Shinya Arataki

Study Design: Retrospective cohort study.Purpose: To determine whether preoperative trunk and lower limb muscle quality predicts achievement of the minimal clinically important difference (MCID) in the 6-minute walk distance (6MWD) after lumbar spinal stenosis (LSS) surgery.Overview of Literature: LSS commonly causes intermittent claudication and reduced walking ability. Previous studies have suggested that muscle quality affects postoperative recovery, but its association with clinically meaningful improvements in the 6MWD remains unclear.Methods: This retrospective study included 150 patients aged ≥60 years who underwent decompression or fusion surgery for LSS at Okayama Rosai Hospital between April 2021 and April 2023. Preoperative assessments included demographic and surgical factors, Zurich Claudication Questionnaire (ZCQ) scores, visual analog scale scores, the 6MWD, and computed tomography-based muscle quality. The functional cross-sectional areas of the psoas major, erector spinae (ES), multifidus, gluteus maximus, and gluteus medius were quantified in Hounsfield units. Muscle quality was expressed as the low-attenuation muscle area (LAMA) ratio. Patients were classified according to whether they achieved the MCID (80 m) in the postoperative 6MWD. Logistic regression analyses were used to identify predictors of the achievement of the MCID.Results: Among the 150 patients, 86 (57%) achieved the MCID. Univariate analysis showed that younger age, higher preoperative ZCQ scores, a shorter 6MWD, and lower LAMA ratios of all examined muscles were significantly associated with the achievement of the MCID in postoperative walking ability. In multivariate analysis, younger age (p <0.001), a shorter preoperative 6MWD (p =0.016), and a lower ES LAMA ratio (p <0.001) remained independent predictors. These results indicate that better preoperative ES muscle quality independently contributes to postoperative walking recovery in patients with LSS.Conclusions: Preoperative younger age, shorter 6MWD, and lower ES LAMA ratio independently predicted meaningful postoperative improvement in walking. Enhancing preoperative ES muscle quality is crucial for postoperative walking recovery in patients with LSS.

Lateral lumbar disc herniation presents a technical challenge because the herniated fragment may elevate the exiting nerve root and dorsal root ganglion within the narrow foraminal-extraforaminal corridor. During unilateral biportal endoscopy (UBE), limited depth perception in the early stages of decompression may increase the risk of premature neural contact and postoperative dysesthesia. We developed a medial-caudal first access strategy supported by O-arm navigation to establish a safe disc-side working corridor before direct neural exposure. Four patients with symptomatic lateral lumbar disc herniation underwent decompression using an anatomy-based strategy. Preoperative computed tomography/magnetic resonance imaging fusion imaging was used to identify a reproducible medial-caudal disc-side corridor according to the anatomical relationship between the disc fragment, pedicle, facet complex, iliac crest, and exiting nerve root. Portal placement was planned to reproduce this corridor, and O-arm navigation was used as an adjunct to facilitate the reproduction of the planned trajectory and portal geometry during surgery. The planned medial-caudal corridor was successfully reproduced in all four patients. Sufficient disc-side working space was established before direct exposure of the exiting nerve root, allowing gradual cranial and lateral decompression under continuous endoscopic observation. Adequate decompression was achieved without neurological complications, postoperative dysesthesia, or conversion to open surgery. Postoperative imaging confirmed sufficient decompression with limited medial bone removal. The proposed strategy may provide a practical and reproducible workflow for UBE treatment of lateral lumbar disc herniation. By prioritizing the creation of a limited disc-side working corridor before neural exposure, this technique may improve early depth control, reduce unnecessary neural manipulation, and preserve the surrounding bony structures. O-arm navigation serves as an adjunct to reproduce the preplanned surgical corridor, rather than as the primary objective of the procedure.

Prospective cohort study. To assess the responsiveness of the Brief Balance Evaluation Systems Test (Brief B... Asian Spine Journal 2026;():-.

Retrospective cohort study. To identify factors predictive of a postoperative gain in thoracic kyphosis (TK)... Asian Spine Journal 2026;():-.

Morbid obesity increases operative depth and soft-tissue thickness in lumbar spine surgery, potentially complicating portal placement and working-corridor stability in unilateral biportal endoscopic (UBE) procedures. Although previous studies have reported acceptable clinical outcomes of UBE in obese patients, technical considerations for depth-adapted portal design and working corridor management at extreme operative depths have not been sufficiently described. A male patient in his late 20s, with a height of 183 cm and body weight of 137 kg (body mass index 41 kg/m2), presented with a large left L5/S1 lumbar disc herniation. Preoperative imaging suggested a deep operative corridor, with the relevant working depth ranging approximately from 80 to 100 mm depending on the laminar working area and the oblique trajectory toward the L5/S1 disc space. Because the skin contours were incompletely visualized on preoperative computed tomography (CT) due to the patient’s body habitus, intraoperative O-arm navigation was used as an adjunctive tool to confirm and refine the planned portal trajectories. Two 10-mm longitudinal skin incisions were created approximately 23 mm lateral to the midline, with an interportal distance of 35 mm. Adequate fascial release wider than the skin incisions was performed to reduce soft-tissue constraint at the fascial level. UBE discectomy was completed without dural injury or technical restriction, using standard UBE instruments. Postoperatively, radicular symptoms improved promptly without neurological deficits. This case illustrates depth-dependent amplification of soft-tissue constraints in UBE. As operative depth increases, small restrictions at the fascial level may proportionally narrow the functional working corridor. Adequate fascial release and thoughtful portal spacing may help preserve triangulation and facilitate irrigation outflow in deep operative fields. Rather than proposing a fixed portal template or requiring navigation, this report emphasizes individualized, depth-aware portal planning. Navigation may be useful in selected extreme cases when surface anatomy is difficult to evaluate reliably, but the same planning principles may also be applied using fluoroscopy and careful preoperative CT/MRI assessment. In morbidly obese patients with substantial operative depth, depth-aware portal planning combined with tailored fascial management may improve the reproducibility and technical stability of UBE discectomy. These findings should be interpreted as technical observations from a single case.

Upper lumbar spinal stenosis at L1/2 and L2/3 is technically demanding because of the narrow interlaminar spaces, steep facet orientation, and deep working corridors. Excessive bone work on the approach side may increase the risk of ipsilateral facet violation. This study aimed to describe a navigation-assisted unilateral biportal endoscopic (UBE) technique using a 0-degree endoscope for upper lumbar spinal stenosis and to discuss a structural rationale by which the straight-view configuration may function as a procedural control strategy for preserving the approach-side facet joint. This retrospective technical note included six consecutive patients with degenerative upper lumbar spinal stenosis (L1/2 or L2/3) treated with navigation-assisted UBE using a 0-degree endoscope. Patients with ossification of the ligamentum flavum, marked deformity, or concomitant fusion procedures were excluded. Perioperative outcomes and postoperative computed tomography (CT) findings were reviewed to assess the adequacy of decompression and facet preservation. All procedures were completed successfully without intraoperative complications or conversion to open surgery. Adequate bilateral decompression was achieved in all patients. Postoperative CT confirmed sufficient decompression with preservation of the approach-side facet joint. Clinical symptoms improved, with Visual Analogue Scale (VAS) scores for back pain decreasing from 75.0 to 35.8 and leg pain from 73.3 to 32.5. Navigation-assisted UBE using a 0-degree endoscope is a feasible and intuitive option for upper lumbar decompression. Under specific anatomical and navigational conditions, the straight-view configuration may help control excessive approach-side exposure and contribute to facet joint preservation.

Cage subsidence is a common radiographic finding after anterior cervical discectomy and fusion (ACDF), particularly with stand-alone cages, and may compromise postoperative alignment and stability. Blade-anchored zero-profile cages have been developed to provide immediate fixation while avoiding plate-related complications; however, their influence on subsidence characteristics has not been fully elucidated. This study aimed to compare the magnitude and direction of radiographic subsidence between blade-anchored zero-profile cages and stand-alone cages after single-level ACDF. This retrospective single-center study included 76 patients who underwent single-level ACDF between 2017 and 2024 using either a blade-anchored zero-profile cage or a stand-alone cage. The anterior disc height (ADH) and posterior disc height (PDH) were measured preoperatively, immediately postoperatively, and at 6 months after surgery. The mean disc height was defined as the average of the ADH and PDH. Radiographic subsidence was calculated as the difference between the immediate postoperative and 6-month mean disc heights. Anterior and posterior subsidence were analyzed separately. Multivariable linear regression analyses were performed in two steps: Model 1 adjusted for demographic and baseline radiographic variables, and Model 2 further adjusted for disc height recovery to account for the effect of intraoperative disc height restoration. Mean subsidence was significantly greater in the blade-anchored zero-profile cage group than in the stand-alone cage group, and the incidence of subsidence ≥ 3 mm was higher with blade-anchored cages. Directional analysis demonstrated significantly greater anterior subsidence in the blade-anchored group, whereas posterior subsidence did not differ between the groups. In the multivariate analysis, cage type was independently associated with subsidence in Model 1; however, this association was attenuated after adjustment for disc height recovery in Model 2. Blade-anchored zero-profile cages were associated with greater radiographic subsidence after single-level ACDF compared with stand-alone cages, primarily due to increased anterior subsidence. The attenuation of the cage-type effect after adjustment for disc height recovery suggests a potential role of restoration-related factors. Directional assessment of subsidence may provide additional insights into implant-specific behavior.

Background/Objectives: Vertebral body stenting (VBS) and balloon kyphoplasty (BKP) are widely used for the treatment of osteoporotic vertebral fractures (OVFs). However, it remains unclear whether the theoretical biomechanical advantages of VBS translate to superior clinical or radiographic outcomes. This study aimed to compare VBS and BKP with respect to clinical outcomes, radiographic parameters, and complications. Methods: In this multicenter retrospective comparative cohort study, 123 patients with OVF treated with VBS (n = 24) or BKP (n = 99) were analyzed. VBS was indicated for complex fracture patterns, including severe endplate injury, split-type fractures, and absence of interbody sclerosis; other fractures were treated with BKP. Pain outcomes, operative parameters, cement volume and leakage, and radiographic measures of vertebral kyphosis angle (VKA) and local kyphosis angle (LKA) were assessed. For group comparisons, we used independent-samples t tests or Mann–Whitney U tests for continuous variables and chi-squared or Fisher’s exact tests for categorical variables. Results: Baseline demographics and bone mineral density were comparable between groups. Surgical time was longer for VBS (39 ± 6 vs. 35 ± 9 min, p = 0.007). Both procedures produced significant pain reductions (p < 0.001), and postoperative VAS did not differ between VBS and BKP (18 ± 11 vs. 13 ± 12 mm, p = 0.06). Although VKA immediately after surgery was lower for VBS (4.8 ± 4.4° vs. 7.0 ± 4.9°, p = 0.03), the magnitude of correction, VKA, and LKA at final follow-up were comparable. Cement volume was similar (6.4 ± 1.4 vs. 6.7 ± 1.9 mL, p = 0.45), but cement leakage occurred more frequently with VBS (54% vs. 24%, p = 0.005). Rates of adjacent vertebral fracture (13% vs. 26%, p = 0.12) and revision surgery (4% vs. 8%, p = 0.44) were comparable between groups. Conclusions: Despite VBS being reserved for more complex fracture morphologies with split-type fractures and severe endplate defects, while BKP was generally used for uncomplicated OVF cases, VBS provided pain relief and radiographic correction comparable to BKP.

We describe a C-arm-free, O-arm-based navigation-guided endoscopy-assisted extraforaminal decompression using a navigated burr in a 74-year-old woman with L5 radiculopathy due to far-out syndrome. Navigated instruments were used to plan the skin entry point and accurately target the extraforaminal L5 root corridor. Under endoscopic visualization, a navigated high-speed diamond burr was used to drill the hypertrophic transverse process, followed by meticulous perineural soft-tissue release from the foramen to the extraforaminal zone. No intraoperative complications occurred. The operative time was 78 minutes, and the estimated blood loss was 50 mL. Postoperative computed tomography (CT) and plain radiographs confirmed adequate decompression of the extraforaminal region. Clinically, the patient reported marked improvement in right L5 radicular pain, with resolution of preoperative numbness on standing and disappearance of intermittent claudication. At the 6-month follow-up, she was able to walk more than 1 km without claudication; sensory disturbance in the L5 dermatome had almost completely resolved and Visual Analogue Scale (VAS) score for leg pain (0–100 mm) improved from 65 mm preoperatively to 23 mm at 1 year follow-up. Posterolateral C-arm-free endoscopic extraforaminal decompression using O-arm navigation demonstrates a feasible and minimally invasive option for far-out syndrome, simplifying access to the deep extraforaminal corridor, minimizing soft-tissue trauma, and eliminating continuous fluoroscopic radiation to the surgical team.