Development of Notch-Free, Pre-Bent Rod Applicable for Posterior Corrective Surgery of Thoracolumbar/Lumbar Adolescent Idiopathic Scoliosis.

Adolescent idiopathic scoliosis (AIS), the most common pediatric musculoskeletal disorder, causes a three-dimensional spine deformity. Lenke type 5 AIS is defined as a structural thoracolumbar/lumbar curve with nonstructural thoracic curves. Although a rod curvature will affect clinical outcomes, intraoperative contouring of the straight rod depends on the surgeon's knowledge and experience. This study aimed to determine the optimum rod geometries to provide a pre-bent rod system for posterior spinal surgery in patients with Lenke type 5 AIS. These pre-bent rods will be beneficial for achieving proper postoperative outcomes without rod contouring based on surgeon experience. We investigated 20 rod geometries traced in posterior spinal reconstruction in patients with Lenke type 5 AIS. The differences between the center point clouds in each cluster were evaluated using the iterative closest point (ICP) method with modification. Before the evaluation using the ICP method, the point clouds were divided into four clusters based on the rod length using a hierarchical cluster analysis. Because the differences in the values derived from the ICP method were <5 mm for each length-based cluster, four representative rod shapes were generated from the length-based clusters. We identified four optimized rod shapes that will reduce operation time, leading to a decreased patient and surgeon burden.

Elucidation of the Mechanism of Occasional Anterior Longitudinal Ligament Rupture with Posterior Correction Procedure for Adult Spinal Deformity Using LLIF-Finite Element Analysis of the Impact of the Lordotic Angle of Intervertebral LLIF Cage.

Background and Objectives: There are several advantages of using lateral lumbar interbody fusion (LLIF) for correction surgeries for adult spinal deformity (ASD); however, we currently have unresolved new issues, including occasional anterior longitudinal ligament (ALL) rupture during the posterior correction procedure. When LLIF was initially introduced, only less lordotic cages were available and ALL rupture was more frequently experienced compared with later periods when more lordotic cages were available. We performed finite element analysis (FEA) regarding the mechanism of ALL rupture during a posterior correction procedure. Methods: A spring (which mimics ALL) was introduced at the location of ALL in the FEA and an LLIF cage with two different lordotic angles, 6 and 12 degrees (6DC/12DC), was employed. To assess the extent of burden on the ALL, the extension length of the spring during the correction procedure was measured and the location of the rotation center was examined. Results: We observed a significantly higher degree of length extension of the spring during the correction procedure in the FEA model with 6DC compared with that of 12DC. We also observed that the location of the rotation center was shifted posteriorly in the FEA model with 6DC compared with that of 12DC. Conclusions: It is considered that the posterior and rostral edge of the less lordotic angle cage became a hinge, and the longer lever arm increased the burden on ALL as the principle of leverage. It is important to use an LLIF cage with a sufficient lordotic angle, that is compatible with the degree of posterior osteotomy in ASD correction.

Percutaneous Endoscopic Transforaminal Lumbar Interbody Fusion (PETLIF): Current Techniques, Clinical Outcomes, and Narrative Review.

Full endoscopic techniques are becoming more popular for degenerative lumbar pathologies. Percutaneous endoscopic lumbar interbody fusion (PETLIF) is a minimally invasive surgical technique for spondylolisthesis and lumbar spinal canal stenosis with instability. Nagahama first introduced PETLIF in 2019. This study investigated the clinical outcomes and complications of 24 patients who underwent PETLIF in our facility and compared them with previous studies. Literature searches were conducted on PubMed and Web of Science. The PETLIF surgical technique involves three steps to acquire disc height under general anesthesia. The procedure includes bone harvesting, spondylolisthesis reduction, endoscopic foraminoplasty, disc height expansion using an oval dilator, and intervertebral disc curettage. A cage filled with autologous bone is inserted into the disc space and secured with posterior fixation. Patients underwent PETLIF with an average operation time of 130.8 min and a blood loss of 24.0 mL. Postoperative hospital stays were 9.5 days. Improvement in VAS, disc height, spinal canal area, and % slip was observed, while lumbar lordosis remained unchanged. Complications included end plate injury, subsidence, and exiting nerve root injury. The differences between PETLIF and the extracted literature were found in patients' age, direct decompression, epidural or local anesthesia, approach, order of PPS, and cage insertion. In conclusion, PETLIF surgery is a practical, minimally invasive surgical technique for patients with lumbar degenerative diseases suffering from back and leg pain, demonstrating significant improvements in pain scores. However, it is essential to carefully consider the potential complications and continue to refine the surgical technique further to enhance the safety and efficacy of this procedure.

Evaluation of Surgical Indications for Full Endoscopic Discectomy at Lumbosacral Disc Levels Using Three-Dimensional Magnetic Resonance/Computed Tomography Fusion Images Created with Artificial Intelligence.

Background and Objectives: Although full endoscopic lumbar discectomy with the transforaminal approach (FED-TF) is a minimally invasive spinal surgery for lumbar disc herniation, the lumbosacral levels present anatomical challenges when performing FED-TF surgery due to the presence of the iliac bone. Materials and Methods: In this study, we simulated whether FED-TF surgery could be safely performed on a total of 52 consecutive cases with L5-S1 or L5-L6 disc herniation using fused three-dimensional (3D) images of the lumbar nerve root on magnetic resonance imaging (MRI) created with artificial intelligence and of the lumbosacral spine and iliac on computed tomography (CT) images. Results: Thirteen of the fifty-two cases were deemed operable according to simulated FED-TF surgery without foraminoplasty using the 3D MRI/CT fusion images. All 13 cases underwent FED-TF surgery without neurological complications, and their clinical symptoms significantly improved. Conclusions: Three-dimensional simulation may allow for the assessment from multiple angles of the endoscope entry and path, as well as the insertion angle. FED-TF surgery simulation using 3D MRI/CT fusion images could be useful in determining the indications for full endoscopic surgery for lumbosacral disc herniation.

Influence of Lateral Translation of Lowest Instrumented Vertebra on L4 Tilt and Coronal Balance for Thoracolumbar and Lumbar Curves in Adolescent Idiopathic Scoliosis.

This study aimed to evaluate the lowest instrumented vertebra translation (LIV-T) in the surgical treatment of thoracolumbar/lumbar adolescent idiopathic scoliosis and to analyze the radiographic parameters in relation to LIV-T and L4 tilt and global coronal balance. A total of 62 patients underwent posterior spinal fusion (PSF, n = 32) or anterior spinal fusion (ASF, n = 30) and were followed up for a minimum of 2 years. The mean preoperative LIV-T was significantly larger in the ASF group than the PSF (p < 0.01), while the final LIV-T was equivalent. LIV-T at the final follow-up was significantly correlated with L4 tilt and the global coronal balance (r = 0.69, p < 0.01, r = 0.38, p < 0.01, respectively). Receiver-operating characteristic analysis for good outcomes, with L4 tilt <8° and coronal balance <15 mm at the final follow-up, calculated the cutoff value of the final LIV-T as 12 mm. The cutoff value of preoperative LIV-T that would result in the LIV-T of ≤12 mm at the final follow-up was 32 mm in PSF, although no significant cutoff value was calculated in ASF. ASF can centralize the LIV better than PSF with a shorter segment fusion, and could be useful in obtaining a good curve correction and global balance without fixation to L4 in cases with large preoperative LIV-T.

Prediction of Cobb Angle Using Deep Learning Algorithm with Three-Dimensional Depth Sensor Considering the Influence of Garment in Idiopathic Scoliosis.

Adolescent idiopathic scoliosis (AIS) is the most common pediatric spinal deformity. Early detection of deformity and timely intervention, such as brace treatment, can help inhibit progressive changes. A three-dimensional (3D) depth-sensor imaging system with a convolutional neural network was previously developed to predict the Cobb angle. The purpose of the present study was to (1) evaluate the performance of the deep learning algorithm (DLA) in predicting the Cobb angle and (2) assess the predictive ability depending on the presence or absence of clothing in a prospective analysis. We included 100 subjects with suspected AIS. The correlation coefficient between the actual and predicted Cobb angles was 0.87, and the mean absolute error and root mean square error were 4.7° and 6.0°, respectively, for Adam's forward bending without underwear. There were no significant differences in the correlation coefficients between the groups with and without underwear in the forward-bending posture. The performance of the DLA with a 3D depth sensor was validated using an independent external validation dataset. Because the psychological burden of children and adolescents on naked body imaging is an unignorable problem, scoliosis examination with underwear is a valuable alternative in clinics or schools.

Less-invasive decompression procedures can reduce risk of reoperation for lumbar spinal stenosis with diffuse idiopathic skeletal hyperostosis extended to the lumbar segment: analysis of two retrospective cohorts.

PURPOSE: Clinical outcomes after decompression procedures are reportedly worse for lumbar spinal stenosis (LSS) with diffuse idiopathic skeletal hyperostosis (DISH), especially DISH extended to the lumbar segment (L-DISH). However, no studies have compared the effect of less-invasive surgery versus conventional decompression techniques for LSS with DISH. The purpose of this study was to compare the long-term risk of reoperation after decompression surgery focusing on LSS with L-DISH. METHODS: This study compared open procedure cohort (open conventional fenestration) and less-invasive procedure cohort (bilateral decompression via a unilateral approach) with ≥ 5 years of follow-up. After stratified analysis by L-DISH, patients with L-DISH were propensity score-matched by age and sex. RESULTS: There were 57 patients with L-DISH among 489 patients in the open procedure cohort and 41 patients with L-DISH among 297 patients in the less-invasive procedure cohort. The reoperation rates in L-DISH were higher in the open than less-invasive procedure cohort for overall reoperations (25% and 7%, p = 0.026) and reoperations at index levels (18% and 5%, p = 0.059). Propensity score-matched analysis in L-DISH demonstrated that open procedures were significantly associated with increased overall reoperations (hazard ratio [HR], 6.18; 95% confidence interval [CI], 1.37-27.93) and reoperations at index levels (HR, 4.80; 95% CI, 1.04-22.23); there was no difference in reoperation at other lumbar levels. CONCLUSIONS: Less-invasive procedures had a lower risk of reoperation, especially at index levels for LSS with L-DISH. Preserving midline-lumbar posterior elements could be desirable as a decompression procedure for LSS with L-DISH.

Comparison of Safety and Perioperative Outcomes Between Patient-specific Template-Guided and Fluoroscopic-Assisted Freehand Lumbar Screw Placement Using Cortical Bone Trajectory Technique.

STUDY DESIGN: Non-randomized prospective controlled study. OBJECTIVES: To compare the safety and perioperative outcomes between patient-specific template-guided and fluoroscopic-assisted freehand techniques in transforaminal lumbar interbody fusion (TLIF) using cortical bone trajectory (CBT). METHODS: The subjects consisted of 94 consecutive patients who underwent single-level TLIF using CBT. The standard trajectory was set so as to start from the pars interarticularis, pass the inferior border of the pedicle, and end around the middle of the vertebral endplate. Template guide technique was performed in 66 patients (Guide group), and fluoroscopic-assisted freehand technique was performed in 28 patients (Freehand group). Intraoperative parameters, screw placement accuracy, and complications were compared between the two techniques. RESULTS: The Guide group had significantly shorter operative and radiation exposure times than the Freehand group (operative time 84.6 ± 16.7 vs 93.0 ± 15.0 minutes; P = .023, radiation exposure time 7.0 ± 6.0 vs 20.4 ± 11.8 seconds; P < .001, respectively). The screw diameter and the screw insertion depth in the vertebra in the Guide group were significantly greater than those in the Freehand group. The degree and incidence of facet joint violation were comparable between the two groups, while the accuracy of screw placement was significantly different, with no perforation rate of 97.7% in the Guide group vs 82.1% in the Freehand group (P < .001). No significant difference was found in the rate of clinically relevant complications between the two groups. CONCLUSIONS: The template-guided technique provided a safe and highly accurate option for CBT screw placement.

Risk Factors for Reoperation at Same Level after Decompression Surgery for Lumbar Spinal Stenosis in Patients with Diffuse Idiopathic Skeletal Hyperostosis Extended to the Lumbar Segments.

INTRODUCTION: Diffuse idiopathic skeletal hyperostosis (DISH) extended to the lumbar segments (L-DISH) reportedly has adverse effects on the surgical outcomes of lumbar spinal stenosis (LSS). However, the risk factors in patients with L-DISH have not been clarified. The purpose of this study was to investigate the long-term risk factors for reoperation at the same level after decompression surgery alone for LSS in patients with L-DISH in a retrospective cohort study. METHODS: A postoperative postal survey was sent to 1,150 consecutive patients who underwent decompression surgery alone for LSS from 2002 to 2010. Among all respondents, patients who exhibited L-DISH by preoperative total spine X-ray were included in this study. We investigated risk factors for reoperation at the same level as the initial surgery among various demographic and radiological parameters, including the lumbar ossification condition and computed tomography (CT) or magnetic resonance imaging findings. RESULTS: A total of 57 patients were analyzed. Reoperations at the same level as that of the index surgery were performed in 10 patients (17.5%) and at 11 levels within a mean of 9.2 years. Cox proportional hazard regression analysis indicated that the independent risk factors for reoperation were a sagittal rotation angle ≥10° (adjusted hazard ratio: 5.17) and facet opening on CT (adjusted hazard ratio: 4.82). Neither sagittal translation nor the ossification condition in the lumbar segments affected reoperations. CONCLUSIONS: A sagittal rotation angle ≥10° and facet opening on preoperative CT were risk factors for reoperation at the same level as that of the index surgery in patients with L-DISH. The surgical strategy should be carefully considered in those patients.

Unintentional Fusion in Preserved Facet Joints without Bone Grafting after Percutaneous Endoscopic Transforaminal Lumbar Interbody Fusion.

INTRODUCTION: A percutaneous endoscopic transforaminal lumbar interbody fusion (PETLIF) procedure has been previously developed. During postoperative follow-up, in some patients, bone fusion occurred between opened facet joints, despite not having bone grafting in the facet joints. Here, we investigated facet fusion's frequency and tendencies following PETLIF. METHODS: A retrospective analysis was conducted on a prospectively collected, nonrandomized series of patients. Forty-two patients (6 males and 36 females, average age: 69.9 years) who underwent single-level PETLIF at our hospital from February 2016 to March 2019 were included in this study. Patients were assessed with lumbar X-ray images and computed tomography (CT) prior to, immediately after, and 1 year after surgery. RESULTS: Pseudarthrosis was not observed in any patients, and facet fusion was observed in 26 of 42 post-PETLIF patients (61.9%) by CT 1 year postoperatively. The average interfacet distance increased from 1.3 mm preoperatively to 4.5 mm postoperatively, and facet fusion was observed under the opened conditions of 3.8 mm at 1 year. Segmental lordotic angle of the fusion segment in the lumbar X-ray images was significantly larger in the facet fusion subgroup prior to surgery, immediately following surgery, and 1 year after surgery compared to the facet non-fusion group (p=0.02, p<0.01, p=0.01, respectively). There were no significant differences in patient background, correction loss of segmental lordosis, interfacet distance, or clinical score between the facet fusion and facet non-fusion subgroups. CONCLUSIONS: Facet fusion was achieved over time within the facet joints that were opened through indirect decompression after PETLIF. We hypothesized that the preserved facet joints potentially became the base bed for spontaneous bone fusion due to the preserved facet joint capsule and surrounding soft tissue, which maintained cranio-caudal facet traffic and blood circulation in the facet joints. The complete preservation of the facet joints was a key advantage of minimally invasive lumbar interbody fusion procedures. LEVEL OF EVIDENCE: Level III.

Novel Technique for Sacral-Alar-Iliac Screw Placement Using Three-Dimensional Patient-Specific Template Guide.

INTRODUCTION: The sacral-alar-iliac (SAI) screw technique is becoming popular for sacropelvic fixation. However, appropriately placing SAI screws is technically demanding because of a narrow safe corridor and the risk of neurovascular/visceral injuries. Recently, a three-dimensional patient-specific template guiding technique for pedicle screw placement has been considered a promising method to improve accuracy and safety. The objective of the present study was to investigate the accuracy of SAI screw placement with a patient-specific template guide using cadaveric and prospective clinical pilot studies. METHODS: Three-dimensional planning of SAI screw placement, including entry point, screw trajectory, length, and diameter, was performed using a computer simulation software. Then, three-dimensional printed patient-specific template guides were created based on the plan. Firstly, a total of 12 SAI screws were placed for 6 cadaveric specimens using the guides. Next, in a prospective clinical trial, a total of 20 SAI screws were placed for 10 consecutively enrolled patients. The safety and accuracy of screw placement were analyzed using postoperative computed tomography by the evaluation of any cortical breach and measurement of screw deviations between the planned and actual screw positions. RESULTS: All the screws showed no perforation. In the cadaveric study, the mean horizontal and vertical deviations from the planned screw position at the entry point were 1.40±1.21 mm and 1.34±1.09 mm, respectively. The mean angular deviations in the sagittal and transverse planes were 1.68°±1.24° and 1.53°±1.06°, respectively. The results of the clinical study showed comparable accuracy with those of the cadaveric study, except for the vertical deviation at the entry point (p=0.048). CONCLUSIONS: This is the first study to evaluate the feasibility and accuracy of using a patient-specific template guide for SAI screw placement. This technique could become an effective solution to achieve accurate screw placement.

Surgical Outcome Prediction Using a Four-Dimensional Planning Simulation System With Finite Element Analysis Incorporating Pre-bent Rods in Adolescent Idiopathic Scoliosis: Simulation for Spatiotemporal Anatomical Correction Technique.

An optimal surgical strategy for adolescent idiopathic scoliosis (AIS) is to provide maximal deformity correction while preserving spinal mobile segments as much as possible and obtaining a balanced posture. From a spatiotemporal deformity correction standpoint, we recently showed that anatomical four-dimensional (4D) spinal correction could be accomplished by curving the rod. In the surgical procedure, two rods are bent identically to confirm spinal anatomical alignment without referring to the intraoperative alignment of the deformity. Therefore, anatomically designed rods have been developed as notch-free, pre-bent rods for easier anatomical reconstruction. In addition to providing the best spinal instrumentation configurations as pre-bent rods, prediction of surgical outcome along with its biomechanical impact can be obtained by simulation of the surgical procedures with computer modeling. However, an objective model that can simulate the surgical outcome in patients with AIS has not been completely elucidated. The present study aimed to compare simulated deformity corrections based on our newly developed spatiotemporal morphological 4D planning simulation system incorporating pre-bent rods and actual deformity corrections in patients with AIS. A consecutive series of 47 patients who underwent anatomical posterior correction for AIS curves were prospectively evaluated. After multilevel facetectomy, except for the lowest instrumented segment, 11 types of pre-bent rods were used. Patient demographic data, radiographic measurements, and sagittal rod angles were analyzed within 1 week of surgery. Our simulation system incorporating pre-bent rods showed a significant correlation with the actual postoperative spinal alignment. The present study demonstrated the feasibility of our simulation system and the ability to simulate the surgical procedure using the pre-bent rods. The simulation system can be used to minimize the differences between the optimal and possible outcomes related to the instrumentation levels and rod shapes. Preoperative assumption of rod shape and length can contribute to a reduction in operative time which decreases blood loss and risk of infection. The results of the finite element analysis in the simulation system measured for each individual patient would also provide a more realistic representation of the surgical procedures.

Morphological analysis of Kambin's triangle using 3D CT/MRI fusion imaging of lumbar nerve root created automatically with artificial intelligence.

PURPOSE: We developed a software program that automatically extracts a three-dimensional (3D) lumbar nerve root image from magnetic resonance imaging (MRI) lumbar nerve volume data using artificial intelligence. The aim of this study is to evaluate the morphology of Kambin's triangle in three dimensions based on an actual endoscopic transforaminal surgical approach using three-dimensional (3D) computed tomography (CT)/ magnetic resonance imaging (MRI) fusion images of the lumbar spine and nerve tissue. METHODS: Three-dimensional lumbar spine/nerve images of 100 patients (31 males and 69 females; mean age, 66.8 years) were used to evaluate the relationship between the superior articular process (SAP), exiting nerve root (ENR), and dural canal at the L2/3, L3/4, and L4/5 levels at 45° and 60° approach angles. RESULTS: The SAP-ENR distance at 60° was the greatest at L4/5 and was significantly greater at L2/3 and L4/5 than at L3/4 (P < 0.01, P < 0.01, respectively). The SAP-ENR distance at 45° was the greatest at L2/3, and it was larger in L2/3 and L4/5 than in L3/4 (P < 0.01, P < 0.01, respectively). The SAP-ENR distances at L4/5 were significantly greater at 60° than at 45° (P < 0.01). The dural canal was located within Kambin's triangle on the plane of the upper endplate of the lower vertebra at L2/3 in 41.5% of the cases and at L3/4 in 14% of the cases at 60° but not at L4/5. CONCLUSION: The 3D lumbar spine/nerve image enabled a combined assessment of the positional relationship between the SAP, ENR, and dural canal to quantify the safety zone of practical endoscopic spinal surgery using a transforaminal approach. Three-dimensional lumbar spine/nerve images could be useful for examining parameters, including bones and nerves, to ensure the safety of surgery.

In vivo deformation of anatomically pre-bent rods in thoracic adolescent idiopathic scoliosis.

Some surgical strategies can maintain or restore thoracic kyphosis (TK); however, next-generation surgical schemes for adolescent idiopathic scoliosis (AIS) should consider anatomical corrections. A four-dimensional correction could be actively achieved by curving the rod. Thus, anatomically designed rods have been developed as notch-free, pre-bent rods for easier anatomical reconstruction. This study aimed to compare the initial curve corrections obtained using notch-free rods and manually bent, notched rods for the anatomical reconstruction of thoracic AIS. Two consecutive series of 60 patients who underwent anatomical posterior correction for main thoracic AIS curves were prospectively followed up. After multilevel facetectomy, except for the lowest instrumented segment, either notch-free or notched rods were used. Patient demographic data, radiographic measurements, and sagittal rod angles were analyzed within 1 week after surgery. Patients with notch-free rods had significantly higher postoperative TK than patients with notched rods (P < .001), but both groups achieved three-dimensional spinal corrections and significantly increased postoperative rates of patients with T6-T8 TK apex (P = .006 for notch-free rods and P = .008 for notched rods). The rod deformation angle at the concave side was significantly lower in the notch-free rods than in the notched rods (P < .001). The notch-free, pre-bent rod can maintain its curvature, leading to better correction or maintenance of TK after anatomical spinal correction surgery than the conventional notched rod. These results suggest the potential benefits of anatomically designed notch-free, pre-bent rods over conventional, manually bent rods.

Impact of multilevel facetectomy on segmental spinal flexibility in patients with thoracic adolescent idiopathic scoliosis.

BACKGROUND: The aim of this study was to intraoperatively assess the effects of multilevel facetectomy on segmental spinal flexibility in patients with thoracic adolescent idiopathic scoliosis. METHODS: Twenty patients who underwent posterior thoracic adolescent idiopathic scoliosis curve correction were evaluated. Compressive or distractive loaded force of 50N was applied on the handle of a compressor or distractor connected to the necks of pedicle screws inserted at T7 to T11. Segmental spinal flexibility rates were calculated based on the distance between screw heads under the loaded and unloaded conditions. In addition, the flexibility rates were obtained before and after multilevel facetectomy. FINDINGS: Absolute flexibility rates of all segments significantly increased after multilevel facetectomy under both compressive and distractive forces (P < 0.01). The absolute change in the flexibility rate was significantly higher at the concave side than at the convex side under both compressive (P < 0.01) and distractive loaded forces (P = 0.046). No significant correlation was found between change in the flexibility rates and preoperative Cobb angle or preoperative curve flexibility. INTERPRETATION: From a biomechanical point of view, multilevel facetectomy provides proper spinal flexibility to improve the correction rate of posterior adolescent idiopathic scoliosis surgery. The effects are higher at the concave side than at the convex side.

An algorithm for using deep learning convolutional neural networks with three dimensional depth sensor imaging in scoliosis detection.

BACKGROUND CONTEXT: Timely intervention in growing individuals, such as brace treatment, relies on early detection of adolescent idiopathic scoliosis (AIS). To this end, several screening methods have been implemented. However, these methods have limitations in predicting the Cobb angle. PURPOSE: This study aimed to evaluate the performance of a three-dimensional depth sensor imaging system with a deep learning algorithm, in predicting the Cobb angle in AIS. STUDY DESIGN: Retrospective analysis of prospectively collected, consecutive, nonrandomized series of patients at five scoliosis centers in Japan. PATIENT SAMPLE: One hundred and-sixty human subjects suspected to have AIS were included. OUTCOME MEASURES: Patient demographics, radiographic measurements, and predicted Cobb angle derived from the deep learning algorithm were the outcome measures for this study. METHODS: One hundred and sixty data files were shuffled into five datasets with 32 data files at random (dataset 1, 2, 3, 4, and 5) and five-fold cross validation was performed. The relationships between the actual and predicted Cobb angles were calculated using Pearson's correlation coefficient analyses. The prediction performances of the network models were evaluated using mean absolute error and root mean square error between the actual and predicted Cobb angles. The shuffling into five datasets and five-fold cross validation was conducted ten times. There were no study-specific biases related to conflicts of interest. RESULTS: The correlation between the actual and the mean predicted Cobb angles was 0.91. The mean absolute error and root mean square error were 4.0° and 5.4°, respectively. The accuracy of the mean predicted Cobb angle was 94% for identifying a Cobb angle of ≥10° and 89% for that of ≥20°. CONCLUSIONS: The three-dimensional depth sensor imaging system with its newly innovated convolutional neural network for regression is objective and has significant ability to predict the Cobb angle in children and adolescents. This system is expected to be used for screening scoliosis in clinics or physical examination at schools.

Characterization of Push-Pull-Type Benzo[X]quinoline Derivatives (X = g or f): Environmentally Responsive Fluorescent Dyes with Multiple Functions.

Benzo[X]quinoline (X = g or f: BQX) derivatives bearing bis-trifluoromethyl and amine groups have been designed as push-pull-type fluorescent dyes. Through the synthesis of BQX derivatives from 2,7-diaminonaphthalene, linear-type (BQL) and angular-type (BQA) structural isomers were obtained. X-ray structures of single crystals from six given BQX derivatives revealed that the BQL and BQA series adopt planar- and bowl-shaped structures. In the fluorescence spectra, interestingly, the BQL series emitted in the near-infrared region over 700 nm in polar solvents. Based on the visible absorptions and base properties related to the amine moiety, the ammonia responsiveness was investigated using an ion-exchange reaction by the BQX-HCl salt. By exploiting the environmentally responsive fluorescence probe, cell imaging through confocal laser microscopy was conducted using HeLa and 3T3-L1 cells, emitting specific lipid droplets. The results indicate that BQX derivatives have multiple functions and may be applied in materials chemistry and biochemistry.

Accuracy of cortical bone trajectory screw placement using patient-specific template guide system.

Cortical bone trajectory (CBT) can facilitate both minimum invasiveness and strong screw fixation; however, ensuring the ideal cortical trajectory is challenging due to the narrow corridor, necessitating high-level surgical skill. A patient-specific template guide for CBT screw placement may be a promising solution to improve accuracy and safety. Little has been reported on the use of a CBT screw guide in clinical practice. The aim of the present study was to evaluate the accuracy of CBT screw placement using the template guide. This study was a retrospective clinical evaluation of prospectively collected patients. Forty-three consecutively enrolled patients who underwent posterior lumbar spinal fusion using the guide system were included. First, three-dimensional planning of CBT screw placement was performed using computer simulation software. The trajectory was directed in a more anterior position of the vertebral body, compared with the original CBT, and the standard size was set as 5-6 mm in diameter and 40-45 mm in length. Then, screw guides were created for each vertebra preoperatively and used. The safety and accuracy of a total of 198 inserted screws (L1 to L5) were analyzed using postoperative computed tomography by evaluation of pedicle perforation and measurement of screw deviations between the planned and actual screw positions. A total of 193 screws (97.5%) were placed completely inside the pedicle and there was no incidence of neurovascular injuries. The mean screw deviation from the planned trajectory on the coronal plane at the midpoint of the pedicle was 0.62 ± 0.42 mm, and the mean angular deviations in the sagittal and transverse planes were 1.68 ± 1.24° and 1.27 ± 0.77°, respectively. CBT screw placement using a patient-specific template guide was accurate enough for clinical application. This technique could be an effective solution to achieve both correct screw insertion and a reduction of complications.

Perioperative complications of spine surgery in patients 80 years of age or older: a multicenter prospective cohort study.

OBJECTIVE: The number of spine surgeries performed in elderly patients is consistently increasing. However, to date the prevalence of and risk factors for perioperative complications remain unclear, especially in patients 80 years of age or older. This study had two goals: 1) determine the perioperative complications of spine surgery associated with patients 80 years of age or older; and 2) investigate the risk factors for perioperative systemic complications. METHODS: In this paper, the authors describe a multicenter prospective cohort study. Seven spine centers with board-certified spine surgeons participated in this all-case investigation. A total of 270 consecutively enrolled patients (109 males and 161 females), 80 years of age or older, underwent spine surgery between January and December 2017. Patients with trauma, infection, or tumor were excluded in this cohort. Perioperative complications were defined as adverse events that occurred intraoperatively or within 30 days postoperatively. The patients' preoperative health status was determined using the following means of assessment: 1) the Charlson Comorbidity Index, 2) the American Society of Anesthesiologists Physical Status Classification System, 3) the Eastern Cooperative Oncology Group Performance Status (ECOG-PS), 4) the presence of sarcopenia, and 5) the Geriatric Nutritional Risk Index. Associations among patient age, preoperative health status, surgical factors (instrumentation surgery, operation time, number of spinal levels treated, and estimated blood loss), and perioperative systemic complications were analyzed. RESULTS: Overall perioperative, surgical site, and minor systemic complications were observed in 20.0%, 8.1%, and 14.8% of patients, respectively. Major systemic complications, on the other hand, were not observed. The reoperation rate was low-only 4.1%. Multivariate analysis revealed that the ECOG-PS (p = 0.013), instrumentation surgery (p = 0.024), and an operation time longer than 180 minutes (p = 0.016) were associated with minor systemic complications. CONCLUSIONS: To the best of the authors' knowledge, this is the first multicenter prospective all-case investigation of perioperative complications of spine surgery in elderly patients. Although decreased daily activity (ECOG-PS), instrumentation surgery, and longer operation time were associated with minor systemic complications, no major systemic complications were observed in these elderly patients. Thus, spine surgery can be safely performed in elderly patients 80 years of age or older.