Factors associated with loss of vertebral height and kyphosis correction after intermediate screws in short segment pedicular fixation for type-A fractures of the thoracolumbar spine: A retrospective study.

In this article, we attempted to identify risk factors affecting the loss of vertebral height and kyphosis correction on type A thoracolumbar fractures. Patients with type A thoracolumbar fractures who underwent short segments with intermediate screws at the fracture level management between 2017 and 2022 were included in this study. Clinical factors including patients' demographic characteristics (age, sex), history (smoking, hypertension and/or diabetes), value of height/kyphosis correction, the thoracolumbar injury classification and severity score (TLICS), the load sharing classification (LSC) scores and bone mineral density were collected. Correlation coefficient, simple linear regression analysis and multivariate regression analysis were performed to identify the clinical factors associated with the loss of vertebral height/kyphosis correction. Finally, 166 patients were included in this study. The mean height and kyphosis correction were 21.8% ±â€…7.5% and 9.9°â€…±â€…3.8°, respectively, the values of the loss were 6.5% ±â€…4.0% and 3.9°â€…±â€…1.9°, respectively. Simple linear regression analysis and multivariate regression analysis showed that age, value of height correction, LSC scores and bone mineral density were significantly associated with the loss of vertebral height and kyphosis correction (P < .01) We could draw the conclusion that patients with older age, lower bone mineral density, higher LSC scores and diabetes are at higher risk of vertebral height and kyphosis correction loss increase. For these patients, appropriate clinical measures such as long segment fixation, control of blood glucose, and increase of bone density must be taken to reduce the loss of correction.

Optimizing the distal anchorage in stabilization for the traumatic adjacent lumbar vertebra fracture in an adolescent idiopathic scoliosis patient who had posterior spinal fusion: a novel surgical technique.

The incidence of traumatic spine fractures (TSF) is increasing worldwide, with a reported annual incidence of up to 32.8 per 100000 persons. However, there are only a few cases of spine fractures reported in adolescent idiopathic scoliosis (AIS) patients after posterior spinal fusion (PSF) in the literature. Fractures adjacent to fusion blocks that extend into the lower lumbar spine pose a unique challenge as stabilization of such fractures might require an extension of instrumentation to L5 or the pelvis. We report a novel surgical technique where bilateral pedicle and cortical screws at L4 and supplementary rods that connect the cortical screws to the main rods via dominos were implemented for optimizing the distal anchorage for TSF stabilization following an L3 Chance fracture in an AIS patient who had undergone T4-L2 posterior spinal fusion.

Subject-level spinal osteoporotic fracture prediction combining deep learning vertebral outputs and limited demographic data.

Automated screening for vertebral fractures could improve outcomes. We achieved an AUC-ROC = 0.968 for the prediction of moderate to severe fracture using a GAM with age and three maximal vertebral body scores of fracture from a convolutional neural network. Maximal fracture scores resulted in a performant model for subject-level fracture prediction. Combining individual deep learning vertebral body fracture scores and demographic covariates for subject-level classification of osteoporotic fracture achieved excellent performance (AUC-ROC of 0.968) on a large dataset of radiographs with basic demographic data. PURPOSE: Osteoporotic vertebral fractures are common and morbid. Automated opportunistic screening for incidental vertebral fractures from radiographs, the highest volume imaging modality, could improve osteoporosis detection and management. We consider how to form patient-level fracture predictions and summarization to guide management, using our previously developed vertebral fracture classifier on segmented radiographs from a prospective cohort study of US men (MrOS). We compare the performance of logistic regression (LR) and generalized additive models (GAM) with combinations of individual vertebral scores and basic demographic covariates. METHODS: Subject-level LR and GAM models were created retrospectively using all fracture predictions or summary variables such as order statistics, adjacent vertebral interactions, and demographic covariates (age, race/ethnicity). The classifier outputs for 8663 vertebrae from 1176 thoracic and lumbar radiographs in 669 subjects were divided by subject to perform stratified fivefold cross-validation. Models were assessed using multiple metrics, including receiver operating characteristic (ROC) and precision-recall (PR) curves. RESULTS: The best model (AUC-ROC = 0.968) was a GAM using the top three maximum vertebral fracture scores and age. Using top-ranked scores only, rather than all vertebral scores, improved performance for both model classes. Adding age, but not ethnicity, to the GAMs improved performance slightly. CONCLUSION: Maximal vertebral fracture scores resulted in the highest-performing models. While combining multiple vertebral body predictions risks decreasing specificity, our results demonstrate that subject-level models maintain good predictive performance. Thresholding strategies can be used to control sensitivity and specificity as clinically appropriate.

Risk Factors for Nonunion After Nonoperative Treatment for Pediatric Lumbar Spondylolysis: A Retrospective Case-Control Study.

BACKGROUND: Pediatric lumbar spondylolysis, a stress fracture of the lumbar spine, frequently affects young athletes, and nonoperative treatment is often the first choice of management. Because the union rate in lumbar spondylolysis is lower than that in general fatigue fractures, identifying risk factors for nonunion is essential for optimizing treatment. PURPOSE: To determine the risk factors for nonunion after nonoperative treatment of acute pediatric lumbar spondylolysis through multivariate analysis. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: We analyzed 574 pediatric patients (mean age, 14.3 ± 1.9 years) with lumbar spondylolysis who underwent nonoperative treatment between 2015 and 2022. Nonoperative treatment included the elimination of sports activities, bracing, and weekly athletic rehabilitation, with follow-up computed tomography. Patient data, lesion characteristics, sports history, presence of spina bifida occulta at the lamina with a lesion or at the lumbosacral spine excluding the lesion level, and lumbosacral parameters were examined. Differences between the union and nonunion groups were investigated using multivariate analysis to determine the risk factors for nonunion. RESULTS: Of the 574 patients, 81.7% achieved bone union. Multivariate analysis revealed that an L5 lesion and the progression of the main and contralateral lesion stages were significant independent risk factors for nonunion. An L5 lesion had a lower union rate than non-L5 lesions. As the main lesion progressed, the likelihood of nonunion increased significantly, and the progression of the contralateral lesion also showed a similar trend. Spina bifida occulta and lumbosacral parameters were not significant predictors of nonunion in this study. CONCLUSION: We identified the L5 lesion level and the progression of the main and contralateral lesion stages as independent risk factors for nonunion in pediatric lumbar spondylolysis after nonoperative treatment. These findings aid in treatment decision-making. When bone union cannot be expected with nonoperative treatment, symptomatic treatment is required without prolonged external fixation and rest, and without aiming for bone union. Individualized treatment plans are crucial based on identified risk factors.

Suboptimal osteoporosis care in hospitalized patients: a retrospective analysis of vertebral compression fractures detected on computed tomography.

Vertebral compression fractures (VCFs) are the most common osteoporotic fractures. Only 1/3 of patients with VCFs are clinically diagnosed. In our institution, the Fracture Liaison Service (FLS) was launched in 2017 to improve osteoporosis management for hospitalized patients. (1) To assess osteoporosis awareness among medical providers for emergency department (ED)/hospitalized patients aged 50 or greater; (2) To estimate the rate of FLS consults or referrals to primary care providers (FLS/PCP) by primary teams. A centralized radiology system was used to examine all thoracic and lumbar computed tomography (CT) scans conducted between June 1, 2017 and June 1, 2022. 449 studies were identified with the radiologic impression "compression fracture". 182 studies were excluded after manual chart review. 267 hospitalizations/ED visits with lumbar and/or thoracic spine CT scans were included. Referrals to FLS (26) or PCP (27) were made in 53 cases (~ 20% of the total). In the ED subgroup (131 hospitalizations), only 17 patients had FLS/PCP referrals. The "compression fracture" was mentioned in 227 (85%) discharge notes (any part), while "osteoporosis" was mentioned in only 74 (28%) hospitalizations. A statistically significant difference was found between the two groups when "osteoporosis" was mentioned in the "assessment and plan" section (p = 0.02). Our data show that the overall osteoporosis care for affected patients is suboptimal. Medical providers often overlook the presence of osteoporosis, leading to a lack of consultation with the FLS of referral to PCPs for further evaluation and treatment.

Development of a deep learning model for detecting lumbar vertebral fractures on CT images: An external validation.

OBJECTIVE: To develop and externally validate a binary classification model for lumbar vertebral body fractures based on CT images using deep learning methods. METHODS: This study involved data collection from two hospitals for AI model training and external validation. In Cohort A from Hospital 1, CT images from 248 patients, comprising 1508 vertebrae, revealed that 20.9% had fractures (315 vertebrae) and 79.1% were non-fractured (1193 vertebrae). In Cohort B from Hospital 2, CT images from 148 patients, comprising 887 vertebrae, indicated that 14.8% had fractures (131 vertebrae) and 85.2% were non-fractured (756 vertebrae). The AI model for lumbar spine fractures underwent two stages: vertebral body segmentation and fracture classification. The first stage utilized a 3D V-Net convolutional deep neural network, which produced a 3D segmentation map. From this map, region of each vertebra body were extracted and then input into the second stage of the algorithm. The second stage employed a 3D ResNet convolutional deep neural network to classify each proposed region as positive (fractured) or negative (not fractured). RESULTS: The AI model's accuracy for detecting vertebral fractures in Cohort A's training set (n = 1199), validation set (n = 157), and test set (n = 152) was 100.0 %, 96.2 %, and 97.4 %, respectively. For Cohort B (n = 148), the accuracy was 96.3 %. The area under the receiver operating characteristic curve (AUC-ROC) values for the training, validation, and test sets of Cohort A, as well as Cohort B, and their 95 % confidence intervals (CIs) were as follows: 1.000 (1.000, 1.000), 0.978 (0.944, 1.000), 0.986 (0.969, 1.000), and 0.981 (0.970, 0.992). The area under the precision-recall curve (AUC-PR) values were 1.000 (0.996, 1.000), 0.964 (0.927, 0.985), 0.907 (0.924, 0.984), and 0.890 (0.846, 0.971), respectively. According to the DeLong test, there was no significant difference in the AUC-ROC values between the test set of Cohort A and Cohort B, both for the overall data and for each specific vertebral location (all P>0.05). CONCLUSION: The developed model demonstrates promising diagnostic accuracy and applicability for detecting lumbar vertebral fractures.

Finite Element Analysis of Bilateral Double Rod Constructs in Thoracolumbar Fractures.

AIM: To evaluate bilateral double rod contructs in thoracolumbar fractures in a Finite Element model MATERIAL and METHODS: A computed tomography of a 35-year old male have been chosen to create a vertebra model and 1/3 of the T12 was removed to create the burst fracture model. In model A, transpedicular polyaxial screws were inserted two levels above and two levels below the burst fracture. On each side the screws were connected with a single rod. In model B, the screws were connected with two rods on each side attached to two lateral connectors. A uniform 150 N axial load and 10 N/m torque was applied on the superior T10. RESULTS: ROM and von Mises stress nephrograms revealed that the bilateral double-rod construct is being the most rigid and that the force on the pedicle screws were significantly lower compared to model A. CONCLUSION: We believe that bilateral double-rod constructs for the stabilization of thoracolumbar fractures have a decreased load on pedicle screws and rods compared to the classic bilateral single rod stabilization system and can lower the risk of implant failure and the risk for secondary complications and revision surgery.

[Robot-assisted versus traditional fluoroscopy-assisted posterior fixation in treatment of thoracolumbar fractures with ankylosing spondylitis: a retrospective study].

Objective: To compare the effectiveness of robot-assisted (RA) minimally invasive surgery versus traditional fluoroscopy-assisted (FA) open posterior fixation surgery in treating thoracolumbar fractures with ankylosing spondylitis (AS). Methods: A clinical data of 21 cases of thoracolumbar fractures with AS who met the selection criteria between December 2016 and December 2023 was retrospectively analyzed. Ten cases underwent RA minimally invasive surgery group (RA group) and 11 cases underwent FA open posterior fixation surgery (FA group). There was no significant difference in gender, age, fracture segment distribution, fracture type, time from injury to surgery, visual analogue scale (VAS) score, and American Spinal Injury Association (ASIA) grading between RA group and FA group ( P>0.05). The operation time, intraoperative blood loss, radiation exposure time, radiation dose, hospital stay, and complications of the two groups were recorded. According to Gertzbein-Robbins criteria, the accuracy of screw implantation was evaluated by CT within 1 week after surgery. During follow-up, pain and nerve function were evaluated by VAS score and ASIA grading. Results: All patients underwent surgery successfully, and there was no significant difference in operation time ( P>0.05). The intraoperative blood loss and hospital stay in the RA group were significantly less than those in the FA group ( P<0.05), and the radiation exposure time and radiation dose were significantly more than those in the FA group ( P<0.05). A total of 249 pedicle screws were implanted in the two groups, including 118 in the RA group and 131 in the FA group. According to the Gertzbein-Robbins criteria, the proportion of clinically acceptable screws (grades A and B) in the RA group was significantly higher than that in the FA group ( P<0.05). Patients in both groups were followed up 3-12 months, with an average of 6.8 months. The VAS scores of the two groups after surgery were significantly lower than those before surgery, and the differences were significant ( P<0.05). The RA group had lower scores than the fluoroscopy group at 1 week and 3 months after surgery ( P<0.05). There was no significant difference in neurological function grading between groups at 1 week and 3 months after surgery ( P>0.05). In the FA group, 1 case of deep infection and 1 case of deep vein thrombosis of lower extremity occurred, while no complication occurred in the RA group, and there was no significant difference in the incidence of complications between groups ( P>0.05). Conclusion: Both RA minimally invasive surgery and FA open posterior fixation surgery can achieve good effectiveness. Compared with the latter, the former has more advantages in terms of intraoperative blood loss, hospital stay, and accuracy of pedicle screw insertion.

Pars Interarticularis and Pedicle Stress Injuries in Young Athletes With Low Back Pain: A Retrospective Cohort Study of 902 Patients Evaluated With Magnetic Resonance Imaging.

BACKGROUND: Previous studies have reported that spondylolysis occurs predominantly at the L5 and L4 levels, with defects at higher levels occurring in <5% of cases. However, computed tomography and radiography were the primary imaging modalities in these studies. Current evidence regarding diagnostic imaging for pediatric lumbar spondylolysis suggests that magnetic resonance imaging (MRI) is as accurate as computed tomography in detecting early stress reactions of the pars interarticularis or pedicles without fractures while avoiding radiation exposure. The early detection of spondylolysis results in a higher likelihood of bony union and a decreased likelihood of spondylolisthesis. HYPOTHESIS: The increased use of MRI may reveal a larger proportion of spondylolysis in patients who experience an injury at a higher spinal level than previously reported. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: The medical records of 902 pediatric and adolescent athletes (364 female, 538 male) diagnosed with symptomatic pars interarticularis and pedicle stress injuries at 2 academic medical centers between 2016 and 2021 were retrospectively reviewed. All patients had MRI scans taken at the time of diagnosis. Only patients with pars/pedicle edema on MRI were included. Data regarding spondylolysis stage, spinal level of injury, unilateral versus bilateral injury, sport participation, and MRI protocol over the 5-year study period were analyzed. RESULTS: Male patients presented at older ages than female patients (P < .001). Soccer was the most common sport at symptom onset and the second most common single-sport activity among those who specialized (participating in 1 sport year-round at the exclusion of others), behind gymnastics. The mean symptom duration was 4.0 months. Although most patients (83.5%) had exclusively lower lumbar stress injuries, 9.1% of injuries occurred at or above the L3 level. Over half of the patients had active single-level pars/pedicle fractures on MRI, with a mean symptom duration before presentation in this subgroup of 4.0 months. Even when pars/pedicle stress reactions were excluded from analysis, 7.1% of patients were injured at or above the L3 level. CONCLUSION: Among male and female athletes aged 8 to 21 years presenting with symptomatic pars interarticularis and pedicle stress injuries evaluated by MRI at the time of initial diagnosis, there was a higher incidence of upper lumbar stress injuries than previously reported.

New Technique for Treatment of Spondylolysis and Contralateral Facet Fracture Using Navigation and Robotics: A Case Report.

CASE: A healthy 15-year-old male competitive hockey player presented with acute-on-chronic lower back pain was found to have a bilateral pars defect. After conservative treatment, subsequent computed tomography imaging demonstrated partial healing of the right-sided facet fracture but persistent left-sided pars fracture. A novel technique was performed, using robotic navigation to assist in laminar screw placement and to determine the optimal trajectory for subsequent microscopic surgery and bone grafting. CONCLUSION: Robotic navigation can be safely used to not only guide precise laminar screw placement for fixation and direct repair but also to provide guidance for microscopic tubular bone grafting of the pars defect.

Successful Management by Posterior Approach Only of a Highly Comminuted L4 Fracture with 8 years of Follow-up: A Case Report.

CASE: A 28-year old male patient was involved in a RTA and sustained a highly comminuted L4 burst fracture with more than 90% canal compromise.Considering the complete loss of power in the respective myotomes but the preservation of sacral sparing there were controversially different surgical options. We successfully performed a posterior only surgical procedure, which applied a modified transpedicle access technique to decompress the spinal canal and to restore the anterior column, achieving full neurological recovery at the final follow-up. CONCLUSION: A well-planned and executed posterior surgery alone can achieve excellent clinical and radiological result in the treatment of severely comminuted lumbar fractures.

Thoracolumbar fracture and spinal cord injury in blunt trauma: a systematic review, meta-analysis, and meta-regression.

Thoracolumbar (TL) fractures are among the most common vertebral fractures. These patients have high morbidity and mortality due to injury mechanisms and associated injuries. Spinal cord injury (SCI) is a prevalent complication of spinal fractures of the thoracolumbar region. AIM: To determine the pooled rate of thoracolumbar fractures and SCI in blunt trauma patients. METHODS: A systematic review and meta-analysis of observational studies were performed. The search was conducted in the PubMed, Scopus, Web of Science, and Embase databases. The authors screened and selected studies based on predefined inclusion and exclusion criteria. Studies were then evaluated for risk of bias using the JBI checklist. The pooled event rate and 95% confidence intervals (CI) were calculated using random effects models. Subgroup and meta-regression analyses were performed to explore sources of heterogeneity. RESULTS: Twenty-one studies fulfilled the selection criteria. The pooled rate of TL fractures was 8.08% (CI = 6.18-10.50%), with high heterogeneity (I2 = 99.98%, P < 0.001). Thoracic and lumbar fractures accounted for 45.23% and 59.01% of the TL fractures, respectively. Meta-regression revealed that the midpoint of the study period was a significant moderator. The pooled event rate of SCI among TL fracture patients was 15.81% (CI = 11.11 to 22.01%) with high heterogeneity (I2 = 98.31%, P < 0.001). The country of study was identified as a source of heterogeneity through subgroup analysis, and studies from the United States reported higher rates of SCI. Meta-regression revealed that the critical appraisal score was negatively associated with event rate. CONCLUSION: Our study evaluated the rate of TL fractures in multiple countries at different time points. We observed an increase in the rate of TL fractures over time. SCI results also seemed to vary based on the country of the original study.

Deep learning application of vertebral compression fracture detection using mask R-CNN.

Vertebral compression fractures (VCFs) of the thoracolumbar spine are commonly caused by osteoporosis or result from traumatic events. Early diagnosis of vertebral compression fractures can prevent further damage to patients. When assessing these fractures, plain radiographs are used as the primary diagnostic modality. In this study, we developed a deep learning based fracture detection model that could be used as a tool for primary care in the orthopedic department. We constructed a VCF dataset using 487 lateral radiographs, which included 598 fractures in the L1-T11 vertebra. For detecting VCFs, Mask R-CNN model was trained and optimized, and was compared to three other popular models on instance segmentation, Cascade Mask R-CNN, YOLOACT, and YOLOv5. With Mask R-CNN we achieved highest mean average precision score of 0.58, and were able to locate each fracture pixel-wise. In addition, the model showed high overall sensitivity, specificity, and accuracy, indicating that it detected fractures accurately and without misdiagnosis. Our model can be a potential tool for detecting VCFs from a simple radiograph and assisting doctors in making appropriate decisions in initial diagnosis.

Bilateral Back Extensor Exosuit for multidimensional assistance and prevention of spinal injuries.

Lumbar spine injuries resulting from heavy or repetitive lifting remain a prevalent concern in workplaces. Back-support devices have been developed to mitigate these injuries by aiding workers during lifting tasks. However, existing devices often fall short in providing multidimensional force assistance for asymmetric lifting, an essential feature for practical workplace use. In addition, validation of device safety across the entire human spine has been lacking. This paper introduces the Bilateral Back Extensor Exosuit (BBEX), a robotic back-support device designed to address both functionality and safety concerns. The design of the BBEX draws inspiration from the anatomical characteristics of the human spine and back extensor muscles. Using a multi-degree-of-freedom architecture and serially connected linear actuators, the device's components are strategically arranged to closely mimic the biomechanics of the human spine and back extensor muscles. To establish the efficacy and safety of the BBEX, a series of experiments with human participants was conducted. Eleven healthy male participants engaged in symmetric and asymmetric lifting tasks while wearing the BBEX. The results confirm the ability of the BBEX to provide effective multidimensional force assistance. Moreover, comprehensive safety validation was achieved through analyses of muscle fatigue in the upper and the lower erector spinae muscles, as well as mechanical loading on spinal joints during both lifting scenarios. By seamlessly integrating functionality inspired by human biomechanics with a focus on safety, this study offers a promising solution to address the persistent challenge of preventing lumbar spine injuries in demanding work environments.

A Prediction Nomogram for Fractured Vertebra Recollapse After Posterior Reduction and Pedicle Screw Fixation in Thoracolumbar Fractures.

OBJECTIVE: This study aimed to establish a predictive nomogram model for recollapse of fractured vertebra after posterior pedicle screw fixation in thoracolumbar fractures (TLFs). METHODS: Patients undergoing posterior pedicle screw fixation for TLFs at our hospital between January 2016 and December 2021 were retrospectively reviewed. Patients were divided into 2 groups according to the presence or absence of recollapse of the fractured vertebra at the final follow-up. The predictors for fractured vertebra recollapse were identified by univariate and multivariable logistic regression analysis, and a nomogram model was developed. The prediction performance and internal validation were established. RESULTS: A total of 224 patients were included in this study. Of these, 46 (20.5%) patients developed recollapse of fractured vertebra. Age, thoracic and lumbar injury severity score, screw distribution in the fractured vertebra, and anterior vertebral height compression ratio were associated with vertebral recollapse. These predictors were used to construct a predictive nomogram. The area under the receiver operating characteristic curve of the nomogram model was 0.891. The concordance index was 0.891, and it was 0.877 with bootstrapping validation. The calibration curves and decision curve analysis also suggested that the nomogram model had excellent predictive performances for fractured vertebra recollapse. CONCLUSIONS: A clinical nomogram incorporating 4 variables was constructed to predict fractured vertebra recollapse after posterior pedicle screw fixation for TLFs. The nomogram demonstrated good calibration and discriminative abilities, which may help clinicians to make better treatment decisions.

Evaluation and Management of Thoracolumbar Spine Trauma in Pediatric Patients: A Critical Analysis Review.

¼ Pediatric thoracolumbar trauma, though rare, is an important cause of morbidity and mortality and necessitates early, accurate diagnosis and management.¼ Obtaining a detailed history and physical examination in the pediatric population can be difficult. Therefore, the threshold for advanced imaging, such as magnetic resonance imaging, is low and should be performed in patients with head injuries, altered mental status, inability to cooperate with examination, and fractures involving more than 1 column of the spine.¼ The classification of pediatric thoracolumbar trauma is based primarily on adult studies and there is little high-level evidence examining validity and accuracy in pediatric populations.¼ Injury pattern and neurologic status of the patient are the most important factors when determining whether to proceed with operative management.

Effect of different lumbar-iliac fixation and sacral slope for Tile C1.3 pelvic fractures: a biomechanical study.

BACKGROUND: Lumbar-iliac fixation (LIF) is a common treatment for Tile C1.3 pelvic fractures, but different techniques, including L4-L5/L5 unilateral LIF (L4-L5/L5 ULIF), bilateral LIF (BLIF), and L4-L5/L5 triangular osteosynthesis (L4-L5/L5 TOS), still lack biomechanical evaluation. The sacral slope (SS) is key to the vertical shear of the sacrum but has not been investigated for its biomechanical role in lumbar-iliac fixation. The aim of this study is to evaluate the biomechanical effects of different LIF and SS on Tile C1.3 pelvic fracture under two-legged standing load in human cadavers. METHODS: Eight male fresh-frozen human lumbar-pelvic specimens were used in this study. Compressive force of 500 N was applied to the L4 vertebrae in the two-legged standing position of the pelvis. The Tile C1.3 pelvic fracture was prepared, and the posterior pelvic ring was fixed with L5 ULIF, L4-L5 ULIF, L5 TOS, L4-L5 TOS, and L4-L5 BLIF, respectively. Displacement and rotation of the anterior S1 foramen at 30° and 40° sacral slope (SS) were analyzed. RESULTS: The displacement of L4-L5/L5 TOS in the left-right and vertical direction, total displacement, and rotation in lateral bending decreased significantly, which is more pronounced at 40° SS. The difference in stability between L4-L5 and L5 ULIF was not significant. BLIF significantly limited left-right displacement. The ULIF vertical displacement at 40° SS was significantly higher than that at 30° SS. CONCLUSIONS: This study developed an in vitro two-legged standing pelvic model and demonstrated that TOS enhanced pelvic stability in the coronal plane and cephalad-caudal direction, and BLIF enhanced stability in the left-right direction. L4-L5 ULIF did not further improve the immediate stability, whereas TOS is required to increase the vertical stability at greater SS.

Surgical outcomes of robotic-assisted percutaneous fixation for thoracolumbar fractures in patients with ankylosing spondylitis.

BACKGROUND: Spinal fractures in patients with ankylosing spondylitis (AS) mainly present as instability, involving all three columns of the spine, and surgical intervention is often considered necessary. However, in AS patients, the significant alterations in bony structure and anatomy result in a lack of identifiable landmarks, which increases the difficulty of pedicle screw implantation. Therefore, we present the clinical outcomes of robotic-assisted percutaneous fixation for thoracolumbar fractures in patients with AS. METHODS: A retrospective review was conducted on a series of 12 patients diagnosed with AS. All patients sustained thoracolumbar fractures between October 2018 and October 2022 and underwent posterior robotic-assisted percutaneous fixation procedures. Outcomes of interest included operative time, intra-operative blood loss, complications, duration of hospital stay and fracture union. The clinical outcomes were assessed using the visual analogue scale (VAS) and Oswestry Disability Index (ODI). To investigate the achieved operative correction, pre- and postoperative radiographs in the lateral plane were analyzed by measuring the Cobb angle. RESULTS: The 12 patients had a mean age of 62.8 ± 13.0 years and a mean follow-up duration of 32.7 ± 18.9 months. Mean hospital stay duration was 15 ± 8.0 days. The mean operative time was 119.6 ± 32.2 min, and the median blood loss was 50 (50, 250) ml. The VAS value improved from 6.8 ± 0.9 preoperatively to 1.3 ± 1.0 at the final follow-up (P < 0.05). The ODI value improved from 83.6 ± 6.1% preoperatively to 11.8 ± 6.6% at the latest follow-up (P < 0.05). The average Cobb angle changed from 15.2 ± 11.0 pre-operatively to 8.3 ± 7.1 at final follow-up (P < 0.05). Bone healing was consistently achieved, with an average healing time of 6 (5.3, 7.0) months. Of the 108 screws implanted, 2 (1.9%) were improperly positioned. One patient experienced delayed nerve injury after the operation, but the nerve function returned to normal upon discharge. CONCLUSION: Posterior robotic-assisted percutaneous internal fixation can be used as an ideal surgical treatment for thoracolumbar fractures in AS patients. However, while robot-assisted pedicle screw placement can enhance the accuracy of pedicle screw insertion, it should not be relied upon solely.