMID: 37408054; PMCID: PMC10324176.\u003c/li\u003e\n\u003cli\u003eChu PL, Wang T, Zheng JL, Xu CQ, Yan YJ, Ma QS, Meng-Chen Y, Da-Sheng T. Global and Current Research Trends of Unilateral Biportal Endoscopy/Biportal Endoscopic Spinal Surgery in the Treatment of Lumbar Degenerative Diseases: A Bibliometric and Visualization Study. Orthop Surg. 2022 Apr;14(4):635-643. doi: 10.1111/os.13216. Epub 2022 Mar 16. PMID: 35293686; PMCID: PMC9002063.\u003c/li\u003e\n\u003cli\u003eLyu Y, Liu GG, Li FL. [One-hole split endoscope-assisted transforaminal lumbar interbody fusion for the treatment of lumbar degenerative diseases:an early efficacy observation]. Zhongguo Gu Shang. 2025 Nov 25;38(11):1106-11. Chinese. doi: 10.12200/j.issn.1003-0034.20250208. PMID: 41340298.\u003c/li\u003e\n\u003cli\u003eShen SC, Chen HC, Tsou HK, Lin RH, Shih YT, Huang CW, Tang CL, Chen HT, Chang CC, Tzeng CY. Percutaneous endoscopic lumbar discectomy for L5-S1 disc herniation based on image analysis and clinical findings: A retrospective review of 345 cases. Medicine (Baltimore). 2023 Feb 3;102(5):e32832. doi: 10.1097/MD.0000000000032832. PMID: 36749265; PMCID: PMC9901959.\u003c/li\u003e\n\u003cli\u003eZhang J, Yan R, Xu S, Shao B, Dou Y. Short-term lumbar disc and lumbar stability changes of one-hole split endoscope technique treatment of spinal stenosis. BMC Musculoskelet Disord. 2024 Apr 24;25(1):325. doi: 10.1186/s12891-024-07443-9. PMID: 38659005; PMCID: PMC11040931.\u003c/li\u003e\n\u003cli\u003eLyu Y, Liu GG, Li FL. [One-hole split endoscope-assisted transforaminal lumbar interbody fusion for the treatment of lumbar degenerative diseases:an early efficacy observation]. Zhongguo Gu Shang. 2025 Nov 25;38(11):1106-11. Chinese. doi: 10.12200/j.issn.1003-0034.20250208. PMID: 41340298.\u003c/li\u003e\n\u003cli\u003eFang N, Yan S, Yang A. Research advances in unilateral endoscopic spinal surgery for the treatment of lumbar disc herniation: a review. J Orthop Surg Res. 2025 Jul 11;20(1):643. doi: 10.1186/s13018-025-06071-w. PMID: 40646647; PMCID: PMC12255086.\u003c/li\u003e\n\u003cli\u003eAbd-Elsayed A, Kurt E, Kollenburg L, Hasoon J, Wahezi SE, Storlie NR. Lumbar Multifidus Dysfunction and Chronic Low Back Pain: Overview, Therapies, and an Update on the Evidence. Pain Pract. 2025 Jun;25(5):e70044. doi: 10.1111/papr.70044. PMID: 40361257.\u003c/li\u003e\n\u003cli\u003eStevens S, Agten A, Timmermans A, Vandenabeele F. Unilateral changes of the multifidus in persons with lumbar disc herniation: a systematic review and meta-analysis. Spine J. 2020 Oct;20(10):1573-1585. doi: 10.1016/j.spinee.2020.04.007. Epub 2020 Apr 20. PMID: 32325246.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTables 1 to 4 are available in the Supplementary Files section.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-musculoskeletal-disorders","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmsd","sideBox":"Learn more about [BMC Musculoskeletal Disorders](http://bmcmusculoskeletdisord.biomedcentral.com/)","snPcode":"","submissionUrl":"https://author-welcome.nature.com/12891","title":"BMC Musculoskeletal Disorders","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-8742945/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8742945/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eBackground and Objective\u003c/p\u003e \u003cp\u003eSingle-port endoscopic (open surgical excision [OSE]) discectomy and unilateral biportal endoscopic (UBE) discectomy have demonstrated effective therapeutic outcomes in lumbar disc herniation (LDH) treatment. However, there is a lack of clear guidelines for selecting surgical techniques for LDH at Michigan State University (MSU) grade 2. This study aimed to compare the clinical efficacy and imaging data of OSE and UBE in treating L5/S1 LDH at MSU grade 2.\u003c/p\u003e \u003cp\u003eMethods\u003c/p\u003e \u003cp\u003eThis retrospective cohort study enrolled patients with L5/S1 LDH who were admitted between September 2022 and July 2024. Patients were stratified into OSE (n\u0026thinsp;=\u0026thinsp;97) and UBE (n\u0026thinsp;=\u0026thinsp;119) groups according to the surgical technique performed. Each group was further stratified into two subgroups based on the MSU classification of LDH (types 2B and 2C). All patients were followed for a minimum of one year. Perioperative parameters, serum levels of prostaglandin E2 (PGE2) and transthyretin (TTR), visual analog scale (VAS) score, Oswestry Disability Index (ODI), postoperative complication rate, recurrence rate, and modified MacNab criteria at the final follow-up were recorded and compared between groups to assess clinical efficacy. Surgical outcomes were further evaluated using radiological parameters, including bone loss volume (BLV), disc height index (DHI), lumbar range of motion (ROM), sagittal translation (ST), and paraspinal muscle relative cross-sectional area (RCSA).\u003c/p\u003e \u003cp\u003eResults\u003c/p\u003e \u003cp\u003eNo significant difference was observed in the operation time and hospital stay between the two groups (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05). Incision length, intraoperative blood loss, and number of intraoperative fluoroscopy exposures were significantly lower in the OSE group than in the UBE group (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). During a minimum of 1 year of postoperative follow-up, no statistically significant difference was observed in the VAS scores of the waist and legs and ODI at any assessed time point between the two groups (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05). However, the VAS scores of incision-related pain in the OSE group were lower than those in the UBE group on days 1 and 3 postoperatively (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). No significant difference was observed between the two groups in complication rates, recurrence rates, modified MacNab scores, DHI, ROM, ST, erector spinae RCSA, or psoas major RCSA within 1 year postoperatively (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05). However, the OSE group demonstrated significantly better outcomes than the UBE group with respect to bone loss, serum PGE2, TTR levels, and multifidus RCSA (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003eConclusion\u003c/p\u003e \u003cp\u003eOSE and UBE can achieve good therapeutic effects in the treatment of grade 2 LDH at the L5/S1 segment in patients with MSU. Compared with UBE, OSE demonstrated advantages, including reduced surgical trauma, less early postoperative incision pain, a lower perioperative inflammatory response, improved preservation of bone structure, and enhanced protection of the multifidus muscle, reflecting higher surgical precision and a more minimally invasive profile. In clinical practice, treatment should be individualized based on the specific conditions of each patient.\u003c/p\u003e","manuscriptTitle":"Comparison of Short-Term Efficacy of Single-port Endoscopic Discectomy and Unilateral Biportal Endoscopic Discectomy in the Treatment of L5/S1 Lumbar Disc Herniation at Michigan State University Grade 2","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-09 17:36:13","doi":"10.21203/rs.3.rs-8742945/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2026-04-02T14:31:43+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"228272593575138059815223833450628393893","date":"2026-04-02T14:25:56+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-14T12:58:51+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-07T08:26:30+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"78978266261678774649903351216701789131","date":"2026-03-05T20:07:33+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"130678427760672018432966614014147162052","date":"2026-03-05T09:03:36+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"43732069605538402973864763372408294158","date":"2026-03-05T08:41:24+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-03-03T18:41:20+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-03T18:37:09+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-02-16T13:18:44+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-02-15T15:22:57+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Musculoskeletal Disorders","date":"2026-02-15T15:17:20+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-musculoskeletal-disorders","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmsd","sideBox":"Learn more about [BMC Musculoskeletal Disorders](http://bmcmusculoskeletdisord.biomedcentral.com/)","snPcode":"","submissionUrl":"https://author-welcome.nature.com/12891","title":"BMC Musculoskeletal Disorders","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"8b974da6-f9f9-4ffc-828a-d5ad2d2c1d5c","owner":[],"postedDate":"March 9th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-03-09T17:36:14+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-09 17:36:13","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8742945","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8742945","identity":"rs-8742945","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}