Study DesignRetrospective study.PurposeTo compare the clinical and radiographic outcomes of unilateral biportal endoscopy-assisted extraforaminal lumbar interbody fusion (BE-ELIF) and oblique lateral interbody fusion (OLIF).Overview of LiteratureOLIF is widely recognized for its strong realignment capability, achieved through placing a large interbody cage, and its favorable clinical outcomes with indirect decompression. ELIF, similar to OLIF, does not entail exposure of the spinal canal. At our hospital, BE-ELIF involves removing the superior articular processes on both sides, inserting two expandable cages, and performing indirect canal decompression. BE-ELIF is a lumbar interbody fusion technique that provides indirect decompression similar to OLIF. However, no studies have compared the efficacy of ELIF performed under unilateral biportal endoscopy with that of OLIF.MethodsForty-nine adults who underwent single-level L4/5 interbody fusion for degenerative spondylolisthesis were divided into BE-ELIF (n=27) and OLIF (n=22) groups based on the surgical approach used. Clinical outcomes were assessed using the Visual Analog Scale and the Japanese Orthopedic Association Back Pain Evaluation Questionnaire (JOABPEQ). Radiographic parameters, including distance of spondylolisthesis, disc height, segmental lordosis, lumbar lordosis, pelvic tilt, and sagittal vertical axis, were evaluated preoperatively and at final follow-up.ResultsOLIF provided significantly better relief of pain in lower limbs and buttocks at 1-year follow-up. No significant between-group differences were observed in JOABPEQ domains. BE-ELIF resulted in greater improvements in spondylolisthesis distance and disc height, while other parameters did not differ significantly between the two groups.ConclusionsFor L4/5 degenerative spondylolisthesis, BE-ELIF demonstrated superior spondylolisthesis reduction and disc height improvement than OLIF. Although BE-ELIF was associated with some inferior clinical outcomes, it provided satisfactory results, effective realignment, and a low complication risk.

Study DesignTechnical case report.PurposeTo present a novel navigation-assisted transforaminal unilateral biportal endoscopy (UBE) lumbar discectomy technique for managing upper lumbar disc herniation.Overview of LiteratureUpper lumbar disc herniation is significantly less common than lower lumbar disc herniation, accounting for only 1%–2% of cases. However, treatment is more challenging and is associated with worse outcomes. Anatomical differences between the upper and lower lumbar spine complicate the standard interlaminar approach using UBE, making it insufficient for complete removal of herniated discs. Integrating endoscopic spine surgery with intraoperative navigation provides three-dimensional computer-reconstructed visual data, thereby enhancing the feasibility of the technique.MethodsThe UBE approach targeted the ventral part of the superior articular process in the transforaminal UBE setup, specifically for upper lumbar disc herniation, with an approach angle of approximately 30º on the axial plane. Intraoperative navigation was employed to improve puncture accuracy for this relatively unfamiliar surgical technique. Navigation-assisted transforaminal UBE lumbar discectomy was performed on four patients presenting with back or leg discomfort due to disc herniation at the L1–L2 or L2–L3 levels.ResultsAll patients experienced symptom relief and were discharged on postoperative day 2.ConclusionsTransforaminal UBE lumbar discectomy is a viable therapeutic option for upper lumbar paracentral disc herniation, which is typically associated with poor prognosis. Integrating navigation integration into this novel approach enhances precision and safety.

The application area of biportal endoscopic spine surgery (BESS) is gradually expanding. Compared with conventional fusion surgery, transforaminal interbody fusion (TLIF) using BESS (BESS-TLIF) has the advantages of less bleeding, minimal postoperative pain, and faster recovery. This technical note highlights its application in managing complex conditions such as scar tissue adhesion, altered anatomy, and implant removal, common in reoperations. The method focuses on precise dissection, endoscopic visualization, and careful tissue handling to ensure effective decompression and stabilization. Three representative cases, including reoperations for recurrent disc herniation, adjacent segment disease (ASD) following prior fusion, and ASD with nonunion of the prior fusion site requiring fusion extension, were described. All three cases exhibited clinical improvement following surgery. BESS is an effective and safe method for spinal revision surgery not only in simple decompression surgery but also in cases that required fusion surgery. As BESS is advancing, its role in complex spinal surgeries is expected to expand, potentially setting new standards in minimally invasive spine surgery.

Study DesignA retrospective cohort study.PurposeTo assess differences in 30-day morbidity and mortality and postoperative complications between two surgical treatment options.Overview of LiteratureThe choice of decompression with fusion or decompression alone for the management of degenerative spondylolisthesis (DS) is controversial.MethodsThe American College of Surgeons National Quality Improvement Program database was queried for laminectomy or laminotomy with and without fusion from 2015 to 2020. The estimated 30-day mortality and morbidity, 30-day complications, and American Society of Anesthesiologist (ASA) classification were evaluated through chi-square and analysis of variance tests, with the results further stratified according to the ASA classification.ResultsOf the 4,120 patients, 2,384 (58%) underwent a laminectomy or laminotomy without fusion and 1,736 (42%) underwent a laminectomy or laminotomy with fusion. Patients undergoing decompression with fusion had higher mean mortality (estimated probability 0.0034 vs. 0.0027, p<0.001), mean morbidity (estimated probability 0.053 vs. 0.048, p<0.001), mean length of stay (3.62±3.4 days vs. 3.15±4.3 days, p<0.001), and bleeding risk necessitating transfusion (9.5% vs. 7.6%, p=0.038). There was a higher rate of overall 30-day postoperative complications associated with an increasing ASA score for both cohorts.ConclusionsDecompression with fusion was associated with higher estimated mortality, morbidity, and 30-day complications. Decompression alone is an appealing treatment option for lumbar DS, particularly for patients with higher ASA scores and those at higher risk.

Adult spinal deformity (ASD) surgery aims to correct abnormal spinal alignment in both the sagittal and coronal planes to alleviate pain and improve functional activities of daily living. Despite the advancements in surgical techniques that have led to better clinical outcomes, postoperative mechanical complications remain. These complications include instrumentation failure, with proximal junctional kyphosis (PJK), proximal junctional failure (PJF), and rod fractures (RFs) being the most common. Such complications deteriorate clinical outcomes and often require revision surgery, which can be more burdensome for surgeons and patients, than index surgery. Thus, the risk factors for mechanical complications must be identified, and effective preventive strategies established. Therefore, this study aimed to review the risk factors for mechanical complications, focusing on PJK, PJF, and RF, and explore prevention strategies for these complications in ASD surgery, drawing upon recent literature.

Retrospective study. We investigated cantilever reduction and fusion technique in high-grade spondylolisthesis (HGS) with minimally invasive surgery-transforaminal interbody fusion (MIS-TLIF). Most publications that describe minimally invasive surgeries for HGS, especially grade 4 or 5 listhesis, utilized a combined anterior and posterior approach. To the best of our knowledge, a detailed report that provides specific technical nuances for optimal use of a posterior-only approach utilizing MIS-TLIF is greatly lacking. This study included 36 patients with HGS in whom reduction, posterior instrumentation, and fusion were achieved with MIS- TLIF. They were evaluated for lower back pain and radicular pain, scaled by Visual Analog Scale (VAS) score. Erect radiographs were performed to calculate slip angle (SA) and sacropelvic and spinopelvic parameters preoperatively, postoperatively, and at each follow-up until 4 years. This study identified 30 patients with grade III HGS and six patients with grade IV/V HGS. Spinopelvic parameters were unbalanced in 13 patients. Complete reduction was achieved in 24 patients, with end-stage reduction of grade I with adequate spinopelvic balance achieved in 12 patients. Intraoperative neuromonitoring demonstrated no loss of signals throughout the procedure in any of the patients. Excellent functional outcome was achieved with back pain as well as leg pain VAS score improvements postoperatively in all patients. No implant-related complications or pseudoarthrosis incidences were reported at long-term follow-up at 4 years. MIS-TLIF for HGS is a specific solution for a complex pathology, enabling one to achieve an excellent clinical as well as radiological outcome.

This was a retrospective study. The current study aimed to investigate the clinical efficacy of atlantodentoplasty using the anterior retropharyngeal approach against irreducible atlantoaxial dislocation with atlantodental bony obstruction. In cases of atlantoaxial dislocation with atlantodental bony obstruction, owing to the presence of an osteogenic mass between the atlas and odontoid process, reduction is challenging to complete using the posterior approach. Transoral odontoidectomy is technically demanding and is associated with several risks. The clinical data of 26 patients diagnosed with irreducible atlantoaxial dislocation complicated by atlantodental bony obstruction were analyzed retrospectively. All patients underwent anterior retropharyngeal atlantodentoplasty, followed by posterior occipitocervical fusion. Details including surgical duration and blood loss volume were recorded. Radiographic data such as the anterior atlantodental interval, O-C2 angle, space available for the cord, clivus-canal angle, and cervical medullary angle, and clinical data including the Japanese Orthopedic Association (JOA) score were assessed. The fusion time of the grafted bone and the development of complications were examined. In patients undergoing anterior retropharyngeal atlantodentoplasty, the surgical duration and blood loss volume were 120.1±16.4 minutes and 100.6±33.5 mL, respectively. The anterior atlantodental interval decreased significantly after the surgery (p <0.001). The O-C2 angle, space available for the cord, clivus-canal angle, and cervical medullary angle increased significantly after the surgery (p <0.001). The JOA score during the latest follow-up significantly increased compared with that before the surgery (p <0.001). The improvement rate of the JOA score was 80.8%±18.1%. The fusion time of the grafted bone was 3-8 months, with an average of 5.7±1.5 months. In total, 11 patients presented with postoperative dysphagia and three with irritating cough. However, none of them exhibited other major complications. Anterior retropharyngeal atlantodentoplasty can anatomically reduce the atlantoaxial joint with a satisfactory clinical outcome in patients with irreducible atlantoaxial dislocation with atlantodental bony obstruction.

Study DesignA prospective web-based survey.PurposeAlthough intraoperative neurophysiological monitoring (IONM) is critical in spine surgery, its usage is largely based on the surgeon’s discretion, and studies on its usage trends in Asia–Pacific countries are lacking. This study aimed to examine current trends in IONM usage in Asia–Pacific countries.Overview of LiteratureIONM is an important tool for minimizing neurological complications and detecting spinal cord injuries after spine surgery. IONM can be performed using several modalities, such as transcranial electrical stimulation-muscle evoked potentials (Tc-MEP) and somatosensory evoked potentials (SEP).MethodsSpine surgeons of the Asia–Pacific Spine Society were asked to respond to a web-based survey on IONM. The questionnaire covered various aspects of IONM, including its common modality, Tc-MEP details, necessities for consistent use, and recommended modalities in major spine surgeries and representative surgical procedures.ResultsResponses were received from 193 of 626 spine surgeons. Among these respondents, 177 used IONM routinely. Among these 177 respondents, 17 mainly used SEP, whereas the majority favored Tc-MEPs. Although a >50% decrease is the commonly used alarm point in Tc-MEP, half of the Tc-MEP users had no protocols planned for such scenarios. Moreover, half of the Tc-MEP users experienced complications, with bite injuries being the most common. Most respondents strongly recommended IONM in deformity surgery for pediatric and adult populations and tumor resection surgery for intramedullary spinal cord tumors. Conversely, IONM was the least recommended in lumbar spinal canal stenosis surgery.ConclusionsSpine surgeons in Asia–Pacific countries favored IONM use, indicating widespread routine utilization. Tc-MEP was the predominant modality for IONM, followed by SEPs.