Clinical Efficacy of Unilateral Biportal Endoscopic Transforaminal Lumbar Interbody Fusion Versus Minimally Invasive Transforaminal Lumbar Interbody Fusion in the Treatment of Mild Degenerative Lumbar Spondylolisthesis

Clinical Efficacy of Unilateral Biportal Endoscopic Transforaminal Lumbar Interbody Fusion Versus Minimally Invasive Transforaminal Lumbar Interbody Fusion in the Treatment of Mild Degenerative Lumbar Spondylolisthesis | 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 Clinical Efficacy of Unilateral Biportal Endoscopic Transforaminal Lumbar Interbody Fusion Versus Minimally Invasive Transforaminal Lumbar Interbody Fusion in the Treatment of Mild Degenerative Lumbar Spondylolisthesis Bangjun Wen, Shutong Yang, Aiguo Gao This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9149477/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Objective To compare the clinical and radiological outcomes of unilateral biportal endoscopic transforaminal lumbar interbody fusion (UBE-TLIF) and minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) in the treatment of single-level mild degenerative lumbar spondylolisthesis. Methods A retrospective analysis was conducted on 80 patients with single-level mild degenerative lumbar spondylolisthesis, including 40 patients treated with UBE-TLIF and 40 patients treated with MIS-TLIF. Perioperative parameters, visual analog scale (VAS) scores, Oswestry Disability Index (ODI), modified MacNab scores, fusion rates, trabecular bone remodeling (TBR) at 3 months postoperatively, and multifidus atrophy and fat infiltration rates at 12 months postoperatively were compared between the two groups. Results The UBE-TLIF group demonstrated significantly less intraoperative blood loss and shorter hospital stays, but longer operative times compared with the MIS-TLIF group (all P < 0.01). At 3 days postoperatively, the VAS score for low back pain was significantly lower in the UBE-TLIF group than in the MIS-TLIF group (P 0.05). The UBE-TLIF group showed significantly higher TBR positivity at 3 months and a higher fusion rate at 6 months postoperatively compared with the MIS-TLIF group (P < 0.05), while no significant difference in fusion rate was observed at 12 months. At 12 months postoperatively, the multifidus atrophy rate and fat infiltration rate were both significantly lower in the UBE-TLIF group than in the MIS-TLIF group (P < 0.05). Conclusion Both UBE-TLIF and MIS-TLIF provide satisfactory clinical outcomes in the treatment of single-level mild degenerative lumbar spondylolisthesis. Compared with MIS-TLIF, UBE-TLIF demonstrates certain advantages in early postoperative pain relief, preservation of paraspinal muscles, and early osteointegration during the fusion process. Lumbar spondylolisthesis unilateral biportal endoscopic༛Muscle atrophy༛transforaminal lumbar interbody fusion Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction With the acceleration of population aging, the prevalence of degenerative lumbar spondylolisthesis (DLS) has increased rapidly. Among individuals aged 66–70 years, DLS affects up to 15% of men and more than 50% of women [ 1 ] . DLS is characterized by anterior displacement of the superior vertebral body relative to the inferior vertebra, a pathological change that may lead to spinal instability and subsequent neural compression [ 2 ] . Clinically, DLS commonly presents with chronic low back pain with or without radicular lower extremity pain, significantly impairing patients’ quality of life. When conservative treatment fails, surgical intervention is commonly adopted in clinical practice. Lumbar fusion surgery can effectively alleviate symptoms and help maintain spinopelvic sagittal balance [ 3 ] . Since Harms and Jeszenszky first provided a detailed description of transforaminal lumbar interbody fusion (TLIF) in 1998 [ 4 , 5 ] , this technique has become a widely adopted surgical approach in clinical practice due to its high safety in intervertebral disc space preparation and cage implantation, as well as its low incidence of postoperative radiculitis. Conventional open TLIF provides reliable clinical outcomes and adequate decompression; however, it is associated with substantial soft tissue injury, leading to increased postoperative muscle atrophy and higher infection rates. With the advancement of minimally invasive techniques, an increasing number of surgeons have adopted small-incision, endoscopy-assisted approaches for lumbar interbody fusion [ 6 ] . In 2004, Foley [ 7 ] introduced a minimally invasive TLIF technique by combining tubular retractors with microscopic assistance, known as minimally invasive transforaminal lumbar interbody fusion(MIS-TLIF), Compared with open surgery, MIS-TLIF markedly reduces iatrogenic injury caused by extensive muscle retraction that obstructs the surgical field. However, because of the depth of the surgical corridor, complete separation of all soft tissues cannot be achieved, and visualization may still be limited. In addition, prolonged retraction of the paraspinal soft tissues by the tubular system can result in ischemic injury to the paraspinal muscles, thereby adversely affecting postoperative recovery. With the advancement of spinal endoscopic techniques and the introduction of a fluid medium, unilateral biportal endoscopic transforaminal lumbar interbody fusion (UBE-TLIF) has gained increasing attention because of its clear surgical field and greater flexibility in instrument selection [ 8 , 9 ] . Based on this background, the present study adopted a single-center retrospective design to comparatively analyze the clinical and radiological outcomes of patients with single-level mild degenerative lumbar spondylolisthesis treated with UBE-TLIF or MIS-TLIF. The primary focus was to evaluate differences between the two surgical techniques in terms of clinical efficacy, perioperative parameters, early trabecular bone remodeling during fusion, and changes in paraspinal muscle morphology. Through a comprehensive assessment integrating multidimensional imaging and functional outcomes, this study aims to provide new clinical evidence to inform the optimal selection of minimally invasive lumbar fusion techniques and to enhance the understanding of fusion-related biological mechanisms. Methods Inclusion criteria (1) Single-level grade I degenerative lumbar spondylolisthesis (Meyerding classification) with radiological findings consistent with clinical symptoms; (2) a definitive preoperative diagnosis confirmed by lumbar hyperextension and flexion radiographs, lumbar computed tomography (CT), and magnetic resonance imaging (MRI); (3) failure to achieve significant symptom relief after more than three months of conservative treatment; and (4) completion of at least one year of postoperative follow-up. Exclusion criteria (1) A history of previous lumbar spine surgery; (2) the presence of spinal tumors, spinal fractures, spinal tuberculosis, severe scoliosis, or severe osteoporosis; (3) coagulation disorders, severe cardiopulmonary dysfunction, or other conditions rendering the patient unable to tolerate surgery; and (4) incomplete clinical data. A retrospective analysis was performed on 80 patients with single-level mild degenerative lumbar spondylolisthesis who met the inclusion criteria and were treated at our institution between March 2020 and January 2025. Among them, 40 patients in the study group underwent UBE-TLIF, while 40 patients in the control group received MIS-TLIF. There were no significant differences between the two groups in baseline characteristics, including sex, age, body mass index (BMI), surgical level, preoperative visual analog scale (VAS) scores for low back and leg pain, or Oswestry Disability Index (ODI) scores (all P > 0.05), indicating good comparability. All patients provided written informed consent, and this study was approved by the institutional ethics committee. Surgical Technique All procedures were performed by the same surgeon with more than five years of experience in minimally invasive spinal surgery. Observation group (UBE-TLIF) After satisfactory induction of general anesthesia, the patient was placed in the prone position, and the operating table was adjusted to achieve a horizontal lumbar alignment. The surgical level was confirmed using C-arm fluoroscopy. Surface landmarks corresponding to the target intervertebral space, the spinous processes of the adjacent vertebrae, and the bilateral pedicle projections were marked. After routine skin preparation and draping, a puncture needle was inserted along the surface projection of the pedicle under fluoroscopic guidance. Once the needle entered the vertebral body, a guidewire was placed for localization.On the symptomatic side, two oblique transverse skin incisions of approximately 1 cm were made at the surface projections of the upper and lower pedicles. Taking the left side as an example, the cranial incision was used as the viewing portal and the caudal incision as the working portal, with the configuration reversed on the right side. Tubular dilators were used to establish the portals, and fluoroscopy was repeated to confirm accurate access to the target level. Continuous saline irrigation was applied to maintain a clear endoscopic field. Through the working portal, a radiofrequency probe was introduced to remove soft tissues surrounding the lamina, fully exposing the inferior lamina of the cranial vertebra, the medial border of the inferior articular process of the cranial vertebra, and the superior lamina of the caudal vertebra on the operative side.An osteotome and Kerrison rongeur were used to resect the inferior lamina of the cranial vertebra, the superior lamina of the caudal vertebra, and the superior and inferior articular processes. The resected bone was preserved for grafting. The attachment points of the ligamentum flavum were fully exposed, and the ligamentum flavum and epidural adipose tissue were removed. A nerve root retractor was inserted to gently retract the nerve root and dural sac contralaterally, thereby exposing the intervertebral disc. The nucleus pulposus was removed using pituitary forceps, and the cartilaginous endplates were carefully curetted under direct endoscopic visualization until punctate bleeding was observed, indicating adequate endplate preparation.After cage trialing, an appropriately sized interbody cage was selected and packed with autologous bone and artificial bone before insertion. Following confirmation of adequate decompression and relaxation of the nerve root and dural sac, the endoscope was withdrawn. Percutaneous pedicle screw–rod fixation was then performed along the guidewires. After fluoroscopic confirmation of correct cage and instrumentation positioning, the surgical field was irrigated with saline, a drainage tube was placed, and the incision was closed and covered with sterile dressings. Control group (MIS-TLIF) After satisfactory induction of general anesthesia, the patient was placed in the prone position, and the operating table was adjusted to achieve a horizontal lumbar alignment. The target surgical level was confirmed using C-arm fluoroscopy, and surface landmarks corresponding to the involved intervertebral space, the spinous processes of the adjacent vertebrae, and the bilateral pedicle projections were marked. After routine skin preparation and draping, a skin incision of approximately 2 cm was made about 3 cm lateral to the midline along the line connecting the spinous processes. The dorsal fascia was incised, and blunt dissection was performed through the intermuscular plane between the multifidus and longissimus muscles until the bony surface was reached.Sequential tubular dilators were then inserted and fixed in place, and the soft tissues overlying the facet joints were thoroughly cleared. After adequate exposure, the superior and inferior articular processes at the affected level and a portion of the lamina were resected and preserved for bone grafting. The dural sac and nerve root were fully exposed, and a nerve root retractor was used to gently retract the nerve root and dural sac contralaterally, thereby exposing the intervertebral disc. The nucleus pulposus was removed using pituitary forceps, and the cartilaginous endplates were curetted. Bone grafting was performed, followed by insertion of an appropriately sized interbody cage.Pedicle access was achieved by inserting a puncture needle along the surface projection of the pedicle under fluoroscopic guidance. After confirmation of needle entry into the vertebral body, a guidewire was placed, and cannulated pedicle screws of appropriate length were inserted. Following fluoroscopic confirmation of correct cage and instrumentation positioning, the surgical field was irrigated with saline, a drainage tube was placed, and the incision was closed and covered with sterile dressings. Postoperative Management All patients received prophylactic antibiotics 30 minutes before surgery and for 48 hours postoperatively to prevent infection. Short-term nonsteroidal anti-inflammatory drugs were administered for postoperative analgesia. Patients in both groups were maintained on strict bed rest immediately after surgery, and systemic corticosteroids were administered at 24 hours postoperatively for anti-inflammatory purposes. The drainage tube was removed 48 hours after surgery. Ambulation was encouraged 2 days postoperatively under the protection of a brace, which was worn for at least 2 months. Bending, heavy lifting, and other load-bearing activities were prohibited for 3 months after surgery. Follow-up evaluations were scheduled at 1, 6, and 12 months after discharge, during which lumbar anteroposterior and lateral radiographs, flexion–extension radiographs, lumbar CT, and lumbar MRI were performed. Outcome Assessment: Clinical efficacy outcomes Low back pain and leg pain VAS scores were compared between groups preoperatively and at 3 days, 3 months, and 12 months postoperatively. The ODI scores were compared between groups preoperatively and at 12 months postoperatively, and the modified MacNab scores were compared between groups at 12 months after surgery) [ 10 ] . Perioperative parameters Surgery time, intraoperative blood loss, and length of hospital stay were compared between the two groups. Trabecular bone remodeling (TBR) Trabecular bone morphology on CT images at 3 months postoperatively was compared between patients. TBR was defined on coronal CT images as a radiological manifestation observed in adjacent vertebrae and was distinguished by comparison with the morphology and density of normal vertebral trabeculae. TBR represents newly formed bone structures that appear after surgery and are not observed on preoperative or immediate postoperative CT images. TBR may extend vertically or obliquely from the contact area between the interbody cage and the vertebral endplate toward the pedicle screws. In addition, because TBR exhibits higher density (higher Hounsfield unit values), similar to cortical bone, it can be clearly differentiated from the background trabecular bone [ 11 , 12 ] , (Fig. 1 ). Fusion status Fusion was evaluated on postoperative CT scans at 6 months and 1 year by two independent and experienced radiologists using the Bridwell interbody fusion grading system. According to this system, Grade I was defined as a reconstructed fusion mass with trabecular bone remodeling; Grade II as an intact graft with incomplete remodeling; Grade III as an intact graft with radiolucent areas at the cranial or caudal interface; and Grade IV as nonunion with graft collapse or resorption. Bridwell Grades I and II were considered indicative of successful fusion. Impact of surgery on paraspinal muscles Image J software was used to measure the cross-sectional area (CSA) of the multifidus muscle on the surgical approach side at the mid-disc level of the fused segment on preoperative and 12-month postoperative images. Fat tissue within the region of interest was identified by threshold-based segmentation, and the fat area was quantified. The multifidus atrophy rate was calculated as (preoperative CSA − postoperative CSA) / preoperative CSA×100%. The multifidus fat infiltration rate (FI ratio) was defined as the ratio of fat area to total muscle CSA. All measurements were performed three times, and the mean values were included in the analysis to minimize measurement error.(Fig. 2 ) Statistical Analysis Statistical analyses were performed using SPSS version 27.0. Continuous variables were tested for normality and are presented as mean ± standard deviation. Between-group comparisons of continuous variables were conducted using the independent-samples t test. Categorical variables were compared using the chi-square (χ²) test. Repeated-measures analysis of variance was used for within-group comparisons across different time points. Ordinal data were analyzed using the rank-sum test. A two-sided P value < 0.05 was considered statistically significant. To evaluate measurement reliability, intra-observer and inter-observer agreement were assessed using intraclass correlation coefficients (ICCs). Result Demographic Characteristics A total of 80 patients were included in this study, with 40 patients in the UBE-TLIF group and 40 patients in the MIS-TLIF group. There were no statistically significant differences between the two groups in baseline characteristics, including sex, age, body mass index (BMI), or surgical level (all P > 0.05), indicating good comparability between groups (Table 1 ). Operation parameters Operative time was significantly longer in the UBE-TLIF group than in the MIS-TLIF group (143.57 ± 37.12 vs. 114.79 ± 19.01 min, P < 0.01). In contrast, intraoperative blood loss was significantly lower in the UBE-TLIF group (163.89 ± 60.61 mL) compared with the MIS-TLIF group (234.20 ± 86.02 mL, P < 0.01). Additionally, the length of hospital stay was significantly shorter in the UBE-TLIF group than in the MIS-TLIF group (7.99 ± 1.42 vs. 9.35 ± 1.80 days, P < 0.01) (Table 1 .Figure.3). Table 1 ༎ Demographic and Clinical Characteristics of Patients Undergoing UBDTLIF and MIS-TLIF Demographic UBE-TLIF Group MIS-TLIF Group P Gender Male 13 18 0.251 Female 27 22 Age(years) 64.28 ± 9.39 61.78 ± 8.79 0.223 BMI(kg/m 2 ) 23.02 ± 2.56 22.98 ± 2.43 0.942 Surgery level L4-5 26 23 0.491 L5-S1 14 17 Length of Surgery Time (mins) 143.57 ± 37.12 114.79 ± 19.01 < 0.01 Estimated Blood Loss (mL) 163.89 ± 60.61 234.20 ± 86.02 < 0.01 Length of Hospital Stay (days) 7.99 ± 1.42 9.35 ± 1.80 0.05). At postoperative day 3, the UBE-TLIF group demonstrated a significantly lower VAS score for low back pain (2.96 ± 1.19) compared with the MIS-TLIF group (3.54 ± 1.27) (P 0.05).ODI and MacNab scores: No significant differences were identified between the two groups in ODI scores at any preoperative or postoperative time point, nor in the modified MacNab scores at 12 months postoperatively (all P > 0.05). (Fig. 4 ) Fusion status: At 6 months postoperatively, the fusion rate in the UBE-TLIF group (85.0%) was significantly higher than that in the MIS-TLIF group (65.0%) (P 0.05). TBR: At 3 months postoperatively, the positive rate of TBR was significantly higher in the UBE-TLIF group (57.5%) than in the MIS-TLIF group (30.0%) (P < 0.05) (Table 2 . ). Table 2 Comparative Analysis of Patient-Reported Outcomes Measures Following UBD-TLIF and MIS-TLIF Subjects UBE-TLIF Group MIS-TLIF Group P Vas of back pain Preoperative 6.42 ± 1.20 6.28 ± 1.19 0.622 D3 postoperative 2.96 ± 1.19 3.54 ± 1.27 < 0.05 3M postoperative 1.60 ± 0.65 1.68 ± 0.77 0.620 12M postoperative 0.69 ± 0.41 0.74 ± 0.42 0.548 Vas of leg pain Preoperative 6.28 ± 1.28 6.36 ± 1.44 0.775 D3 postoperative 1.57 ± 0.62 1.74 ± 0.71 0.272 3M postoperative 1.44 ± 0.64 1.59 ± 0.57 0.276 12M postoperative 0.77 ± 0.40 0.79 ± 0.34 0.825 ODI Preoperative 58.62 ± 8.98 59.12 ± 9.49 0.810 3M postoperative 24.06 ± 5.29 26.15 ± 6.12 0.106 12M postoperative 12.33 ± 3.83 13.64 ± 3.86 0.129 12M Macnab satisfaction Excellent 21 20 0.924 Good 16 18 Fair 1 1 Poor 2 1 Bridewell 6M postoperative 34,6 26,14 < 0.05 12M postoperative 39,1 37,3 0.615 TBR TBR(+) 23 12 < 0.05 TBR(-) 17 28 Imaging outcomes The intra-observer and inter-observer ICC values for all radiological measurements were greater than 0.80, indicating good reliability. • Multifidus muscle atrophy rate: The multifidus muscle atrophy rate was significantly lower in the UBE-TLIF group (29.50 ± 7.72%) than in the MIS-TLIF group (34.04 ± 10.55%) (P 0.05). At 12 months postoperatively, the fat infiltration rate in the UBE-TLIF group (34.85 ± 7.69%) was significantly lower than that in the MIS-TLIF group (38.19 ± 6.02%) (P < 0.05).(Table 3 . Figure 5 ) Table 3 Comparative analysis of muscle characteristics changes in the Multiffdus (MF) Subjects UBE-TLIF Group MIS-TLIF Group P MF atrophy rate(%) 29.50 ± 7.72 34.04 ± 10.55 < 0.05 Fat infiltration rate of MF(%) Preoperative 23.21 ± 8.43 21.31 ± 6.93 0.275 12M postoperative 34.85 ± 7.69 38.19 ± 6.02 < 0.05 Discussion DLS is a common and frequently encountered condition in the elderly population. It typically presents with low back pain, with or without radicular lower extremity pain, and some patients may also develop symptoms of intermittent claudication. This condition can substantially impair patients’ quality of life [ 13 , 14 ] . With the acceleration of global population aging, the incidence of this condition has continued to rise steadily, making it one of the most common degenerative disorders of the spine encountered in clinical practice [ 15 ] .When conservative treatment fails to provide adequate symptom relief, lumbar fusion surgery is often indicated [ 16 ] . Conventional open lumbar fusion surgery is associated with substantial soft tissue trauma. With continuous advances in spinal endoscopic techniques, minimally invasive lumbar fusion procedures have progressively replaced traditional open surgery and have become the predominant surgical approach in clinical practice [ 17 , 18 ] . Accordingly, whether different minimally invasive fusion techniques differ in terms of perioperative surgical trauma, early bone integration during fusion, and preservation of paraspinal musculature—while maintaining comparable clinical efficacy—remains to be further elucidated. In this single-center retrospective study, we compared the clinical outcomes and radiological characteristics of UBE-TLIF and MIS-TLIF for the treatment of single-level mild DLS. The results indicated that both surgical techniques achieved satisfactory clinical outcomes; however, differences were observed with respect to early postoperative pain relief, perioperative parameters, early TBR during fusion, and preservation of paraspinal muscle structure. These findings suggest that different minimally invasive fusion techniques may offer distinct advantages in terms of soft tissue injury and the early biological processes involved in spinal fusion. Comparable overall clinical efficacy of minimally invasive fusion techniques In the present study, both groups showed improvements in VAS scores for low back pain and leg pain, as well as ODI scores, at all postoperative follow-up time points compared with preoperative values. Except for the low back pain VAS score at postoperative day 3, no statistically significant differences were observed between the two groups. These findings indicate that UBE-TLIF and MIS-TLIF provide comparable mid-term efficacy in terms of neural decompression and functional improvement. This result is consistent with previous studies comparing MIS-TLIF and UBE-TLIF in the treatment of lumbar spondylolisthesis and degenerative lumbar spine disorders [ 19 – 21 ] . In addition, no significant difference in the modified MacNab scores was observed between the two groups, indicating that both surgical techniques achieved satisfactory clinical outcomes from the perspectives of patient-reported satisfaction and recovery of daily function. These findings further suggest that, when adequate decompression and spinal stability are ensured, the two minimally invasive approaches yield comparable mid-term functional outcomes. Differences in early postoperative low back pain and potential soft tissue injury mechanisms Although comparable mid-term outcomes were achieved, the results of this study demonstrated that the low back pain VAS score at postoperative day 3 was significantly lower in the UBE-TLIF group than in the MIS-TLIF group, suggesting a distinct advantage of UBE-TLIF in early postoperative pain relief. Previous studies have indicated that early postoperative low back pain is closely associated with the extent of paraspinal muscle injury, the pressure exerted by retractors, and local inflammatory responses [ 19 , 22 , 23 ] . A possible explanation for this finding is that, although MIS-TLIF utilizes the Wiltse intermuscular approach, it relies on tubular retractors to maintain the surgical field. Prolonged radial retraction may result in ischemia of the multifidus muscle and impairment of local microcirculation, which can subsequently activate oxidative stress–related pathways and lead to muscle injury, thereby contributing to early postoperative pain [ 23 , 24 ] . In contrast, the initial working space in UBE-TLIF is established within the multifidus triangle, a potential anatomical interval between the multifidus muscle and the posterior lamina–spinous process complex. The use of a biportal endoscopic system allows for the creation of a dynamic operative corridor without the need for fixed retractors, thereby substantially reducing compression-related ischemic injury to the paraspinal musculature [ 25 – 27 ] . In addition, continuous saline irrigation under endoscopic visualization not only facilitates a clear operative field but may also attenuate postoperative inflammatory responses by reducing local tissue temperature, diluting inflammatory mediators, and minimizing compression of microvascular structures [ 19 , 26 , 28 ] . Collectively, these mechanisms may account for the observed advantage of UBE-TLIF in early postoperative low back pain control. Explanations for differences in perioperative parameters In the present study, the UBE-TLIF group exhibited significantly lower intraoperative blood loss and a shorter length of hospital stay compared with the MIS-TLIF group. These findings are highly consistent with the results reported by Huang et al.[29] and several other studies. The magnified endoscopic view enables more precise identification of the epidural venous plexus and active bleeding sites, allowing for more efficient hemostasis using radiofrequency coagulation and thereby reducing both overt and occult blood loss [ 20 , 30 ] . Moreover, the UBE technique achieves accurate endoscopic decompression through a biportal approach, which may result in less iatrogenic injury to the paraspinal muscles and facet joints [ 31 ] . However, the operative time was significantly longer in the UBE-TLIF group.Under endoscopic conditions, extensive identification of anatomical landmarks, thorough decompression, meticulous endplate preparation, and percutaneous pedicle screw fixation are all time-consuming procedures. In addition, effective control of intraoperative bleeding and maintenance of a clear surgical field are critical factors that further influence operative duration [ 30 ] . Previous studies have suggested that this phenomenon is largely attributable to a pronounced learning curve associated with the UBE technique. Statistical analyses indicate that operative efficiency improves substantially after approximately 34 cases, particularly during endoscopic endplate preparation and intervertebral disc manipulation [ 32 ] .With increasing surgical experience, operative time can be progressively reduced; therefore, the longer operative time observed in the present study may not necessarily reflect a long-term disadvantage of UBE-TLIF. Significance of trabecular bone remodeling (TBR) as a novel indicator of early osseointegration during spinal fusion Conventional assessment of spinal fusion primarily relies on fusion grading systems or the presence of continuous bony bridging; however, these methods are limited in their ability to capture the dynamic biological processes occurring in the early phase of fusion. Vertebral endplate cysts (VECs) have traditionally been regarded as predictive indicators of nonunion or delayed union after fusion surgery. When micromotion occurs at the instrumented segment, stress-related microfractures or bone resorption may be induced, leading to the formation of VECs. Nevertheless, owing to their potential reversibility, VECs cannot directly predict successful fusion and instead require serial CT examinations to monitor changes in cyst size over time [ 33 , 34 ] . Segi et al. [ 35 ] were the first to propose TBR as a novel radiological indicator of early osseointegration following lumbar interbody fusion. TBR was defined as a high-density (high Hounsfield unit) trabecular pattern extending vertically or obliquely from the interface between the interbody cage and the vertebral endplate toward the pedicle screw. This radiological feature can be observed as early as 3 months after fusion surgery and is considered to reflect effective early osteoconduction between the cage and adjacent vertebral bodies. Their study demonstrated that patients with positive early TBR findings had a significantly lower incidence of vertebral endplate cysts at 1 year postoperatively (P = 0.003), while severe complications such as pedicle screw loosening requiring revision surgery and pseudarthrosis were observed exclusively in the TBR-negative group. Collectively, these findings suggest that TBR may serve as a positive imaging marker of initial postoperative stability and the early activation of osseointegration [ 35 ] . In the present study, the UBE-TLIF group exhibited a significantly higher positive rate of TBR at 3 months postoperatively compared with the MIS-TLIF group, indicating that a microenvironment conducive to osseointegration may be established at an earlier stage. A plausible explanation is that, relative to MIS-TLIF, UBE-TLIF enables more thorough removal of the cartilaginous endplate under direct endoscopic visualization while maximally preserving the integrity of the bony endplate, with punctate endplate bleeding serving as an intuitive indicator of adequate endplate preparation [ 8 ] . This approach may facilitate the formation of an optimal graft–endplate interface and improve mechanical load transfer between the interbody cage and the adjacent bony surfaces. Although the follow-up period in this study is limited, the higher early TBR positivity rate in the UBE-TLIF group, which aligns with its trend toward a higher fusion rate at 6 months, suggests that TBR may serve as a promising imaging biomarker for predicting the fusion progression. Imaging Evidence of Paraspinal Muscle Structural Changes and Their Clinical Significance The paraspinal muscles, particularly the multifidus, play a crucial role in maintaining lumbar segmental stability, facilitating sagittal rotation, and controlling fine movements [ 36 , 37 ] .Sihvonen et al. [ 38 ] indicated that postoperative paraspinal muscle atrophy is closely associated with iatrogenic denervation of these muscles during lumbar surgery. Previous studies have confirmed that atrophy and fat infiltration of the multifidus muscle are significantly correlated with chronic low back pain, functional impairment, and unfavorable postoperative outcomes [ 39 – 41 ] . Magnetic resonance imaging (MRI) serves as an excellent modality for soft tissue differentiation. In contrast to CT, it does not expose patients to ionizing radiation, offering a safer method for the quantitative and qualitative assessment of muscles. MRI is superior to CT in discriminating fat infiltration among muscle fibers, particularly in the context of atrophic changes [ 42 ] . Axial MRI scans are a reliable tool for evaluating multifidus morphology, utilizing established grading methods such as fat infiltration rate or total CSA to assess muscle quality [ 43 ] . In the present study, quantitative MRI analysis demonstrated that at 12 months postoperatively, the UBE-TLIF group had significantly lower rates of multifidus CSA atrophy and fat infiltration compared to the MIS-TLIF group. These findings suggest a potential long-term advantage of UBE-TLIF in preserving paraspinal muscle integrity. The underlying mechanisms may include avoidance of prolonged retractor-induced muscle ischemia, reduced soft-tissue dissection, and better preservation of local neurovascular supply—factors that are inherently less optimized in the MIS-TLIF approach [ 20 , 22 ] .Furthermore, the lower rates of multifidus atrophy and fat infiltration observed in the UBE-TLIF group may, at least in part, account for its more favorable early clinical presentation characterized by reduced pain at postoperative day 3 and a quicker recovery trajectory. Limitations This study has several inherent limitations. First, as a single-center retrospective analysis, it is inevitably subject to selection bias and potential confounding factors, despite the comparability of baseline characteristics between the two groups. Second, the operative time and some perioperative parameters for UBE-TLIF may have been influenced by the learning curve associated with the technique, which could introduce a degree of interference in the comparative results. Third, the follow-up period was primarily focused on the early to mid-term postoperative phase, which is insufficient to comprehensively evaluate long-term fusion stability, adjacent segment degeneration, and sustained functional outcomes. From an imaging perspective, TBR, as a newly proposed indicator of early osseointegration, currently lacks a unified quantitative standard for its interpretation. Furthermore, this study did not correlate the observed TBR findings with vertebral endplate cysts (VECs) to discuss their combined impact on the fusion process. Future research should involve multicenter, prospective studies with longer follow-up durations and standardized imaging evaluation protocols to further validate the conclusions drawn from this study. Conclusions This study compared the clinical and radiological efficacy of UBE-TLIF and MIS-TLIF for the treatment of single-level mild degenerative lumbar spondylolisthesis. The results demonstrate that both techniques achieved comparable and satisfactory pain relief and functional improvement at mid-term follow-up. Compared with MIS-TLIF, UBE-TLIF demonstrated advantages in terms of early postoperative pain relief, reduced intraoperative blood loss, shorter hospital stay, superior preservation of paraspinal muscle structure, and more favorable early trabecular bone remodeling. These findings suggest that UBE-TLIF may be more conducive to minimizing soft tissue injury and promoting the early biological processes of spinal fusion. Although UBE-TLIF was associated with a longer operative time, this difference is likely attributable to its associated learning curve. Both techniques are effective for mild degenerative lumbar spondylolisthesis, with UBE-TLIF showing potential benefits in facilitating early recovery and optimizing the fusion environment, thereby providing valuable evidence to inform clinical decision-making regarding minimally invasive fusion techniques. Abbreviations UBE Unilateral Biportal Endoscopy UBE-TLIF Unilateral Biportal Endoscopic Transforaminal Lumbar Interbody Fusion MIS-TLIF Minimally Invasive Transforaminal Lumbar Interbody Fusion TLIF Transforaminal Lumbar Interbody Fusion DLS Degenerative Lumbar Spondylolisthesis VAS Visual Analog Scale ODI Oswestry Disability Index TBR Trabecular Bone Remodeling VECs Vertebral Endplate Cysts CSA Cross-Sectional Area FI Fat Infiltration MF Multifidus MRI Magnetic Resonance Imaging CT Computed Tomography BMI Body Mass Index Declarations Ethics approval and consent to participate This study protocol was approved by the institutional ethics committee before data collection and analysis. The research adhered to the principles of the Declaration of Helsinki, and informed consent was obtained from all patients for MIS-TLIF or UBE-TLIF surgery. As this investigation was not a prospective clinical study assessing health outcomes, a clinical trial number was not applicable. Funding This study was supported by research funding from the authors’ institution. Author Contribution Wen and Yang completed the data analysis and wrote the manuscript text. Gao checked the results and revised the manuscript. Wen prepared the figures and the tables. Wen designed this project. All authors reviewed the manuscript. Data Availability The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request. References Y I, C C, G N, et al. Is radiographic lumbar spondylolisthesis associated with occupational exposures? Findings from a nested case control study within the Wakayama spine study[J]. BMC musculoskeletal disorders, BMC Musculoskelet Disord, 2019, 20(1). Cl G-R, J V-G, Vb B-Á, et al. Degenerative spondylolisthesis I: general principles[J]. Acta ortopedica mexicana, Acta Ortop Mex, 2020, 34(5). Ould-Slimane M, Lenoir T, Dauzac C, et al. Influence of transforaminal lumbar interbody fusion procedures on spinal and pelvic parameters of sagittal balance[J]. European Spine Journal, 2012, 21(6): 1200–1206. Harms J G, Jeszenszky D. [Not Available][J]. Operative Orthopadie Und Traumatologie, 1998, 10(2): 90–102. Cole C D, McCall T D, Schmidt M H, et al. Comparison of low back fusion techniques: transforaminal lumbar interbody fusion (TLIF) or posterior lumbar interbody fusion (PLIF) approaches[J]. Current Reviews in Musculoskeletal Medicine, 2009, 2(2): 118–126. Youn M S, Shin J K, Goh T S, et al. Full endoscopic lumbar interbody fusion (FELIF): technical note[J]. European Spine Journal: Official Publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society, 2018, 27(8): 1949–1955. Kambin P. Re: Foley KT, Holly LT, Schwender JD. Minimally invasive lumbar fusion. Spine 2003;28:S26-35[J]. Spine, 2004, 29(5): 598–599. Heo D H, Son S K, Eum J H, et al. Fully endoscopic lumbar interbody fusion using a percutaneous unilateral biportal endoscopic technique: technical note and preliminary clinical results[J]. Neurosurgical Focus, 2017, 43(2): E8. Yang L, Zhou L, Wang G, et al. Unilateral Bi/Multi-Portal Endoscopy for the Treatment of Complicated Lumbar Degenerative Diseases with Utilization of Uniaxial Spinal Endoscope, Instead of Arthroscope: Technique Note and Clinical Results[J]. Clinical Interventions in Aging, 2023, 18: 1295–1308. J T, K T, N H, et al. The normative score and the cut-off value of the Oswestry Disability Index (ODI)[J]. European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society, Eur Spine J, 2012, 21(8). N S, H N, R S, et al. Trabecular Bone Remodeling as a New Indicator of Osteointegration After Posterior Lumbar Interbody Fusion[J]. Global spine journal, Global Spine J, 2024, 14(1). Y N, N S, S I, et al. Fine versus Sclerotic Trabecular Bone Remodeling/Restructure: A Refined Radiographic Predictor for Long-Term Segment Stability After Posterior Lumbar Interbody Fusion[J]. Global spine journal, Global Spine J, 2025. L K, Dh K, L L, et al. Spondylolysis and spondylolisthesis: prevalence and association with low back pain in the adult community-based population[J]. Spine, Spine (Phila Pa 1976), 2009, 34(2). Cl G-R, J V-G, Vb B-Á, et al. Lumbar degenerative spondylolisthesis II: treatment and controversies[J]. Acta ortopedica mexicana, Acta Ortop Mex, 2020, 34(6). Fo O. Lumbar lordotic change and its fulcrum in low back pain disorders: Radiographic evaluation[J]. Nigerian journal of clinical practice, Niger J Clin Pract, 2020, 23(11). P P, Y P, V A, et al. Anterolateral versus posterior minimally invasive lumbar interbody fusion surgery for spondylolisthesis: comparison of outcomes from a global, multicenter study at 12-months follow-up[J]. The spine journal : official journal of the North American Spine Society, Spine J, 2023, 23(10). Zhan Y, Yang F, Ye Z, et al. Comparative analysis of the efficacy and functional recovery of unilateral biportal endoscopy-assisted lumbar interbody fusion for the treatment of lumbar disc herniation[J]. Scientific Reports, 2025, 15: 41924. Y Z, J C, H X, et al. Comparison of the application value of two commonly used minimally invasive spinal surgery in the treatment of lumbar disc herniation[J]. Experimental and therapeutic medicine, Exp Ther Med, 2021, 21(4). J Q, M L, T S, et al. Comparison of unilateral biportal endoscopic lumbar fusion and modified minimally invasive tubular lumbar fusion for lumbar disc herniation: a two-year retrospective study[J]. Frontiers in neurology, Front Neurol, 2025, 16. J Y, M T, M W, et al. Comparative Analysis of Paraspinal Muscle Fat Infiltration and Clinical Efficacy Following Single-Level UBD-TLIF versus MIS-TLIF: A Retrospective MRI-Based Study[J]. Journal of pain research, J Pain Res, 2025, 18. Z Z, B H, J S, et al. Unilateral biportal endoscopic lumbar interbody fusion (ULIF) versus minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) for the treatment of degenerative lumbar spondylolisthesis: a retrospective analysis[J]. BMC musculoskeletal disorders, BMC Musculoskelet Disord, 2025, 26(1). Arunakul R, Anumas S, Pattharanitima P, et al. Unilateral biportal endoscopic versus microscopic transforaminal lumbar interbody fusion for lumbar degenerative disease: a retrospective study[J]. Journal of Orthopaedic Surgery and Research, 2024, 19(1): 326. Jl H, O O A, W C, et al. Long-term clinical outcome of minimally invasive versus open single-level transforaminal lumbar interbody fusion for degenerative lumbar diseases: a meta-analysis[J]. The spine journal : official journal of the North American Spine Society, Spine J, 2021, 21(12). Y K, H M, H T. Back muscle injury after posterior lumbar spine surgery. Part 2: Histologic and histochemical analyses in humans[J]. Spine, Spine (Phila Pa 1976), 1994, 19(22). B T, Yh Z, C L, et al. Unilateral biportal endoscopy vs. open decompression for lumbar epidural lipomatosis-cohort study using a prospective registry[J]. Frontiers in neurology, Front Neurol, 2024, 15. Dh H, Sk S, Jh E, et al. Fully endoscopic lumbar interbody fusion using a percutaneous unilateral biportal endoscopic technique: technical note and preliminary clinical results[J]. Neurosurgical focus, Neurosurg Focus, 2017, 43(2). Dh H, Dc L, Hs K, et al. Clinical Results and Complications of Endoscopic Lumbar Interbody Fusion for Lumbar Degenerative Disease: A Meta-Analysis[J]. World neurosurgery, World Neurosurg, 2021, 145. R P, Ma L, R V, et al. Biportal Endoscopic Spinal Surgery versus Microscopic Decompression for Lumbar Spinal Stenosis: A Systematic Review and Meta-Analysis[J]. World neurosurgery, World Neurosurg, 2020, 138. X H, W W, G C, et al. Comparison of surgical invasiveness, hidden blood loss, and clinical outcome between unilateral biportal endoscopic and minimally invasive transforaminal lumbar interbody fusion for lumbar degenerative disease: a retrospective cohort study[J]. BMC musculoskeletal disorders, BMC Musculoskelet Disord, 2023, 24(1). H H, Y S, Y L, et al. Short-term clinical efficacy and safety of unilateral biportal endoscopic transforaminal lumbar interbody fusion versus minimally invasive transforaminal lumbar interbody fusion in the treatment of lumbar degenerative diseases: a systematic review and meta-analysis[J]. Journal of orthopaedic surgery and research, J Orthop Surg Res, 2023, 18(1). Q Y, Hg L, Xk P, et al. Unilateral biportal endoscopic transforaminal lumbar interbody fusion versus conventional interbody fusion for the treatment of degenerative lumbar spine disease: a systematic review and meta-analysis[J]. BMC musculoskeletal disorders, BMC Musculoskelet Disord, 2023, 24(1). Kim J-E, Yoo H-S, Choi D-J, et al. Learning Curve and Clinical Outcome of Biportal Endoscopic-Assisted Lumbar Interbody Fusion[J]. BioMed Research International, 2020, 2020: 8815432. S F, M T, M I, et al. Does the formation of vertebral endplate cysts predict nonunion after lumbar interbody fusion?[J]. Spine, Spine (Phila Pa 1976), 2012, 37(19). S T, S F, B O, et al. Vertebral Endplate Cyst as a Predictor of Nonunion After Lumbar Interbody Fusion: Comparison of Titanium and Polyetheretherketone Cages[J]. Spine, Spine (Phila Pa 1976), 2016, 41(20). N S, H N, R S, et al. Trabecular Bone Remodeling as a New Indicator of Osteointegration After Posterior Lumbar Interbody Fusion[J]. Global spine journal, Global Spine J, 2024, 14(1). Je M, N B. The biomechanics of the lumbar multifidus[J]. Clinical biomechanics (Bristol, Avon), Clin Biomech (Bristol), 1986, 1(4). M P, K A, J D, et al. Spinal stability and intersegmental muscle forces. A biomechanical model[J]. Spine, Spine (Phila Pa 1976), 1989, 14(2). T S, A H, L P, et al. Local denervation atrophy of paraspinal muscles in postoperative failed back syndrome[J]. Spine, Spine (Phila Pa 1976), 1993, 18(5). Xu F, Zhou S, Sun Z, et al. Relationship between the postoperative variations of paraspinal muscles and adjacent-segment degeneration in patients with degenerative lumbar spinal stenosis after posterior instrumented lumbar fusion[J]. 2024. S L, H S, K Z, et al. Inter-software and inter-threshold reliability of quantitative paraspinal muscle segmentation[J]. European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society, Eur Spine J, 2024, 33(2). L S, Ae G, G C-W, et al. Examining the Role of Paraspinal Musculature in Postoperative Disability After Lumbar Fusion Surgery for Degenerative Spondylolisthesis[J]. Spine, Spine (Phila Pa 1976), 2024, 49(14). Cho S-M, Kim S-H, Ha S-K, et al. Paraspinal muscle changes after single-level posterior lumbar fusion: volumetric analyses and literature review[J]. BMC Musculoskeletal Disorders, 2020, 21: 73. R G, Y K, T K, et al. Magnetic resonance imaging and histologic evidence of postoperative back muscle injury in rats[J]. Spine, Spine (Phila Pa 1976), 2000, 25(8). Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-9149477","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":614118420,"identity":"6ca23ead-86c5-458d-bd61-53432a2dcb87","order_by":0,"name":"Bangjun Wen","email":"","orcid":"","institution":"1.\tNanjing Medical University","correspondingAuthor":false,"prefix":"","firstName":"Bangjun","middleName":"","lastName":"Wen","suffix":""},{"id":614118421,"identity":"4acb2523-39c6-4ea7-99f4-5c86a908a4cd","order_by":1,"name":"Shutong Yang","email":"","orcid":"","institution":"1.\tNanjing Medical University","correspondingAuthor":false,"prefix":"","firstName":"Shutong","middleName":"","lastName":"Yang","suffix":""},{"id":614118428,"identity":"45dbcc76-746c-4a3a-987e-07dcf337e340","order_by":2,"name":"Aiguo Gao","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA4ElEQVRIiWNgGAWjYLCCBCDmZ28++CChooYELZI9x5INHpw5RoJNBjdyzCQftjATVinvfvjghwe/DstJzsgxq0hsYGPgb+9OwKvF8ExaskRi32Fjfp5nZTcSd8gwSJw5uwG/loYcA4nEnsOJM9uTt91IPMPGYCCRS0BL/xvjHyAtGw4kmBUktjET1iIvkWMmkfADqOVEihkDUVoMJJ6lWSQ2pBuDAlki4cwxHoJ+ke9PPnzzxx9rOVBUfvxRUSPH395LwJYDQIKxDSHAg1c52JYGEPmHoLpRMApGwSgYyQAAxaVRwARpFikAAAAASUVORK5CYII=","orcid":"","institution":"Department of Orthopedics,the Affiliated Wuxi People′s Hospital of Nanjing Medical University","correspondingAuthor":true,"prefix":"","firstName":"Aiguo","middleName":"","lastName":"Gao","suffix":""}],"badges":[],"createdAt":"2026-03-17 13:38:35","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9149477/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9149477/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":106069167,"identity":"d09da9c5-a4f6-4e4d-b1f2-a8f9133a5f98","added_by":"auto","created_at":"2026-04-03 06:22:57","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":182058,"visible":true,"origin":"","legend":"\u003cp\u003eTBR: vertically or obliquely oriented high-density trabecular bone extending from the contact area between the interbody cage and the vertebral endplate toward the pedicle screws)\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-9149477/v1/ed2bc6c2b3fca08c47d440cc.png"},{"id":106094177,"identity":"df79e2a0-dbd2-41a8-ab10-549c9ad11c76","added_by":"auto","created_at":"2026-04-03 11:41:27","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":568850,"visible":true,"origin":"","legend":"\u003cp\u003eQuantitative assessment of paraspinal muscle CSA and FI on MRI using ImageJ. \u003cstrong\u003eA\u003c/strong\u003e: CSA of the multifidus muscle; \u003cstrong\u003eB\u003c/strong\u003e: threshold-based segmentation to identify adipose tissue; \u003cstrong\u003eC\u003c/strong\u003e: intramuscular fat within the multifidus muscle.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-9149477/v1/646fb264f8ba07d9b148763a.png"},{"id":106095094,"identity":"28e1f13d-af0a-4ced-8c44-0b02688ce398","added_by":"auto","created_at":"2026-04-03 11:44:21","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":49338,"visible":true,"origin":"","legend":"\u003cp\u003eComparison of perioperative conditions.\u003cstrong\u003e A\u003c/strong\u003e: Comparison of surgical time. \u003cstrong\u003eB\u003c/strong\u003e: Comparison of blood loss.\u003cstrong\u003eC\u003c/strong\u003e: Comparison of hospital stays. Note: **P \u0026lt; 0.01 compared with the control group.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-9149477/v1/ea9aaabbb09ebe6b60f6f011.png"},{"id":106069171,"identity":"123f317b-15e2-491d-8adf-8c9b467890cc","added_by":"auto","created_at":"2026-04-03 06:22:57","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":91517,"visible":true,"origin":"","legend":"\u003cp\u003eComparison of Preoperative and Postoperative Scale Scores Between the Two Groups . A-B: VAS scores for leg pain and low back pain, respectively, before surgery and at postoperative follow-up.C: ODI score before surgery and at follow-up.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-9149477/v1/3ffe348b9384647f26d696e0.png"},{"id":106069169,"identity":"6a380f84-80be-42c8-8ecf-7b89353715c3","added_by":"auto","created_at":"2026-04-03 06:22:57","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":50886,"visible":true,"origin":"","legend":"\u003cp\u003eComparative analysis of muscle characteristics changes in the MF. \u003cstrong\u003eA\u003c/strong\u003e: MF atrophy rate 12 months after surgery. \u003cstrong\u003eB\u003c/strong\u003e : The FI rate of MF before the operation and 12 months after the operation.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-9149477/v1/aa94b72a5876eb5e645ad27f.png"},{"id":109293881,"identity":"cf79d18a-51e7-4f98-a00b-21fd7abd8581","added_by":"auto","created_at":"2026-05-15 08:12:40","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1196908,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9149477/v1/41556178-112f-4b56-a931-9a8f8944c190.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Clinical Efficacy of Unilateral Biportal Endoscopic Transforaminal Lumbar Interbody Fusion Versus Minimally Invasive Transforaminal Lumbar Interbody Fusion in the Treatment of Mild Degenerative Lumbar Spondylolisthesis","fulltext":[{"header":"Introduction","content":"\u003cp\u003eWith the acceleration of population aging, the prevalence of degenerative lumbar spondylolisthesis (DLS) has increased rapidly. Among individuals aged 66\u0026ndash;70 years, DLS affects up to 15% of men and more than 50% of women\u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]\u003c/sup\u003e. DLS is characterized by anterior displacement of the superior vertebral body relative to the inferior vertebra, a pathological change that may lead to spinal instability and subsequent neural compression\u003csup\u003e[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]\u003c/sup\u003e. Clinically, DLS commonly presents with chronic low back pain with or without radicular lower extremity pain, significantly impairing patients\u0026rsquo; quality of life. When conservative treatment fails, surgical intervention is commonly adopted in clinical practice. Lumbar fusion surgery can effectively alleviate symptoms and help maintain spinopelvic sagittal balance\u003csup\u003e[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]\u003c/sup\u003e. Since Harms and Jeszenszky first provided a detailed description of transforaminal lumbar interbody fusion (TLIF) in 1998\u003csup\u003e[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e, this technique has become a widely adopted surgical approach in clinical practice due to its high safety in intervertebral disc space preparation and cage implantation, as well as its low incidence of postoperative radiculitis. Conventional open TLIF provides reliable clinical outcomes and adequate decompression; however, it is associated with substantial soft tissue injury, leading to increased postoperative muscle atrophy and higher infection rates. With the advancement of minimally invasive techniques, an increasing number of surgeons have adopted small-incision, endoscopy-assisted approaches for lumbar interbody fusion\u003csup\u003e[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e. In 2004, Foley\u003csup\u003e[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/sup\u003e introduced a minimally invasive TLIF technique by combining tubular retractors with microscopic assistance, known as minimally invasive transforaminal lumbar interbody fusion(MIS-TLIF), Compared with open surgery, MIS-TLIF markedly reduces iatrogenic injury caused by extensive muscle retraction that obstructs the surgical field. However, because of the depth of the surgical corridor, complete separation of all soft tissues cannot be achieved, and visualization may still be limited. In addition, prolonged retraction of the paraspinal soft tissues by the tubular system can result in ischemic injury to the paraspinal muscles, thereby adversely affecting postoperative recovery. With the advancement of spinal endoscopic techniques and the introduction of a fluid medium, unilateral biportal endoscopic transforaminal lumbar interbody fusion (UBE-TLIF) has gained increasing attention because of its clear surgical field and greater flexibility in instrument selection \u003csup\u003e[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/sup\u003e .\u003c/p\u003e \u003cp\u003eBased on this background, the present study adopted a single-center retrospective design to comparatively analyze the clinical and radiological outcomes of patients with single-level mild degenerative lumbar spondylolisthesis treated with UBE-TLIF or MIS-TLIF. The primary focus was to evaluate differences between the two surgical techniques in terms of clinical efficacy, perioperative parameters, early trabecular bone remodeling during fusion, and changes in paraspinal muscle morphology. Through a comprehensive assessment integrating multidimensional imaging and functional outcomes, this study aims to provide new clinical evidence to inform the optimal selection of minimally invasive lumbar fusion techniques and to enhance the understanding of fusion-related biological mechanisms.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e \u003cstrong\u003eInclusion criteria\u003c/strong\u003e \u003cp\u003e(1) Single-level grade I degenerative lumbar spondylolisthesis (Meyerding classification) with radiological findings consistent with clinical symptoms; (2) a definitive preoperative diagnosis confirmed by lumbar hyperextension and flexion radiographs, lumbar computed tomography (CT), and magnetic resonance imaging (MRI); (3) failure to achieve significant symptom relief after more than three months of conservative treatment; and (4) completion of at least one year of postoperative follow-up.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eExclusion criteria\u003c/strong\u003e \u003cp\u003e(1) A history of previous lumbar spine surgery; (2) the presence of spinal tumors, spinal fractures, spinal tuberculosis, severe scoliosis, or severe osteoporosis; (3) coagulation disorders, severe cardiopulmonary dysfunction, or other conditions rendering the patient unable to tolerate surgery; and (4) incomplete clinical data.\u003c/p\u003e \u003c/p\u003e \u003cp\u003eA retrospective analysis was performed on 80 patients with single-level mild degenerative lumbar spondylolisthesis who met the inclusion criteria and were treated at our institution between March 2020 and January 2025. Among them, 40 patients in the study group underwent UBE-TLIF, while 40 patients in the control group received MIS-TLIF. There were no significant differences between the two groups in baseline characteristics, including sex, age, body mass index (BMI), surgical level, preoperative visual analog scale (VAS) scores for low back and leg pain, or Oswestry Disability Index (ODI) scores (all P\u0026thinsp;\u0026gt;\u0026thinsp;0.05), indicating good comparability. All patients provided written informed consent, and this study was approved by the institutional ethics committee.\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eSurgical Technique\u003c/strong\u003e \u003cp\u003eAll procedures were performed by the same surgeon with more than five years of experience in minimally invasive spinal surgery.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eObservation group (UBE-TLIF)\u003c/strong\u003e \u003cp\u003eAfter satisfactory induction of general anesthesia, the patient was placed in the prone position, and the operating table was adjusted to achieve a horizontal lumbar alignment. The surgical level was confirmed using C-arm fluoroscopy. Surface landmarks corresponding to the target intervertebral space, the spinous processes of the adjacent vertebrae, and the bilateral pedicle projections were marked. After routine skin preparation and draping, a puncture needle was inserted along the surface projection of the pedicle under fluoroscopic guidance. Once the needle entered the vertebral body, a guidewire was placed for localization.On the symptomatic side, two oblique transverse skin incisions of approximately 1 cm were made at the surface projections of the upper and lower pedicles. Taking the left side as an example, the cranial incision was used as the viewing portal and the caudal incision as the working portal, with the configuration reversed on the right side. Tubular dilators were used to establish the portals, and fluoroscopy was repeated to confirm accurate access to the target level. Continuous saline irrigation was applied to maintain a clear endoscopic field. Through the working portal, a radiofrequency probe was introduced to remove soft tissues surrounding the lamina, fully exposing the inferior lamina of the cranial vertebra, the medial border of the inferior articular process of the cranial vertebra, and the superior lamina of the caudal vertebra on the operative side.An osteotome and Kerrison rongeur were used to resect the inferior lamina of the cranial vertebra, the superior lamina of the caudal vertebra, and the superior and inferior articular processes. The resected bone was preserved for grafting. The attachment points of the ligamentum flavum were fully exposed, and the ligamentum flavum and epidural adipose tissue were removed. A nerve root retractor was inserted to gently retract the nerve root and dural sac contralaterally, thereby exposing the intervertebral disc. The nucleus pulposus was removed using pituitary forceps, and the cartilaginous endplates were carefully curetted under direct endoscopic visualization until punctate bleeding was observed, indicating adequate endplate preparation.After cage trialing, an appropriately sized interbody cage was selected and packed with autologous bone and artificial bone before insertion. Following confirmation of adequate decompression and relaxation of the nerve root and dural sac, the endoscope was withdrawn. Percutaneous pedicle screw\u0026ndash;rod fixation was then performed along the guidewires. After fluoroscopic confirmation of correct cage and instrumentation positioning, the surgical field was irrigated with saline, a drainage tube was placed, and the incision was closed and covered with sterile dressings.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eControl group (MIS-TLIF)\u003c/strong\u003e \u003cp\u003eAfter satisfactory induction of general anesthesia, the patient was placed in the prone position, and the operating table was adjusted to achieve a horizontal lumbar alignment. The target surgical level was confirmed using C-arm fluoroscopy, and surface landmarks corresponding to the involved intervertebral space, the spinous processes of the adjacent vertebrae, and the bilateral pedicle projections were marked. After routine skin preparation and draping, a skin incision of approximately 2 cm was made about 3 cm lateral to the midline along the line connecting the spinous processes. The dorsal fascia was incised, and blunt dissection was performed through the intermuscular plane between the multifidus and longissimus muscles until the bony surface was reached.Sequential tubular dilators were then inserted and fixed in place, and the soft tissues overlying the facet joints were thoroughly cleared. After adequate exposure, the superior and inferior articular processes at the affected level and a portion of the lamina were resected and preserved for bone grafting. The dural sac and nerve root were fully exposed, and a nerve root retractor was used to gently retract the nerve root and dural sac contralaterally, thereby exposing the intervertebral disc. The nucleus pulposus was removed using pituitary forceps, and the cartilaginous endplates were curetted. Bone grafting was performed, followed by insertion of an appropriately sized interbody cage.Pedicle access was achieved by inserting a puncture needle along the surface projection of the pedicle under fluoroscopic guidance. After confirmation of needle entry into the vertebral body, a guidewire was placed, and cannulated pedicle screws of appropriate length were inserted. Following fluoroscopic confirmation of correct cage and instrumentation positioning, the surgical field was irrigated with saline, a drainage tube was placed, and the incision was closed and covered with sterile dressings.\u003c/p\u003e \u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003ePostoperative Management\u003c/h2\u003e \u003cp\u003eAll patients received prophylactic antibiotics 30 minutes before surgery and for 48 hours postoperatively to prevent infection. Short-term nonsteroidal anti-inflammatory drugs were administered for postoperative analgesia. Patients in both groups were maintained on strict bed rest immediately after surgery, and systemic corticosteroids were administered at 24 hours postoperatively for anti-inflammatory purposes. The drainage tube was removed 48 hours after surgery. Ambulation was encouraged 2 days postoperatively under the protection of a brace, which was worn for at least 2 months. Bending, heavy lifting, and other load-bearing activities were prohibited for 3 months after surgery.\u003c/p\u003e \u003cp\u003eFollow-up evaluations were scheduled at 1, 6, and 12 months after discharge, during which lumbar anteroposterior and lateral radiographs, flexion\u0026ndash;extension radiographs, lumbar CT, and lumbar MRI were performed.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eOutcome Assessment:\u003c/h3\u003e\n\u003cp\u003e \u003cstrong\u003eClinical efficacy outcomes\u003c/strong\u003e \u003cp\u003eLow back pain and leg pain VAS scores were compared between groups preoperatively and at 3 days, 3 months, and 12 months postoperatively. The ODI scores were compared between groups preoperatively and at 12 months postoperatively, and the modified MacNab scores were compared between groups at 12 months after surgery)\u003csup\u003e[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003ePerioperative parameters\u003c/strong\u003e \u003cp\u003eSurgery time, intraoperative blood loss, and length of hospital stay were compared between the two groups.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eTrabecular bone remodeling (TBR)\u003c/strong\u003e \u003cp\u003eTrabecular bone morphology on CT images at 3 months postoperatively was compared between patients. TBR was defined on coronal CT images as a radiological manifestation observed in adjacent vertebrae and was distinguished by comparison with the morphology and density of normal vertebral trabeculae. TBR represents newly formed bone structures that appear after surgery and are not observed on preoperative or immediate postoperative CT images. TBR may extend vertically or obliquely from the contact area between the interbody cage and the vertebral endplate toward the pedicle screws. In addition, because TBR exhibits higher density (higher Hounsfield unit values), similar to cortical bone, it can be clearly differentiated from the background trabecular bone\u003csup\u003e[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/sup\u003e, (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eFusion status\u003c/strong\u003e \u003cp\u003eFusion was evaluated on postoperative CT scans at 6 months and 1 year by two independent and experienced radiologists using the Bridwell interbody fusion grading system. According to this system, Grade I was defined as a reconstructed fusion mass with trabecular bone remodeling; Grade II as an intact graft with incomplete remodeling; Grade III as an intact graft with radiolucent areas at the cranial or caudal interface; and Grade IV as nonunion with graft collapse or resorption. Bridwell Grades I and II were considered indicative of successful fusion.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eImpact of surgery on paraspinal muscles\u003c/strong\u003e \u003cp\u003eImage J software was used to measure the cross-sectional area (CSA) of the multifidus muscle on the surgical approach side at the mid-disc level of the fused segment on preoperative and 12-month postoperative images. Fat tissue within the region of interest was identified by threshold-based segmentation, and the fat area was quantified. The multifidus atrophy rate was calculated as (preoperative CSA\u0026thinsp;\u0026minus;\u0026thinsp;postoperative CSA) / preoperative CSA\u0026times;100%. The multifidus fat infiltration rate (FI ratio) was defined as the ratio of fat area to total muscle CSA. All measurements were performed three times, and the mean values were included in the analysis to minimize measurement error.(Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e)\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003eStatistical analyses were performed using SPSS version 27.0. Continuous variables were tested for normality and are presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation. Between-group comparisons of continuous variables were conducted using the independent-samples \u003cem\u003et\u003c/em\u003e test. Categorical variables were compared using the chi-square (χ\u0026sup2;) test. Repeated-measures analysis of variance was used for within-group comparisons across different time points. Ordinal data were analyzed using the rank-sum test. A two-sided \u003cem\u003eP\u003c/em\u003e value\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant. To evaluate measurement reliability, intra-observer and inter-observer agreement were assessed using intraclass correlation coefficients (ICCs).\u003c/p\u003e \u003c/div\u003e"},{"header":"Result","content":"\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eDemographic Characteristics\u003c/h2\u003e \u003cp\u003eA total of 80 patients were included in this study, with 40 patients in the UBE-TLIF group and 40 patients in the MIS-TLIF group. There were no statistically significant differences between the two groups in baseline characteristics, including sex, age, body mass index (BMI), or surgical level (all P\u0026thinsp;\u0026gt;\u0026thinsp;0.05), indicating good comparability between groups (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eOperation parameters\u003c/h2\u003e \u003cp\u003eOperative time was significantly longer in the UBE-TLIF group than in the MIS-TLIF group (143.57\u0026thinsp;\u0026plusmn;\u0026thinsp;37.12 vs. 114.79\u0026thinsp;\u0026plusmn;\u0026thinsp;19.01 min, P\u0026thinsp;\u0026lt;\u0026thinsp;0.01). In contrast, intraoperative blood loss was significantly lower in the UBE-TLIF group (163.89\u0026thinsp;\u0026plusmn;\u0026thinsp;60.61 mL) compared with the MIS-TLIF group (234.20\u0026thinsp;\u0026plusmn;\u0026thinsp;86.02 mL, P\u0026thinsp;\u0026lt;\u0026thinsp;0.01). Additionally, the length of hospital stay was significantly shorter in the UBE-TLIF group than in the MIS-TLIF group (7.99\u0026thinsp;\u0026plusmn;\u0026thinsp;1.42 vs. 9.35\u0026thinsp;\u0026plusmn;\u0026thinsp;1.80 days, P\u0026thinsp;\u0026lt;\u0026thinsp;0.01) (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e .Figure.3).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003e\u003cb\u003e༎\u003c/b\u003eDemographic and Clinical Characteristics of Patients Undergoing UBDTLIF and MIS-TLIF\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDemographic\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eUBE-TLIF Group\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMIS-TLIF Group\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGender\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.251\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFemale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge(years)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e64.28\u0026thinsp;\u0026plusmn;\u0026thinsp;9.39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e61.78\u0026thinsp;\u0026plusmn;\u0026thinsp;8.79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.223\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBMI(kg/m\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e23.02\u0026thinsp;\u0026plusmn;\u0026thinsp;2.56\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e22.98\u0026thinsp;\u0026plusmn;\u0026thinsp;2.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.942\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSurgery level\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eL4-5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.491\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eL5-S1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLength of Surgery Time (mins)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e143.57\u0026thinsp;\u0026plusmn;\u0026thinsp;37.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e114.79\u0026thinsp;\u0026plusmn;\u0026thinsp;19.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEstimated Blood Loss (mL)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e163.89\u0026thinsp;\u0026plusmn;\u0026thinsp;60.61\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e234.20\u0026thinsp;\u0026plusmn;\u0026thinsp;86.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLength of Hospital Stay (days)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7.99\u0026thinsp;\u0026plusmn;\u0026thinsp;1.42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9.35\u0026thinsp;\u0026plusmn;\u0026thinsp;1.80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eClinical outcomes\u003c/h3\u003e\n\u003cp\u003eVAS score: There were no significant differences between the two groups in preoperative VAS scores for low back pain or leg pain (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05). At postoperative day 3, the UBE-TLIF group demonstrated a significantly lower VAS score for low back pain (2.96\u0026thinsp;\u0026plusmn;\u0026thinsp;1.19) compared with the MIS-TLIF group (3.54\u0026thinsp;\u0026plusmn;\u0026thinsp;1.27) (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). No significant differences in VAS scores were observed between the two groups at the remaining postoperative time points (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05).ODI and MacNab scores: No significant differences were identified between the two groups in ODI scores at any preoperative or postoperative time point, nor in the modified MacNab scores at 12 months postoperatively (all P\u0026thinsp;\u0026gt;\u0026thinsp;0.05). (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e)\u003c/p\u003e \u003cp\u003eFusion status: At 6 months postoperatively, the fusion rate in the UBE-TLIF group (85.0%) was significantly higher than that in the MIS-TLIF group (65.0%) (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). However, no significant difference in fusion rates was observed between the two groups at 12 months postoperatively (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003eTBR: At 3 months postoperatively, the positive rate of TBR was significantly higher in the UBE-TLIF group (57.5%) than in the MIS-TLIF group (30.0%) (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparative Analysis of Patient-Reported Outcomes Measures Following UBD-TLIF and MIS-TLIF\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSubjects\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eUBE-TLIF Group\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMIS-TLIF Group\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVas of back pain\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePreoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6.42\u0026thinsp;\u0026plusmn;\u0026thinsp;1.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6.28\u0026thinsp;\u0026plusmn;\u0026thinsp;1.19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.622\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eD3 postoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.96\u0026thinsp;\u0026plusmn;\u0026thinsp;1.19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.54\u0026thinsp;\u0026plusmn;\u0026thinsp;1.27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.05\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3M postoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.60\u0026thinsp;\u0026plusmn;\u0026thinsp;0.65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.68\u0026thinsp;\u0026plusmn;\u0026thinsp;0.77\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.620\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e12M postoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.69\u0026thinsp;\u0026plusmn;\u0026thinsp;0.41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.74\u0026thinsp;\u0026plusmn;\u0026thinsp;0.42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.548\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eVas of leg pain\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePreoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6.28\u0026thinsp;\u0026plusmn;\u0026thinsp;1.28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6.36\u0026thinsp;\u0026plusmn;\u0026thinsp;1.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.775\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eD3 postoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.57\u0026thinsp;\u0026plusmn;\u0026thinsp;0.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.74\u0026thinsp;\u0026plusmn;\u0026thinsp;0.71\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.272\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3M postoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.44\u0026thinsp;\u0026plusmn;\u0026thinsp;0.64\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.59\u0026thinsp;\u0026plusmn;\u0026thinsp;0.57\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.276\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e12M postoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.77\u0026thinsp;\u0026plusmn;\u0026thinsp;0.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.79\u0026thinsp;\u0026plusmn;\u0026thinsp;0.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.825\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eODI\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePreoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e58.62\u0026thinsp;\u0026plusmn;\u0026thinsp;8.98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e59.12\u0026thinsp;\u0026plusmn;\u0026thinsp;9.49\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.810\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3M postoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e24.06\u0026thinsp;\u0026plusmn;\u0026thinsp;5.29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e26.15\u0026thinsp;\u0026plusmn;\u0026thinsp;6.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.106\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e12M postoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e12.33\u0026thinsp;\u0026plusmn;\u0026thinsp;3.83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e13.64\u0026thinsp;\u0026plusmn;\u0026thinsp;3.86\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.129\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e12M Macnab satisfaction\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eExcellent\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.924\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGood\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFair\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePoor\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eBridewell\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6M postoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e34,6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e26,14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.05\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e12M postoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e39,1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e37,3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.615\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eTBR\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTBR(+)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.05\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTBR(-)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eImaging outcomes\u003c/h3\u003e\n\u003cp\u003eThe intra-observer and inter-observer ICC values for all radiological measurements were greater than 0.80, indicating good reliability.\u003c/p\u003e \u003cp\u003e\u0026bull; Multifidus muscle atrophy rate: The multifidus muscle atrophy rate was significantly lower in the UBE-TLIF group (29.50\u0026thinsp;\u0026plusmn;\u0026thinsp;7.72%) than in the MIS-TLIF group (34.04\u0026thinsp;\u0026plusmn;\u0026thinsp;10.55%) (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003eFat infiltration rate: No significant difference in fat infiltration rate was observed between the two groups preoperatively (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05). At 12 months postoperatively, the fat infiltration rate in the UBE-TLIF group (34.85\u0026thinsp;\u0026plusmn;\u0026thinsp;7.69%) was significantly lower than that in the MIS-TLIF group (38.19\u0026thinsp;\u0026plusmn;\u0026thinsp;6.02%) (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05).(Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. Figure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e)\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparative analysis of muscle characteristics changes in the Multiffdus (MF)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSubjects\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eUBE-TLIF Group\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMIS-TLIF Group\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMF atrophy rate(%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e29.50\u0026thinsp;\u0026plusmn;\u0026thinsp;7.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e34.04\u0026thinsp;\u0026plusmn;\u0026thinsp;10.55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.05\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFat infiltration rate of MF(%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePreoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e23.21\u0026thinsp;\u0026plusmn;\u0026thinsp;8.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e21.31\u0026thinsp;\u0026plusmn;\u0026thinsp;6.93\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.275\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e12M postoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e34.85\u0026thinsp;\u0026plusmn;\u0026thinsp;7.69\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e38.19\u0026thinsp;\u0026plusmn;\u0026thinsp;6.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.05\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eDLS is a common and frequently encountered condition in the elderly population. It typically presents with low back pain, with or without radicular lower extremity pain, and some patients may also develop symptoms of intermittent claudication. This condition can substantially impair patients\u0026rsquo; quality of life\u003csup\u003e[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/sup\u003e. With the acceleration of global population aging, the incidence of this condition has continued to rise steadily, making it one of the most common degenerative disorders of the spine encountered in clinical practice \u003csup\u003e[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]\u003c/sup\u003e.When conservative treatment fails to provide adequate symptom relief, lumbar fusion surgery is often indicated \u003csup\u003e[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/sup\u003e. Conventional open lumbar fusion surgery is associated with substantial soft tissue trauma. With continuous advances in spinal endoscopic techniques, minimally invasive lumbar fusion procedures have progressively replaced traditional open surgery and have become the predominant surgical approach in clinical practice \u003csup\u003e[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e. Accordingly, whether different minimally invasive fusion techniques differ in terms of perioperative surgical trauma, early bone integration during fusion, and preservation of paraspinal musculature\u0026mdash;while maintaining comparable clinical efficacy\u0026mdash;remains to be further elucidated.\u003c/p\u003e \u003cp\u003eIn this single-center retrospective study, we compared the clinical outcomes and radiological characteristics of UBE-TLIF and MIS-TLIF for the treatment of single-level mild DLS. The results indicated that both surgical techniques achieved satisfactory clinical outcomes; however, differences were observed with respect to early postoperative pain relief, perioperative parameters, early TBR during fusion, and preservation of paraspinal muscle structure. These findings suggest that different minimally invasive fusion techniques may offer distinct advantages in terms of soft tissue injury and the early biological processes involved in spinal fusion.\u003c/p\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eComparable overall clinical efficacy of minimally invasive fusion techniques\u003c/h2\u003e \u003cp\u003eIn the present study, both groups showed improvements in VAS scores for low back pain and leg pain, as well as ODI scores, at all postoperative follow-up time points compared with preoperative values. Except for the low back pain VAS score at postoperative day 3, no statistically significant differences were observed between the two groups. These findings indicate that UBE-TLIF and MIS-TLIF provide comparable mid-term efficacy in terms of neural decompression and functional improvement. This result is consistent with previous studies comparing MIS-TLIF and UBE-TLIF in the treatment of lumbar spondylolisthesis and degenerative lumbar spine disorders \u003csup\u003e[\u003cspan additionalcitationids=\"CR20\" citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]\u003c/sup\u003e .\u003c/p\u003e \u003cp\u003eIn addition, no significant difference in the modified MacNab scores was observed between the two groups, indicating that both surgical techniques achieved satisfactory clinical outcomes from the perspectives of patient-reported satisfaction and recovery of daily function. These findings further suggest that, when adequate decompression and spinal stability are ensured, the two minimally invasive approaches yield comparable mid-term functional outcomes.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eDifferences in early postoperative low back pain and potential soft tissue injury mechanisms\u003c/h2\u003e \u003cp\u003eAlthough comparable mid-term outcomes were achieved, the results of this study demonstrated that the low back pain VAS score at postoperative day 3 was significantly lower in the UBE-TLIF group than in the MIS-TLIF group, suggesting a distinct advantage of UBE-TLIF in early postoperative pain relief. Previous studies have indicated that early postoperative low back pain is closely associated with the extent of paraspinal muscle injury, the pressure exerted by retractors, and local inflammatory responses \u003csup\u003e[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]\u003c/sup\u003e .\u003c/p\u003e \u003cp\u003eA possible explanation for this finding is that, although MIS-TLIF utilizes the Wiltse intermuscular approach, it relies on tubular retractors to maintain the surgical field. Prolonged radial retraction may result in ischemia of the multifidus muscle and impairment of local microcirculation, which can subsequently activate oxidative stress\u0026ndash;related pathways and lead to muscle injury, thereby contributing to early postoperative pain \u003csup\u003e[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]\u003c/sup\u003e. In contrast, the initial working space in UBE-TLIF is established within the multifidus triangle, a potential anatomical interval between the multifidus muscle and the posterior lamina\u0026ndash;spinous process complex. The use of a biportal endoscopic system allows for the creation of a dynamic operative corridor without the need for fixed retractors, thereby substantially reducing compression-related ischemic injury to the paraspinal musculature \u003csup\u003e[\u003cspan additionalcitationids=\"CR26\" citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]\u003c/sup\u003e .\u003c/p\u003e \u003cp\u003eIn addition, continuous saline irrigation under endoscopic visualization not only facilitates a clear operative field but may also attenuate postoperative inflammatory responses by reducing local tissue temperature, diluting inflammatory mediators, and minimizing compression of microvascular structures \u003csup\u003e[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]\u003c/sup\u003e. Collectively, these mechanisms may account for the observed advantage of UBE-TLIF in early postoperative low back pain control.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eExplanations for differences in perioperative parameters\u003c/h2\u003e \u003cp\u003eIn the present study, the UBE-TLIF group exhibited significantly lower intraoperative blood loss and a shorter length of hospital stay compared with the MIS-TLIF group. These findings are highly consistent with the results reported by Huang et al.[29] and several other studies. The magnified endoscopic view enables more precise identification of the epidural venous plexus and active bleeding sites, allowing for more efficient hemostasis using radiofrequency coagulation and thereby reducing both overt and occult blood loss \u003csup\u003e[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]\u003c/sup\u003e. Moreover, the UBE technique achieves accurate endoscopic decompression through a biportal approach, which may result in less iatrogenic injury to the paraspinal muscles and facet joints\u003csup\u003e[\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eHowever, the operative time was significantly longer in the UBE-TLIF group.Under endoscopic conditions, extensive identification of anatomical landmarks, thorough decompression, meticulous endplate preparation, and percutaneous pedicle screw fixation are all time-consuming procedures. In addition, effective control of intraoperative bleeding and maintenance of a clear surgical field are critical factors that further influence operative duration\u003csup\u003e[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]\u003c/sup\u003e. Previous studies have suggested that this phenomenon is largely attributable to a pronounced learning curve associated with the UBE technique. Statistical analyses indicate that operative efficiency improves substantially after approximately 34 cases, particularly during endoscopic endplate preparation and intervertebral disc manipulation\u003csup\u003e[\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]\u003c/sup\u003e .With increasing surgical experience, operative time can be progressively reduced; therefore, the longer operative time observed in the present study may not necessarily reflect a long-term disadvantage of UBE-TLIF.\u003c/p\u003e \u003cp\u003e \u003cb\u003eSignificance of trabecular bone remodeling (TBR) as a novel indicator of early osseointegration during spinal fusion\u003c/b\u003e \u003c/p\u003e \u003cp\u003eConventional assessment of spinal fusion primarily relies on fusion grading systems or the presence of continuous bony bridging; however, these methods are limited in their ability to capture the dynamic biological processes occurring in the early phase of fusion. Vertebral endplate cysts (VECs) have traditionally been regarded as predictive indicators of nonunion or delayed union after fusion surgery. When micromotion occurs at the instrumented segment, stress-related microfractures or bone resorption may be induced, leading to the formation of VECs. Nevertheless, owing to their potential reversibility, VECs cannot directly predict successful fusion and instead require serial CT examinations to monitor changes in cyst size over time \u003csup\u003e[\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]\u003c/sup\u003e .\u003c/p\u003e \u003cp\u003eSegi et al. \u003csup\u003e[\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]\u003c/sup\u003e were the first to propose TBR as a novel radiological indicator of early osseointegration following lumbar interbody fusion. TBR was defined as a high-density (high Hounsfield unit) trabecular pattern extending vertically or obliquely from the interface between the interbody cage and the vertebral endplate toward the pedicle screw. This radiological feature can be observed as early as 3 months after fusion surgery and is considered to reflect effective early osteoconduction between the cage and adjacent vertebral bodies. Their study demonstrated that patients with positive early TBR findings had a significantly lower incidence of vertebral endplate cysts at 1 year postoperatively (P\u0026thinsp;=\u0026thinsp;0.003), while severe complications such as pedicle screw loosening requiring revision surgery and pseudarthrosis were observed exclusively in the TBR-negative group. Collectively, these findings suggest that TBR may serve as a positive imaging marker of initial postoperative stability and the early activation of osseointegration\u003csup\u003e[\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eIn the present study, the UBE-TLIF group exhibited a significantly higher positive rate of TBR at 3 months postoperatively compared with the MIS-TLIF group, indicating that a microenvironment conducive to osseointegration may be established at an earlier stage. A plausible explanation is that, relative to MIS-TLIF, UBE-TLIF enables more thorough removal of the cartilaginous endplate under direct endoscopic visualization while maximally preserving the integrity of the bony endplate, with punctate endplate bleeding serving as an intuitive indicator of adequate endplate preparation \u003csup\u003e[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/sup\u003e. This approach may facilitate the formation of an optimal graft\u0026ndash;endplate interface and improve mechanical load transfer between the interbody cage and the adjacent bony surfaces.\u003c/p\u003e \u003cp\u003eAlthough the follow-up period in this study is limited, the higher early TBR positivity rate in the UBE-TLIF group, which aligns with its trend toward a higher fusion rate at 6 months, suggests that TBR may serve as a promising imaging biomarker for predicting the fusion progression.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eImaging Evidence of Paraspinal Muscle Structural Changes and Their Clinical Significance\u003c/h2\u003e \u003cp\u003eThe paraspinal muscles, particularly the multifidus, play a crucial role in maintaining lumbar segmental stability, facilitating sagittal rotation, and controlling fine movements\u003csup\u003e[\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]\u003c/sup\u003e.Sihvonen et al. \u003csup\u003e[\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]\u003c/sup\u003eindicated that postoperative paraspinal muscle atrophy is closely associated with iatrogenic denervation of these muscles during lumbar surgery. Previous studies have confirmed that atrophy and fat infiltration of the multifidus muscle are significantly correlated with chronic low back pain, functional impairment, and unfavorable postoperative outcomes\u003csup\u003e[\u003cspan additionalcitationids=\"CR40\" citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]\u003c/sup\u003e .\u003c/p\u003e \u003cp\u003eMagnetic resonance imaging (MRI) serves as an excellent modality for soft tissue differentiation. In contrast to CT, it does not expose patients to ionizing radiation, offering a safer method for the quantitative and qualitative assessment of muscles. MRI is superior to CT in discriminating fat infiltration among muscle fibers, particularly in the context of atrophic changes\u003csup\u003e[\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e]\u003c/sup\u003e. Axial MRI scans are a reliable tool for evaluating multifidus morphology, utilizing established grading methods such as fat infiltration rate or total CSA to assess muscle quality\u003csup\u003e[\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eIn the present study, quantitative MRI analysis demonstrated that at 12 months postoperatively, the UBE-TLIF group had significantly lower rates of multifidus CSA atrophy and fat infiltration compared to the MIS-TLIF group. These findings suggest a potential long-term advantage of UBE-TLIF in preserving paraspinal muscle integrity. The underlying mechanisms may include avoidance of prolonged retractor-induced muscle ischemia, reduced soft-tissue dissection, and better preservation of local neurovascular supply\u0026mdash;factors that are inherently less optimized in the MIS-TLIF approach\u003csup\u003e[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]\u003c/sup\u003e.Furthermore, the lower rates of multifidus atrophy and fat infiltration observed in the UBE-TLIF group may, at least in part, account for its more favorable early clinical presentation characterized by reduced pain at postoperative day 3 and a quicker recovery trajectory.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003eLimitations\u003c/h2\u003e \u003cp\u003eThis study has several inherent limitations. First, as a single-center retrospective analysis, it is inevitably subject to selection bias and potential confounding factors, despite the comparability of baseline characteristics between the two groups. Second, the operative time and some perioperative parameters for UBE-TLIF may have been influenced by the learning curve associated with the technique, which could introduce a degree of interference in the comparative results. Third, the follow-up period was primarily focused on the early to mid-term postoperative phase, which is insufficient to comprehensively evaluate long-term fusion stability, adjacent segment degeneration, and sustained functional outcomes.\u003c/p\u003e \u003cp\u003eFrom an imaging perspective, TBR, as a newly proposed indicator of early osseointegration, currently lacks a unified quantitative standard for its interpretation. Furthermore, this study did not correlate the observed TBR findings with vertebral endplate cysts (VECs) to discuss their combined impact on the fusion process.\u003c/p\u003e \u003cp\u003eFuture research should involve multicenter, prospective studies with longer follow-up durations and standardized imaging evaluation protocols to further validate the conclusions drawn from this study.\u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusions","content":"\u003cp\u003eThis study compared the clinical and radiological efficacy of UBE-TLIF and MIS-TLIF for the treatment of single-level mild degenerative lumbar spondylolisthesis. The results demonstrate that both techniques achieved comparable and satisfactory pain relief and functional improvement at mid-term follow-up. Compared with MIS-TLIF, UBE-TLIF demonstrated advantages in terms of early postoperative pain relief, reduced intraoperative blood loss, shorter hospital stay, superior preservation of paraspinal muscle structure, and more favorable early trabecular bone remodeling. These findings suggest that UBE-TLIF may be more conducive to minimizing soft tissue injury and promoting the early biological processes of spinal fusion. Although UBE-TLIF was associated with a longer operative time, this difference is likely attributable to its associated learning curve. Both techniques are effective for mild degenerative lumbar spondylolisthesis, with UBE-TLIF showing potential benefits in facilitating early recovery and optimizing the fusion environment, thereby providing valuable evidence to inform clinical decision-making regarding minimally invasive fusion techniques.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eUBE Unilateral Biportal Endoscopy\u003c/p\u003e \u003cp\u003eUBE-TLIF Unilateral Biportal Endoscopic Transforaminal Lumbar Interbody Fusion\u003c/p\u003e \u003cp\u003eMIS-TLIF Minimally Invasive Transforaminal Lumbar Interbody Fusion\u003c/p\u003e \u003cp\u003eTLIF Transforaminal Lumbar Interbody Fusion\u003c/p\u003e \u003cp\u003eDLS Degenerative Lumbar Spondylolisthesis\u003c/p\u003e \u003cp\u003eVAS Visual Analog Scale\u003c/p\u003e \u003cp\u003eODI Oswestry Disability Index\u003c/p\u003e \u003cp\u003eTBR Trabecular Bone Remodeling\u003c/p\u003e \u003cp\u003eVECs Vertebral Endplate Cysts\u003c/p\u003e \u003cp\u003eCSA Cross-Sectional Area\u003c/p\u003e \u003cp\u003eFI Fat Infiltration\u003c/p\u003e \u003cp\u003eMF Multifidus\u003c/p\u003e \u003cp\u003eMRI Magnetic Resonance Imaging\u003c/p\u003e \u003cp\u003eCT Computed Tomography\u003c/p\u003e \u003cp\u003eBMI Body Mass Index\u003c/p\u003e "},{"header":"Declarations","content":"\u003ch2\u003eEthics approval and consent to participate\u003c/h2\u003e\n\u003cp\u003eThis study protocol was approved by the institutional ethics committee before data collection and analysis. The research adhered to the principles of the Declaration of Helsinki, and informed consent was obtained from all patients for MIS-TLIF or UBE-TLIF surgery. As this investigation was not a prospective clinical study assessing health outcomes, a clinical trial number was not applicable.\u003c/p\u003e\n\u003ch2\u003eFunding\u003c/h2\u003e\n\u003cp\u003eThis study was supported by research funding from the authors\u0026rsquo; institution.\u003c/p\u003e\n\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\n\u003cp\u003eWen and Yang completed the data analysis and wrote the manuscript text. Gao checked the results and revised the manuscript. Wen prepared the figures and the tables. Wen designed this project. All authors reviewed the manuscript.\u003c/p\u003e\n\u003ch2\u003eData Availability\u003c/h2\u003e\n\u003cp\u003eThe datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eY I, C C, G N, et al. Is radiographic lumbar spondylolisthesis associated with occupational exposures? Findings from a nested case control study within the Wakayama spine study[J]. BMC musculoskeletal disorders, BMC Musculoskelet Disord, 2019, 20(1).\u003c/li\u003e\n\u003cli\u003eCl G-R, J V-G, Vb B-\u0026Aacute;, et al. Degenerative spondylolisthesis I: general principles[J]. Acta ortopedica mexicana, Acta Ortop Mex, 2020, 34(5).\u003c/li\u003e\n\u003cli\u003eOuld-Slimane M, Lenoir T, Dauzac C, et al. Influence of transforaminal lumbar interbody fusion procedures on spinal and pelvic parameters of sagittal balance[J]. 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Vertebral Endplate Cyst as a Predictor of Nonunion After Lumbar Interbody Fusion: Comparison of Titanium and Polyetheretherketone Cages[J]. Spine, Spine (Phila Pa 1976), 2016, 41(20).\u003c/li\u003e\n\u003cli\u003eN S, H N, R S, et al. Trabecular Bone Remodeling as a New Indicator of Osteointegration After Posterior Lumbar Interbody Fusion[J]. Global spine journal, Global Spine J, 2024, 14(1).\u003c/li\u003e\n\u003cli\u003eJe M, N B. The biomechanics of the lumbar multifidus[J]. Clinical biomechanics (Bristol, Avon), Clin Biomech (Bristol), 1986, 1(4).\u003c/li\u003e\n\u003cli\u003eM P, K A, J D, et al. Spinal stability and intersegmental muscle forces. A biomechanical model[J]. Spine, Spine (Phila Pa 1976), 1989, 14(2).\u003c/li\u003e\n\u003cli\u003eT S, A H, L P, et al. Local denervation atrophy of paraspinal muscles in postoperative failed back syndrome[J]. Spine, Spine (Phila Pa 1976), 1993, 18(5).\u003c/li\u003e\n\u003cli\u003eXu F, Zhou S, Sun Z, et al. 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Spine, Spine (Phila Pa 1976), 2000, 25(8).\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"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":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Lumbar spondylolisthesis, unilateral biportal endoscopic༛Muscle atrophy༛transforaminal lumbar interbody fusion","lastPublishedDoi":"10.21203/rs.3.rs-9149477/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9149477/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eObjective\u003c/h2\u003e \u003cp\u003eTo compare the clinical and radiological outcomes of unilateral biportal endoscopic transforaminal lumbar interbody fusion (UBE-TLIF) and minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) in the treatment of single-level mild degenerative lumbar spondylolisthesis.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eA retrospective analysis was conducted on 80 patients with single-level mild degenerative lumbar spondylolisthesis, including 40 patients treated with UBE-TLIF and 40 patients treated with MIS-TLIF. Perioperative parameters, visual analog scale (VAS) scores, Oswestry Disability Index (ODI), modified MacNab scores, fusion rates, trabecular bone remodeling (TBR) at 3 months postoperatively, and multifidus atrophy and fat infiltration rates at 12 months postoperatively were compared between the two groups.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eThe UBE-TLIF group demonstrated significantly less intraoperative blood loss and shorter hospital stays, but longer operative times compared with the MIS-TLIF group (all P\u0026thinsp;\u0026lt;\u0026thinsp;0.01). At 3 days postoperatively, the VAS score for low back pain was significantly lower in the UBE-TLIF group than in the MIS-TLIF group (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05), whereas no significant differences were observed between groups in VAS, ODI, or modified MacNab scores at other time points (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05). The UBE-TLIF group showed significantly higher TBR positivity at 3 months and a higher fusion rate at 6 months postoperatively compared with the MIS-TLIF group (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05), while no significant difference in fusion rate was observed at 12 months. At 12 months postoperatively, the multifidus atrophy rate and fat infiltration rate were both significantly lower in the UBE-TLIF group than in the MIS-TLIF group (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eBoth UBE-TLIF and MIS-TLIF provide satisfactory clinical outcomes in the treatment of single-level mild degenerative lumbar spondylolisthesis. Compared with MIS-TLIF, UBE-TLIF demonstrates certain advantages in early postoperative pain relief, preservation of paraspinal muscles, and early osteointegration during the fusion process.\u003c/p\u003e","manuscriptTitle":"Clinical Efficacy of Unilateral Biportal Endoscopic Transforaminal Lumbar Interbody Fusion Versus Minimally Invasive Transforaminal Lumbar Interbody Fusion in the Treatment of Mild Degenerative Lumbar Spondylolisthesis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-03 06:22:52","doi":"10.21203/rs.3.rs-9149477/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"7dbd620a-cbeb-44b1-ba88-0b645666661a","owner":[],"postedDate":"April 3rd, 2026","published":true,"recentEditorialEvents":[{"type":"decision","content":"Withdrawn","date":"2026-05-15T07:58:40+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-04T11:16:33+00:00","index":88,"fulltext":""},{"type":"reviewerAgreed","content":"140870428333653426503469953353898415231","date":"2026-05-04T10:09:02+00:00","index":87,"fulltext":""},{"type":"reviewerAgreed","content":"81531297290309271501814275974737557848","date":"2026-05-01T01:53:19+00:00","index":86,"fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-05-15T08:11:46+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-03 06:22:52","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9149477","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9149477","identity":"rs-9149477","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}