IntroductionTrapped fourth ventricle (TFV), which is a rare neurosurgical condition with multifactorial etiology, requires a prompt diagnosis and appropriate therapeutic method selection. We report a case of post-hemorrhagic hydrocephalus and TFV incited/worsened by prematurity, sepsis, acute respiratory distress syndrome (ARDS), mechanical ventilation, and concomitant fourth ventricle outlets stenosis; which displayed a delayed onset. This article addresses the proposed pathophysiology and the clinical importance of appropriate therapeutic strategies with a mini-review of the literature.Case presentationWe encountered a case involving a premature Asian male newborn with sepsis and posthemorrhagic hydrocephalus who required ventriculoperitoneal shunt surgery. However, after three years, the baby was diagnosed with a trapped fourth ventricle and subsequently underwent retrograde endoscopic surgery with stent insertion.DiscussionTFV is traditionally known as a complication of lateral ventricle shunting. However, in rare cases such as our neonate patient, it develops as a consequence of multiple pathophysiological processes including ventricular system inflammation along with associated anatomic and physiologic alterations, which necessitates prompt diagnosis and a case-specific therapeutic strategy.ConclusionUnderstanding the multifactorial pathophysiological mechanisms leading to the development of TFV is crucial. The presence of comorbidities such as prematurity, neonatal sepsis, and ARDS increased the risk of intraventricular hemorrhage and subsequent inflammation and further exacerbated obstructions in cerebrospinal fluid pathways. When posthemorrhagic TFV is accompanied by collapsed lateral ventricles, the optimal treatment approach is retrograde endoscopic fenestration with stent insertion. This treatment option has proven effective in alleviating the condition and restoring proper cerebrospinal fluid flow.

The blood–cerebrospinal fluid barrier (BCSFB) tightly regulates molecular exchanges between the bloodstream and cerebrospinal fluid (CSF), creating challenges for effective central nervous system (CNS) drug delivery. This review assesses intrathecal (IT) nanoparticle (NP) delivery systems that aim to enhance drug delivery by circumventing the BCSFB, complementing approaches that target the blood–brain barrier (BBB). Active pharmaceutical ingredients (APIs) face hurdles like restricted CNS distribution and rapid clearance, which diminish the efficacy of IT therapies. NPs can be engineered to extend drug circulation times, improve CNS penetration, and facilitate sustained release. This review discusses key pharmacokinetic (PK) parameters essential for the effectiveness of these systems. NPs can quickly traverse the subarachnoid space and remain within the leptomeninges for extended periods, often exceeding three weeks. Some designs enable deeper brain parenchyma penetration. Approximately 80% of NPs in the CSF are cleared through the perivascular glymphatic pathway, with microglia-mediated transport significantly contributing to their paravascular clearance. This review synthesizes recent progress in IT-NP delivery across the BCSFB, highlighting critical findings, ongoing challenges, and the therapeutic potential of surface modifications and targeted delivery strategies.

This review highlights the need for therapeutic guidelines for syringomyelia associated with tethered cord syndrome (TCS) caused by spinal dysraphism (SD). A comprehensive literature review was conducted, selecting twelve articles to analyze common therapeutic strategies. Surgical cord untethering alone has recently become a preferred treatment, with 45 ± 21.1% of patients experiencing remission or improvement, 47 ± 20.4% unchanged and asymptomatic, and 4 ± 8% worsened. Untethering with direct surgical drainage for the syrinx had better outcomes than untethering alone (78% vs. 45%, p = 0.05). Terminal syringostomy was beneficial for syrinxes extending to the filum terminale but not for asymptomatic small syrinxes with a syrinx index < 0.4. Syrinx shunting was recommended for symptomatic large syrinxes (>2 cm in length and syrinx index > 0.5). Various shunt procedures for syrinxes are still advocated, mainly for refractory syringomyelia in Chiari malformation, posttraumatic cases, SD, or other causes. Personalized surgical methods that address the root cause of syringomyelia, particularly those improving cerebrospinal fluid flow, offer promising results with minimized complications. Ongoing studies are required to enhance management strategies for syringomyelia associated with TCS, optimize patient outcomes, and reduce the risk of recurrent symptoms.

Tuberculous meningitis (TBM) presents a critical neurologic emergency characterized by high mortality and morbidity rates, necessitating immediate therapeutic intervention, often ahead of definitive microbiological and molecular diagnoses. The primary hurdle in effective TBM treatment is the blood–brain barrier (BBB), which significantly restricts the delivery of anti-tuberculous medications to the central nervous system (CNS), leading to subtherapeutic drug levels and poor treatment outcomes. The standard regimen for initial TBM treatment frequently falls short, followed by adverse side effects, vasculitis, and hydrocephalus, driving the condition toward a refractory state. To overcome this obstacle, intrathecal (IT) sustained release of anti-TB medication emerges as a promising approach. This method enables a steady, uninterrupted, and prolonged release of medication directly into the cerebrospinal fluid (CSF), thus preventing systemic side effects by limiting drug exposure to the rest of the body. Our review diligently investigates the existing literature and treatment methodologies, aiming to highlight their shortcomings. As part of our enhanced strategy for sustained IT anti-TB delivery, we particularly seek to explore the utilization of nanoparticle-infused hydrogels containing isoniazid (INH) and rifampicin (RIF), alongside osmotic pump usage, as innovative treatments for TBM. This comprehensive review delineates an optimized framework for the management of TBM, including an integrated approach that combines pharmacokinetic insights, concomitant drug administration strategies, and the latest advancements in IT and intraventricular (IVT) therapy for CNS infections. By proposing a multifaceted treatment strategy, this analysis aims to enhance the clinical outcomes for TBM patients, highlighting the critical role of targeted drug delivery in overcoming the formidable challenges presented by the blood–brain barrier and the complex pathophysiology of TBM.

This study investigates the impact of increasing air bladder numbers in car seats on ride comfort through X-ray analysis. It assesses how these changes affect the driver's lumbar support, exploring the relationship between seat design and comfort. Participants, with varied demographics, were tested using seats with different air bladder counts. Utilizing X-ray imagery, the study compares spinal alignment in different sitting positions. Results showed that seats with more air bladders significantly enhanced comfort. This suggests that more air bladders in car seats can improve driver support and reduce discomfort, contributing valuable insights for automotive seat design.

Surgical site infections (SSIs) after spinal surgery present significant challenges, including poor antibiotic penetration and biofilm formation on implants, leading to frequent treatment failures. Polymethylmethacrylate (PMMA) is widely used for localized drug delivery in bone infections, yet quantifying individual drug release kinetics is often impractical. This retrospective study analyzed 23 cases of deep SSIs (DSSIs) following spinal surgery treated with antibiotic-loaded PMMA. A mathematical model estimated personalized drug release kinetics from PMMA, considering disease types, pathogens, and various antibiotics. The study found that vancomycin (VAN), ceftriaxone (CRO), and ceftazidime (CAZ) reached peak concentrations of 15.43%, 15.42%, and 15.41%, respectively, within the first two days, which was followed by a lag phase (4.91–4.92%) on days 2–3. On days 5–7, concentrations stabilized, with CRO at 3.22% and CAZ/VAN between 3.63% and 3.65%, averaging 75.4 µg/cm2. Key factors influencing release kinetics include solubility, diffusivity, porosity, tortuosity, and bead diameter. Notably, a patient with a low glomerular filtration rate (ASA IV) was successfully treated with a shortened 9-day intravenous VAN regimen, avoiding systemic complications. This study affirms the effectiveness of local drug delivery systems (DDS) in treating DSSIs and underscores the value of mathematical modeling in determining drug release kinetics. Further research is essential to optimize release rates and durations and to mitigate risks of burst release and tissue toxicity.

Radiation therapy results in radiation-induced vasculopathy, characterized by alterations in the vascular architecture stemming from radiation exposure. The exact molecular pathways and associated pathologies of this condition have yet to be comprehensively understood. This study aimed to identify specific markers’ roles in cerebral vascular endothelial injury pathogenesis after radiosurgery and explore their unique expression patterns in diverse pathologies post-stereotactic radiosurgery. A retrospective cohort study was conducted to assess the expression profiles of endothelial markers via immunohistochemical analysis in 25 adult patients (13 males and 12 females) who had undergone neurosurgical resection for various central nervous system pathologies following stereotactic radiosurgery or radiotherapy from 2001 to 2015. Our findings revealed strong immunohistochemical expression of ICAM-1 and E-selectin across various disease states, while MMP-9, PAI-1, and eNOS exhibited moderate expression levels. In contrast, VCAM-1 and P-Selectin had the weakest expression across all groups. Notably, while individual markers showed significant variations in expression levels when comparing different diseases ( P < .001), no substantial differences were found in the overall immunohistochemical expression patterns across the 5 distinct pathologies studied ( P = .407, via 2-way ANOVA). Despite the varied long-term effects of radiotherapy on the vascular endothelium, a common thread of inflammation runs through the pathology of these conditions. The distinct patterns of marker expression identified in our study suggest that different markers play unique roles in the development of radiation-induced vasculopathy. These findings offer insights that could lead to the development of novel preventive strategies and treatments.

Objective: Double microcatheter technique (dMC) can be the alternative to Single microcatheter technique (sMC) for challenging cases, but there is lack of studies comparing dMC to sMC especifically for small ruptured aneurysms. Our objective was to compare the safety and efficacy of dMC to sMC in treating small (≤5 mm) and tiny (≤3 mm) ruptured aneurysms.Methods: This study focused on 91 out of 280 patients who had ruptured aneurysms and underwent either single or double microcatheter coil embolization. These patients were treated with either single or double microcatheter coil embolization. We divided the patients into two groups based on the procedural method and evaluated clinical features and outcomes. Subgroup analyses were conducted specifically for tiny aneurysms, comparing the two methods, and within the dMC group, we also examined whether the aneurysm was tiny or not. In addition, univariate logistic regression analysis was performed to assess the impact of coil packing density.Results: The mean values for most outcome measures in the dMC group were higher than those in the sMC group, but these differences did not reach statistical significance (coil packing density, 45.739% vs. 39.943%; procedural complication, 4.17% vs. 11.94%; recanalization, 8.3% vs. 10.45%; discharge discharge modified Rankin Scale (mRS), 1.83 vs. 1.97). The comparison between tiny aneurysms and other sizes within the dMC group did not reveal any significant differences in terms of worse outcomes or increased risk. The only factor that significantly influenced coil packing density in the univariate logistic regression analysis was the size of the aneurysm (OR 0.309, 95% CI 0.169–0.566, p=0.000).Conclusions: The dMC proved to be a safe and viable alternative to the sMC for treating small ruptured aneurysms in challenging cases.

The Insurance Institute for Highway Safety (IIHS) uses BioRid II dummies to evaluate seat safety. However, it is necessary to verify whether this dummy actually represents the body well when seated. In the case of women, the incidence of whiplash injury is two to three times higher than that of men, so a new dummy was created for this purpose. In addition, since there is a difference in the driver's median height by country, it is necessary to verify whether the dummy used in the actual vehicle crash test adequately represents the difference in the standard body size of the driver in that country.Purpose: A decision was made to compare the specifications of the BioRid II dummy used in the crash test and the numerical values of the evaluation items when the actual participants sat in the test condition. The height of the participants was classified into the height of the 50th percentile for the males and females of each country, and the difference was analyzed through a comparison with the parameter data of BioRID II.Method: A total of 15 participants were seated in a crashworthiness situation including the seatback angle, and side-view X-rays were taken and data were acquired. On the X-ray, the angle of the occipital interface plate relative to horizontal, the angle of the T2 vertebra relative to horizontal, the H-point indicator to occipital condyle pin (horizontal), and the H-point to indicator to occipital condyle (vertical) were measured. Then, after classifying according to the median height of Korea, China, and Japan, each data was compared with the parameters of BioRID II.Result: In the angle of the occipital interface plate relative to horizontal, which is a parameter used for testing in IIHS, BioRID II was measured as 29.5 ± 0.5°. When the average height was 175.6cm, the angle of the occipital interface plate relative to horizontal was 18.3 ± 5.89°, 170.4cm was 18.60 ± 5.36, and 162.3cm was 19.05 ± 4.93°. The angle of the T2 vertebra relative to horizontal was 37 ± 0.5° for BioRID II, 11.7 ± 8.38° for the average height of 175.6cm, 10.21 ± 7.55° for 170.4cm, and 7.60 ± 5.9° for 162.3cm. The H-point indicator to occipital condyle pin (horizontal) was 156 ± 3mm for BioRID II, 272.3 ± 60.57mm for the average height of 175.6cm, 251.1 ± 63.97mm for 170.4cm, and 219.2 ± 59.62mm for 162.3cm. The H-point indicator to occipital condyle (vertical) was 609 ± 3mm for BioRID II, 734.5 ± 39.18mm for the average height of 175.6cm, 708.2 ± 46.90mm for 170.4cm, and 668.6 ± 23.91mm for 162.3cm. As such, there was a difference in the values of the parameters presented in BioRID II and the values according to the height corresponding to each country's actual height.

The design of automotive seats is an important design factor that affects the biomechanical alignment of the driver's spinopelvic alignment when in a seated state. However, there is a lack of biomechanical studies evaluating body changes in a driver's seated state in a driving environment. Therefore, urgent research is needed on driver-specific basic data that can be used as basic data to be considered in the development and design of automotive seats.Purpose: The purpose of this study is to measure the difference in the alignment of the spine and pelvis according to the driver's sitting posture when voluntarily participating drivers sit at their preferred car seat back angle and to use this data as basic biomechanical data for car seat design.Method: A total of 15 participants were seated in their preferred posture, and the lateral view of their spine and pelvis was evaluated using X-rays. The sagittal seatback angle at the time of sitting and the distance from the HCP (hip center point) to the VBC (vertebral body center) were measured. The HCP was determined as being the center of the femoral head, which is the point where the horizontal line and the vertical line bisecting the horizontal line meet after drawing a circle enclosing the femoral head on the lateral X-ray. VBC was defined as being the point at which the lines connecting the four ends of the vertebral body with intersections met in the side view of the X-ray. Then, based on the HCP, the distance of the VBC from the 5th lumbar vertebra to the 10th thoracic vertebra was measured with the x-coordinate for the horizontal line and the y-coordinate for the vertical line.Result: When the angle of the seatback was optimized when sitting, the angle was 10.9.4°±2.997°. And the distance of all vertebral bodies (L5, L4, L3, L2, L1, T12, T11, T10) from the HCP was 128±15.96, 147.3±19.44, 167.6±22.39, 187.5±24.87, 202.9±26.93, 216.2±29.89, 226.4±32.42, and 234±33.46, respectively, and the y (mm) values were 64.67±21.93, 106.1±22.91, 143.8±24.78, 181.6±23.30, 218.1±24.32, 253.6±27.80, 283.8±30.6.57, 331.6.57, respectively. Thus, as the change in distance from the HCP from the 5th lumbar vertebra to the 10th thoracic vertebra increases, x-axis increases by 15%, 13.78%, 11.87%, 8.2%, 6.55%, 4.72%, and 3.4%, respectively, and y-axis increases by 64.67%, 35.53%, 26.29%, 20.1%, 16.28%, 11.9%, and 10.6%, respectively, were observed.Conclusion: The results of this study will be used as basic data that can be reflected in an optimal ergonomic seat design by providing the vertebral body coordinate shift in the thoracic and lumbar region from the HCP through actual X-ray imaging, not virtual simulation, for optimal car seat design.

A 41-year-old man suffered from progressive radiculomyelopathy caused by spinal epidural mass primarily encasing the spinal cord at the cervicothoracic vertebrae that extended into the thoracic cavity through the neural foramen. An urgent decompressive laminectomy and epidural tumor resection were performed to prevent neurological deterioration and effective spinal cord decompression. The histopathologic diagnosis was diffuse large B-cell lymphoma. As first-line treatment for stage II extranodal lymphoma, he received 6 cycles of R-CHOP (rituximab/cyclophosphamide, hydroxydaunorubicin, Oncovin, and prednisone) chemotherapy. Consequently, follow-up positron-emission tomography CT and MR images demonstrated a complete metabolic response (Deauville score 1). This rare occurrence of primarily extranodal spinal epidural lymphoma with limited disease will be presented in a literature review.

PURPOSE: The comfort of a seat in a seated posture has been reported to be affected by the alignment of the spine and pelvis in a standing posture when designing an automotive seat. Therefore, in order to find items to improve vehicle seat comfort performance, this study was conducted to measure the change in spinopelvic parameter values according to a change from a standing posture to a seat sitting posture and to reflect them in the design of vehicle seats to improve comfort.METHOD: X-ray data for 15 participants was measured and analyzed while standing and sitting in the optimal posture on an automotive seat. Cervical lordosis angle, thoracic kyphosis angle, lumbar lordosis angle, sacral inclination angle, and C7-SVA (sagittal vertical axis) were measured.RESULTS: Compared to standing, there were no statistically significant changes in the cervical lordosis and thoracic kyphosis angles when sitting in the car seat in the optimal posture, but only the lumbar lordosis changed (from 32.13° ± 8.356° to 6.568° ± 3.048°, p<0.0001). Cervical lordosis varied from 12.78° ± 8.15 to 12.58° ± 9.14° and thoracic kyphosis from 30.34° ± 8.10° to 31.6° ± 9.48° when standing and sitting in an optimal posture, but there was no statistical significance. However, the lumbar lordosis decreased from 32.13° ± 8.36° to 6.57° ± 3.05° and the sacral inclination angle decreased from 27° ± 11.13° to -21.79° ± 6.48°, respectively, and both were statistically significant in the paired t-test (p< 0.0001, p<0.0001, respectively). In the case of C7-SVA, there was a statistically significant change from 22.26 ± 15.17mm to 94.23 ± 46.14mm (p=0.0007). Except for the differences in the cervical lordosis angle change and the thoracic kyphosis angle change, there were statistically significant differences in standing and sitting conditions.CONCLUSION: As a result of this study, the changes in lumbar lordosis angle, sacral inclination angle, and C7-SVA were greater when sitting on a seat than when standing. This is related to the performance of comfort when sitting on a seat, and this data is expected to be used as useful data for designing seat shapes and lumbar support when developing seat designs in the future.

This study aimed to evaluate prognostic factors associated with nidus obliteration following stereotactic radiosurgery (SRS) for cerebral arteriovenous malformations. From January 2001 to January 2018, 119 patients who underwent SRS with AVM were studied to analyze major prognostic factors (age, prescription dose (Gy), volume (mm3), nidus size (cm), and Spetzler–Martin (SM) grade) for nidus obliteration. A random forest and tree explainer was used to construct a predictive model of nidus obliteration. The prognostic factors affecting nidus obliteration from most to least important were age, nidus size, volume, total prescription dose, and SM grade, using a predictive model. In a specific case for nidus size (1.5 cm), total dose (23 Gy), and SM grade (2), the result showed a high obliteration score of 0.75 with the actual obliteration period of 6 months spent; the mean AUC was 0.90 in K-fold cross validation. The predictive model identified the main contributing factors associated with a prognostic of nidus obliteration from linear accelerator-based SRS for cerebral AVM. It was confirmed that the results, including the prognostic factors, are potentially useful for outcome prediction for patient and treatment.

Abstract Background This study evaluates the conformity of using a computer vision-based posture analysis system as a screening assessment for postural deformity detection in the spine that is easily applicable to clinical practice. Methods One hundred forty participants were enrolled for screening of the postural deformation. Factors that determine the presence or absence of spinal deformation, such as shoulder height difference (SHD), pelvic height difference (PHD), and leg length mismatch (LLD), were used as parameters for the clinical decision support system (CDSS) using a commercial computer vision-based posture analysis system. For conformity analysis, the probability of postural deformation provided by CDSS, the Cobb angle, the PHD, and the SHD was compared and analyzed between the system and radiographic parameters. A principal component analysis (PCA) of the CDSS and correlation analysis were conducted. Results The Cobb angles of the 140 participants ranged from 0° to 61°, with an average of 6.16° ± 8.50°. The postural deformation of CDSS showed 94% conformity correlated with radiographic assessment. The conformity assessment results were more accurate in the participants of postural deformation with normal (0–9°) and mild (10–25°) ranges of scoliosis. The referenced SHD and the SHD of the CDSS showed statistical significance (p < 0.001) on a paired t-test. SHD and PHD for PCA were the predominant factors (PC1 SHD for 79.97%, PC2 PHD for 19.86%). Conclusion The CDSS showed 94% conformity for the screening of postural spinal deformity. The main factors determining diagnostic suitability were two main variables: SHD and PHD. In conclusion, a computer vision-based posture analysis system can be utilized as a safe, efficient, and convenient CDSS for early diagnosis of spinal posture deformation, including scoliosis.

Objective The present study aimed to evaluate the effect of baseline frailty status (as measured by modified frailty index-5 [mFI-5]) versus age on postoperative outcomes of patients undergoing surgery for spinal tumors using data from a large national registry. Methods The National Surgical Quality Improvement Program database was used to collect spinal tumor resection patients’ data from 2015 to 2019 (n = 4,662). Univariate and multivariate analyses for age and mFI-5 were performed for the following outcomes: 30-day mortality, major complications, unplanned reoperation, unplanned readmission, hospital length of stay (LOS), and discharge to a nonhome destination. Receiver operating characteristic (ROC) curve analysis was used to evaluate the discriminative performance of age versus mFI-5. Results Both univariate and multivariate analyses demonstrated that mFI-5 was a more robust predictor of worse postoperative outcomes as compared to age. Furthermore, based on categorical analysis of frailty tiers, increasing frailty was significantly associated with increased risk of adverse outcomes. ‘Severely frail’ patients were found to have the highest risk, with odds ratio 16.4 (95% confidence interval [CI],11.21–35.44) for 30-day mortality, 3.02 (95% CI, 1.97–4.56) for major complications, and 2.94 (95% CI, 2.32–4.21) for LOS. In ROC curve analysis, mFI-5 score (area under the curve [AUC] = 0.743) achieved superior discrimination compared to age (AUC = 0.594) for mortality. Conclusion Increasing frailty, as measured by mFI-5, is a more robust predictor as compared to age, for poor postoperative outcomes in spinal tumor surgery patients. The mFI-5 may be clinically used for preoperative risk stratification of spinal tumor patients.

Sitting in a car seat for a long time causes fatigue in muscles such as trapezius and paraspinal muscles, which increases muscle fatigue and tension and eventually causes in degenerative spinal changes and pain. Therefore, the authors attempt to investigate the effect of trapezius and lower back muscle activity changes on whether fatigue may be improved by balancing the buttock contact pressure in the sitting position. The purpose of this study was to assess the electrophysiologic effect of dynamic balance control for the trapezius and lower core back muscles through wireless surface electromyographic evaluation using the smart car seat equipped with an ICT-based air bladder. Surface electromyography (sEMG) was measured for each 32 participant’s trapezius and lumbar back muscles in three phases: 1) initial on standing, 2) seated for 25 minutes without balancing ischial pressure, 3) seated for 25 minutes with balancing ischial pressure, and then sEMG was measured for 1 minute on the standing of three individual phases. In the trapezius and low back muscles, the sEMG value of the three-phase MVIC showed a statistically significant increase in the left side compared to the right side (p0.0001). % MVIC difference increased in unbalanced seating (7.32±0.83) compared to the initial measure (7.24±1.72). However, it decreased with balancing seating(6.73±1.81, p=0.049). There was no statistically significant difference in the overall %MVIC differences between both lower back muscles among three phases (p=0.35), but the balanced seating showed a slightly increased % MVIC difference (p=0.10) in contrast to that of the trapezius. Balanced control of hip pressure using automatic logic control of ICT-based smart car seats has the effect of reducing the left-right difference in muscle activity of upper core muscles compared to that of non-balanced seating. Conclusively, it is believed that the difference in the left and right imbalances in the activity of trapezius can be alleviated through the pressure balance seating at the driver’s seat, and the effect of improving muscle fatigue can be expected. Nevertheless, driving in a sitting position, regardless of balance control, the lower core muscles continue to increase the activity of the lumbar muscles, which inevitably causes pain, discomfort, and fatigue over time. Wireless bio-sensing and balanced seat control using ICT-integrated smart car seats can be used as important application science fields that can improve muscle fatigue and degenerative spinal changes associated with professional workers.

This study aimed to analyze feature importance by applying explainable artificial intelligence (XAI) to postural deformity parameters extracted from a computer vision-based posture analysis system (CVPAS). Overall, 140 participants were screened for CVPAS and enrolled. The main data analyzed were shoulder height difference (SHD), wrist height difference (WHD), and pelvic height difference (PHD) extracted using a CVPAS. Standing X-ray imaging and radiographic assessments were performed. Predictive modeling was implemented with XGBoost, random forest regressor, and logistic regression using XAI techniques for global and local feature analyses. Correlation analysis was performed between radiographic assessment and AI evaluation for PHD, SHD, and Cobb angle. Main global features affecting scoliosis were analyzed in the order of importance for PHD (0.18) and ankle height difference (0.06) in predictive modeling. Outstanding local features were PHD, WHD, and KHD that predominantly contributed to the increase in the probability of scoliosis, and the prediction probability of scoliosis was 94%. When the PHD was >3 mm, the probability of scoliosis increased sharply to 85.3%. The paired t-test result for AI and radiographic assessments showed that the SHD, Cobb angle, and scoliosis probability were significant (p < 0.05). Feature importance analysis using XAI to postural deformity parameters extracted from a CVPAS is a useful clinical decision support system for the early detection of posture deformities. PHD was a major parameter for both global and local analyses, and 3 mm was a threshold for significantly increasing the probability of local interpretation of each participant and the prediction of postural deformation, which leads to the prediction of participant-specific scoliosis.

STUDY DESIGN:Retrospective study. OBJECTIVE:To evaluate the absolute value of L4 trabecular region-of-interest (t-ROI) computed tomography (CT) attenuation, which can predict pedicle screw loosening, and determine the changes in value according to number of fused levels and sagittal balance in patients undergoing lumbar fusion surgery. SUMMARY OF BACKGROUND DATA:Although osteoporosis was not diagnosed in spinal dual x-ray absorptiometry preoperatively, we encountered several cases of screw loosening within 1 year of lumbar fusion surgery. METHODS:We enrolled 478 patients and analyzed factors related to screw loosening. We evaluated the association between L4 t-ROI CT attenuation and screw loosening and determined the best cutoff value of t L4 t-ROI CT attenuation for predicting screw loosening. RESULTS:The number of fused levels, postoperative C7-S1 sagittal vertical axis (SVA), and L4 t-ROI CT attenuation were independently correlated with screw loosening. According to number of fused level and postoperative C7-T1 SVA (≥36.9 mm or <36.9 mm), in patients with one-level fusion and C7-S1 SVA less than 36.9 mm, the optimal cutoff point of the L4 t-ROI CT attenuation predicting screw loosening was 106.5 Hounsfield unit (HU). L4 t-ROI attenuation did not change until two-level fusions. In patients with three-level fusions and C7-S1 SVA less than 36.9 mm, the optimal cutoff point of the L4 t-ROI CT attenuation predicting screw loosening was 159.0 HU. The optimal cutoff point of L4 t-ROI CT attenuation in patients with three-level fusions and C7-S1 SVA more than or equal to 36.9 mm was 191.0 HU. CONCLUSION:L4 t-ROI CT attenuation value considering number of fused levels and sagittal balance is an accurate measurement method to predict screw loosening. Spine surgeons should be aware of the L4 t-ROI attenuation before surgery to improve the fusion rate and reduce instrument-related complications of lumbar spine surgery in osteoporotic patients. LEVEL OF EVIDENCE:3.

Accuracy of position setup and monitoring is a key element in the success of spinal stereotactic radiosurgery. We investigated the reposition and target accuracies of a proposed complementary surface imaging guided (SIG) application to infrared (IR) fiducial marker system for patient setup in the spinal radiosurgery. Among the iterative closest point (ICP) and normal distribution transformation (NDT) algorithm, the appropriate method for SIG system was selected by measuring the reposition accuracy. To evaluate the performance of SIG and marker systems, the reposition and target accuracies was measured by dividing into three groups; Group 1 (infrared (IR)-fiducial marker system alone), Group 2 (SIG alone), and Group 3 (combination of Group1 and 2). Overall, six degrees of freedom (DOF) and the root-mean-square (RMS) values were calculated to evaluate the performance of reposition and target accuracies. The RMS value of ICP and NDT was 3.18 ± 1.80 mm and 0.88 ± 0.71 mm, respectively. The real-time reposition accuracy using NDT algorithm were 0.29 ± 0.50 mm in Group 1, 0.79 ± 0.62 mm in Group 2 and 0.13 ± 0.05 mm in Group 3. Target accuracy of Group 3 (RMS of 0.90 ± 0.62 mm) was superior to that of Group 1and 2 (1.23 ± 0.81 mm and 1.93 ± 1.26 mm, respectively). The positioning and target accuracy were statistically significantly improved by implementing real-time SIG system complementary to conventional IR—fiducial marker-guided system in stereotactic body radiosurgery.