Objective: Although several studies have reported successful fusion rates after oblique lumbar interbody fusion (OLIF) using allografts or dimerized bone matrix (DBM) instead of autografts, whether OLIF can achieve satisfactory solid fusion without the use of autografts remains unclear. This study investigated the real fusion rates after OLIF using allografts and DBM, which were evaluated using both dynamic radiographs and computed tomography scans.Methods: We enrolled 79 consecutive patients who underwent minimally invasive OLIF followed by percutaneous pedicle screw fixation. All patients were treated with OLIF between L2 and L5 and underwent radiographic and clinical follow-ups at 12, 18, and 24 months after surgery. Radiographic assessment of fusion was performed using the modified BrantigaSteffee-Fraser (mBSF) scale, which was categorized as follows: grades I (radiographic pseudoarthrosis), II (indeterminate fusion), and III (solid radiographic fusion). Other radiologic and clinical outcomes were evaluated using the following parameters: vertebral slippage distance, disc height, subsidence, Oswestry Disability Index (ODI), and visual analogue scale (VAS).Results: Clinical outcomes demonstrated significant improvements in the VAS scores for back pain, leg pain, and ODI after surgery. Subsidence was present in 34 cases (35.4%) at 12 months postoperatively, which increased to 47.9% and reached 50.0% at 1.5 years and 2 years after surgery, respectively. The solid fusion rate after OLIF was 32.3% at 1 year, increased to 58.3% at 1.5 years, and reached 72.9% at 2 years. Radiographic pseudoarthrosis was 24.0% at 1 year, which decreased to 6.3% at 1.5 years and 3.1% at 2 years.Conclusion: OLIF is a safe and effective surgical procedure for the treatment of degenerative lumbar diseases. The mBSF scale, which simultaneously evaluates both dynamic angles and bone bridge formation, offers great reliability for the radiological assessment of fusion. Moreover, OLIF using allografts and DBM, which is performed on one or 2 levels at L2–5, can achieve satisfactory fusion rates within 2 years after surgery.

Background: Oblique lumbar interbody fusion (OLIF) results in less tissue damage than in other surgeries, but immediate postoperative pain occurs. Notably, facet joint widening occurs in the vertebral body after OLIF. We hypothesized that the application of a facet joint block to the area of widening would relieve facet joint pain. The purpose of this study was to evaluate the analgesic effects of such injections on postoperative pain. Methods: This double-blinded, placebo-controlled study randomized patients into 2 groups. Patients assigned to the active group received an intra-articular injection of a compound mixture of bupivacaine and triamcinolone, whereas patients in the placebo group received an equivalent volume of normal saline solution injection. Back and dominant leg pain were evaluated with use of a visual analog scale (VAS) at 12, 24, 48, and 72 hours postoperatively. Clinical outcomes were evaluated preoperatively and at 6 months postoperatively with use of the Oswestry Disability Index (ODI) and VAS for back and dominant leg pain. Results: Of the 61 patients who were included, 31 were randomized to the placebo group and 30 were randomized to the active group. Postoperative fentanyl consumption from patient-controlled analgesia was higher in the placebo group than in the active group at up to 36 hours postoperatively (p < 0.001) and decreased gradually in both groups. VAS back pain scores were significantly higher in the placebo group than in the active group at up to 48 hours postoperatively. On average, patients in the active group had a higher satisfaction score (p = 0.038) and were discharged 1.3 days earlier than those in the placebo group. Conclusions: The use of an intraoperative facet joint block decreased pain perception during OLIF, thereby reducing opioid consumption and the severity of postoperative pain. This effect was also associated with a reduction in the length of the stay. Level of Evidence: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

The reduction-first technique in unilateral biportal endoscopy (UBE) lumbar interbody fusion is a novel approach designed to overcome the limitations of conventional UBE fusion for spondylolisthesis. UBE fusion has gained popularity as a minimally invasive procedure, yet its ability to achieve satisfactory vertebral reduction remains limited, particularly in patients with higher-grade spondylolisthesis. This paper introduces a modified technique in which a right-sided pedicle screw is placed prior to cage insertion, facilitating early reduction of spondylolisthesis and improving interbody cage positioning. By addressing both the ipsilateral and contralateral facet joints under endoscopic visualization, the reduction-first technique enhances reduction and disc height restoration while maintaining minimal invasiveness. We present two clinical cases in which this technique was successfully applied, resulting in significant improvements in lumbar lordosis, sagittal vertical alignment, and clinical outcomes. Immediate postoperative radiographs and follow-up imaging demonstrated improved reduction and solid fusion at six months postoperatively. Although long-term outcomes have not yet been determined, this technique shows promise in expanding the indications for UBE fusion, even in patients with higher-grade spondylolisthesis.

Objective: Unilateral biportal endoscopic (UBE) lumbar decompression is an effective minimally invasive spine surgery, but postoperative spinal epidural hematoma (PSEH) remains a practical concern. This study evaluated the clinical necessity of routine application of a bioabsorbable cellulose-based hemostatic agent in UBE lumbar decompression. Methods: This retrospective comparative study included 115 patients who underwent UBE unilateral laminectomy and bilateral decompression for lumbar spinal stenosis. Patients were divided into a control group without routine hemostatic agent application (n = 66) and a hemostatic group with routine hemostatic agent application (n = 49). Clinical outcomes, operation time, postoperative drain output, hemoglobin change, and PSEH on postoperative day (POD) 2 MRI were compared. Results: Baseline characteristics were comparable between the groups. Total drain output was significantly lower in the hemostatic group than in the control group (61.50 [50.00–78.50] mL vs. 77.00 [59.85–96.75] mL, p = 0.002), particularly on POD 2 (19.00 [11.20–22.50] mL vs. 25.00 [18.25–40.00] mL, p < 0.001). Operation time was also shorter in the hemostatic group (41.43 ± 6.69 min vs. 45.91 ± 6.32 min, p < 0.001). However, hemoglobin change, clinical outcomes, and PSEH incidence did not significantly differ between the groups. Symptomatic PSEH requiring revision surgery occurred in one control patient and in no hemostatic patients. Conclusions: Routine hemostatic agent application was not associated with a significant reduction in PSEH after UBE lumbar decompression. Although lower POD 2 drain output and shorter operative time were observed in the hemostatic group, the clinical significance of these findings remains uncertain and warrants further prospective study.

Objective: Anterior odontoid screw fixation (AOSF) has several advantages over posterior C1–2 fusion for Grauer type II and shallow type III odontoid fractures. However, the risk factors for fusion failure, particularly in terms of 3-dimensional (3D) measurements, remain unclear. This study investigated the impact of fracture deficit volume (FDV), a novel 3D measurement, on fusion outcomes in patients undergoing AOSF.Methods: We enrolled 44 patients with Grauer type II or shallow type III odontoid fractures treated with AOSF at a single institution. Radiological assessments included preoperative and postoperative measurements of the fracture gap and fracture displacement on computed tomography (CT) scans. FDV was calculated through 3D CT reconstruction of preoperative and immediate postoperative CT to quantify the spatial gap between the edges of the fractures. Fusion outcomes were defined as solid union, fibrous union, or nonunion. Logistic regression and a generalized additive model (GAM) were used to identify risk factors for fusion failure after AOSF.Results: Solid fusion was achieved in 77.3% of patients. A reduction in the FDV with respect to the preoperative value was significantly associated with successful fusion (p=0.028), whereas patients presenting an increased FDV postoperatively were more likely to exhibit fusion failure (p=0.006). Age≥65 years, a fracture gap≥2 mm, and an increased FDV postoperatively were significant risk factors for fusion failure. GAM analysis revealed a linear relationship between a reduced FDV and improved fusion rates (adjusted R2=0.186, p=0.018).Conclusion: The risk of fusion failure is greater in elderly patients, those with a fracture gap greater than 2 mm, and those with an increased FDV postoperatively. Among the modifiable risk factors, FDV had the greatest impact on fusion outcomes after AOSF.