Asian Spine Journal最新文献

Study design: Retrospective cohort study.

Purpose: To identify whether the presence and features of epidural metastases are risk factors for metastatic spinal cord compression (MSCC).

Overview of literature: Several factors are associated with the development of MSCC in patients with spinal metastases. However, the relationship between epidural metastasis and the development of MSCC is not well understood.

Methods: Among patients with spinal metastases at the spinal cord level treated at a single institution from 2017 to 2023, 191 cases (age: 66.4±12.9 years; sex: 120 male patients) were studied. We defined MSCC as a decrease of one or more grades in the American Spinal Injury Association (ASIA) impairment scale due to spinal metastases. Patients were diagnosed with epidural metastasis at the level of spinal metastasis. When the features of epidural metastases could be evaluated, the epidural spinal cord compression (ESCC) scale and circumferential angle of spinal cord compression (CASCC) were assessed. The risk factors for developing MSCC and high-risk epidural metastases were analyzed.

Results: Of the patients with spinal metastases who developed MSCC during follow-up, 97.6% had epidural metastases before the onset of MSCC. Multivariate logistic regression analysis identified the presence of epidural metastasis as an independent risk factor for MSCC. In patients with evaluable epidural metastases, multivariate logistic regression analysis identified the ESCC scale and CASCC as high-risk factors. The cutoffs were determined to be 3 for the ESCC scale and 180° for CASCC.

Conclusions: Epidural metastasis was identified as a risk factor for MSCC in patients with spinal metastases. Additionally, epidural metastases in those with an ESCC scale of 3 and a CASCC greater than 180° were categorized as high-risk tumors.

Study design: A retrospective study.

Purpose: To develop a nomogram to predict functional independence (FI) in patients undergoing lumbosacral spine surgery (LSSS).

Overview of literature: LSSS aims to improve functional outcomes and restore activities of daily living. We hypothesized that demographic, clinical, surgical, and neurological characteristics could be used to predict FI, as defined by the Barthel index (BI) scores.

Methods: The medical records of patients who underwent LSSS between October 2023 and September 2024 were reviewed. Univariate and multivariate logistic regression analyses were used to construct a predictive nomogram. Model performance was assessed using receiver operating characteristic curve analysis for discrimination and a bootstrap-based plot for calibration. Decision curve analysis and the Youden index were used to determine the optimal threshold probability for identifying patients requiring additional rehabilitation.

Results: The study included 111 patients (35 men and 76 women; mean age, 63.66±11.37 years), of whom 68 (61.26%) achieved FI. The nomogram, incorporating preoperative BI score, hospital stay <7 days, and absence of metabolic comorbidities and postoperative anemia, demonstrated excellent discrimination (area under the receiver operating characteristic curve=0.91; 95% confidence interval, 0.84- 0.98) and good calibration with the goodness-of-fit test (p>0.05). The optimal threshold probability cutoff was 0.58, with a sensitivity of 84% and specificity of 88%. This tool demonstrated excellent discriminative ability between patients who required further rehabilitation and those who did not, with a Youden index of 0.71.

Conclusions: This nomogram exhibited excellent discrimination and good calibration and could serve as a predictive tool for FI on the day of hospital discharge. Its application may support discharge planning and facilitate patient stratification to optimize postoperative rehabilitation.

Lumbar endoscopic unilateral laminotomy for bilateral decompression (LE-ULBD) is a minimally invasive procedure designed to treat lumbar spinal stenosis. While traditional uniportal endoscopic decompression already reduces tissue damage and promotes faster recovery compared to open surgery, this work introduces standardized terminology and specific endoscope-camera maneuvers to improve visualization and precision during both ipsilateral and contralateral decompression. By describing endoscope ("shaft") and camera head ("optic") rotations in a degree-degree format (e.g., 0-0, 90-0, 135-135, 180-180), the technique allows reproducible, targeted access to key anatomical areas while minimizing unnecessary bone removal. This systematic approach addresses the steep learning curve and technical intricacies of lumbar endoscopy, aiding intraoperative communication and potentially decreasing complications from inadequate decompression or poor visualization. The method aims to improve training, safety, and consistency of outcomes in endoscopic lumbar decompression procedures stenosis.

Study design: Systematic review and meta-analysis.

Purpose: To perform a comprehensive meta-analysis comparing clinical outcomes of uniportal versus biportal endoscopic spine surgery across decompression procedures in patients with lumbar degenerative disease (LDD).

Overview of literature: Uniportal endoscopic spine surgery has been a widely adopted minimally invasive technique, whereas biportal endoscopy has recently emerged as a promising alternative with potential advantages in surgical outcomes.

Methods: A systematic review and meta-analysis of comparative studies was conducted in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. PubMed, Embase, and Scopus databases were searched to identify relevant studies. Eleven studies encompassing 374 uniportal and 368 biportal patients were included. Outcomes analyzed were Oswestry Disability Index (ODI), Visual Analog Scale (VAS) scores for back and leg pain, complication rates, operative time, and length of hospital stay.

Results: Biportal endoscopic surgery was associated with a significantly lower ODI at 1-3 months and at final follow-up compared with uniportal surgery. However, uniportal discectomy demonstrated significantly shorter operative time and length of hospital stay than biportal discectomy. No significant differences were observed between approaches in terms of VAS scores, complication rates, or ODI at other time points.

Conclusions: Both uniportal and biportal endoscopic spine surgeries yield comparable postoperative outcomes in LDD. Although biportal surgery showed a modest advantage in ODI improvement, it did not reach the minimal clinically important difference. Uniportal surgery demonstrated greater efficiency in terms of operative time and recovery, particularly for discectomy procedures.

Purpose: This meta-analysis evaluated the impact of sarcopenia on the efficacy and safety of percutaneous vertebroplasty and kyphoplasty in patients with osteoporotic vertebral compression fractures.

Methods: Following PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines, a systematic literature search was conducted to identify studies comparing outcomes between patients with and without sarcopenia undergoing vertebroplasty or kyphoplasty. Twelve studies involving 1,786 patients were included. The primary outcomes were pain (measured using the Visual Analog Scale), refractures, disability (using the Oswestry Disability Index), length of hospital stay, and mortality rates. Heterogeneity was assessed using the I2 statistic. Mean differences (MDs) and odds ratios (ORs) with 95% confidence intervals (CIs) were calculated, applying a random-effects model when heterogeneity was present.

Results: Patients with sarcopenia experienced significantly higher pain (MD, 0.82; 95% CI, 0.47-1.17; p<0.00001), greater disability (MD, 5.70; 95% CI, 4.54-6.87; p<0.00001), and increased refracture risk (OR, 2.58; 95% CI, 1.13-5.89; p=0.02) compared with those without sarcopenia. Length of hospital stay was also longer, and mortality rates were significantly higher in the sarcopenia group.

Conclusions: Sarcopenia is an important risk factor for adverse outcomes after vertebroplasty and kyphoplasty. A systematic assessment of sarcopenia and the development of tailored perioperative strategies may help mitigate these risks and improve patient outcomes (PROSPERO registration no., CRD42024628263).

Study design: Retrospective cohort study.

Purpose: This study aimed to investigate bone quality and the trajectories of modified paravertebral foramen screw (mPVFS) on computed tomography (CT) images compared with those of PVFS and lateral mass screw (LMS).

Overview of literature: With increasing demand for cervical posterior fusion in aging populations, achieving optimal fixation remains challenging. The PVFS offers biomechanical stability with a safer trajectory than traditional pedicle screw and LMS. However, its efficacy in elderly patients with poor bone quality is a concern.

Methods: We analyzed the cervical CT images of 40 patients (10 patients per group), stratified by age and sex. Bone mineral density was assessed using CT attenuation values of the C5 vertebral body and lateral mass. We compared screw length, insertion area, and CT attenuation values along the screw trajectory across techniques.

Results: Bone quality decreased significantly with age, particularly in women. The mPVFS had a significantly longer trajectory than that of the PVFS (2.5-3.0 mm longer) and the LMS (1 mm longer) and a larger screw-bone contact area (1.2× that of PVFS, 1.4× that of LMS). CT attenuation values were higher along the mPVFS trajectory than along the PVFS and LMS trajectories. The differences were not consistently significant.

Conclusions: mPVFS provides a biomechanical advantage by increasing screw length and contact area while targeting dense cancellous bone. mPVFS could safely accommodate screws that are 2.5-3.0 mm longer than conventional PVFS, irrespective of patient age or sex, which may be a potential clinical advantage. To validate its efficacy and long-term stability, further biomechanical and clinical studies are required.

Study design: Single-center retrospective study.

Purpose: By utilizing three-dimensional (3D) reconstruction models, our study aimed to investigate the three-dimensional changes in vertebral body tethering (VBT) and assess the relationship between axial-plane parameters and postoperative outcomes.

Overview of literature: Previous studies mainly focused on coronal plane correction but lacked investigation on axial plane changes following VBT.

Methods: We included consecutive patients who underwent VBT in our institution (Queen Mary Hospital and Duchess of Kent Children's Hospital, Hong Kong) from February 2019 to April 2024. We used EOS radiographs to generate 3D reconstruction models, and parameters were analyzed preoperatively, immediately postoperatively, 1 year postoperatively, and 2 years postoperatively. The primary outcomes were changes in coronal, axial, and sagittal profiles at different time points. Secondary outcomes included the relationship between axial parameters with short-to-medium term changes in coronal/sagittal profiles.

Results: We included 44 patients (seven males, 37 females) with 58 instrumented curves, with an average follow-up of 36.3±17.1 months. The mean Cobb angle, apical vertebral rotation (AVR), and maximal vertebral rotation (MVR) improved from 48.0°±10.7°, 9.1°±5.7°, and 13.4°±5.7° preoperatively to 22.3°±8.9°, 6.2°±4.8°, and 9.8°±4.3° postoperatively, respectively, with correction maintained at 2 years. Preoperative AVR, MVR, and intraoperative derotation were significantly correlated with 1-year and 2-year correction rate and curve regression (Pearson correlation coefficient [r ]=0.35-0.63; p <0.001). Multivariate analysis confirmed AVR derotation and preoperative MVR as significant predictors for the 1-year correction rate. Tether breakage occurred in 27.6% (16/58) of patients.

Conclusions: VBT was effective in correcting coronal and axial deformity at 2 years, but most correction occurred intraoperatively. Axial parameters were predictive for postoperative outcomes, with increased preoperative rotation associated with greater coronal correction. More aggressive derotation corresponded to greater correction. To improve surgical outcomes, clinicians should aim to achieve adequate correction by screw positioning and appropriate tensioning.

Adult spinal deformity (ASD) is a complex condition associated with significant disability and reduced health-related quality of life (HRQOL). Surgical correction has increasingly emphasized restoration of sagittal alignment; however, the optimal radiographic targets and their relationships to clinical outcomes and mechanical complications remain subjects of debate. This narrative review summarizes five major alignment strategies in ASD surgery and examines their relevance to HRQOL and the prevention of proximal junctional kyphosis/ failure (PJK/PJF). The Scoliosis Research Society-Schwab classification introduced the first standardized thresholds for sagittal imbalance that demonstrated strong associations with HRQOL, although its ability to predict PJK/PJF is limited. Age-adjusted alignment goals highlighted the importance of avoiding overcorrection, demonstrating that functionally appropriate targets in older patients can reduce junctional complications while maintaining HRQOL benefits. The Global Alignment and Proportion (GAP) score proposed a proportionality-based framework and demonstrated early promise in predicting mechanical complications; however, subsequent validation studies have reported inconsistent results across different populations. The Roussouly classification emphasized restoration of a patient's inherent sagittal profile, with lower complication rates observed when type-matched correction was achieved. More recently, vertebral-pelvic angle-based metrics, including the T1 pelvic angle and the T4-L1-hip axis, have shown strong correlations with HRQOL and PJK risk while offering reproducible and practical intraoperative applicability. Although each system provides valuable insights, no single approach is universally superior. Future research should focus on integrating radiographic, biological, and functional factors into predictive models and validating these approaches through prospective multicenter studies to better guide individualized alignment strategies.

Study design: Retrospective multicenter cohort study.

Purpose: This study aimed to evaluate the incidence of cage subsidence and its impact on the clinical outcomes of anterior-posterior spinal fixation (APSF) for osteoporotic vertebral fractures (OVFs). It also aimed to identify the risk factors for cage subsidence.

Overview of literature: The risk factors for cage subsidence after APSF for OVFs remain unclear.

Methods: This multicenter retrospective cohort study included patients who underwent combined APSF using an expandable cage system, with a minimum 1-year follow-up at multiple centers. Patients were divided into cage subsidence (n=53) and non-subsidence (n=47) groups. Demographic data, surgery-related factors, and radiographic parameters were analyzed. After univariate analysis of factors associated with cage subsidence, multivariate logistic regression was used to identify related factors.

Results: The demographic data showed a significant difference in Hounsfield unit (HU) (102.6±28.3 vs. 80.0±30.6, p=0.005) and endplate injury (p<0.001). Furthermore, 1A1B fixation was significantly more common in the subsidence group (p<0.001). Radiographic data showed significant differences in Δlocal kyphosis (supine-standing) (-7.1°±9.2° vs. -14.6°±11.5°, p=0.001). Multivariate analysis showed that Δlocal kyphosis (supine-standing) (adjusted odds ratio [aOR], 12.8; p=0.010), HU (aOR, 8.1; p=0.033), fixation range (aOR, 8.2; p=0.020), and endplate injury (aOR, 18.8; p=0.011) were significant risk factors for subsidence.

Conclusions: Intraoperative endplate injury, low HU (<87.5), short fusion, and preoperative vertebral instability (Δlocal kyphosis [supinestanding] <-14) were identified as risk factors for cage subsidence in APSF. Therefore, extending the fusion levels in patients with low HU values and significant preoperative vertebral instability should be considered to avoid intraoperative endplate injury.

Study design: Finite element analysis.

Purpose: To investigate the biomechanical response of posterior short-segment fixation with or without intermediate screws at the index vertebra in osteoporotic thoracolumbar burst fractures using finite element analysis.

Overview of literature: Spinal fixation in elderly patients with osteoporotic vertebral fractures is challenging because osteoporosis weakens the screw-bone interface, leading to screw loosening and loss of fracture reduction. Short segment fixation with intermediate screws has been proposed to reduce kyphosis recurrence and implant failure in unstable thoracolumbar fractures. However, the mechanisms by which intermediate screws enhance fixation strength in osteoporotic spines remain unclear.

Methods: Six finite element models of T12 burst fractures were developed to simulate short-segment stabilization under normal or osteoporotic bone conditions, with/without augmentation screws at the fractured vertebra. Spinal stiffness, implant stresses, and axial displacement/micromotion of the bony defect were measured and compared under mechanical loading.

Results: Osteoporotic models exhibited a greater range of motion (ROM) than normal bone. All six-screw constructs reduced ROM across all motions compared with traditional four-screw models. Osteoporotic fracture models gained greater benefit from intermediate screw augmentation at the fracture vertebra, which also lowered axial displacement/micromotion. In six-screw models, rod stress increased while pedicle screw stress decreased. Intermediate screws at fractured vertebrae produced similar changes in stress distribution across all fixation models, regardless of bone quality.

Conclusions: Our findings may facilitate implant selection for osteoporotic burst fractures, supporting the use of more rigid fixation sixscrew constructs to reduce the risk of mechanical failure and postoperative re-collapse.