Search

Introduction: Pedicle screws are commonly used in fixation to treat various spinal disorders. However, screw loosening is a prevalent complication, particularly in patients with osteoporosis. Various biomechanical studies have sought to address this issue, but the optimal depth and trajectory to increase the fixation strength of pedicle screws remain controversial. Therefore, a biomechanical study was conducted using finite element models. Methods: Three-dimensional finite element models of the L3 vertebrae were developed from the preoperative computed tomography images of nine patients with osteoporosis and nine patients without who underwent spine surgery. Unicortical and bicortical pedicle screws were inserted into the center and into the anterior wall of the vertebrae, respectively, in different trajectories in the sagittal plane: straightforward, cephalad, and caudal. Subsequently, three different external loads were applied to each pedicle screw at the entry point: axial pullout, craniocaudal, and lateromedial loads. Nonlinear analysis was conducted to examine the fixation strength of the pedicle screws. Results: Irrespective of osteoporosis, the bicortical pedicle screws had greater fixation strength than the unicortical pedicle screws in all trajectories and external loads. The fixation strength of the bicortical pedicle screws was not substantially different among the trajectories against any external loads in the nonosteoporotic vertebrae. However, the fixation strength of the bicortical pedicle screws against craniocaudal load in the cephalad trajectory was considerably greater than those in the caudal (P=0.016) and straightforward (P=0.023) trajectories in the osteoporotic vertebrae. However, this trend was not observed in pullout and lateromedial loads. Conclusions: Our results indicate that bicortical pedicle screws should be used, regardless of whether the patient has osteoporosis or not. Furthermore, pedicle screws should be inserted in the cephalad trajectory in patients with osteoporosis.

Introduction: Spinal fusion surgery with instrumentation is a treatment of choice for many spinal disorders; however, there is little data related to factors associated with early and late outcomes, especially among patients with poor bone quality (e.g., osteoporosis). We conducted this study to characterize the epidemiology and outcomes of patients undergoing spinal fusion surgery with instrumentation in Japan, especially in patients with poor bone quality and those needing additional fixation methods. Methods: This retrospective observational study used real-world health insurance claims data from the Japanese Medical Data Vision. Adult patients undergoing an index spinal fusion procedure from April 1, 2010, to September 30, 2017, with procedural details, length of stay (LOS), total in-hospital costs, spine-related reoperation, all-cause readmission, and postoperative complications recorded. Data were summarized descriptively overall, by osteoporosis status, and additional fixation method used, and were analyzed in bivariate analyses. Multivariate logistic and linear regressions were used to explore associations between covariates and variables of interest. Results: A total of 22,932 patients (mean age, 67.3 years; 51.2% male) met the study criteria and were included. A total of 5,288 (23.0%) patients had osteoporosis, and 2,507 (10.9%) needed additional fixation methods; these patients were older, more frequently female, and had higher Elixhauser comorbidity index scores. Osteoporosis and additional fixation use were also associated with longer LOS, higher hospital costs, and higher rates of complications. Conclusions: Patients with osteoporosis and those needing additional fixation methods have a higher risk for procedural and postoperative complications, reoperation, longer LOS, and higher total hospital costs.

Study Design: Systematic review and meta-analysis. Objectives: To evaluate the accuracy of placement for cervical pedicle screws with and without the use of spinal navigation. Methods: A structured search was conducted in electronic databases without any language or date restrictions. Eligible studies reported the proportion of accurately placed cervical pedicle screws measured on intraoperative or postoperative 3D imaging, and reported whether intraoperative navigation was used during screw placement. Randomized Studies (MINORS) criteria were used to evaluate the methodological quality of how accuracy was assessed for cervical pedicle screws. Results: After screening and critical appraisal, 4697 cervical pedicle screws from 18 studies were included in the meta-analysis. The pooled proportion for cervical pedicle screws with a breach up to 2 mm was 94% for navigated screws and did not differ from the pooled proportion for non-navigated screws (96%). The pooled proportion for cervical pedicle screws placed completely in the pedicle was 76% for navigated screws and did not differ from the pooled proportion for non-navigated screws (82%). Intraoperative screw reposition rates and screw revision rates as a result of postoperative imaging also did not differ between navigated and non-navigated screw placement. Conclusions: This systematic review and meta-analysis found that the use of spinal navigation systems does not significantly improve the accuracy of placement of cervical pedicle screws compared to screws placed without navigation. Future studies evaluating intraoperative navigation for cervical pedicle screw placement should focus on the learning curve, postoperative complications, and the complexity of surgical cases. [ABSTRACT FROM AUTHOR]

ObjectiveTo propose a technique of gradual expansion of pedicle diameter to place screws on the thinner pedicle that is difficult to place screws in scoliosis orthopedic surgery, in order to place thicker pedicle screws in the premise of good safety to achieve good stability and orthopaedic effect.MethodsThe authors reviewed that 36 patients with Adolescent idiopathic scoliosis (AIS) (20 females, 16 males) in our department from June 2020 to March 2024 underwent posterior spinal correction and internal fixation were enrolled in the present study. 194 pedicles had narrower diameter ranging from 0 mm to 4.5 mm. After analysis, 155 pedicles (internal diameter: 2.5 mm–4.5 mm) were treated with gradually expanding pedicles technology. The angle between the inserted screws and the upper endplate of the vertebral body was measured 1 week after operation and 3 months after operation to evaluate the placement of the screws after pedicle expansion.ResultsAll operations were completed without dura mater rupture, nerve root injury, infection and poor incision healing. There was no screw breaking or screw pull-out in DR film at 3 months after operation compared with 1 week after operation. There was no significant difference in the angle between screw and upper endplate measured by the three observers at 3 months and 1 week after operation (Wilcoxon's signed rank test, p > 0.05). In the measurement at 1 week or 3 months after operation, there was no statistically significant difference among the three observers. There is a good consistency between the observers (Cronbach's alpha > 0.80).ConclusionIn AIS patients, the thinner pedicle with a diameter range of 2.5 mm to 4.5 mm can be safely inserted with relatively thicker pedicle screws after gradually expanding pedicle technology.

Objective: Unilateral transpedicular screw is widely used in lumbar spine surgery due to its primary role in enhancing arthrodesis with less tissue damage when combined with posterolateral lumbar interbody fusion (PLIF). Unilateral instrumentation can achieve similar outcomes to those of bilateral instrumentation. Its advantage is that it precludes the possibility of damaging the contralateral soft tissues and muscles. Our study assess the operative efficacy and benefits of unilateral pedicle screw (PS) fixation and decompression with interbody diagonal cage for lower lumbar degenerative diseases (LDD). Patients and Methods: A total of 60 consecutive patients who underwent either a bilateral or unilateral procedure (30 patients in each group) for treating lower LDD were included in this study. Radiological and clinical assessments were performed at 3, 6, and 12 months after surgery to assess interbody fusion rates and clinical outcomes. Results: No significant differences were observed between the two cohorts regarding age, gender, weight, presence of comorbidities, or baseline neurologic deficit. The unilateral cases showed statistically significant less surgical trauma in terms of fluoroscopy time, operative time, intraoperative blood transfusion, and length of incision. The clinical and radiological outcomes in both cohorts were quite similar. Conclusion: Both unilateral and bilateral PS fixations with PLIF have quite similar outcomes for LDD. However, based on its minimal invasiveness, the unilateral approach can be an attractive alternative to bilateral instrumentation. Our study recommends unilateral short-segment fixation as an appropriate choice in selected cases.

Abstract Background Nowadays, both lateral mass screw (LMS) and pedicle screw were effective instrumentation for posterior stabilization of cervical spine. This study aims to evaluate the feasibility of a new free-hand technique of C7 pedicle screw insertion without fluoroscopic guidance for cervical spondylotic myelopathy (CSM) patients with C3 to C6 instrumented by lateral mass screws. Methods A total of 53 CSM patients underwent lateral mass screws instrumentation at C3 to C6 levels and pedicle screw instrumentation at C7 level were included. The preoperative 3-dimenional computed tomography (CT) reconstruction images of cervical spine were used to determine 2 different C7 pedicle screw trajectories. Trajectory A passed through the axis of the C7 pedicle while trajectory B selected the midpoint of the base of C7 superior facet as the entry point. All these 53 patients had the C7 pedicle screw inserted through trajectory B by free-hand without fluoroscopic guidance and the postoperative CT images were obtained to evaluate the accuracy of C7 pedicle screw insertion. Results Trajectory B had smaller transverse angle, smaller screw length, and smaller screw width but both similar sagittal angle and similar pedicle height when compared with trajectory A. A total of 106 pedicle screws were inserted at C7 through trajectory B and only 8 screws were displaced with the accuracy of screw placement as high as 92.5%. Conclusion In CSM patients with C3 to C6 instrumented by LMS, using trajectory B for C7 pedicle screw insertion is easy to both identify the entry point and facilitate the rod insertion.

IntroductionRecent neurosurgical applications based on artificial intelligence (AI) have demonstrated its potential in surgical planning and anatomical measurement. We aimed to evaluate the performance of an AI planning software application on screw length/diameter selection and insertion accuracy in comparison with freehand surgery.MethodsA total of 45 patients with 208 pedicle screw placements on thoracolumbar segments were included in this analysis. The novel AI planning software was developed based on a deep learning model. AI-based pedicle screw placements were selected on the basis of preoperative computed tomography (CT) data, and freehand surgery screw placements were observed based on postoperative CT data. The performance of AI pedicle screw placements was evaluated on the components of screw length, diameter, and Gertzbein grade in comparison with the results achieved by freehand surgery.ResultsAmong 208 pedicle screw placements, the average screw length/diameters selected by the AI model and used in freehand surgery were 48.65 ± 5.99 mm/7.39 ± 0.42 mm and 44.78 ± 2.99 mm/6.1 ± 0.27 mm, respectively. Among AI screw placements, 85.1% were classified as Gertzbein Grade A (no cortical pedicle breach); among free-hand surgery placements, 64.9% were classified as Gertzbein Grade A.ConclusionThe novel AI planning software application could provide an accessible and safe pedicle screw placement strategy in comparison with traditional freehand pedicle screw placement strategies. The choices of pedicle screw dimensional parameters made by the model, including length and diameter, may provide potential inspiration for real clinical discretion.

Abstract Background Dynesys stabilization (DS) is utilized to preserve mobility at the instrumental segments and prevent adjacent segment pathology in clinical practice. However, the advantages of DS method in medium and long-term follow-up remain controversial. Objective To compare the radiographic and clinical outcomes between DS and instrumented fusion in the treatment of degenerative lumbar spine disease with or without grade I spondylolisthesis with a minimum follow-up period of 2 years. Methods We conducted a comprehensive search of PubMed, EMBASE, Cochrane, and Web of Science databases, Chinese National Knowledge Databases, and Wanfang Database for potentially eligible articles. Clinical outcomes were assessed in terms of VAS and ODI scores, screw loosening and breakage, and surgical revision. Radiographic outcomes were assessed in terms of postoperative range of movement (ROM) and disc heigh. Moreover, adjacent segment degeneration (ASDeg) and adjacent segment disease (ASDis) were evaluated. Results Seventeen studies with 1296 patients were included in the meta-analysis. The DS group was associated with significantly lower postoperative VAS scores for low-back and leg pain, and lower rate of surgical revision than the fusion group. Moreover, the Dynesys group showed significantly less ASDeg than the fusion group but showed no significant advantage over the fusion group in terms of preventing ASDis. Additionally, the ROM at the stabilized segments of the fusion group decreased significantly and that at the adjacent segments increased significantly compared with those of the DS group. Conclusion DS showed comparable clinical outcomes and provided benefits in preserving the motion at the stabilized segments, thus limiting the hypermobility at the adjacent segments and preventing ASDeg compared with the fusion method in degenerative disease with or without grade I spondylolisthesis.

Objective: This study summarized and analyzed the clinical data, preoperative preparation, surgical process and postoperative recovery of patients, to explore the clinical effect of posture-aware surgical tool in adolescent idiopathic scoliosis orthopedic surgery. Methods: This study demonstrated the whole process of using posture-aware surgical tools to assist the placement of screws in orthopedic surgery of adolescent idiopathic scoliosis. A 14-year-old and 8-month-old male with height 166 ​cm and weight 60 ​kg was diagnosed as Lenke type 1A adolescent idiopathic scoliosis. The preoperative X-ray films of the patients showed that the Cobb angle was 66°, CSVL-C7PL (Central Sacral Vertical Line -C7 plumb line) was 4 ​mm, SVA (sagittal vertical axis) was 5 ​mm. The operative fixed segment was T5∼L3 vertebral body. Renaissance and other three-dimensional software were utilized for screw placement angle, entry point and other related information before operation. The use of posture-aware surgical tools during surgery can accurately select screw length, type and screw placement angle, as planned by using three-dimensional software before operation. Results: The entire operation process was smooth. The intraoperative blood loss was about 600 ​ml, and the operation time was about 445 ​min. A total of 18 screws were placed during the whole operation.The patient's Cobb Angle was 8.94°, CSVL-C7PL was 2 ​mm, and SVA was 3 ​mm on postoperative radiographs. Conclusion: The implantation of pedicle screw assisted by posture-aware surgical tool is safe and effective with a smooth operation process and favorable patient outcomes.

Abstract Background To compare the CT values and length of the screw tracks of traditional trajectory (TT), cortical bone trajectory (CBT), and modified cortical bone trajectory (MCBT) screws and investigate the effects on the biomechanics of lumbar fixation. Methods CT scan data of 60 L4 and L5 lumbar spine were retrieved and divided into 4 groups (10 male and 10 female cases in the 20–30 years old group and 20 male and 20 female cases in the 30–40 years old group). 3-dimentional (3D) model were established using Mimics 19.0 for each group and the placement of three techniques was simulated on the L4 and L5, and the part of the bone occupied by the screw track was set as the region of interest (ROI). The mean CT value and the actual length of the screw track were measured by Mimics 19.0. Results The CT values of ROI for the three techniques were significantly different between the same gander in each age group (P CBT > TT, the MCBT screw track has greater bone-screw surface strength and longer screw tracks than CBT, which is easier to reach the anterior column of the vertebral body contributing to superior biomechanical properties.

Abstract Background To perform a comparative assessment of percutaneous transfacet screws (TFS) and percutaneous bilateral pedicle screws (BPS) in oblique lateral interbody fusion (OLIF) for the treatment of single-level degenerative lumbar spine diseases in terms of radiological examinations and clinical outcomes. Methods Sixty-six patients who received single-level OLIF with percutaneous supplementary fixation assisted by the robot for the treatment of degenerative lumbar spine diseases were selected. There were 16 cases of OLIF with TFS and 50 cases of OLIF with BPS. The propensity score matching method selected 11 patients in each group with matched characteristics to perform a clinical comparison. Results The estimated blood loss was 68.2 ± 25.2 ml in the OLIF with TFS group compared to 113.6 ± 39.3 ml in the OLIF with BPS group (P 0.05). Quantitative assessments of back/leg pain of the two groups reached a healthy level in the late period of the follow-up. Conclusion Both TFS and BPS techniques for the OLIF surgery relieve back pain caused by degenerative lumbar spine diseases. The TFS technique exhibits less blood loss compared with the BPS. A moderate cage subsidence is present in TFS but no complication is reported.

Abstract Background Traditional minimally invasive fluoroscopy-based techniques for pedicle screw placement utilize guidance, which may require fluoroscopic shots. Computerized tomography (CT) navigation results in more accurate screw placement. Robotic surgery seeks to establish access and trajectory with greater accuracy. Objective This study evaluated the screw placement accuracy of a robotic platform. Methods Demographic data, preoperative/postoperative CT scans, and complication rates of 127 patients who underwent lumbosacral pedicle screw placement with minimally invasive navigated robotic guidance using preoperative CT were analyzed. Results On the GRS scale, 97.9% (711/726) of screws were graded A or B, 1.7% (12/726) of screws graded C, 0.4% (3/726) of screws graded D, and 0% graded E. Average offset from preoperative plan to final screw placement was 1.9 ± 1.5 mm from tip, 2.2 ± 1.4 mm from tail and 2.9 ± 2.3° of angulation. Conclusions Robotic-assisted surgery utilizing preoperative CT workflow with intraoperative fluoroscopy-based registration improves pedicle screw placement accuracy within a patient’s pedicles.

Abstract Background Although thoracic pedicle (TP) screw has gained increasingly popularity in the surgical treatment of adolescent idiopathic scoliosis (AIS) patients, questions remain about the accurate selection of entry point for TP screw placement in these patient. The main objective of the present study was to evaluate the accuracy of TP screw placement in AIS patients using the entry point identified by new landmarks. Methods Thirty-four thoracic AIS patients treated with posterior TP screw instrumentation were included. All these TP screws were inserted through the entry point identified by new landmarks with free-hand technique. Postoperative CT scans were obtained to evaluate the screw position. The perforations of the pedicle were classified as grade 0 (no perforation), grade 1 (≤ 2 mm), grade 2 (2.1–4 mm), grade 3 (4.1–6 mm) and grade 4 (6.1–8.0 mm). Screws in grade 0, displaced either medially or anteriorly in grade 1 and displaced laterally in grades 1 to 2 were considered acceptable. Results Of the 495 TP screws inserted, 34 (6.9%) screws were displaced with 7 screws (1.4%) displaced medially, 20 screws (4.1%) displaced laterally and 7 screws (1.4%) displaced anteriorly (P

Objective. To evaluate short-term result of selective navigation templates application in idiopathic scoliosis surgery. Material and Methods. A total of 12 patients aged 14–17 years with idiopathic scoliosis were included in the study. Group A included 6 patients treated with selective application of navigation templates for pedicle screws insertion in the most difficult zones. Group B (control) included 6 patients in whom all the pedicle screws were placed with free-hand technique. Number of screws inserted was 16–20 per patient. There was no significant difference between the groups in sex, age, Cobb angle, number of vertebrae instrumented, number of pedicle screws and laminar hooks. Surgery duration, blood loss, absolute and relative correction were compared. In Group A, duration of the 3D-objects fabrication and printing, as well as pedicle screw accuracy based on 2-mm increment grading system were evaluated. Results. Selective application of navigation templates as compared with total free-hand screw placement significantly reduced surgery duration. Difference in blood loss and deformity correction was not significant. A total of 107 pedicle screws were placed in Group A, 48 of them with navigation templates and 59 by free-hand technique. Average pedicle width in screw installation with navigation templates was 4.28 ± 1.43 mm, and in that with free-hand technique 6.53 ± 1.72 mm, with significant difference. Accurate screw placement with navigation templates and by free-hand technique were 93.7 % and 88.0 %, respectively, with no significant difference. Duration of 3D-objects manufacturing was 1419 ± 190 minutes. Active operator’s involvement was required in about 10 % of the while. Conclusion. Selective application of a pair of two-level navigation templates for most difficult pedicles in idiopathic scoliosis significantly reduces surgery duration. Difference in blood loss and deformity correction is insignificant. Refusal of total templates usage for combination of navigation templates for selected difficult pedicles and free-hand technique for the rest is an option for shortening the preoperative preparation, but provides screw placement accuracy comparable with total templates usage (92.5–97.6 % as reported).

The presence of thick sub-cutaneous fat and bulky paraspinal musculature mandates extensive surgical dissection in obese patients undergoing open Transforaminal lumbar interbody fusion surgery. Securing a ‘converging’ pedicle screw trajectory becomes difficult by the counterforces of the erector spinae muscles and thick sub-cutaneous fat in obese patients, especially at the L5-S1 level. We describe the use of a limited standard posterior midline exposure and a separate, far lateral ‘satellite’ incision to insert pedicle screws in an optimal trajectory in obese patients. Through proper pre-operative planning of the axial and sagittal MRI, the appropriate entry site is determined which is executed intra-operatively to insert pedicle screws freehand. Through a single 1.5 cm incision, both L5-S1 screws were inserted. Fourteen obese patients (mean BMI was 30.5 ± 1.1) received 56 satellite pedicle screws for TLIF at L5-S1 level. The mean age was 48.3 ± 9.7 years. The mean blood loss was 244.8 ± 114 ml and the mean operative time was 126.7 ± 82.8 min. In all patients, the screws were inserted as per pre-operative planning without any difficulties. All wounds healed well without wound complications. There were no screw related complications, and in the antero-posterior and lateral radiographs, there were no screw breaches. Satellite free-hand pedicle screws are safe and easily reproducible. They enable limited dissection of the main surgical wound and well-medialised converging pedicle screws in obese patients.

IntroductionPedicle screw fixation (PSF) has been the standard therapy for the treatment of various spinal diseases. Although complications are identified regularly, iatrogenic vascular injury is one of the rare but life-threatening complications. In this literature, we describe the first case of inferior vena cava (IVC) injury during pedicle screw removal.Case descriptionA 31-year-old man was treated by percutaneous pedicle screw fixation for an L1 compression fracture. After a year, the fracture healed well and hardware removal surgery was performed. During the procedure, the hardware on the right was removed unremarkably except for the L2 pedicle screw which slipped into the retroperitoneum because of the improper technique. The CT angiogram revealed the screw had breached the anterior cortex of the L2 vertebral body and penetrated the IVC. After multidisciplinary cooperation, the defect of IVC was reconstructed and the L2 screw was removed from the posterior approach in the end.ResultThe patient recovered well and was discharged after 3 weeks without further events. The removal of the contralateral implants was unremarkable at 7 months postoperatively. At the 3-year follow-up, the patient returned to his normal daily activity without any complaints.ConclusionAlthough pedicle screw removal is a rather simple procedure, severe complications may have occurred from this procedure. Surgeons should keep vigilant to avoid the complication noted in this case.

Posterior stabilization using pedicle screw is a basic procedure in lumbar spine surgery. The success of this procedure requires learning curve, experience as well as knowledge on anatomical landmarks. Breach into vital structures of or around the spine due to mistakes in screw insertion may result in detrimental results. This technical note proposes a technique to insert lumbar pedicle screws in a relatively easier manner and more consistent for each lumbar vertebral level.

Introduction: A number of imaging technologies have been developed to reduce the risk of pedicle screw (PS) misplacement. For example, preoperative three-dimensional (3D) planning can reportedly enhance implant placement accuracy in some orthopedic surgeries. However, no study has investigated the effect of preoperative 3D planning on PS placement without intraoperative 3D navigation. Thus, in this study, we aim to examine the accuracy of PS placement and identify the risk factors for PS misplacement in thoracolumbar surgeries performed using preoperative 3D planning software with intraoperative fluoroscopic guidance in a retrospective study. Methods: In total, 25 consecutive patients (197 PSs) underwent thoracic or lumbar spinal fusion surgeries using preoperative 3D planning with intraoperative fluoroscopic guidance. PS misplacement was graded based on the degree of perforation (Grade 0, no perforation; Grade 1, 4 mm) observed in postoperative computed tomography (CT). Deviations between planned and actual PSs were evaluated by matching preoperative and postoperative CT volume images for each vertebra. Results: The overall PS misplacement rate was 6.6% (Grade 1: 4.0%, Grade 2: 1.5%, Grade 3: 1.0%). The median linear deviations of PS entry points between planned and actual locations were determined to be 3.3 mm and 3.3 mm for the horizontal and vertical axes, respectively. The median angular deviations of the PS axis were 6.2° and 4.5° for the transverse and sagittal planes, respectively. Multivariate analysis revealed that horizontal deviation of the PS entry point was the sole factor associated with Grade 1 PS misplacement (odds ratio=2.47, p

Abstract Background Fungal spondylodiscitis is a rare infectious disease. The secondary lumbar spinal stenosis and postoperative discal pseudocyst were even rarer. The surgical interventions were disputed, yet endoscopic and robot-assisted techniques may be helpful under different circumstances. Case presentation A 62-year-old female was diagnosed as infectious spondylodiscitis at the L4/5 level and a posterolateral endoscopic debridement was performed after invalid conservative therapy. Causative organism culture revealed a rare fungus, Candida tropicalis. A secondary spinal stenosis with refractory radiculopathy occurred almost 3 years after the first surgery and a successful endoscopic surgery was implemented aiming to decompress the nerve in a minimally invasive way. However, 2 months later, the patient manifested severe acute cauda equina syndrome and radiological examinations suggested a rare postoperative discal pseudocyst. A laminectomy followed by a pseudocystectomy was applied to achieve thorough decompression. An innovative double trajectory system (simultaneous traditional pedicle screw and cortical bone trajectory screw) accompanied by posterolateral fusion was designed and executed by the professional robot-assisted system. Conclusion Endoscopic and robot-assisted techniques may provide alternative solutions for fungal spondylodiscitis and accompanied sequelae.

BackgroundAugmented reality (AR) is an emerging technology that can overlay computer graphics onto the real world and enhance visual feedback from information systems. Within the past several decades, innovations related to AR have been integrated into our daily lives; however, its application in medicine, specifically in minimally invasive spine surgery (MISS), may be most important to understand. AR navigation provides auditory and haptic feedback, which can further enhance surgeons’ capabilities and improve safety.PurposeThe purpose of this article is to address previous and current applications of AR, AR in MISS, limitations of today's technology, and future areas of innovation.MethodsA literature review related to applications of AR technology in previous and current generations was conducted.ResultsAR systems have been implemented for treatments related to spinal surgeries in recent years, and AR may be an alternative to current approaches such as traditional navigation, robotically assisted navigation, fluoroscopic guidance, and free hand. As AR is capable of projecting patient anatomy directly on the surgical field, it can eliminate concern for surgeon attention shift from the surgical field to navigated remote screens, line-of-sight interruption, and cumulative radiation exposure as the demand for MISS increases.ConclusionAR is a novel technology that can improve spinal surgery, and limitations will likely have a great impact on future technology.

PurposeThoracolumbar fracture is one of the most common fractures of spine. And short-segment posterior fixation including the fractured vertebra (SSPFI) is usually used for the surgical treatment of it. However, the outcomes of SSPFI for different types of thoracolumbar fractures are not clear, and whether it is necessary to perform transpedicular bone grafting is still controversial. This study was conducted to determine the clinical efficacy of SSPFI for the treatment of different types of single-level thoracolumbar fracture, and make clear what kind of fractures need transpedicular bone grafting during the surgery.MethodsPatients with single-level thoracolumbar fracture undergoing SSPFI surgery between January 2013 and June 2020 were included in this study. The operative duration, intraoperative blood loss, anterior vertebral height ratio (AVHR) and anterior vertebral height compressive ratio (AVHC) of the fractured vertebra, local kyphotic Cobb angle (LKA), vertebral wedge angle (VWA) and correction loss during follow up period were recorded. Outcomes between unilateral and bilateral pedicle screw fixation for fractured vertebra, between SSPFI with and without transpedicular bone grafting (TBG), and among different compressive degrees of fractured vertebrae were compared, respectively.ResultsA total of 161 patients were included in this study. All the patients were followed up, and the mean follow-upped duration was 25.2 ± 3.1 months (6–52 months). At the final follow-up, the AVHR was greater, and the LKA and VWA were smaller in patients with bilateral fixation (6-screw fixation) than those with unilateral fixation (5-screw fixation) of AO type A3/A4 fractures (P 50% (P 50%, the correction loss in patients with TBG were less than those without TBG at the final follow-up (P 50%, the loss of correction was more obvious and it can be decreased by transpedicular bone grafting.

PurposeThis study was designed to compare the pedicle screw fixation by four different posterior approaches for the treatment of type A thoracolumbar fractures without neurologic injury.MethodsA total of 165 patients with type A thoracolumbar fractures without neurologic injury who received pedicle screw fixation by posterior approaches from February 2017 to August 2018 were enrolled in this study. They were further divided into the following four groups according to different posterior approaches: Open-C group (conventional open approach), Open-W group (Wiltse approach), MIS-F group (percutaneous approach with fluoroscopy guidance), and MIS-O group (percutaneous approach with O-arm navigation). The demographic data, clinical outcomes, and radiologic parameters were evaluated and compared among the four groups.ResultsThere were no significant differences in age, gender, fracture segment, and follow-up time. The incision length, blood loss, hospital stay time, and VAS (Visual Analog Scale) and ODI (Oswestry Disability Index) scores at the early stage of post-operation were the worst in the Open-C group. The MIS-O group showed significantly higher accuracy rate of pedicle position than other groups. The preoperative and postoperative AVH (anterior vertebral height) and VWA (vertebral wedge angle) obtain obvious correction in all patients immediately after and 1 year post-operation. No difference was found among the four groups at the final radiographic follow-up.ConclusionsThe four different posterior approaches are effective in treating type A thoracolumbar fractures in our study. Each approach has its own individual strengths and weaknesses and therefore requires comprehensive consideration prior to use. Proper approaches selection is critical to patients.

ObjectiveThis study aims to compare the efficacy and safety of freehand atlantoaxial pedicle screws against custom 3D printed navigation template screws in the treatment of upper cervical fractures.MethodsIn our institution from 2010 to 2020, a retrospective cohort analysis of 23 patients with upper cervical fractures was done. These patients were separated into two groups: group A (N = 12), which received customized 3D printed navigation template-assisted screws with virtual reality techniques, and group B (N = 11), which received freehand screws assisted by intraoperative fluoroscopy. Every patient was monitored for more than 1 year. The two groups were contrasted in terms of screw implant accuracy, cervical spine Japanese Orthopaedic Association (JOA) score, American Spinal Injury Association (ASIA) score, visual analogue scale (VAS) score, surgical time, fluoroscopy times, and intraoperative blood loss.ResultsA total of 88 atlantoaxial pedicle screws in all, 46 in group A and 42 in group B, were implanted. In group A, the screw insertion accuracy rate was 95.7%, compared to 80.0% in group B (P

BackgroundA prospective controlled study was conducted to compare the short-term clinical results and postoperative complications of minimally invasive transforaminal lumbar decompression and fusion (minimally invasive surgery transforaminal lumbar interbody fusion, MIS-TLIF) and percutaneous endoscope-assisted transforaminal lumbar interbody fusion (endoscopic lumbar interbody fusion, Endo-LIF) in the treatment of single-segment degenerative lumbar diseases, to provide some scientific guidance for clinicians to select surgical treatment for patients with lumbar degeneration.MethodsFrom October 2020 to October 2021, a total of 62 patients were enrolled, with 31 patients in the MIS-TLIF group and 31 patients in the Endo-LIF group. All patients were followed up for 6 months. The following information from the two groups of patients was recorded: (1) operation time, radiation exposure time, intraoperative blood loss, bed rest time, and hospital stay; (2) ODI score (The Oswestry Disability Index), low back pain VAS score (Visual Analogue Scale), and lumbar vertebra JOA score (Japanese Orthopaedic Association Scores) 1 day before the operation; 1, 3, 6 days after operation; and 1, 3 and 6 months after operation. (3) X-ray evaluations of lumbar fusion at the last follow-up.ResultsThere were significant differences in operation time, intraoperative fluoroscopy time, and hospitalization cost between the two groups. The MIS-TLIF group was significantly better than the Endo-LIF group, and the intraoperative bleeding volume of the Endo-LIF group was significantly better than that of the MIS-TLIF group, but there was no significant difference in postoperative bed rest time and postoperative hospital stay. There was no significant difference in the scores of ODI, VAS, and JOA between the two groups before and after the operation. At the last follow-up, the fusion rate was 100% in the MIS-TLIF group and 100% in the Endo-LIF group.ConclusionsThere was no significant difference in short-term clinical efficacy and safety between Endo-LIF and MIS-TLIF in the treatment of single-segment degenerative lumbar diseases, but MIS-TLIF was significantly better than Endo-LIF in terms of the operation time, hospitalization cost, and fluoroscopy time, and Endo-LIF was significantly better than MIS-TLIF in terms of intraoperative blood loss.

Interest in robotic-assisted spine surgery has grown as surgeon comfort and technology has evolved to maximize benefits of time saving and precision. However, the Food and Drug Administration (FDA) has currently only approved robotics to assist in determining the ideal trajectory for pedicle screw placement after extensive research supporting its efficacy and efficiency. To be considered a durable and effective option, robotics need to expand beyond the indication of just placing pedicle screws. This article aims to illustrate a multi-surgeon, single-institution experience with unique applications of robotic technologies in spine surgery. We will explore accessing Kambin’s Triangle in percutaneous transforaminal interbody fusion (percLIF), iliac fixation in metastatic cancer, and sacroiliac (SI) fusions. Each of these topics will be covered in depth with associated background information and subsequent discussion. We show that with proper understanding of its limitations, robots can help surgeons perform difficult surgeries in a safe manner.

Objectives: Preserving muscle function and integrity during and after posterior lumbar surgical intervention is a cornerstone for good surgical results. Prolonged application of fixed retractors results in ischemic changes of the paraspinal muscles, postoperative persistent back pain, and muscle dysfunction. Fixed retractors may alter the projection of pedicle screw insertion resulting in breaching the pedicle wall and misdirected screws. We describe a new technique for muscle retraction using intermittent during pedicle screw insertion. Methods: We use a less-invasive technique for pedicle screw insertion through a midline 3 cm skin incision per level and traditional appendectomy “Langenbeck” retractors for paraspinal muscle intermittent retraction during pedicle screw insertion. Results: Despite the small incision, our technique allows freedom to direct the screw trajectory and lessens the need for a fixed retractor except during the discectomy. Blood transfusion is applied only for patients with medical co-morbidity such as anemia or impaired coagulation. Post operative analgesia included paracetamol and non steroidal injection if required with smooth wound healing. Patients, recovery is usually uneventful with improvement of their complains. Conclusion: This technique combines the benefits of both traditional and minimally invasive surgery and is a useful advance in the field of posterior lumbar surgery and pedicle screw insertion.

Introduction: Osteoporosis is a global burden with the prevelance ranging from 15 to 20% in women and 4–7% in men across the globe. This is the age group which most commonly presents in spine clinic with pathologies requiring pedicle screw fixation. Pedicle screw fixation in osteoporotic spine is a challenge pertaining to the poor bone quality leading to various complication like screw backout, loosening and pedicle breach. With the advent of O arm and navigation, it is now possible to place pedicle screw with reported accuracy of 96%. Here, in this one of a kind study, we study the accuracy of O arm guided pedicle screw insertion in osteoporotic spine. Materials and method: This is a retrospective study of patients operated between July 2020 to December 2020 for pedicle screw fixation at a tertiary care center by a single senior spine surgeon using O arm (O2) Navigation. All patients, over the age of 55 years having osteoporosis; defined by Singh’s index; who were operated for lumbar pedicle screw fixation were included in the study. All patients under the age of 55 or having Singh’s index of more than 3 were excluded. Results: All the patients operated at a tertiary care center by a single senior spine surgeon was considered in our study. Of 67 patients operated between July 2020 to December 2020 using O arm navigation, 32 patients fit into our criteria. Total 172 pedicle screws were inserted in osteoporotic spine. One of the patients had one pedicle breach in our group intra operatively which needed reinsertion of screw. Conclusion: O arm guided pedicle screw placement is a novel technique which seems to be the most accurate technique till date. With an accuracy of 99.5% in osteoporotic spine, this should be the method of choice when using pedicle screws, whenever available.

Introduction: Cervical pedicle screw (CPS) fixation provides the strongest mechanical stability. It needs, however, wide soft tissue detachment to expose the entry point and carries the potential risk of iatrogenic damage to neurovascular structures. Malposition of the CPS cannot be completely avoided even using the navigation system. Technical Note: Using the bone biopsy needle as drill guide, we developed a novel accurate CPS insertion technique. (1) The entry point of CPS was exposed using Southwick's technique for anterior fixation or Tokioka's technique for posterior fixation. (2) A 13G bone biopsy needle was inserted from the entry point established by the fluoroscopy-assisted pedicle axis view technique described by Yukawa et al. to within a few millimeters of the pedicle. (3) The external sleeve of the bone biopsy needle was left in place as a drill guide, and the 1.25 mm guidewire for a 4.0 mm cannulated screw was then inserted into the pedicle cavity. (4) The external sleeve of the bone biopsy needle was removed, and the screw trajectory was created by a 2.7 mm cannulated drill bit over the guidewire. (5) Tapping was conducted prior to CPS insertion. Using this method, 29 CPSs in nine patients were inserted. Postoperative computed tomography scans revealed that all the CPSs were placed accurately. Conclusions: Utilizing the bone biopsy needle as drill guide, our procedure enables accurate positioning of CPS without expensive instruments.

The placement of cervical spine pedicle screws and lateral mass screws are technically demanding due to their proximity to vital structures such as the spinal cord and the vertebral arteries. In the case of multilevel cervical spine trauma, the fracture location and the size of the pedicle often limits the choice of the pedicle screw. This case report analyses the possibility of pedicle screw placement in the upper cervical spine with the help of a three-dimensional (3D)-image model as preoperative planning. Here, we present a 29-year-old patient who suffered from a motor vehicle accident. He had a cervical injury for which we designed a reduction plan with the help of 3D models shaped from his computed tomography image. The operation of reduction and fixation was performed from the level of C5 to T1 smoothly and no complication occurred through to follow-up. As shown in this case, 3D reconstruction technology can help us plan for reduction surgery in a highly complicated case of cervical spine fracture and provide the operator with a better way to visualize the surgical anatomy. 3D reconstruction technology can help us plan for reduction surgery and perform the preoperative surgical simulation. The surgeon can select the size of the pedicle screw correctly and save the operative time.

Modern operating rooms are becoming increasingly advanced thanks to the emerging medical technologies and cutting-edge surgical techniques. Current surgeries are transitioning into complex processes that involve information and actions from multiple resources. When designing context-aware medical technologies for a given intervention, it is of utmost importance to have a deep understanding of the underlying surgical process. This is essential to develop technologies that can correctly address the clinical needs and can adapt to the existing workflow. Surgical Process Modeling (SPM) is a relatively recent discipline that focuses on achieving a profound understanding of the surgical workflow and providing a model that explains the elements of a given surgery as well as their sequence and hierarchy, both in quantitative and qualitative manner. To date, a significant body of work has been dedicated to the development of comprehensive SPMs for minimally invasive baroscopic and endoscopic surgeries, while such models are missing for open spinal surgeries. In this paper, we provide SPMs common open spinal interventions in orthopedics. Direct video observations of surgeries conducted in our institution were used to derive temporal and transitional information about the surgical activities. This information was later used to develop detailed SPMs that modeled different primary surgical steps and highlighted the frequency of transitions between the surgical activities made within each step. Given the recent emersion of advanced techniques that are tailored to open spinal surgeries (e.g., artificial intelligence methods for intraoperative guidance and navigation), we believe that the SPMs provided in this study can serve as the basis for further advancement of next-generation algorithms dedicated to open spinal interventions that require a profound understanding of the surgical workflow (e.g., automatic surgical activity recognition and surgical skill evaluation). Furthermore, the models provided in this study can potentially benefit the clinical community through standardization of the surgery, which is essential for surgical training.

Introduction: Cortical screws offer a less invasive alternative compared to traditional pedicle screws. These screws are inserted in an inferomedial to superolateral trajectory achieving greater cortical bone purchase. Similar fusion rates, pain relief, and decreased surgical morbidity at 12-month follow-up have been documented when compared to traditional pedicle screws. Using intra-operative imaging, neuronavigation, and individual neurophysiological monitoring of each screw, we showed that this is a safe surgical approach. Methods: Institutional review board (IRB) approved retrospective review of medical records for 173 patients to determine eligibility. Cases had to be elective one-or two-level fusion with surgical indication. Functional improvement was measured with Oswestry Disability Index (ODI) at pre and post-operative visits. Surgical morbidity data, individual screw thresholds, and radiographic evidence of stability was collected from electronic medical records (EMR). Results: A total of 153 patients met criteria with mean age 66.60 ± 9.30 (range: 34–84) and mean BMI of 28.76 ± 4.47 kg/m2. Of 558 screws inserted, no screws recorded

Introduction: This retrospective study compared rates of bony fusion and screw loosening after multilevel posterior decompression and fusion (PDF) with short monocortical screws (SMS) as a novel mid-cervical anchor versus C5 pedicle screws (PS) as a mid-cervical anchor. Methods: We analyzed 15 consecutive patients who underwent C2-T1 PDF with C5 PS as mid-cervical anchor (PS group) and 18 consecutive patients who underwent the procedure with SMS at C4-C6 as mid-cervical anchor (SMS group). Radiological outcomes, including rates of bony fusion at each level and screw loosening, and clinical outcomes, including Japanese Orthopedic Association (JOA) score, neck pain, neck disability index (NDI), and EuroQol 5 Dimension (EQ-5D), were compared between groups. In the SMS group, screw perforation types and appropriate screw insertion procedure were also investigated. Results: The fusion rate at C2/3 in the SMS group (56%) was significantly higher than that in PS group (13%; P = 0.0272). None of the patients had SMS loosening postoperatively. Clinical outcomes, including JOA score, neck pain, NDI, and EQ-5D, did not differ between the groups. In the SMS group, facet perforation was the most common type of perforation. The recommended direction for SMS insertion at C4-C6 was 35°-37° in the cranial direction and 25°-30° in the medial direction; the recommended screw length was 10 mm. Conclusions: SMS at C4-C6 was as effective as C5 PS as a mid-cervical anchor in PDF, according to clinical and radiological outcomes. The fusion rate at C2/3 in the SMS group was significantly higher than that in the PS group. There was no postoperative loosening of the C5 PS or C4-C6 SMS in either group.

Abstract Background The accuracy and safety of pedicle screw insertion was markedly improved with the introduction of intraoperative three-dimensional navigation system during the last decade. This study aimed to evaluate the accuracy of pedicle screw placement using O-arm-based navigation system versus conventional freehand technique. Methods We reviewed the accuracy of 341 thoracic (n = 173) and lumbosacral (n = 168) pedicle screws placed in 60 consecutive patients using either O-arm-based navigation or freehand technique in the Department of Neurosurgery of Beijing Tsinghua Changgung Hospital between January 2015 and June 2018. Patient-specific characteristics, treatment-related characteristics, and screw-specific accuracy were analyzed. The accuracy of pedicle screw placement was measured by Gertzbein-Robbins scale and screw grades A and B were clinically acceptable. Results One hundred ninety-one screws were inserted in the O-arm-based navigation group and 150 in the freehand group. One hundred eighty-three (95.81%) clinically acceptable screws were placed in the navigation group and 135 (90.00%) in the freehand group (p = 0.034). Twenty-three (6.74%) screw revisions were performed in the two groups (8 screws in the navigation group and 15 screws in the freehand group) and significant difference was observed in thoracic spine (p = 0.018), while no statistical significance was presented in lumbosacral spine (p > 0.05). Twenty-four (12.57%) screws in the navigation group and 24 (16.00%) in the freehand group violated the cortex (p > 0.05). Medial screw deviation was the most common problem in the two groups. Conclusion The O-arm-based navigation exhibits higher accuracy for pedicle screw insertion than the freehand insertion technique.

Abstract Objective Atlantoaxial fixation is technically demanding and challenging, especially in cases with anatomical abnormality. The purpose of this study is to report the effectiveness of the three-dimensional (3D)-customized guiding template for placement of C1 and C2 screws in cases with abnormalities. Method Two patients with anatomical abnormality and one without were included. The preoperative computed tomography (CT) image was analyzed using our software. The entry point, trajectory, and depth of the screws were designed based on these images. Templates with screw guiding cylinders and cervical spine model were created. In operation, guiding templates were applied directly to the laminae. Drilling, tapping, and screwing were performed through the cylinders. To evaluate the accuracy, deviation of the screw axis from the preplanned trajectory was measured on postoperative CT. A classification system was taking to evaluate the pedicle screw insertion. Results In complex cases, one of C2 screws has grade 2 deviation, and two has grade 1. There was no deviation in screws of C1. All patients achieved symptoms free after 6 months follow-up. Conclusion Although 3D-printed template for atlantoaxial fixation still has limitation in complex cases, it has been proved usefulness and makes the most difficult and dangerous spinal posterior fixation easy to achieve.

Abstract Background Different methods for lumbar pedicular screw insertion have been advocated; however, each technique has its cons and pros. Limited resources for O-arm and navigation in our locality enforced us to use our surgical skills to minimize the need for such advanced modalities. The aim of the study is to clarify the benefits of the use of free-hand technique using direct visualization of the pedicles and disc space as the only guide for pedicular screw insertion using postoperative CT for evaluation of the accuracy of pedicle screw insertion. Patients and methods One hundred forty-four screws were inserted in 32 patients using direct pedicle visualization and disc space orientation as a single intraoperative reference guide. The study was conducted in Zagazig University Hospitals from May, 2014, to June, 2015. CT was done for all patients as a direct postoperative evaluation tool. Results There were 24 cases of single-level lumbar degenerative spondylolisthesis (96 screws) and eight with double-level degenerative spondylolisthesis DSL (48 screws). One hundred forty-four screws were inserted. Only three out of 144 screws were not purely intrapedicular; superior and lateral violations were not clinically significant. Conclusions Direct pedicle visualization with the use of disc space orientation as a reference guide is a good alternative to the most advanced intraoperative monitoring techniques that are more readily available in developed countries. Trial registration ClinicalTrials.gov identifier: NCT03327298. Registered 30 October 2017.

Introduction: An occipital-cervical surgery for children is challenging for surgeons because of the immature bone quality, extensive anatomical variability, and small osseous structures. Furthermore, occipital-C2 fusion in children results in great stress on the C2 screws. We report a technique that uses both C2 pedicle and bilateral lateral mass screws (C2 hybrid screws) in children with an upper cervical disorder to preserve motion segment and secure strength in those who require occipital-cervical fusion. Case Report: Case 1 was that of a 5-year-old girl with Down syndrome who had atlantoaxial dislocation and os odontoideum. Owing to the C1 hypoplasia, the posterior arch was fractured by the C1 lateral mass screw. Therefore, O-C2 fusion was performed. C2 bilateral lamina screws were added along with the C2 bilateral pedicle screws for reinforcement. Case 2 was that of an 8-year-old boy who presented with torticollis and neck pain. The patient was diagnosed as having atlantoaxial rotatory fixation. The right vertebral artery was obstructed, and the left vertebral artery was dominant. The C1 posterior arch was bifid and assimilated with the occipital bone. C2 bilateral lamina screws were added with the right C2 pedicle screw for reinforcement. Both cases attained bone union after O-C2 fusion surgery using hybrid screws. Conclusions: The use of C2 hybrid screws with both C2 pedicle and bilateral lateral mass screws can preserve mobile segments in the fusion area in young children who require occipital-cervical fixation.

Purpose: In surgical correction of scoliosis with pedicle screw dual-rod systems, frequently used freehand technique of screw positioning is challenging due to 3D deformity. Screw malposition can be associated with serious complications. Image-guided technologies are already available to improve accuracy of screw positioning and decrease radiation to surgeon. This study was conducted to measure intraoperative radiation to patients in freehand technique, evaluate screw-related complications and compare radiation values to published studies using navigation techniques. Methods: Retrospective analysis of prospectively collected data of 73 patients with idiopathic scoliosis, who underwent surgical correction with pedicle screw dual-rod system. Evaluated parameters were age, effective radiation dose (ED), fluoroscopy time, number of fused segments, correction and complications. Parameters were compared with regarding single thoracic curve (SC) and double thoracic and lumbar curves (DC), adolescent (10–18 years) or adult (> 18 years) idiopathic scoliosis, length of instrumentation. ED was compared with values for navigation from online database. Results: Average age was 21.0 ± 9.7 years, ED was 0.17 ± 0.1 mSv, time of fluoroscopy was 24.1 ± 18.6 s, 9.5 ± 1.9 fused segments. Average correction for SC was 75.7%, for DC 69.9% (thoracic) and 76.2% (lumbar). No screw-related complications. ED was significantly lower for SC versus DC (p < 0.01), short versus long fusions (p < 0.01), no significant difference for age (p = 0.1). Published navigation data showed 6.5- to 8.8-times higher radiation exposure for patients compared to our results. Conclusion: Compared to navigation procedures, freehanded positioning of pedicle screws in experienced hands is a safe and effective method for surgical correction of idiopathic scoliosis with a significant decrease in radiation exposure to patients. [ABSTRACT FROM AUTHOR]

Study Design: Retrospective chart review.Objective: To determine if obtaining a prone computed tomography (CT)-scan can better delineate a questionable screw-aorta relationship.Summary Of Background Data: Pedicle screw misplacement rate is reported between 6% and 15%. Studies looking at misplacements on a per patient basis show up to 14% of patients have screws at risk (impinging vital structures). A screw abutting the aorta is a management challenge and often requires vascular surgery intervention. However, CT scans routinely done in supine position may overestimate screw-aorta relationship. Change in patient position may allow the aorta to roll away and, in most cases, reveal an uncompromised aorta. This will allow safe removal of pedicle screws without any vascular intervention.Methods: One hundred eleven spinal deformity patients who underwent Posterior spinal fusion from 2004 to 2009 were evaluated. Patients with concerning screw-aorta relationship underwent additional prone CT scan. Mobility of the aorta was determined and distance was compared using prone and supine CT scans.Results: Two thousand two hundred ninety five screws were reviewed, 36 screws in 18 patients were in proximity to the aorta. Fourteen screws (nine patients) appeared to be impinging the aorta. On prone CT, 13 out of the 14 instances the aorta moved away from the screw. The average distance at the screw level was 13.6 ± 4.8 mm in supine position and 8.9 ± 5.4 mm in prone position (P = 0.001). In one instance the relationship was unchanged on prone CT. No screw was noted to violate the lumen or distort the aorta.Conclusion: Supine CT scan alone is not entirely accurate in determining screw-aorta relationship. Prone-CT scan provides additional information for better delineation. This additional diagnostic step can change the treatment option by limiting the need for vascular intervention. When in doubt, the additional use of an arteriogram can allow for improved visualization.Level Of Evidence: 3. [ABSTRACT FROM AUTHOR]

BACKGROUND: The morbidity rate of thoracolumbar burst fracture is high; however, the simple posterior distraction and reduction technique has poor patient satisfaction on maintaining vertebral height and reducing complications. Therefore, we attempt to explore a better therapeutic regimen. OBJECTIVE: To assess the efficacy of inverse arch roof breaking technique combined with pedicle screw and bone graft in treatment of thoracolumbar burst fractures. METHODS: This was a retrospective study of 78 patients with thoracolumbar burst fractures. All the patients suffered from fresh closed fractures, and all of them were operated by posterior approach. The time from injury to surgery ranged from 4 to 14 days, with an average of 7.8 days. They were randomly assigned to two groups. The 38 cases in the simple distraction group were treated with simple vertebra pedicle screw-rod system distraction and reduction fixation. The 40 cases in the inverse arch roof breaking and bone graft group were treated with inverse arch roof breaking technique combined with pedicle screw and bone graft in fractured vertebra. All patients signed the informed consent. The study was approved by the Hospital Ethics Committee. Operation time, intraoperative blood loss, fracture healing time, anterior height ratio of injured vertebrae, Cobb angle, visual analogue score, Barthel Index and postoperative complications were measured between the two groups. RESULTS AND CONCLUSION: (1) The follow-up period for all patients was 10-22 months. (2) Operation time and intraoperative blood loss were better in the simple distraction group than in the inverse arch roof breaking and bone graft group (P < 0.01). (3) The ratio of anterior height of injured vertebra and Cobb angle were significantly different between the two groups (P < 0.01 ). Above indexes were better in the inverse arch roof breaking and bone graft group than in the simple distraction group. (4) There were significant differences in fracture healing time and life activity function (Barthel index) between the two groups (P < 0.01 ), and above indexes were better in the inverse arch roof breaking and bone graft group than in the simple distraction group. (5) No deep infection was found in both groups. There were no complications such as internal fixation failure and excessive loss of vertebral height in arch roof breaking and bone graft group. In the simple distraction group, there were 3 cases of screw pull-out because of failed internal fixation, 2 cases of titanium rod breakage, and 10 cases of obvious vertebral height loss. (6) These findings suggest that compared with simple distraction and reduction fixation, inverse arch roof breaking technique combined with pedicle screw and bone graft can provide bony support to compression center of fractured vertebra. The efficacy was identified in reconstructing the height of anterior and middle columns. This method has the advantages of high mechanical strength, strong vertebral height maintenance, high bone healing rate and few complications, which will be the ideal choice in the treatment of thoracolumbar burst fracture. [ABSTRACT FROM AUTHOR]

The same correspondence between general mechanics and civil engineering is true for biomechanics and surgical implants. Currently, numerous mechanical processes are required until a prosthesis is offered to its target audience. These processes typically require human or animal vertebrae, as well as all the complexity involving such tissues, for example, an ethics committee, the availability of materials, etc. Thus, finite element models (FEMs) have become a great option to carry out biomechanical tests independently from anatomical specimens, and, at the same time, to obtain mathematical data to assist in the general physical understanding. The present review discusses the mechanical principles involved in bioengineering, clarifies the steps for the development of FEMs, and shows application scenarios for these models. To the knowledge of the authors, the present paper is the first review study in Portuguese aimed to health care professionals in a language accessible to them.

Bicortical screw fixation is an established technique to increase screw strength in vertebral bodies, although it is associated with several complications, for example screw-loosening. Cement augmentation can increase stability of screw-fixation but can also cause various complications, such as cement-leakage or cement embolism. In this study, we tested a new, multicortical screw fixation technique in the sacrum. Four fresh-frozen sacrums were used. In group 1, standard screw insertion, with sagittal parallel and axial convergent screw-drive was performed. In group 2, the screw-drive of the first screw was similar to the screw-drive in group 1. In addition, a second screw was inserted descending into the intended hole in the head of the screw and at a stable angle. Therefore, the screws of the multiloc humerus nail-system (Synthes) were used. The specimens were connected to a testing-machine and underwent cyclic axial loading with an increase in the load after each completed stage. Multicortical screw fixation leads to a significant increase in the number of completed cycles and a significantly increased load until failure. Multicortical screw fixation in the sacrum offers a stronger attachment of the screws. In the future, multicortical implants, which fulfil the criteria demanded in spine surgery, can offer higher stability and may decrease the loosening rates of the implanted screws. • Sacral bicortical screw fixation is commonly used for strength and stability. • This study tested a new, multicortical screw fixation technique. • Fresh-frozen sacrums were used to compare bicortical and multicortical techniques. • Multicortical screw fixation resulted in more strength, stability and load bearing. [ABSTRACT FROM AUTHOR]