Purpose
Thoracolumbar vertebral compression fractures (VCFs) are a leading cause of kyphosis and related biomechanical complications, often resulting in chronic back pain and reduced function. Balloon kyphoplasty has been widely used as a minimally invasive intervention to provide pain relief and restore vertebral height. The SpineJack system is a relatively novel technique that introduces mechanical distraction, offering potentially enhanced vertebral restoration. This study aims to compare these two effective treatments for thoracolumbar fractures.
Materials and Methods
This study analyzed 30 patients with thoracolumbar VCFs surgically treated, using the Spine-Jack system (n=10) or balloon kyphoplasty (n=20). Back pain was evaluated as VAS pain score and functional disability was assessed with Oswestry Disability Index (ODI) preoperatively and immediately postoperatively. Radiological outcomes were measured on plain lateral X-rays, including vertebral height restoration, segmental kyphosis angle, and sagittal vertical axis (SVA). Complications, such as cement leakage and adjacent vertebrae fractures, were recorded. Continuous variables – with t-tests and categorical variables- with chi-square tests, were analyzed. P-value less than 0.05 was considered statistically significant.
Results
Both the Spine-Jack system and balloon kyphoplasty were effective in reducing back pain and improving patients’ function, with significant improvements in VAS and ODI scores. However, the Spine-Jack system demonstrated superior vertebral height restoration (85% vs. 72%, p=0.03) and segmental kyphosis angle correction (12° vs. 9°, p=0.032) when compared to balloon kyphoplasty. Complication rates were all low and comparable between the two groups.
Conclusions
Although the Spine-Jack system and balloon kyphoplasty are all effective for thoracolumbar VCFs, the Spine-Jack system offered superior radiological outcomes in selected cases. Further studies may explore their complementary roles in managing thoracolumbar VCFs.

Purpose
This study aimed to compare the clinical effectiveness and potential benefits of ultrasound (US)-guided versus fluoroscopy (FL)-guided cervical retrolaminar block (RLB) in patients with cervical facet joint pain.
Materials and Methods
A total of 27 patients aged 40 years or older who were diagnosed with cervical facet joint syndrome based on physical examination and imaging modalities were included. 12 patients of group I treated with US-guided RLB and 15 patients of group II treated with FL-guided RLB. The position of the needle and the distribution of contrast agent were confirmed using fluoroscopic images, and the changes in numeric rating scale (NRS) and neck disability index (NDI) before and 2 weeks after the procedure were compared in the two groups.
Results
Radiologically, the target agreement of needle placement in group I was 75%. There was no difference in contrast medium spread between the two groups. Clinically, the mean NRS improved from 7.08±0.52 to 3.08±0.90 in group I (p=0.01) and from 7.20±0.56 to 3.33±0.72 in group II (p=0.01). The mean NDI decreased from 41.67±2.27 before the procedure to 20.83±2.33 after the procedure in group I (p=0.01), and from 40.87±2.61 before the procedure to 21.67±2.02 after the procedure in group II (p=0.01), with no difference between the two groups.
Conclusions
US-guided cervical RLB is an effective, radiation-free alternative to FL-guided RLB for managing cervical facet joint pain, offering comparable pain relief and functional improvement.

Advanced imaging technologies have revolutionized the diagnosis and management of spinal pathologies by providing superior precision and efficiency. Modalities such as PET-CT, SPECT, diffusion tensor imaging (DTI), and magnetic resonance spectroscopy (MRS) offer unique insights into the metabolic, structural, and functional aspects of spinal diseases, enabling better differentiation of lesions, improved surgical planning, and early detection of pathological changes. Furthermore, the integration of artificial intelligence (AI) has enhanced imaging workflows by enabling automated analysis, prediction of clinical outcomes, and segmentation of spinal structures. Despite these advancements, challenges such as technical limitations, high costs, and ethical concerns, including issues of data privacy and AI-generated inaccuracies, hinder widespread adoption. This review explores the clinical applications, limitations, and future directions of these emerging technologies, highlighting the need for multidisciplinary collaboration and large-scale research to standardize protocols and optimize patient outcomes. The seamless integration of advanced imaging and AI represents a transformative potential for improving diagnostic accuracy and treatment efficacy in spinal care.

Purpose
This study was conducted to identify risk factors predicting the loss of cervical lordosis (LCL) in patients with multilevel ossification of the posterior longitudinal ligament (OPLL) following laminoplasty. Material and Methods: We conducted a retrospective analysis of data from patients who underwent laminoplasty at Chonnam National University Hospital between January 2013 and December 2022. Various radiological parameters and clinical outcome measures were collected perioperatively. Patients were divided into 2 groups according to the severity of LCL. We examined preoperative radiological parameters associated with LCL.
Results
We analyzed data from 109 patients (92 men and 17 women; mean age, 60.31±10.80 years). A higher T1 slope (odds ratio [OR], 1.420; p<0.001) and a lower extension ratio (OR, 0.883; p=0.019) were associated with a higher risk of LCL. T1 slope was shown to be an excellent predictor of LCL, with a cut-off value of 28° (p<0.001, area under the curve=0.918). Also, The T1 slope and extension ratio were statistically significant correlated with clinical outcomes.
Conclusions
T1 slope and extension ratio were significantly associated with LCL in patients with multilevel OPLL following laminoplasty. The cut-off value for the T1 slope was 28°, and the cut-off value for the extension ratio was 33. Therefore, in multilevel OPLL patients with a T1 slope exceeding 28° or an extension ratio below 33, a warning regarding the potential LCL should be given before performing cervical laminoplasty.

Objective
Postoperative urinary retention (POUR) is a common complication following lumbar spine surgery, significantly affecting functional recovery and Enhanced Recovery After Surgery (ERAS) protocols. POUR can lead to bladder overdistension, infections, prolonged hospital stays, and long-term detrusor dysfunction. Postoperative delirium (POD) can impair cognitive function and mobility, potentially triggering or exacerbating POUR. This study aims to investigate whether POD serves as an independent risk factor for POUR and to analyze other contributing factors to provide clinical management strategies.
Materials and Methods
A retrospective cohort study was conducted involving 420 patients who underwent lumbar spine surgery at a single tertiary medical institution between March 2021 and February 2024. POUR was defined as a post-void residual (PVR) bladder volume ≥300 mL measured via bladder ultrasound or requiring catheter reinsertion due to urinary retention. POD was diagnosed within 72 hours postoperatively using the Confusion Assessment Method (CAM) and was classified into three subtypes: hyperactive, hypoactive, and mixed. Multivariate logistic regression analysis was employed to identify the relationship between POD and POUR, with sensitivity and specificity assessed through Receiver Operating Characteristic (ROC) curve analysis.
Results
Among 420 lumbar spine surgery patients, 44 (10.5%) experienced POD. Of these, 16 (36.4%) were classified as hyperactive, 20 (45.5%) as hypoactive, and 8 (18.2%) as mixed type. POUR occurred in 28 of the POD patients (63.6%) compared to 71 of 376 patients without POD (18.9%), demonstrating a statistically significant difference (p<0.001). The analysis of POUR incidence by POD subtype revealed rates of 62.5% (10/16) for hyperactive POD, 60.0% (12/20) for hypoactive POD, and 75.0% (6/8) for mixed POD. Patients with mixed POD showed the highest POUR incidence, with a significant difference compared to hyperactive and hypoactive POD (p<0.05). Multivariate logistic regression analysis identified POD as an independent risk factor for POUR, increasing the likelihood by approximately 3.7 times (Odds Ratio, OR: 3.71; 95% Confidence Interval, CI: 1.95–7.06; p<0.001). Among POD subtypes, mixed POD presented the strongest association with POUR, increasing the risk by 4.8 times (OR: 4.84; 95% CI: 2.10–11.15; p<0.001). Hyperactive and hypoactive POD were also significant risk factors, increasing POUR risk by 3.0 times (OR: 3.04; 95% CI: 1.45–6.35; p=0.003) and 3.5 times (OR: 3.48; 95% CI: 1.69–7.19; p=0.001), respectively.
Conclusions
This study confirms that postoperative delirium (POD) is an independent risk factor for postoperative urinary retention (POUR) in lumbar spine surgery. The occurrence and subtype of POD significantly influence POUR incidence, with mixed POD presenting the highest risk. These findings highlight the importance of early diagnosis and prevention of POD as a strategy to effectively reduce POUR. A multidisciplinary approach integrating POD and POUR management could optimize postoperative outcomes and improve patient recovery.

Spinal cord injury (SCI) distinguishes itself from peripheral nerve injury by causing devastating and irreversible damage to the spine, resulting in profound motor, sensory, and autonomic dysfunction. The ensuing complex microenvironment of SCI, characterized by hemorrhage, inflammation, and scar formation, poses substantial challenges to regeneration and complicates numerous transplantation strategies. Recent research has shifted its focus towards manipulating the intricate SCI microenvironment to enhance regeneration, with some approaches demonstrating significant therapeutic efficacy. Consequently, the reconstruction of an appropriate microenvironment post-transplantation emerges as a potential therapeutic solution for SCI. This review aims to provide a comprehensive overview, firstly summarizing the influential compositions of the microenvironment and their diverse effects on regeneration. Secondly, we highlight recent research employing various transplantation strategies to modulate distinct microenvironments induced by SCI, aiming to facilitate regeneration. Lastly, we discuss prospective transplantation strategies for SCI, emphasizing the importance of addressing the complex microenvironment for successful therapeutic outcomes.

Objective
Proximal junctional fracture (PJFx) at the uppermost instrumented vertebra (UIV) or UIV+1 is the most common mechanism of PJF. There are few studies assessing the radiographic progression after PJFx development. Therefore, this study sought to identify the risk factors for radiographic progression of PJFx in surgical treatment for ASD.
Methods
In this retrospective study, among 317 patients aged > 60 years who underwent ≥5-level fusion from the sacrum, 76 with PJFx development were included. According to the change in proximal junctional angle (PJA), two groups were created: Group P (change ≥10°) and Group NP (change <10°). Patient, surgical, and radiographic variables were compared between the groups to demonstrate risk factors for PJFx progression using uni- and multivariate analysis. The receiver operating characteristic (ROC) curve was used to calculate cutoff values. Clinical outcomes, such as visual analog scale (VAS) scores for back and leg pain, the Oswestry Disability Index (ODI) score, and the Scoliosis Research Society (SRS)-22 score, and revision rate were compared between the two groups.
Results
The mean age at the index surgery was 71.1 years, and there were 67 women enrolled in the study (88.2%). There were 45 patients in Group P and 31 in Group NP. A mean increase of PJA was 15.6° (from 23.2° to 38.8°) in Group P and 3.7° (from 17.2° to 20.9°) in Group NP. The clinical outcomes were significantly better in Group NP than Group P, including back VAS score, ODI value, and the SRS-22 scores for all items. Revision rate was significantly greater in group P than in group NP (17.8% vs. 51.6%, p=0.001). Multivariate analysis revealed that overcorrection relative to the age-adjusted ideal pelvic incidence (PI)–lumbar lordosis (LL) target at the index surgery (odds ratio [OR]=4.484, p=0.030], PJA at the time of PJFx identification (OR=1.097, p=0.009), fracture at UIV versus UIV+1 (OR =3.410, p=0.027) were significant risk factors for PJFx progression. The cutoff value of PJA for PJFx progression was calculated as 21° using the ROC curve.
Conclusions
The risk factors for further progression of PJFx were overcorrection relative to age-adjusted PI–LL target at the index surgery, PJA > 21° at initial presentation, and fracture at the UIV level. Close monitoring is warranted for such patients not to miss the timely revision surgery.

Purpose
The biplanar whole body imaging system (EOS) is a new tool for measuring whole body sagittal alignment in a limited space. This tool may affect the sagittal balance of patients compared to conventional whole spine radiography (WSX). This study is to investigate the difference in sagittal alignment between WSX and EOS.
Materials and Methods
We compared spinal and pelvic sagittal parameters in 80 patients who underwent EOS and WSX within one month between July 2018 and September 2019.The patients were divided based on sagittally balanced and imbalanced groups according to pelvic tilt (PT) >20˚, pelvic incidence-lumbar lordosis >10°, C7-sagittal vertical axis (SVA) > 50 mm in WSX.
Results
In sagitally imbalanced group, for WSX versus EOS, the pelvic parameters demonstrated compensation in EOS with smaller PT (27.4±11.6° vs. 24.9±10.9°, p=0.003), greater sacral slope (SS), and patients tended to stand more upright with smaller C7-SVA (58.4±17 mm vs. 48.9±57.3 mm, p=0.003), T1-pelvic angle (TPA), T5-T12, and T2-T12. However, in sagitally balanced group, these differences were less pronounced only with smaller PT (10.8±6.9° vs. 9.4±4.7°, p=0.04), TPA and T2-T12 angle, but SS and C7-SVA were similar (p>0.05).
Conclusions
EOS shows a negative SVA shift and lesser pelvic tilt than WSX especially in patients with sagittal imbalance. When making a surgical plan, surgeon should consider these differences between EOS and WSX.

Background
It is well reported that the patient’s age plays an important role associated with proximal junctional failure (PJF) development. Various characteristics of adult spinal deformity (ASD) patients were different between younger and older age groups. We hypothesized that the radiographic risk factors for PJF would different according to younger and older age groups. This study aimed to evaluate different radiographic risk factor of PJF according to the two age groups undergoing thoracolumbar fusion for ASD.
Methods
ASD patients aged ≥ 60 years who underwent thoracolumbar fusion from low thoracic level (T9~T12) to sacrum were included. The minimum follow-up duration was two years. PJF was defined as proximal junctional angle (PJA) ≥ 20°, fixation failure, fracture, myelopathy, or necessity of revision surgery. Using various radiographic risk factors including age-adjusted ideal pelvic incidence (PI)-lumbar lordosis (LL), univariate and multivariate analyses were performed separately according to the two age groups : <70 years and ≥70 years.
Results
A total of 186 patients were enrolled (mean age=68.5 years old, 90.3% female). Mean follow-up duration was 67.4 months. PJF developed in 98 patients (32.0%). There were fracture in 53 patients, PJA ≥ 20° in 26, fixation failure in 12, and myelopathy in 6. PJF developed more frequently in patients older than 70 years than in younger than 70 years. In patients aged less than 70 years, preoperative LL, PI-LL and change in LL were significant risk factors in univariate analysis. Multivariate analysis showed only change in LL was significant for PJF development (Odds ratio [OR]=1.025, p=0.021). On the other hand, in patients older than 70 years, postoperative LL, postoperative PILL, overcorrection relative to conventional PI-LL target (within ±10°) as well as age-adjusted ideal PI-LL target were significant. On multivariate analysis, only overcorrection of PI-LL relative to age-adjusted ideal target was a single significant factor to cause PJF (OR=5.250, p=0.024).
Conclusions
In patients younger than 70 years, greater change in LL was associated with PJF development regardless of PI-related value. However, in older patients, overcorrection of PI-LL relative to the age-adjusted PI-LL target was important to cause PJF.

Background
Percutaneous-short segment screw fixation (SSSF) without bone fusion has proven to be a safe and effective modality for thoracolumbar spine fractures (TLSFs). When fracture consolidation is confirmed, pedicle screws are no longer essential, but clear indications for screw removal following fracture consolidation have not been established.
Methods
In total, we enrolled 31 patients with TLSFs who underwent screw removal following treatment using percutaneous-SSSF without fusion. Plain radiographs, taken at different intervals, measured local kyphosis using Cobb’ angle (CA), vertebra body height (VBH), and the segmental motion angle (SMA). A visual analogue scale (VAS) and the Oswestry disability index (ODI) were applied pre-screw removal and at the last follow-up.
Results
The overall mean CA deteriorated by 1.58º (p<0.05) and the overall mean VBH decreased by 0.52 mm (p=0.001). SMA preservation was achieved in 18 patients (58.1%) and kyphotic recurrence occurred in 4 patients (12.9%). SMA preservation was statistically significant in patients who underwent screw removal within 12 months following the primary operation (p=0.002). Kyphotic recurrence occurred in patients with a CA ≥20º at injury (p<0.001) with a median interval of 16.5 months after screw removal. No patients reported worsening pain or an increased ODI score after screw removal.
Conclusion
Screw removal within 12 months can be recommended for restoration of SMA with improvement in clinical outcomes. Although, TLSFs with CA ≥20º at the time of injury can help to predict kyphotic recurrence after screw removal, the clinical outcomes are less relevant.

Purpose
Minimally invasive technique in spinal surgery have evolved including cortical bone trajectory (CBT) screw technique which is s new lumbar pedicle screw path, as an alternative fixation technique for lumbar spine. Theoretical advantage is that it provides enhanced screw torque and has biomechanical characteristics, also it minimizes approach-related damages. Midline lumbar fusion (MIDLF) has appeared with CBT screw technique. Many studies of CBT screw reported the effectiveness of MIDLF. We adopted this technique for lumbar degenerative spondylolisthesis and evaluated early radiological outcomes.
Materials and Methods
From May 2014 to March 2015, 17 patients (mean age 65.6±7.5 years; 4 males, 13 females) underwent MIDLF procedures for the treatment of single level lumbar spondylolisthesis. Average follow-up period was 8.8±2.7 months. Initial and last follow-up X-ray and computed tomography (CT) were evaluated for screw malposition, detection of peri-screw halo, loosening of the construct, or signs of spinal instability.
Results
The average bone mineral density (BMD) was -1.9±0.8. Eleven patients were fused at L4-5, 5 were at L3-4, and 1 was at L2-3. Five CBT screws were converted into pedicle screws due to intraoperative misposition of screws, so total 63 CBT screws were evaluated for peri-screw halo and malposition. There were no findings of screw pull-out or breakage in all screws. Four out of 63 (6.3%) screws were judged as peri-screw halo, and 20 (41.2%) screws were judged as malposition (1 medial; 2 superior; 17 lateral pedicle violation). But, there were no screw related nerve root injury. In all cases, interbody bony mass were identified. Four out of 17 (23.6%) patients were detected more than 2 degrees motions on flexion-extension lateral X-rays at final follow-up, and 1 out of these 4 patients was identified loss of reduction. There was no operation related complication.
Conclusion
There is no doubt that MIDLF with CBT screw is the minimally invasive method. Many numbers of screw malposition identified in our series were thought to be due to our earlier experience of trying free hands technique. We recommend the use of intraoperative fluoroscopy, which achieve accuracy. Although MIDLF with CBT has theoretical strengths, we must evaluate further long-term clinical follow-up and measure outcome.

Objective
To evaluate the efficacy and safety of anorganic bone matrix (ABM)/P-15 compared with local autograft bone in posterior lumbar interbody fusion (PLIF) with pedicle screws for degenerative lumbar diseases.
Methods
This is a retrospective analysis of consecutive series of 138 patients undergoing 1 or 2 levels PLIF from 2015 to 2020 in our single institute. Local autograft bone or ABM/P-15 (i-factor, Cerapedics Inc., Westminster, Colorado USA) were used for interbody fusion. The successful fusion was defined as the segmental cobb angle of less than 5 degrees of in flexion/extension X-rays and continuity of the trabecular bony bridging in computed tomography (CT) images.
Results
Among a total of 138 patients, total levels of fusion were 202, of which 74 were in 1 level fusion and 128 were in 2 level fusion. And 93 used ABM/P-15 and 109 used local autograft bone. The evaluation time of fusion status was 1 year after surgery. Successful fusion based on X-ray images was achieved 84.1% (90/107) for local autograft bone and 91.3% (84/92) for ABM/P-15 (p=0.127). Based on CT images, 86.9% (93/107) of autograft group and 95.6%(87/91) of AMP/P-15 group showed successful fusion respectively (p=0.034). Occurrence rate of autolysis was 14% (15/107) for local autograft bone and 17.6% (16/91) for ABM/P-15. Subsidence rates were 11.2% (12/107) for local autograft bone and 9.99% (9/91) for ABM/P-15. Hollow formation around pedicle screw was noted in 9.3% (10/107) for local autograft bone and 2.2% (2/91) for ABM/P-15.
Conclusions
The use of AMP/P-15 for lumbar interbody fusion surgery can be a good substitute for local autograft bone in terms of better fusion rate and similar complication rate on radiologically.

Background
Oblique and anterior lumbar interbody fusion have been widely performed in the lumbar spinal disease but we cannot get a direct decompression effect with these procedure. Objective: The purpose of this study is to report clinical and imaging outcomes of microscope assisted direct decompression combined with oblique lumbar interbody fusion (OLIF) or anterior lumbar interbody fusion (ALIF).
Methods
Twelve patients who received microscope assisted direct decompression during OLIF or ALIF for lumbar spinal stenosis were enrolled. The OLIF was performed for the lesion upper than the L4-5 or in the case of multisegmental disease. The ALIF was performed for the lesion at the L5-S1. After anterior-approaching surgery, percutaneous fixation of pedicle screw was performed and we did not perform an additional decompression posteriorly in all cases. For the clinical outcomes, we evaluated short form 36 (SF-36), Oswestry disability index (ODI) score and visual analog scale (VAS) pain score. For the imaging outcomes, we obtained postoperative lumbar magnetic resonance imaging (MRI).
Results
The OLIF was performed for 9 patients and the ALIF was performed for 3 patients. In the clinical outcomes, SF-36 was improved from 25.40 to 69.83 and ODI score was also improved from 69.83 to 16.50. VAS pain score of back was improved from 4.3 to 1.6 and VAS pain score of leg was improved from 7.5 to 2.2. In the imaging outcomes, all patients had severe stenosis before surgery. After surgery the severity of the stenosis was reduced to mild state in 9 cases and moderate state in 3 cases postoperatively.
Conclusions
We could obtain the good clinical outcomes and effective decompression through microscope assisted direct decompression during OLIF or ALIF.

Oblique lumbar interbody fusion (OLIF) is one of surgical techniques for patients with spondylolisthesis, but an insertion of cage at an ideal location (anterior 1/3 of disc space) is challenging for patient with high grade spondylolisthesis, because vertebra are not aligned. Recently, a technique of simultaneous insertion of pedicle screw and rod system from the back of patient and insertion of cage via retroperitoneal route from the front of patient is possible by using spinal navigation system (OLIF-360). The author present a case and surgical technique of simultaneous re-alignment of high-grade spondylolisthesis at L4-5 and insertion of interbody cage by using OLIF-360. An intervertebral cage was inserted at the ideal location after re-alignment of spondylolisthesis with OLIF-360. Postoperative images showed re-aligned vertebra and successful decompression. The specific utilization of OLIF-360 has not been underscored yet.

Purpose
The current study aims to report the results of analyzed factors that ultimately undergo surgical treatment after selective nerve root block in patients with spinal structural pathology that cause lower back pain and radiating pain in the lower extremities. Material and methods: A retrospective study was performed on 537 patients diagnosed with spinal canal stenosis or disc herniation among patients who underwent selective nerve root block at our hospital for five years from May 2015 to December 2017. The patients were divided into Group A (patients with an only selective spinal nerve root, n=99) and Group B (patients with surgical treatment, n=20). We evaluated the primary demographic factors, including age, sex, onset, symptom duration, diabetes mellitus, hypertension, angina, osteoporosis. The clinical variables included in the analysis were the preoperative visual analog scale (VAS) pain score, the Korean version of the Oswestry Disability Index (K-ODI), and the Roland-Morris disability questionnaire (RMDQ).
Results
The average symptom duration was 22.6±1.2 weeks in group A, and 35.7±0.9 in group B. Of a total of 20 patients (16.8%), four males (20%) and 16 females (80%) were underwent surgical procedures because there was no improvement in symptoms. Group B had a significantly higher proportion of female patients and longer symptom duration than group A. And there were no statistically significant differences between groups in other variables.
Conclusions
Although the frequency of surgical treatment decreased after selective nerve root block, the longer symptom duration and the female gender might be related to the risk factors for surgical treatment.

Background
S2-alar-iliac (S2AI) screws are one of the options for spinopelvic fixation to improve stability across the lumbosacral junction. The S2AI screws cross the cortical surfaces of the sacroiliac joint, which can increase the biomechanical strength of the instrumentation. Objective: To investigate the durability and failure types of S2AI screw by finite element model (FEM) analysis.
Methods
Through the FEM, complex material and geometrical properties of the biological system can be evaluated, and various physical variables, such as stress, and fracture, can be analyzed. We examined the biomechanical stress distribution at the set screw and screw head by using a FEM. Von Mises (V.M.) stress (MPa) is derived from 3-dimensional status of stress. The finite element software Abaqus^® version 6.5 (ABAQUS Inc., Johnston, RI, USA) was used to create a FEM.
Results
We quantified the peak V.M. stress applied to the set screw and screw head when rod to S2AI screw trajectory angle was 30º angled and perpendicular. In FEM analysis, at an angle of 30 degrees rather than perpendicular, the stress increased further around the area where the screw head and rod contacted and the displacement distribution of set screw also increased.
Conclusion
S2AI screw fixation has several drawbacks such as screw fracture and dislodgement of the set screw. This FEM analysis can support the result.

Spinal subdural hematoma (SDH) is a rare complication after spinal surgery. Only a few cases are reported on spinal SDH following open lumbar spinal decompression or fusion surgery. Moreover, there has been no case report on spinal SDH following percutaneous transforaminal endoscopic lumbar discectomy. We report a case of spinal SDH following endoscopic discectomy, review the literature of this complication and discuss the etiology to it and methods to prevent it. A 63-year-old woman presented with severe radiating pain. Pain was not improved with conservative management. Lumbar magnetic resonance imaging (MRI) was checked and revealed right L3-4 ruptured disc with severe L4 root compression. Percutaneous transforaminal endoscopic decompression was performed and the pain subsided promptly after the endoscopic procedure. On 7th post-operative day, pain on Rt. buttock, anterior thigh was deteriorated severely, more than in pre-operatively. Deteriorated pain was not controlled by oral medications and epidural block. Repeat MRI showed no definite recurrence of disc herniation at decompressed level but spinal SDH, severely compressing cauda equina was seen on T12-sacral area. Spinal SDH is a rare complication following spine surgery, including percutaneous endoscopic surgery. A spine surgeon should be aware of the possibility of spinal subdural hematoma, having severe sequel.

Objective
To investigate the association of quantitative paraspinal muscle measurements to the Oswestry disability index (ODI) in patients with lumbar spondylolisthesis.
Materials and Methods
Ninety two patients (mean age, 61.6 years; male, mean age, 71.8 years ; female; mean body mass index [BMI], 24.9 kg/m² ) who had undergone lumbar fusion due to spondylolisthesis with available selfcompleted postoperative ODI were included. The total cross-sectional area (CSA) and functional CSA (FCSA; i.e., area containing only lean muscle tissue) of the paraspinal muscle group (multifidus and erector spinae muscles) and the psoas muscles were measured at L2–L3, L3–L4, and L4–L5 disc levels each on preoperative magnetic resonance imaging (MRI) and the sum of areas at each level served as representative values for each muscle. The FCSA/total CSA ratio and the skeletal muscle index (SMI=muscle area [cm² ]/patient height2 [m² ]) were calculated. Pearson’s correlation analyses were performed to evaluate the relationship between preoperative paraspinal muscle measurements and postoperative ODI.
Results
Quantitative values of low paraspinal muscle showed significant correlation with high ODI values. As a result of this study, the preoperative paraspinal muscle was quantified in the group of patients undergoing spinal fusion. Patients with low value in CSA and FCSA of paraspinal muscle could observe the tendency to transition to low clinical outcomes. Therefore, quantitative values of surrounding muscles are factors affecting clinical outcomes of patients undergoing spinal surgery Conclusion: Smaller muscle bulk (total CSA) of psoas muscles and lean muscle mass (FCSA) of paraspinal muscle group and psoas muscles combined on preoperative MRI were associated with significant postoperative disability based on ODI in patients with lumbar spondylolisthesis.

Lumbar fusion surgery for lumbar degenerative diseases has increased in the past several decades and many techniques for fusion surgery have been introduced. Recently lateral lumbar interbody fusion with minimally invasive technique was introduced and accepted as a useful method for various lumbar degenerative disease. It can produce good correction for sagittal and coronal imbalance with relatively decreased morbidity. The advantage of lateral lumbar interbody fusion is that it can avoid injury to the abdominal large vessels and neural structures which is more common during posterior approaches. However various complications had been reported. Complications related with lateral lumbar interbody fusion include neurologic complications including thigh pain and numbness, vascular complications including arterial injury, cage related complication such as cage subsidence and vertebral body fractures. Therefore special care should be taken to avoid possible complications in lateral lumbar interbody fusion surgery.

Objectives
The primary surgical goals when treating a spinal metastasis are usually pain relief and preservation of ambulatory function. Minimally invasive techniques have become popular, being associated with less morbidity and mortality than conventional open surgeries.
Materials and Methods
Between April 2012 and September 2016, 15 consecutive patients underwent percutaneous pedicle screw fixation (PPSF) to treat spinal metastases. We retrospectively analyzed prospectively collected data, including visual analog scale (VAS) pain scores, Frankel scale scores, and complications.
Results
Fifteen patients (8 males, 7 females; mean age 61 years) underwent surgery under general anesthesia. PPSF was performed on all patients, and two with poor bone quality underwent cement augmentation of the manipulated vertebra(e) just prior to pedicle screw insertion. Seven patients underwent fixation plus distraction (indirect decompression via ligamentotaxis) and two laminectomies (direct decompression) of the spinal cord. Two patients developed screw pullout requiring revision surgery. One patient died 7 days after surgery from liver cirrhosis and sepsis. All patients reported that pain was reduced after surgery. After surgery, 12 patients regained ambulatory capacity. Nine patients died during follow-up; the mean overall survival time was 14.1 months.
Conclusions
PPSF is a safe and minimally invasive palliative surgery option for patients with spinal metastases.

Recently, favorable results of minimally invasive spinal surgery have been reported in comparison to the open decompression or fusion surgery. Biportal endoscopic spine surgery (BESS) has several benefits and Indications for BESS are nearly identical to those for general open spinal surgery. However, it remains a challenging procedure even for an experienced endoscopic surgeon. because it takes a a long operation time while early learning period. If the operation time is prolonged, the advantages of endoscopic surgery are reduced and the incidence of complications can be increased. Therefore, we will investigate the factors affecting the operation time and how to minimize it before and during operation.

Among the complex causes of chronic low back pain, suboptimal injury of ligament in the lumbosacral spine is common. Injured ligaments can become a primary pain source and raise secondary pain with referred pain pattern. Due to the low blood supply to the ligaments, ligaments are notoriously poor healer. In order to compensate the poor healing of ligament, prolotherapy has been introduced and used for more 60 years. To date, no definite recommendations have not been made based on literature available. However, if conventional treatment modalities have failed in patient with chronic back pain in lumbosacral spine, prolotherapy targeted on ligaments around lumbosacral spine should be considered in appropriate patients.

Background
Context: There are few reports of changes in global sagittal alignment and corresponding factors like hand grip strength (HGS) and muscle performance tests to detect changes in global sagittal alignment after surgery for lumbar spinal stenosis (LSS). Purpose: The purpose of the study was to determine whether HGS can be a useful predictive marker of global sagittal alignment changes after decompression with fusion surgery for LSS. Study Design: This is a retrospective observational study. Patient Sample: Patients who underwent spine surgery for LSS were included in the present study. Outcome Measures: Radiological spinopelvic parameters including sagittal vertical axis (SVA), lumbar lordosis (LL), pelvic tilt (PT), pelvic incidence (PI), global tilt (GT), and T1 pelvic angle (T1PA) were assessed. Clinical outcomes parameters like Oswestry Disability Index (ODI), Euro-QOL (EQ-5D), visual analog scale (VAS) scores for back or leg pain were assessed. To assess muscle performance, three functional mobility tests (6-meter walk test, timed up and go test, sit-to-stand test) and HGS were checked.
Materials and Methods
A total 91 consecutive patients who underwent spine fusion surgery for LSS were included. 1 year after posterior decompression and fusion surgery, the patients were further classified into four groups according to preoperative and postoperative SVA. We analyzed radiological parameters like SVA, LL, PT, PI, GT, and T1PA. The ODI, the EQ-5D and VAS scores for back or leg pain were recorded as clinical outcomes assessment. To assess muscle performance, SMT, TUGT, STS, and HGS were checked.
Results
HGS was significantly correlated with age, postoperative SVA, ODI, EQ-5D and muscle performance test. HGS was related with change of preoperative sagittal alignment 1yr after surgery. Using a receiver operating characteristic (ROC) curve to determine the cutoff values of HGS as predictors of postoperative balanced sagittal alignment according to SVA, cutoff value of HGS demonstrated 19.5 kg with a sensitivity of 82.1% and specificity of 66.7%.
Conclusion
Patients with non-balanced sagittal alignment in LSS demonstrated decreased muscle function and muscle strength. If the muscle strength was weak in the group in which the sagittal balance was maintained preoperatively, it could be converted to non-balanced sagittal alignment. Thus, preoperative HGS may be a good predictor of postoperative SVA change.

Purpose
of Study: Purpose of this study is to summarize the technique of UBE surgery in lumbar interbody fusion and review the clinical outcomes and complications of UBE surgery in lumbar interbody fusion.
Materials and Methods
Medical databases were searched for the key words of unilateral biportal endoscopic surgery and lumbar spinal stenosis using PubMed from 2005 to the present.
Conclusion
UBE spinal surgery is a new technique that can be a feasible alternative and an effective treatment modality for spinal degenerative diseases and can achieve the necessary surgical skills for experienced microscopic surgeons, which is still expanding the indications for lumbar spinal surgery.

Spinal cord injury is a devastating condition that leaves permeant disability. Surgical decompression and stabilization with various pharmacological treatments have been tried to prevent secondary injury, however, their results have been disappointing. Therefore, novel therapeutic options are required enthusiastically. Cell transplantation that has the potential of neuroregenerative and neuroprotective ability is regarded as a promising remedy. We would like to describe about the micro-anatomy and the mechanism of injury of spinal cord injury. We also delineate transplanted cells; embryonic stem cell, induced pluripotent stem cell, mesenchymal stem cell as stem cells and Schwan cell, olfactory ensheathing cell as supporting cells with brief reviews of their experimental results.

Interspinous process devices for spinal surgery are designed to keep the spine in a flexed position, to achieve indirect decompression of the mobile segment. Such devices have been fabricated using numerous materials and designs. In this study, the fundamental knowledge required for choosing an appropriate interspinous process device for spinal surgery was reviewed.

Objectives
To verify the hypothesis that nerve compression by postoperative spinal epidural hematoma (POSEH) can be reduced by instillation of heparin through suction drains.
Materials and Methods
The patients who underwent posterior decompression and instrumentation between Jan. 2016 and Jun 2016 were allocated to study (using heparin) group and control group according to the operation date alternately. There were 61 cases in study group and 60 cases in control group. Two lines of suction drain were used in all cases. Thousand unit of heparin and 5ml of normal saline were instilled through the drain lines into the epidural space just before the wound closure. To prove the homogeneity between the two groups, demographic, patient related, operation related and clotting related data were compared. At day 7 after the operation, their MRIs were examined. The area of thecal sac was measured at the T2 weighted axial image that showed the maximal compression of the thecal sac by epidural hematoma. Two orthopedic doctors who were blinded to this study measured independently and the average values of the two were counted as final measured values.
Results
The two groups were homogenous in age, sex, number of fusion segments, whether virgin or revision operation, total blood loss, operation time, blood loss/10 min, whether taking anti-platelet drugs or not, platelet count, PT, aPTT and platelet function analysis. The smallest area of thecal sac in axial MRI was 124.4±49.9 mm² in study group and 121.7±47.4 mm² in control group. There was no significant difference (p=0.761)
Conclusions
In a posterior spine surgery, thecal sac compression by POSEH was not reduced by instillation of heparin into the epidural space.

Purpose
There were few available data regarding the prognosis after the surgical treatment for spinal metastases from non-small cell lung cancer (NSCLC) despite its great frequency. The aim of this study was to investigate the prognostic factors for patients who underwent the surgical treatment for spinal metastases from NSCLC.
Materials and Methods
Eighty-seven patients who underwent surgical treatment for spinal metastases from NSCLC were followed up semi-prospectively. There were 43 patients with metastatic spinal cord compression (MSCC) and 44 patients without MSCC. The prognosis analysis was performed according to 3-categorical variables: patients’ , oncologic, and treatments’ factors. Major complications and mortality rate were recorded. The impact of postoperative chemotherapy was evaluated separately.
Results
The overall survival time was median 6.8 months. Postoperative ECOG-PS (0-2 vs. 3, 4) was shown as a significant prognostic factors in both MSCC and non-MSCC groups with HR (hazards ratio) of 2.46 and 2.54, respectively. Major complications developed in 26 patients and 30-day mortality rate was 8.0%. The presence of major complications was also prognostic factor in both groups with HR of 2.55 and 4.47. Earlier surgery within 72 hours showed better prognosis in MSCC group with HR of 2.46. Patients who underwent postoperative chemotherapy survived longer significantly than those who couldn’t with median survival time of 12.0 vs 2.8 months.
Conclusions
Postoperative ECOG-PS and complications were significant prognostic factors in both groups and earlier surgery in MSCC group. The postoperative chemotherapy was another independent prognostic factor affecting the survival time

The foramen of L5-S1 can develop several degenerative diseases such as extraforaminal lumbar disc herniation, foraminal stenosis with disc height collapse, degenerative or spondylolytic spondylolisthesis, and far-out syndrome. The floating technique in biportal endoscopic spine surgery (BESS) keeps a certain distance between instruments and spinal structures. 1) This key point makes the floating technique different from conventional endoscopic surgery, which uses the Kambin’s safe triangle as a work zone. The floating view can enable the surgeon to see the structures panoramically, under high magnification: consequently, fine discrimination of their margin and safe manipulation of neural structures can be guaranteed. A certain gap between the floating scope and lesion can permit various instruments, generally used in open spine surgery, to be inserted from the sides with fewer limitations. Extraforaminal or foraminal lesions under the lamina can be reached by avoiding the iliac crest, and total facetectomy, which has the potential of iatrogenic instability, is not required to explore the foraminal structures. However, the floating view can be obstructed by small bleeds from laminectomized bone and/or surrounding vessels. This present article describes the technique and provides tips on how to perform BESS with floating technique safely and successfully for various lesions at the L5-S1 foramen.

Purpose
To report a rare case of alveolar soft-part sarcoma in the spine. Alveolar soft-part sarcoma (ASPS) is a rare, distinctive sarcoma typically occurring in young adults. Although it shows a relatively indolent clinical course, the ultimate prognosis is poor and often characterized by late metastases. However, with radical resection, long-term survival is possible. ASPS usually arises in the skeletal muscle and occurs most frequently in the lower limbs.
Materials and Methods
A 17-year-old male patient presented with a palpable mass on the back that enlarged about 1 year before admission. The mass was approximately 4×3 cm, located on the right side of the thoracic midline, and was palpated to be relatively soft and fixed, with no pain. On preoperative magnetic resonance imaging (MRI), a 2.5 ×2.0×4.1-cm lobulating contoured intermuscular mass was located between the spinalis thoracis and logissimus thoracis muscles in the right lumbar area at the T5–6 level. In the T1- and T2-weighted images with enhanced view, the tumor was enhanced with homogeneous intensity.
Results
We considered the possibility of a benign tumor that is frequently found in back muscle, rather than the possibility of a malignant tumor. We performed mass excision and biopsy without prior fine-needle biopsy or incisional biopsy, with the patient under general anesthesia. The tumor was confirmed to be ASPS.
Conclusions
The possibility of malignancy should be considered in the treatment of all tumors, and accurate diagnosis is important before surgery.