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Introduction Challenges of treating the injuries of pubic symphysis in patients with combined pelvic injury require developing new techniques for stable minimally invasive osteosynthesis in the acute period of trauma. Purpose of the work was to assess the application of low invasive fixation of the pubic symphysis with a system of transpedicular screws in the patients with combined unstable pelvic injuries in the acute period of the traumatic disease. Materials and methods The results of treatment of 12 patients with polytrauma with unstable pelvic injury with rupture of the pubic symphysis who were treated at Dzhanelidze Research Institute of Emergency Medicine, St. Petersburg, in the period from 2017 to 2023, were analyzed. All the patients underwent final minimally invasive fixation of the pubic symphysis with a system of transpedicular screws in the early period of the traumatic disease. Results The overall assessment of the results in 12 patients found no complications or technical errors during the installation of transpedicular screws. Control CT scans of the pelvis showed that osteosynthesis was stable in all patients, and the position of metal was correct in all. One patient from the study group died in the clinic from massive pulmonary embolism. The long-term results in 11 patients in the period from 6 months to 3 years after trauma were evaluated as excellent and good anatomical and functional results in 10 patients, one case had fair outcome. Discussion The use of bone plates to fix ruptures of the symphysis pubis leads to disruption of its physiological mobility, and the patient’s activity in the postoperative period can cause an implant fracture. Original dynamic plates and wire cerclage help avoid this complication; however, all these techniques involve significant surgical trauma and blood loss, as well as the risk of postoperative wound suppuration. Minimally invasive methods of fixation using cannulated screws, systems such as Endobutton, Tight Rope can reduce intraoperative trauma and the risk of complications (blood loss, suppuration); however, the procedure for their installation is quite complex and lengthy, and for greater stability, external fixation of the pelvic ring is often required. The proposed minimally invasive fixation of the pubic symphysis with a system of transpedicular screws avoids a lot of shortcomings and is sufficiently stable. Conclusion The method of minimally invasive fixation of the pubic symphysis with a system of transpedicular screws meets current requirements in the treatment of patients with polytrauma and unstable pelvic injury, and it may be successfully used in the acute period of trauma.

Abstract Background Minimally invasive posterior fixation surgery for pyogenic spondylitis is known to reduce invasiveness and complication rates; however, the outcomes of concomitant insertion of pedicle screws (PS) into the infected vertebrae via the posterior approach are undetermined. This study aimed to assess the safety and efficacy of PS insertion into infected vertebrae in minimally invasive posterior fixation for thoracolumbar pyogenic spondylitis. Methods This multicenter retrospective cohort study included 70 patients undergoing minimally invasive posterior fixation for thoracolumbar pyogenic spondylitis across nine institutions. Patients were categorized into insertion and skip groups based on PS insertion into infected vertebrae, and surgical data and postoperative outcomes, particularly unplanned reoperations due to complications, were compared. Results The mean age of the 70 patients was 72.8 years. The insertion group (n = 36) had shorter operative times (146 versus 195 min, p = 0.032) and a reduced range of fixation (5.4 versus 6.9 vertebrae, p = 0.0009) compared to the skip group (n = 34). Unplanned reoperations occurred in 24% (n = 17) due to surgical site infections (SSI) or implant failure; the incidence was comparable between the groups. Poor infection control necessitating additional anterior surgery was reported in four patients in the skip group. Conclusions PS insertion into infected vertebrae during minimally invasive posterior fixation reduces the operative time and range of fixation without increasing the occurrence of unplanned reoperations due to SSI or implant failure. Judicious PS insertion in patients with minimal bone destruction in thoracolumbar pyogenic spondylitis can minimize surgical invasiveness.

Abstract Background In spinal revision surgery, previous pedicle screws (PS) may need to be replaced with new implants. Failure to accurately identify the brand of PS‐based instrumentation preoperatively may increase the risk of perioperative complications. This study aimed to develop and validate an optimal deep learning (DL) model to identify the brand of PS‐based instrumentation on plain radiographs of spine (PRS) using anteroposterior (AP) and lateral images. Methods A total of 529 patients who received PS‐based instrumentation from seven manufacturers were enrolled in this retrospective study. The postoperative PRS were gathered as ground truths. The training, validation, and testing datasets contained 338, 85, and 106 patients, respectively. YOLOv5 was used to crop out the screws' trajectory, and the EfficientNet‐b0 model was used to develop single models (AP, Lateral, Merge, and Concatenated) based on the different PRS images. The ensemble models were different combinations of the single models. Primary outcomes were the models' performance in accuracy, sensitivity, precision, F1‐score, kappa value, and area under the curve (AUC). Secondary outcomes were the relative performance of models versus human readers and external validation of the DL models. Results The Lateral model had the most stable performance among single models. The discriminative performance was improved by the ensemble method. The AP + Lateral ensemble model had the most stable performance, with an accuracy of 0.9434, F1 score of 0.9388, and AUC of 0.9834. The performance of the ensemble models was comparable to that of experienced orthopedic surgeons and superior to that of inexperienced orthopedic surgeons. External validation revealed that the Lat + Concat ensemble model had the best accuracy (0.9412). Conclusion The DL models demonstrated stable performance in identifying the brand of PS‐based instrumentation based on AP and/or lateral images of PRS, which may assist orthopedic spine surgeons in preoperative revision planning in clinical practice.

Introduction: Transpedicular screw placement has superior pullout strength compared to alternative forms of spinal fusion and is often performed in deformity correction surgery with navigation for optimal accuracy and reliability. Freehand technique for pedicle screws minimizes operation time and radiation exposure without fluoroscopy but is not widely adopted given the challenge of difficult anatomical corridors and accurate placement, especially in idiopathic scoliosis and advanced deformity. We used a computer-generated model to assess a proof-of-concept and anatomical feasibility of a freehand screw technique in severe scoliosis. Methods: Three-dimensional (3D) reconstructions of vertebra from a sample of two male patients with severe idiopathic scoliosis deformity (1 thoracic and 1 lumbar) with Cobb angles of 100° were used for planned placement of 17 levels of thoracolumbar (6.5 mm × 45 mm) pedicle screws. 3D reconstruction of each vertebra was created and measurements of screw entries and trajectories were reproduced with a 3D slicer software image computing platform. Results: Accurate transpedicular screw placement is possible with anatomical landmarks based on the 3D reconstructed vertebral levels. A series of 5 figures were assembled to demonstrate sagittal, coronal, and axial planes and key anatomical landmarks and trajectories of thoracic and lumbar freehand pedicle screws in severe idiopathic scoliosis. Conclusions: Anatomical landmarks for freehand transpedicular screw placement (between pedicle, lamina, and superior articulating process) are constant and reliable in severe idiopathic scoliosis as evidenced by 3D computer modeling. Preoperative computed tomography modeling may assist appropriate screw entry and trajectory based on anatomical landmarks for spine surgeons, and guide freehand technique for screw placement in adolescent idiopathic scoliosis.

Introduction: To compare post-operative outcomes of percutaneous pedicle screw fixation (PPSF) vs open pedicle screw fixation (OPSF) in patients with thoracolumbar spine fractures with no neurological deficits. Materials and methods: In a randomised controlled trial, patients received short-segment fixation with intermediate screws. We assessed post-operative back pain (Visual Analog Scale or VAS), blood loss, operative/fluoroscopy times, radiographic parameters, and oswestry disability index (ODI) scores at 1, 2, 3, 6, 9, and 12 months. Results: Between January 2018 and October 2019, 31 patients received PPSF and 30 OPSF. Mean intra-operative blood loss was 66.45 (±44.29) ml for PPSF vs 184.83 (±128.36) ml for OPSF (p

Objective This study aimed to assess the degree of interest in robot-assisted spine surgery (RASS) among residents and to investigate the learning curve for beginners performing robotic surgery. Methods We conducted a survey to assess awareness and interest in RASS among young neurosurgery residents. Subsequently, we offered a hands-on training program using a dummy to educate one resident. After completing the program, the trained resident performed spinal fusion surgery with robotic assistance under the supervision of a mentor. The clinical outcomes and learning curve associated with robotic surgery were then analyzed. Results Neurosurgical residents had limited opportunities to participate in spinal surgery during their training. Despite this, there was a significant interest in the emerging field of robotic surgery. A trained resident performed RASS under the supervision of a senior surgeon. A total of 166 screw insertions were attempted in 28 patients, with 2 screws failing due to skiving. According to the Gertzbein-Robbins classification, 85.54% of the screws were rated as grade A, 11.58% as grade B, 0.6% as grade C, and 1.2% as grade D. The clinical acceptance rate was approximately 96.99%, which is comparable to the results reported by senior experts and time per screw statistically significantly decreased as experience was gained. Conclusion RASS can be performed with high accuracy within a relatively short timeframe, if residents receive adequate training.

BackgroundCervical spinal fusion surgeries require accurate placement of the pedicle screws. Any misplacement/misalignment of these screws may lead to injuries to the spinal cord, arteries and other organs. Template guides have emerged as accurate and cost-effective tools for the safe and rapid insertions of pedicle screws.Questions/PurposesNovel patient-specific single- and multi-level non-covering templates for cervical pedicle screw insertions were designed, 3D-printed, and evaluated.MethodsCT scans of two patients were acquired to reconstruct their 3D spine model. Two sets of single-level (C3-C7) and multi-level (C4-C6) templates were designed and 3D-printed. Pedicle screws were inserted into the 3D-printed vertebrae by free-hand and guided techniques. For single-level templates, a total of 40 screws (2 patients × 5 vertebrae × 2 methods × 2 screws) and for multi-level templates 24 screws (2 patients × 3 vertebrae × 2 methods × 2 screws) were inserted by an experienced surgeon. Postoperative CT images were acquired to measure the errors of the entry point, 3D angle, as well as axial and sagittal plane angles of the inserted screws as compared to the initial pre-surgery designs. Accuracy of free-hand and guided screw insertions, as well as those of the single- and multi-level guides, were also compared using paired t-tests.ResultsDespite the minimal removal of soft tissues, the 3D-printed templates had acceptable stability on the vertebrae during drillings and their utilization led to statistically significant reductions in all error variables. The mean error of entry point decreased from 3.02 mm (free-hand) to 0.29 mm (guided) using the single-level templates and from 5.7 mm to 0.76 mm using the multi-level templates. The percentage reduction in mean of other error variables for, respectively, single- and multi-level templates were as follows: axial plane angle: 72% and 87%, sagittal plane angle: 56% and 78%, and 3D angle: 67% and 83%. The error variables for the multi-level templates generally exceeded those of the single-level templates. The use of single- and multi-level templates also considerably reduced the duration of pedicle screw placements.ConclusionThe novel single- and multi-level non-covering templates are valuable tools for the accurate placement of cervical pedicle screws.

Lumbar disc herniation with dorsal epidural migration is a rare clinical condition that can present with severe neurological deficit and cauda equina syndrome. Diagnosis poses a challenge as it mimics other dorsal epidural pathologies like tumors, cysts, and abscesses. Timely diagnosis and early surgical intervention with wide decompression can improve the neurological outcome. Minimally invasive technique has the advantage of minimal muscle damage, early rehabilitation, and equal clinical outcomes to those of standard laminectomy. In this report, we describe a case of a 63-year-old male with lumbar disc herniation at L3-L4 level with foraminal extension and dorsal epidural migration with neurological deficit managed by minimally invasive microtubular decompression and spinal stabilization.

Pedicle screw fixation technique has been established as the safe standard for instrumentations in all spinal regions. However, the screw position is sometimes suboptimal. Cortical breaches may occur in different regions of the vertebrae. In addition to compromising bone purchase, pedicle perforations may endanger neural, vascular, and visceral structures. Moreover, a mispositioned screw can result in a greater risk of instrumentation failure. The accuracy of screw insertion has become a frequent topic of recent publications on spine surgery. Despite that, there is no unified way of reporting pedicle screws position. Several different scales are used. Given the multitude of used classifications and rarity of reported complications exact clinical relevance of pedicle screw misplacements remain unclear. In this article, the authors review types of scoring systems and propose a structured way for pedicle screw position grading based on a combination of the most used classifications.

This literature review aimed to review the current understanding, indications, and limitations of pedicle screw instrumentation cement augmentation. Since they were first reported in the 1980s, pedicle screw cement augmentation rates have been increasing. Several studies have been published to date that describe various surgical techniques and the biomechanical changes that occur when cement is introduced through the screw-bone interface. This article provides a concise review of the uses, biomechanical properties, cost analysis, complications, and surgical techniques used for pedicle screw cement augmentation to help guide physician practices. A comprehensive review of the current literature was conducted, with key studies, and contributions from throughout history being highlighted. Patients with low bone mineral density are the most well-studied indication for pedicle screw cement augmentation. Many studies show that cement augmentation can improve pullout strength in patients with low bone mineral density; however, the benefit varies inversely with pathology severity and directly with technique. The various screw types are discussed, with each having its own mechanical advantages. Cement distribution is largely dependent on the filling method and volume of cement used. Cement composition and timing of cement use after mixing are critical considerations in practice because they can significantly alter the bone-cement and screw-cement interfaces. Overall, studies have shown that pedicle screw cement augmentation has a low complication rate and increased pullout strength, justifying its universal use in patients with a suboptimal bone-implant interface.

Objective To evaluate the clinical and radiological efficacy of a combine of lateral single screw-rod and unilateral percutaneous pedicle screw fixation (LSUP) for lateral lumbar interbody fusion (LLIF) in the treatment of spondylolisthesis. Methods Sixty-two consecutive patients with lumbar spondylolisthesis who underwent minimally invasive (MIS)-TLIF with bilateral pedicle screw (BPS) or LLIF-LSUP were retrospectively studied. Segmental lordosis angle (SLA), lumbar lordosis angle (LLA), disc height (DH), slipping percentage, the cross-sectional areas (CSA) of the thecal sac, screw placement accuracy, fusion rate and foraminal height (FH) were used to evaluate radiographic changes postoperatively. Visual analogue scale (VAS) and Oswestry Disability Index (ODI) were used to evaluate the clinical efficacy. Results Patients who underwent LLIF-LSUP showed shorter operating time, less length of hospital stay and lower blood loss than MIS-TLIF. No statistical difference was found between the 2 groups in screw placement accuracy, overall complications, VAS, and ODI. Compared with MIS-TLIF-BPS, LLIF-LSUP had a significant improvement in sagittal parameters including DH, FH, LLA, and SLA. The CSA of MIS-TLIF-BPS was significantly increased than that of LLIF-LSUP. The fusion rate of LLIF-LSUP was significantly higher than that of MIS-TLIF-BPS at the follow-up of 3 months postoperatively, but there was no statistical difference between the 2 groups at the follow-up of 6 months, 9 months, and 12 months. Conclusion The overall clinical outcomes and complications of LLIF-LSUP were comparable to that of MIS-TLIF-BPS in this series. Compared with MIS-TLIF-BPS, LLIF-LSUP for lumbar spondylolisthesis represents a significantly shorter operating time, hospital stay and lower blood loss, and demonstrates better radiological outcomes to maintain lumbar lordosis, and reveal an overwhelming superiority in the early fusion rate.

Objective The objective of this study was to evaluate the accuracy of pedicle screw placement in patients undergoing percutaneous pedicle screw fixation with robotic guidance, using a newly developed 3-dimensional quantitative measurement system. The study also aimed to assess the clinical feasibility of the robotic system in the field of spinal surgery. Methods A total of 113 patients underwent pedicle screw insertion using the CUVIS-spine pedicle screw guide system (CUREXO Inc.). Intraoperative O-arm images were obtained, and screw insertion pathways were planned accordingly. Image registration was performed using paired-point registration and iterative closest point methods. The accuracy of the robotic-guided pedicle screw insertion was assessed using 3-dimensional offset calculation and the Gertzbein-Robbins system (GRS). Results A total of 448 screws were inserted in the 113 patients. The image registration success rate was 95.16%. The average error of entry offset was 2.86 mm, target offset was 2.48 mm, depth offset was 1.99 mm, and angular offset was 3.07°. According to the GRS grading system, 88.39% of the screws were classified as grade A, 9.60% as grade B, 1.56% as grade C, 0.22% as grade D, and 0.22% as grade E. Clinically acceptable screws (GRS grade A or B) accounted for 97.54% of the total, with no reported neurologic complications. Conclusion Our study demonstrated that pedicle screw insertion using the novel robot-assisted navigation method is both accurate and safe. Further prospective studies are necessary to explore the potential benefits of this robot-assisted technique in comparison to conventional approaches.

Background: Percutaneous pedicle screw fixation [PPSF], where screws are inserted through small holes in the skin, has become a popular approach for treating thoracolumbar and lumbar fractures. It has been shown to produce satisfactory outcomes.Aim of the work: The aim was to examine the procedure and assess the practicality, safety and results of using PPSF to treat thoracolumbar fractures.Patients and Methods: A prospective cohort study included 20 patients with thoracic or lumbar spine fracture, without neurological deficit, whom were operated upon by percutaneous screw fixation, and were assessed clinically [for improvement and development of complications] and radiologically [for healing and correction of deformity] by follow up over 6 months after surgery.Results: All cases achieved full radiological union by 3 months. The mean union time in our cohort was 2.1±0.5 months. Postoperatively, a statistically significant improvement in the vertebral kyphotic angle to a mean value of 4.7 ± 2.3 was observed [Bonferroni post-hoc test, P = 0.001]. The correction was maintained till last follow-up. Two patients [10%] developed incomplete paraplegia [Frankel grade D]. Misplacement of the pedicle screws was recorded in 6 of 90 screws in six patients.Conclusion: The PPSF is a valuable surgical procedure for patients with thoracic and lumbar vertebral fracture.

Objective To compare the efficacy of oblique lateral interbody fusion (OLIF), OLIF combined with anterolateral screw fixation (OLIF-AF), and OLIF combined with percutaneous pedicle screw fixation (OLIF-PF) in the treatment of single-level or 2-level degenerative lumbar disease. Methods Between January 2017 and 2021, 71 patients were treated with OLIF and combined OLIF. The demographic data, clinical outcomes, radiographic outcomes, and complications were compared among the 3 groups. Results The operative time and intraoperative blood loss in the OLIF (p0.05) or between the OLIF and OLIF-AF groups (p>0.05). There were no significant differences in fusion rates, the incidence of complications, lumbar lordosis, anterior disc height, and cross-sectional area among the 3 groups (p>0.05). The OLIF-PF group had significantly lower rates of subsidence than the OLIF group (p

Objective It is clinically important for pedicle screws to be placed quickly and accurately. Misplacement of pedicle screws results in various complications. However, the incidence of complications varies greatly due to the different professional titles of physicians and surgical experience. Therefore, physicians must minimize pedicle screw dislocation. This study aims to compare the three nail placement methods in this study, and explore which method is the best for determining the anatomical landmarks and vertical trajectories. Methods This study involved 70 patients with moderate idiopathic scoliosis who had undergone deformity correction surgery between 2018 and 2021. Two spine surgeons used three techniques (preoperative computed tomography scan [CTS], visual inspection‐X‐freehand [XFH], and intraoperative detection [ID] of anatomical landmarks) to locate pedicle screws. The techniques used include visual inspection for 287 screws in 21 patients, preoperative planning for 346 screws in 26 patients, and intraoperative probing for 309 screws in 23 patients. Observers assessed screw conditions based on intraoperative CT scans (Grade A, B, C, D). Results There were no significant differences between the three groups in terms of age, sex, and degree of deformity. We found that 68.64% of screws in the XFH group, 67.63% in the CTS group, and 77.99% in the ID group were placed within the pedicle margins (grade A). On the other hand, 6.27% of screws in the XFH group, 4.33% in the CTS group, and 6.15% in the ID group were considered misplaced (grades C and D). The results show that the total amount of upper thoracic pedicle screws was fewer, meanwhile their placement accuracy was lower. The three methods used in this study had similar accuracy in intermediate physicians (P > 0.05). Compared with intermediate physicians, the placement accuracy of three techniques in senior physicians was higher. The intraoperative detection group was better than the other two groups in the good rate and accuracy of nail placement (P

Study Design This study was a retrospective case series. Purpose This study was designed to determine whether direct vertebral rotation (DVR) of the lowest instrumented vertebra (LIV) using a high-density (HD) construct can reduce fusion segments without increasing adverse outcomes in selective thoracic fusion (STF) for adolescent idiopathic scoliosis (AIS). Overview of Literature LIV DVR is used to maximize spontaneous lumbar curve correction and reduce adverse outcomes during STF for AIS. However, evidence is limited on whether LIV DVR can allow a proximally located LIV and reduce fusion segments without increasing adverse outcomes. Methods We reviewed consecutive patients with Lenke 1 AIS who underwent STF from 2000 to 2017. The patients were divided into two groups based on the surgical strategy used: low-density (LD) construct without DVR of the LIV (LD group) versus HD construct with DVR of the LIV (HD group). We collected data on the patient’s demographic characteristics, skeletal maturity, operative data, and measured radiological parameters in the preoperative and final follow-up radiographs. The occurrence of adding-on (AO) and coronal decompensation was also determined. Results In this study, 72 patients (five males and 67 females) with a mean age of 14.1±2.3 years were included. No significant differences in the demographics, skeletal maturity, and Lenke type distribution were observed between the two groups; however, the follow-up duration was significantly longer in the LD group (64.3±25.7 months vs. 40.7±22.2 months, p

This study was designed to systematically review and meta-analyze the functional and radiological outcomes between lateral and posterior approaches in adult degenerative scoliosis (ADS). Both lateral (lumbar, extreme, and oblique) and posterior interbody fusion (posterior lumbar and transforaminal) are used for deformity correction in patients with ADS with unclear comparison in this cohort of patients in the existing literature. A literature search using three electronic databases was performed to identify studies that reported outcomes of lateral (group L) and posterior interbody fusion (group P) in patients with ADS with curves of 10°–40°. Group P was further subdivided into minimally invasive surgery (MIS-P) and open posterior (Op-P) subgroups. Data on functional, radiological, and operative outcomes, length of hospital stay (LOHS), fusion rates, and complications were extracted and meta-analyzed using the random-effects model. A total of 18 studies (732 patients) met the inclusion criteria. No significant difference was found in functional and radiological outcomes between the two groups on data pooling. Total operative time in the MIS-P subgroup was less than that of group L (233.86 minutes vs. 401 minutes, p

Percutaneous pedicle screw fixation (PSF) has emerged as a promising alternative to traditional open surgical approaches for spinal stabilization. Pedicle screws are inserted through percutaneous access sites without substantial soft tissue dissection. To ensure proper screw insertion, the procedure employs fluoroscopic or image-guided navigation devices. The popularity of percutaneous PSF has accelerated because of its prospective advantages and the mounting body of research demonstrating its effectiveness and safety. However, there are a few drawbacks to the procedure, such as a longer learning curve for surgeons, poor visibility when inserting screws, and a requirement for specialized tools and imaging guiding systems. This article provides a comprehensive review of the technique of percutaneous PSF, its clinical outcomes, and recent advancements in the field. It also aims to analyze the efficacy, safety, and limitations of percutaneous PSF, as well as explore the evolving technologies and techniques that have contributed to its improved application.

Study Design This is a finite element study. Purpose This study is aimed to compare the biomechanical behaviors of three screw-based atlantoaxial fixation techniques. Overview of Literature Screw-based constructs that are widely used to stabilize the atlantoaxial joint come with their own challenges in surgery. Clinical and in vitro studies have compared the effectiveness of screw-based constructs in joint fixation. Nevertheless, there is limited information regarding the biomechanical behavior of these constructs, such as the stresses and strains they experience. Methods A finite element model of the upper cervical spine was developed. A type II dens fracture was induced in the intact model to produce the injured model. The following three constructs were simulated on the intact and injured models: transarticular screw (C1–C2TA), lateral mass screw in C1 and pedicle screw in C2 (C1LM1–C2PD), and lateral mass screw in C1 and translaminar screw in C2 (C1LM1–C2TL). Results In the intact model, flexion–extension range of motion (ROM) was reduced by up to 99% with C11–C2TA and 98% with C1LM1–C2PD and C1LM1–C2TL. The lateral bending ROM in the intact model was reduced by 100%, 95%, and 75% with C11–C2TA, C1LM1–C2PD, and C1LM1–C2TL, respectively. The axial rotation ROM in the intact model was reduced by 99%, 98%, and 99% with C11–C2TA, C1LM1–C2PD, and C1LM1–C2TL, respectively. The largest maximum von Mises stress was predicted for C1LM1–C2TL (332 MPa) followed by C1LM1–C2PD (307 MPa) and C11–C2TA (133 MPa). Maximum stress was predicted to be at the lateral mass screw head of the C1LM1–C2TL construct. Conclusions Our model indicates that the biomechanical stability of the atlantoaxial joint in lateral bending with translaminar screws is not as reliable as that with transarticular and pedicle screws. Translaminar screws experience large stresses that may lead to failure of the construct before the required bony fusion occurs.

Objective Spinal fractures often have devastating sequelae. Thoracolumbar fractures are classified using the Thoracolumbar Injury Classification and Severity score (TLICS) to determine the severity of injury and to guide treatment. Recently advancements in minimally invasive spine surgery (MISS) have led to new approaches to high-severity fractures. Studies have suggested that MISS may yield similar outcomes to conventional, more invasive procedures while producing several benefits. Methods This retrospective study involves 46 patients treated from 2005 through 2020 for high grade thoracolumbar trauma from T2 to L5 with a minimum follow-up of 6-months treated with MISS techniques using percutaneous instrumentation. Results Average TLICS was 7.5. Patient derived outcome measures with average length of follow-up of 602 days included Oswestry Disability Index 28.9, Patient Satisfaction Index 4.2, Short Form-12 Mental Component Score 51.9, and Short Form-12 Physical Component Score 37.7. Average estimated blood loss was 119.2 mL. Conclusion The TLICS is a validated tool used to guide surgical intervention in high grade trauma. The utilization of MISS techniques for the treatment and stabilization of thoracolumbar trauma is efficacious and a viable alternative to traditional open approaches.

Objectives: To investigate the prevalence and risk factors of the misplacement of the pedicle screw in patients with thoracolumbar spine fracture. Methods: Patients who underwent posterior stabilization procedure due to thoracolumbar spine fracture were included. Association between potential risk factors and the misplacement of the pedicle screw were evaluated by logistic regression analysis. Results: A total of 88 consecutive patients with thoracolumbar spine fracture who underwent posterior stabilization surgery using pedicle screws and rods (mean age 43 ± 14, male 52.3 %). On post-operation CT evaluation, 98 (14.8 %) pedicle screws were misplaced (34 thoracic screws and 64 lumbar screws) and the prevalence of the misplaced pedicle screw was not significantly different between thoracic and lumbar screws (13.2 % vs. 15.8 %, p = 0.347). Among risk factors including location of spine fracture, multiple spine fracture and location of screws, the AO classification of spine fracture was significantly associated with the misplacement of the pedicle screw (OR = 1.27, 95 % CI 1.06 - 1.53, p = 0.011). Conclusion: High grade spine fracture, as assessed by the AO classification, was significantly associated with pedicle screw misplacement in patients with thoracolumbar spine fracture.

Objective: Posterior screw fixation via a C1 lateral mass screw combined with a C2 pedicle screw is a well-known technique for atlantoaxial instability. However, screw malposition can occur because of the complex anatomical structure of this region. This study aimed to evaluate the accuracy and risk factors of cortical breach following the C1 lateral mass and/or C2 pedicle screw insertion using a preoperative computed tomography (CT)-based navigation system with a single-level vertebral registration method. Methods: This retrospective cohort study included patients who had undergone a C1 lateral mass and/or a C2 pedicle screw placement using a preoperative CT-based navigation system from January 2013 to March 2020 from the university hospital. The extent of screw deviation was classified as: within the pedicle (grade 0), out of pedicle 4 mm (grade III). The risk of cortical breach was evaluated using multivariate analysis. Results: Seventy-eight C1 lateral masses and 71 C2 pedicle screws were inserted into 42 patients. The accuracy of screw placement was as follows: 133 grade 0 (89.3 %), 14 grade I (9.4 %), and two grade II (1.3 %). No screws required repositioning, and no vertebral artery injury or neurological deficit was associated with this technique. Additionally, a diameter of

Objective. To analyze intraoperative data and results of treatment of patients with idiopathic scoliosis with two options of the open insertion of pedicle screws using the free-hand technique. Material and Methods. The data of 457 patients aged 16–35 years who underwent surgical treatment for idiopathic scoliosis by one surgeon were analyzed. In 236 patients (Group I), the screws were placed manually, and in 221 (Group II) – using power tool. The preparation of the canal for pedicle screws in both groups was performed using the free-hand technique. The correct position of the screws was assessed intraoperatively using an image intensifier and neurophysiological monitoring. The duration of surgery and X-ray monitoring, blood loss, and the presence of intra- and postoperative complications were assessed. Results. In Group I, 4243 screws were inserted, and in Group II – 3978. The correct position of pedicle screws was recorded in 89.1 % of cases in Group I, and in 89.6 % of cases in Goup II. In Group I, the incorrect position of anchor elements was detected in 10.9 % of cases, and in Group II – in 10.4 % of cases. The number of screws re-positioned intraoperatively corresponded to the number of incorrectly positioned screws. There was a statistically significant difference in the volume of intraoperative blood loss and duration of surgery between patients of both groups (p < 0.05). Conclusion. The development and active introduction of high-tech methods of surgical treatment of spinal deformities increase the number of interventions performed annually. The proposed combined method of surgical treatment seems to be optimal because manual formation of the canal reduces the risk of intraoperative complications, and the use of power tool during screw placement shortens duration of surgery and reduces blood loss.

Study Design Retrospective cohort study. Purpose To determine whether implant density impact three-dimensional deformity correction in posterior spinal fusion (PSF) without Ponte osteotomies (POs) for patients with Lenke 1 and 2 adolescent idiopathic scoliosis (AIS). Overview of Literature Currently, the optimal pedicle screw (PS) density for flexible moderate-sized thoracic AIS curve correction is still controversial. There are limited data regarding the impact of implant density on three-dimensional correction in PSF without the use of PO for thoracic AIS surgery. Methods A database of patients with AIS with Lenke 1 and 2 curves treated with PSF without PO and instrumented with PSs and ≥2-year follow-up was reviewed. The preoperative, immediate, and final follow-up postoperative radiographs were analyzed. The correlation between PS density and the following factors were determined: major curve correction (MCC), correction index (CI; MCC/curve flexibility), kyphosis angle change, and rib index (RI) correction. Then, patients were divided into low-density (LD) and high-density (HD) groups according to mean PS density for the entire cohort (1.5 PS per level). Demographics and radiographic and clinical outcomes were compared between groups. Results The study included 99 patients with Lenke 1 and 23 patients with Lenke 2 AIS. The average MCC was 67.2%. There was no correlation between screw density and these parameters: MCC (r=0.10, p=0.26), CI (r=0.16, p=0.07), change in T2–T12 kyphosis angle (r=−0.13, p=0.14), and RI correction (r=−0.09, p=0.37). Demographic and preoperative radiographic parameters were similar between the LD and HD groups. At the latest follow-up, there were no differences between the two groups in regard to MCC, CI, change in T2–T12 kyphosis angle, RI correction, and Scoliosis Research Society-30 scores (all p>0.05). Conclusions This study revealed no significant correlation between screw density and curve correction in any planes. HD construct may not provide better deformity correction in patients with flexible and moderate thoracic AIS undergoing PSF without PO.

conventional open pedicle screw fixation (OPSF) with desirable radiological and clinical outcomes. Studies in the Indian context are required to determine the efficiency of MIS over OPSF. Objective To compare restoration and maintenance of vertebral body height (VBH) following MIS versus OPSF. Methods A prospective comparative study was conducted in a tertiary care hospital. Patients (n= 36) aged 18–65 years (males = 23, females = 13) with traumatic TL fractures were identified. Eighteen of them underwent OPSF and other eighteen underwent MIS. The radiological outcomes like anterior and posterior vertebral body height percentage (AVBH % and PVBH %) restoration and maintenance were evaluated. Quantitative variables were analyzed and described using mean ± standard deviation and qualitative variables were presented using frequency and percentage. Student t-test was used to analyse continuous data and Chi-square/Fisher Exact test was used to analyse categorical data. Results The mean age of the patients was 38.8 years. The majority of fractures were seen in the T12-LI segment (52.7 %). The AVBH % restoration and maintenance in OPSF was significantly higher compared to that of MIS at immediate post-operative (IPO) period (p = 0.01), 6 weeks (p = 0.02) and 12 weeks (p = 0.006) post-surgery. Long segment stabilization provided statistically significant AVBH and PVBH values for OPSF compared to MIS (p < 0.05). The presence or absence of pedicle screw at fractured vertebral level did not restore AVBH and PVBH to a statistically significant level in both the groups (p > 0.05). Superficial surgical site infection (SSSI) was seen in both the groups without any statistical significance between them (p > 0.05). Conclusion OPSF is superior over MIS in the restoration of AVBH. Restoration of PVBH was also better with OPSF although not statistically significant. OPSF with longer segment fixation had better restoration of both AVBH and PVBH. The presence or absence of pedicle screw at fractured vertebral level did not seem to have any significance in both the groups. However, the MIS approach can be a reasonable alternative to open surgery with potential advantages like better clinical and functional outcome. A selected population of patients treated with MIS will show better surgical outcomes.

Intraoperative pedicle screw depth adjustment after initial insertion, including both forward and backward adjustments, is sometimes necessary to facilitate rod application and ensure that the screw is in the correct position, which is determined by intraoperative fluoroscopy. Adjusting the screw with forward turns has no negative influence on the screw fixation stability; however, screw turnback may weaken the fixation stability. The aim of this study is to evaluate the biomechanical properties of screw turnback and demonstrate the reduction in the fixation stability after the screw is turned 360° from its full insertion position. Commercially available synthetic closed-cell polyurethane foams with three different densities simulating various degrees of bone density were utilized as substitutes for human bone. Two different screw shapes (cylindrical and conical) together with two different pilot hole profiles (cylindrical and conical) were tested. Following specimen preparation, screw pullout tests were conducted using a material test machine. The mean maximal pullout strength between full insertion and 360-degree turnback from full insertion in each setting was statistically analyzed. The mean maximal pullout strength after 360-degree turnback from full insertion was generally lower than that at full insertion. The reduced mean maximal pullout strength after turnback increased with decreasing bone density. Conical screws had significantly lower pullout strength after 360-degree turnback than cylindrical screws. The mean maximal pullout strength was reduced by up to approximately 27% after 360-degree turnback when using a conical screw in a low bone density specimen. Additionally, specimens treated with a conical pilot hole presented a less reduction in pullout strength after screw turnback as compared to those with a cylindrical pilot hole. The strength of our study was that we systematically investigated the effects of various bone densities and screw shapes on screw stability after turnback, which has rarely been reported in the literature. Our study suggests that pedicle screw turnback after full insertion should be reduced in spinal surgeries, particularly procedures that use conical screws in osteoporotic bone. Pedicle screw secured with a conical pilot hole might be beneficial for screw adjustment.

ABSTRACT Objectives: Investigate the effect of closed reduction and per- cutaneous pedicle screw fixation in treating thoracolumbar fractures. Methods: This retrospective study analyzed 12 cases of single-segment thoracolumbar spine fractures without spinal cord and nerve injury at our department from March 2016 to September 2017. Patients were treated with closed reduction, percutaneous reduction, and internal fixation with solid pedicle screws. The operation time, intraoperative blood loss, anterior vertebral body height ratio (AVHR), Cobb angle (CA) of sagittal kyphosis, and VAS of back pain were determined and statistically compared. Results: The average operation time was 147.2 ± 45.6 min, and the average intraoperative bleeding was 67.8 ± 34.2 mL. All fractured vertebrae were completely reduced, their height was restored, and kyphosis was corrected. The average follow-up period was 10.6 ± 2.7 months, with significant improvements seen in the AVHR, CA of sagittal kyphosis, and VAS score (P < 0.01). One case had a broken rod after three months, and another had a postoperative infection. All the patients achieved bony healing. Conclusion: The treatment of thoracolumbar fractures by closed reduction and internal fixation with a percutaneous solid pedicle screw is simple, effective, and economical. Level of Evidence VI; Therapeutic Study, Case Series.

ABSTRACT Objective: Arthrodesis techniques such as anterior lumbar interbody fusion (ALIF) and lateral lumbar interbody fusion (LLIF) aim to reestablish physiological lordosis and minimize tissue damage to the paravertebral musculature. Supplementation with percutaneous pedicle screws is indicated in most cases, therefore, intraoperative changes in decubitus are necessary, generating costs and risks for the patient. This study aims to present concepts and results of a series of 100 cases of patients undergoing 360° fusion in lateral single position surgery (LSPS). Methods: retrospective analysis of databases collected between 2016 and 2021. Patients who underwent 360° fusion of the lumbar spine in single lateral decubitus to treat degenerative and infectious diseases were included. Cases with arthrodesis greater than 3 levels were excluded. Data collected include demographics, body mass index (BMI) and scores such as visual analog scale (VAS), EuroQOL 5D (EQ5D) and Oswestry disability index (ODI). Results: 100 patients were included in the study, submitted to LLIF and/or ALIF associated with percutaneous pedicle fixation. The lumbar VAS improved from 6.75 to 2.1 after 12 months, while the sciatica VAS started from 4.55 and reached 0.81 after one year. The EQ5D improved from 66.1 to 81.6 after the first year, while the ODI ranged from 28.54 to 14.18 in the same period. Conclusions: the clinical-functional results of the LSPS procedures are favorable and place the LSPS as an option to be studied, developed and practiced by spine surgery teams. Level of evidence: IV. Case series.

Surgical treatment for neuromuscular scoliosis has evolved with pedicle screw instrumentation and the improvement of perioperative management. We aimed to review recent papers related to posterior surgical correction with a pedicle screw system for neuromuscular scoliosis, particularly cerebral palsy and muscular dystrophy, in terms of indication, correction method, and outcomes. The most remarkable change was the posterior-only operation with all-pedicle screw fixations. With this change, operation time, blood loss, and postoperative complications decreased. Furthermore, spinal osteotomy could be performed with the pedicle screw system for severe scoliosis. S2-alar-iliac screws demonstrated favorable outcomes in terms of stability and complication, but a question remains about saving the mobile segment for sitting balance, interaction between the hip and spine, effect to the sagittal balance, and proximal junctional problem. The quality of life improvement was more definite in patients with cerebral palsy. The improvement of respiratory function in Duchenne muscular dystrophy was not certain, although an increase of spinal height, thoracic cavity size, and absolute forced vital capacity have been reported. Further prospective studies or randomized clinical trials are needed to evaluate the long-term outcomes of lumbosacral fixation, preservation of the lumbosacral joint, or functional improvement considering the different etiology.

Objective: To evaluate the incidence of nerve injury and pedicle breach after pedicle screw fixation (PSF) with intraoperative triggered electromyography (tEMG) monitoring. Material and Methods: All patients who underwent PSF with intraoperative tEMG at Vajira Hospital between October 2018 and March 2020 were included. Patients with dysmorphic pedicle features, preoperative infection, or incomplete follow-up data were excluded. PSF was done with intraoperative tEMG. The stimulation threshold was recorded. Stimulation threshold

Abstract Objective The screw path of lumbar pedicle screws in the vertebral body has certain variability. It is not clear whether the screw paths in different directions can obtain the same pull-out resistance. This study intends to use CT (Computed Tomography) to measure the Hounsfield unit (HU value) around the screw paths in different parts of the lumbar vertebral body to obtain the bone mineral density value of the corresponding parts which will provide some reference for the direction of lumbar pedicle screw placement. Methods This retrospective study included 200 patients with lumbar degenerative diseases selected randomly from the case base and the patient’s basic information was recorded. L1-L5 vertebral body was divided equally into the upper, middle and lower 1/3, which was consistent with the three sagittal entry directions of the pedicle screw head tilt, parallel endplate and caudal tilt, and the HU values were measured by CT cross-sectional scanning to indirectly reflect the local bone density values. The paired t-test (randomized block experiment) was used to compare the HU values of the upper, middle and lower 1 / 3 parts, with P

Posterior lumbar fusion is a safe and effective surgical method for diseases, such as lumbar stenosis, spondylolisthesis, lumbar instability, spinal deformity, and tumor. Pedicle screw (PS) fixation was first introduced by Bouche and has been adopted as the gold standard for posterior lumbar fusion. Santoni and colleagues introduced a new methodological screw insertion technique that uses a cortical bone trajectory (CBT), described as that from a medial to lateral path in the transverse axial plane and caudal to the cephalad path in the sagittal plane through the pedicle for maximum contact of the screw with the cortical bone. Owing to the lower invasiveness, superior cortical bone contact, and reduced neurovascular injury incidence, the CBT technique has been widely used in posterior lumbar fusion; however, these advantages have not been proven in clinical/radiological and biomechanical studies. We designed the present study to review the existing evidence and evaluate the merit of CBT screw fixation. Six electronic databases were searched for relevant articles published in August 2020 using the search terms “cortical bone trajectory,” “CBT spine,” “CBT fixation,” “cortical pedicle screws,” and “cortical screws.” Studies were analyzed and divided into the following groups: “biomechanics investigation,” “surgical technique,” and “clinical/radiological studies.” Most studies compared CBT and PS fixation, and the CBT screw fixation method showed better or similar outcomes.

Didik Librianto,1 Ifran Saleh,2 Fachrisal Ipang,1 Dina Aprilya2 1Orthopedic Spine Surgery, Fatmawati General Hospital, Jakarta, Indonesia; 2Department of Orthopedic and Traumatology, Faculty of Medicine Universitas Indonesia, Jakarta, IndonesiaCorrespondence: Dina AprilyaDepartment of Orthopedic and Traumatology, Faculty of Medicine Universitas Indonesia, Prof. Soelarto building, 1st floor, RS Fatmawati Street, Jakarta, 12430, Indonesia, Tel +62 89655106136, Fax +62 21-7660616, Email dina.cia.aprilya@gmail.comBackground: The cantilever method is a standard for two-dimensional deformity correction, as in spondylitis tuberculosis kyphotic deformity. An accurate and secured pedicle screw placement as part of the correction tools is essential to accommodate reduction while preventing screw-related complications. Many literatures have described the pedicle screw misplacement in cases with “normal” bone quality (ie, scoliosis, Scheuermann’s kyphosis, ankylosing spondylitis, trauma) or in the obviously abnormal bone such as osteoporosis. However, to our knowledge, the pedicle screw accuracy in cases of deformity correction of tuberculous kyphosis was not previously reported.Methods: This is a retrospective study of 168 pedicle screws in 14 consecutive cases of spondylitis tuberculosis with kyphotic deformity. The cantilever reduction method with freehand screw insertion technique was done in all cases to correct the deformity. Postoperative computed tomography (CT) evaluation was done to evaluate screw position and breach rates.Results: Among the 168 screws, accurate pedicle screw placement was accomplished in 39.3% screws (Gertzbein–Robbins Grade A). The overall breach rate was 61.9%, which was most commonly occurred on the segment proximal to the apex of the deformity (p=0.001). The lateral breach was more common than the medial breach (52.3% vs 7.7%). The pedicle screw on the thoracal region has a greater breach incidence than those on the lumbar region especially those on T9, T10, and T11. There was no injury to the surrounding neurovascular and pleural structures. No revision surgeries were required.Conclusion: Freehand pedicle screw insertion in spondylitis tuberculosis kyphotic reduction has proved to be safe. However, the accuracy should be improved to prevent long-term screw-related complications.Keywords: thoracolumbar spine, spondylitis tuberculosis, kyphosis, pedicle screws, freehand technique, cantilever method

Cortical bone trajectory (CBT) for posterior fixation with pedicle screws is considered a relatively new alternative trajectory that travels in the medio-lateral direction in the transverse plane and in the caudo-cephalad path in the sagittal plane. Various biomechanical studies have already validated its superior pullout strength and mechanical stability over the traditional trajectory of convergent pedicle screws. Due to the relatively medial starting point of this trajectory, the CBT also poses the clinical advantage of requiring a smaller surgical field of exposure, thus minimizing tissue and muscle injury while reducing operative time and intraoperative blood loss. The evolution of CBT through time has closely been linked to the unwavering philosophy of prioritizing patient outcomes, advancements in neuronavigational technology, and the mounting biomechanical, morphometric, and clinical evidence. In this historical review, we provide a unique perspective on how CBT surgical technique has developed through time, highlighting key milestones and attempting to explain its explosive rise in popularity.

ObjectivePlacement of the pedicle screw is technically challenging during C1-2 fusion surgery in children and different intraoperative image-guided systems have been developed to reduce the risk of screw malposition. The purpose of the present study was to compare surgical outcomes between C-arm fluoroscopy and O-arm navigated pedicle screw placement in the treatment of atlantoaxial rotatory fixation in children.MethodsWe retrospectively evaluated charts of all consecutive children with atlantoaxial rotatory fixation who underwent C-arm fluoroscopy or O-arm navigated pedicle screw placement from April 2014 to December 2020. Outcomes including operative time, estimated blood loss (EBL), accuracy of screw placement (Neo's classification) and completed fusion time were evaluated.ResultsA total of 340 screws were placed in 85 patients. The accuracy of screw placement of the O-arm group was 97.4%, which was significantly higher than that of the C-arm group (91.8%). Both groups had satisfied bony fusion (100%). Statistical significance (230.0 ± 34.6 ml for the C-arm group and 150.6 ± 47.3 ml for the O-arm group, p

Intoduction: Mechanical complications from spinal fusion including implant loosening or junctional failure result in poor outcomes, particularly in osteoporotic patients. While the use of percutaneous vertebral augmentation with polymethylmethacrylate (PMMA) has been studied for augmentation of junctional levels to offset against kyphosis and failure, its deployment around existing loose screws or in failing surrounding bone as a salvage percutaneous procedure has been described in small case series and merits review. Research Question: How effective and safe is the use of PMMA as a salvage procedure for mechanical complications in failed spinal fusion?. Materials and Methods: Systematic search of online databases for clinical studies using this technique. Results: 11 studies were identified, only consisting of two case reports and nine case series. Consistent improvements were observed in pre- to post-operative VAS and with sustained improvements at final follow-up. The extra- or para-pedicular approach was the most frequent access trajectory. Most studies cited difficulties with visibility on fluoroscopy, using navigation or oblique views as a solution for this. Discussion and Conclusions: Percutaneous cementation at a failing screw-bone interface stabilises further micromotion with reductions in back pain. This rarely used technique is manifested by a low but increasing number of reported cases. The technique warrants further evaluation and is best performed within a multidisciplinary setting at a specialist centre. Notwithstanding that underlying pathology may not be addressed, awareness of this technique may allow an effective and safe salvage solution with minimal morbidity for older sicker patients.

Introduction: New technologies providing higher degree of precision, less risk for damage and less harmful exposure to radiation are necessary for correct transpedicular screw trajectory, but their efficacy should be evaluated. Research Question: Evaluate the feasibility, accuracy and safety of Brainlab Cirq® navigated robotic arm assistance for pedicle screw placement in comparison to fluoroscopic guidance. Material and Methods: Group I “Cirq® robotic-assisted group” – 97 screws in 21 prospectively analyzed patients. Group II “Fluoroscopy-guided group” – 98 screws in 16 consecutive patients analyzed retrospectively. Comparative evaluations included screw accuracy on Gertzbein-Robbins’s scale and fluoroscopy time. Time per screw and subjective mental workload (MWL) measured with the raw NASA task load index tool were assessed for Group I. Results: 195 screws were evaluated. Group I: 93 screws grade A (95.88%); 4 grade B (4.12%). In Group II, 87 screws grade A (88.78%); 9 grade B (9.18%); 1 grade C (1.02%); 1 grade D (1.02%). While the screws placed using the Cirq® system were more accurate overall, there was no statistical significance between the two groups, p=0.3714. There was no significant difference in operation length or radiation exposure between the two groups, however with the Cirq® system the radiation exposure for the surgeon was limited. Reduction in time per screw (p

The aim of this study was to explore whether a robot-assisted (RA) technique has advantages over the conventional fluoroscopy-assisted (FA) technique in clinical and radiological outcomes and whether it could decrease the incidence of mis-implantations of pedicle screws in adolescent idiopathic scoliosis (AIS) correction surgery. A total of 101 patients with AIS were recruited (RA group: 45 patients underwent RA screw insertion; FA group: 56 patients underwent FA screw insertion). When comparing the radiological data between the two groups, the major and secondary curves were both corrected proficiently with no difference in Cobb angle comparison at the last follow-up, suggesting that both the RA technique and the FA technique could lead to efficient radiographic correction and similar clinical outcomes (all, p > 0.05). In the RA group, operation time, blood loss, and transfusion volume were significantly greater than those in the FA group, while the accuracy of screw implantations in patients with AIS with a thoracic scoliotic curve in the RA group was higher than that in the FA group. In conclusion, both the RA and FA techniques could approach proficient radiographic correction and similar clinical outcomes in AIS surgery. Compared with the conventional fluoroscopy technique, the RA technique might improve the accuracy of screw implantations in patients with AIS with a thoracic scoliotic curve, while the increased operation time, blood loss, and transfusion volume might be the disadvantages due to the preliminary stage of the learning curve.

Numerous screw fixation systems have evolved in clinical practice as a result of advances in screw insertion technology. Currently, pedicle screw (PS) fixation technology is recognized as the gold standard of posterior lumbar fusion, but it can also have some negative complications, such as screw loosening, pullout, and breakage. To address these concerns, cortical bone trajectory (CBT) has been proposed and gradually developed. However, it is still unclear whether cortical bone trajectory can achieve similar mechanical stability to pedicle screw and whether the combination of pedicle screw + cortical bone trajectory fixation can provide a suitable mechanical environment in the intervertebral space. The present study aimed to investigate the biomechanical responses of the lumbar spine with pedicle screw and cortical bone trajectory fixation. Accordingly, finite element analysis (FEA) and in vitro specimen biomechanical experiment (IVE) were performed to analyze the stiffness, range of motion (ROM), and stress distribution of the lumbar spine with various combinations of pedicle screw and cortical bone trajectory screws under single-segment and dual-segment fixation. The results show that dual-segment fixation and hybrid screw placement can provide greater stiffness, which is beneficial for maintaining the biomechanical stability of the spine. Meanwhile, each segment’s range of motion is reduced after fusion, and the loss of adjacent segments’ range of motion is more obvious with longer fusion segments, thereby leading to adjacent-segment disease (ASD). Long-segment internal fixation can equalize total spinal stresses. Additionally, cortical bone trajectory screws perform better in terms of the rotation resistance of fusion segments, while pedicle screw screws perform better in terms of flexion–extension resistance, as well as lateral bending. Moreover, the maximum screw stress of L4 cortical bone trajectory/L5 pedicle screw is the highest, followed by L45 cortical bone trajectory. This biomechanical analysis can accordingly provide inspiration for the choice of intervertebral fusion strategy.

Study Design Retrospective study. Purpose To compare the clinical and radiological results of minimally invasive spine surgery (MISS) and open posterior instrumentation surgery for the treatment of unstable burst fractures. Overview of Literature MISS has exhibited postoperative outcomes similar to those obtained using open posterior instrumentation in various spine diseases. There remains no consensus regarding the use of MISS in the treatment of unstable burst fracture. Methods We enrolled 40 patients who underwent either MISS (M group, 20 patients) or open posterior instrumentation surgery (O group, 20 patients) for the treatment of traumatic unstable burst fractures. Clinical outcomes were evaluated based on postoperative back pain, operation time, blood loss, hospital stay duration, and perioperative complications. For radiologic evaluation, preoperative magnetic resonance imaging and plain radiography were performed before and after the surgery to evaluate the changes in the kyphotic angle and fracture union. Results The change in the kyphotic angle was −8.2°±5.8° in the M group and −8.0°±7.8° in the O group. No significant difference was noted in terms of the change in the kyphotic angle (p=0.94, t-test) after 12 months of surgery. The Visual Analog Scale score was 1.5±0.7 points in the M group, while it was 5.2±1.4 points in the O group. In the M group, back pain has significantly decreased (p

Aims: Anchorage of pedicle screw rod instrumentation in the elderly spine with poor bone quality remains challenging. Our study aims to evaluate how the screw bone anchorage is affected by screw design, bone quality, loading conditions, and cementing techniques. Methods: Micro-finite element (µFE) models were created from micro-CT (μCT) scans of vertebrae implanted with two types of pedicle screws (L: Ennovate and R: S4). Simulations were conducted for a 10 mm radius region of interest (ROI) around each screw and for a full vertebra (FV) where different cementing scenarios were simulated around the screw tips. Stiffness was calculated in pull-out and anterior bending loads. Results: Experimental pull-out strengths were excellently correlated to the µFE pull-out stiffness of the ROI (R2 > 0.87) and FV (R2 > 0.84) models. No significant difference due to screw design was observed. Cement augmentation increased pull-out stiffness by up to 94% and 48% for L and R screws, respectively, but only increased bending stiffness by up to 6.9% and 1.5%, respectively. Cementing involving only one screw tip resulted in lower stiffness increases in all tested screw designs and loading cases. The stiffening effect of cement augmentation on pull-out and bending stiffness was strongly and negatively correlated to local bone density around the screw (correlation coefficient (R) = -0.95). Conclusion: This combined experimental, µCT and µFE study showed that regional analyses may be sufficient to predict fixation strength in pull-out and that full analyses could show that cement augmentation around pedicle screws increased fixation stiffness in both pull-out and bending, especially for low-density bone. Cite this article: Bone Joint Res 2021;10(12):797–806.

Three key factors are responsible for the biomechanical performance of pedicle screw fixation: screw mechanical characteristics, bone quality and insertion techniques. To the best of the authors’ knowledge, no study has directly compared the biomechanical performance among three trajectories, i.e., the traditional trajectory (TT), modified trajectory (MT) and cortical bone trajectory (CBT), in a porcine model. This study compared the pullout strength and insertion torque of three trajectory methods in single vertebrae, the pullout strength and fixation stiffness including flexion, extension, and lateral bending in a one-level instrumented functional spinal unit (FSU) that mimics the in vivo configuration were clarified. A total of 18 single vertebrae and 18 FSUs were randomly assigned into three screw insertion methods (n = 6 in each trajectory group). In the TT group, the screw converged from its entry point, passed completely inside the pedicle, was parallel to the superior endplate, was located in the superior third of the vertebral body and reached to at least the anterior third of the vertebral body. In the MT group, the convergent angle was similar to that of the TT method but directed caudally to the anterior inferior margin of the vertebral body. The results of insertion torque and pullout strength in single vertebrae were analyzed; in addition, the stiffness and pullout strength in the one-level FSU were also investigated. This study demonstrated that, in single vertebrae, the insertion torque was significantly higher in CBT groups than in TT and MT groups (p < 0.05). The maximal pullout strength was significantly higher in MT groups than in TT and CBT groups (p < 0.05). There was no significant difference in stiffness in the three motions among all groups. The maximal pullout strength in FSUs of MT and CBT groups were significantly higher than the TT groups (p < 0.05). We concluded that either MT or CBT provides better biomechanical performance than TT in single vertebrae or FSUs. The lack of significance of stiffness in FSUs among three methods suggested that MT or CBT could be a reasonable alternative to TT if the traditional trajectory was not feasible.

Spine fixation is required in cases such as congenital spinal curvatures, vertebral fractures, sagittal collapse over time, painful kyphosis, and bone load due to tumors. Although there are many methods in the literature, the most commonly used spine fixation method is the fixation with pedicle screws. In these cases, it is known that pedicle screws are used frequently in the body. In this study, how the radiological exposure of the pedicle screws in the vertebral column that dose was evaluated by simulation methods. First, the elemental analysis of the pedicle screw was analyzed via Scanning Electron Microscopy (SEM) equipped with the Energy Dispersive X-ray Spectroscopy (EDS). Then, the elemental compositions of the pedicle screw obtained were used for simulation codes. subsequently, the half-value thickness and the attenuation coefficient calculations were conducted for the pedicle screw and vertebral column. Both XCOM software and MCNP (Monte Carlo N-Particle) simulation code were used to obtain photon interaction parameters within the energy range of 60-250 keV.

Abstract Background This study aims to analyze postoperative changes of cervical sagittal curvature and to identify independent risk factors for cervical kyphosis in Lenke type 1 adolescent idiopathic scoliosis (AIS) patients. Methods A total of 124 AIS patients who received all-pedicle-screw instrumentation were enrolled. All patients were followed up for at least 2 years. The following parameters were measured preoperatively, immediately after the operation, and at the last follow-up: pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), thoracic kyphosis (TK), global thoracic kyphosis (GTK), proximal thoracic kyphosis (PrTK), T1-slope, cervical lordosis (CL), McGregor slope (McGS), sagittal vertical axis (SVA), C2–7 SVA (cSVA), and main thoracic angle (MTA). Statistical analysis was performed to evaluate postoperative alterations of and correlations between the parameters and to identify risk factors for cervical kyphosis. Statistical significance was set at P 2.35° and immediate postoperative GTK

Study Design Biomechanical study. Purpose To quantitatively investigate the effect of screw size on screw fixation in osteoporotic vertebrae with finite element analysis (FEA) Overview of Literature Osteoporosis poses a challenge in spinal instrumentation; however, the selection of screw size is directly related to fixation and is closely dependent on each surgeon’s experience and preference. Methods Total 1,200 nonlinear FEA with various screw diameters (4.5–7.5 mm) and lengths (30–50 mm) were performed on 25 patients (seven men and 18 women; mean age, 75.2±10.8 years) with osteoporosis. The axial pullout strength, and the vertebral fixation strength of a paired-screw construct against flexion, extension, lateral bending, and axial rotation were examined. Thereafter, we calculated the equivalent stress of the bone-screw interface during nondestructive loading. Then, using diameter parameters (screw diameter or screw fitness in the pedicle [%fill]), and length parameters (screw length or screw depth in the vertebral body [%length]), multiple regression analyses were performed in order to evaluate the factors affecting various fixations. Results Larger diameter and longer screws significantly increased the pullout strength and vertebral fixation strength; further, they decreased the equivalent stress around the screws. Multiple regression analyses showed that the actual screw diameter and %length were factors that had a stronger effect on the fixation strength than %fill and the actual screw length. Screw diameter had a greater effect on the resistance to screw pullout and flexion and extension loading (β=0.38–0.43, p

ABSTRACT Objective: Study the in vitro pullout strength of SpineGuard/Zavation Dynamic Surgical Guidance Z-Direct Screw (DSG Screw), a screw pedicle designed to be inserted using a direct insertion technique. Methods: DSG Screws of 5.5 mm and 6.5 mm were introduced into polyurethane blocks with a density of 10 PCF (0,16 g/cm3). According to the experimental group, screws were inserted without pilot hole, with pilot without tapping, undertapping and line-to-line tapping. Screw pullout tests were performed using a universal test machine after screw insertion into polyurethane blocks. Results: Screws inserted directly into the polyurethane blocks without pilot hole and tapping showed a statistically higher pullout strength. Insertion of the screw without tapping or with undertapping increases the pullout screw strength compared to line-to-line tapping. Conclusion: DSG Screw showed the highest pullout strength after its insertion without pilot hole and tapping. Level of Evidence V, Expert Opinion.

Study Design Retrospective cohort study. Purpose To assess long-term clinical outcomes of adjacent segment disease (ASD) in patients who underwent lumbar interbody fusion with percutaneous pedicle screw (PS) instrumentation. Overview of Literature ASD is a well-known sequela of spinal fusion, and is reported to occur at a rate of 2%–3% per year. There is debate as to whether ASD is a result of the instrumentation and fusion method or is the natural history of the patient’s disease. Minimally invasive percutaneous PS augmentation of lumbar interbody fusion aims to prevent the disruption of posterior soft tissue stabilizers. Methods From 2004–2014, 419 consecutive patients underwent anterior, lateral, or minimally invasive transforaminal lumbar interbody fusion with percutaneous PS placement at a single institution. The mean follow-up was 4.5 years. The primary outcome measure was reoperation due to ASD. Patients were divided into two cohorts: those who underwent revision surgery secondary to ASD and those who did not require further surgery. Radiographic parameters were performed using postoperative radiographs. Patients with a pelvic incidence–lumbar lordosis (PI–LL) mismatch >10° were noted. Results Revision proportion secondary to ASD was 4.77% (n=20). Mean time to revision surgery was 2.5 years. Revision rate secondary to ASD was 1.1% per year. Patients who developed ASD were younger than those who did not (50.5 vs. 56.9 years, p=0.015). There was no difference in number of levels fused between cohorts. Revision proportion secondary to ASD was similar between approaches (anterior, lateral, minimally invasive). There was no significant difference in PI–LL mismatch between those who underwent revision for ASD and those who did not (22.2% vs. 18.8%, p=0.758). Conclusions ASD rates in patients who underwent percutaneous PS placement were lower than those previously published after open PS placement, possibly related to greater preservation of the posterior stabilizing elements of the lumbar spine.

Spinal instrumentation surgery for older patients with osteoporosis is increasing. Implant loosening may occur due to inappropriate fixation in osteoporotic bone. Developing implants that achieve stable surgical results, even in osteoporotic bone, can reduce re-operation, lower medical costs, and maintain the physical status of older patients. Fibroblast growth factor-2 (FGF-2) promotes bone formation; thus, coating pedicle screws with an FGF-2–calcium phosphate (FGF-CP) composite layer is hypothesized to enhance osteointegration in spinal implants. We designed a long-term implantation pilot study that estimated the safety and bone-forming efficacy of pedicle screws coated with an FGF-CP composite layer in cynomolgus monkeys. Titanium alloy screws, either uncoated (controls) or aseptically coated with an FGF-CP composite layer, were implanted in the vertebral bodies of six female adult cynomolgus monkeys (three monkeys per group) for 85 days. Physiological, histological, and radiographic investigations were performed. There were no serious adverse events, and no radiolucent areas were observed around the screws in either group. The bone apposition rate in the intraosseous region was significantly higher in the FGF-CP group than in the controls. Moreover, as analyzed by Weibull plots, the bone formation rate of the FGF-CP group exhibited a significantly higher regression line slope than the control group. These results demonstrated that there was significantly less risk of impaired osteointegration in the FGF-CP group. Our pilot study suggests that FGF-CP-coated implants could promote osteointegration, be safe, and reduce the probability of screw loosening.

Abstract Background CT artifacts induced by orthopedic implants can limit image quality and diagnostic yield. As a number of different strategies to reduce artifact extent exist, the aim of this study was to systematically compare ex vivo the impact of different CT metal artifact reduction (MAR) strategies on spine implants made of either standard titanium or carbon-fiber-reinforced-polyetheretherketone (CFR-PEEK). Methods Spine surgeons fluoroscopically-guided prepared six sheep spine cadavers with pedicle screws and rods of either titanium or CFR-PEEK. Samples were subjected to single- and dual-energy (DE) CT-imaging. Different tube voltages (80, DE mixed, 120 and tin-filtered 150 kVp) at comparable radiation dose and iterative reconstruction versus monoenergetic extrapolation (ME) techniques were compared. Also, the influence of image reconstruction kernels (soft vs. bone tissue) was investigated. Qualitative (Likert scores) and quantitative parameters (attenuation changes induced by implant artifact, implant diameter and image noise) were evaluated by two independent radiologists. Artifact degree of different MAR-strategies and implant materials were compared by multiple ANOVA analysis. Results CFR-PEEK implants induced markedly less artifacts than standard titanium implants (p