Cervical Lateral Mass Screw Research Articles

Current research status and prospects for clinical application of robotics in spinal surgery

With the rapid advancement of artificial intelligence and the increasing integration of medical engineering, robot-assisted (RA) technology in spinal surgery has made significant strides, with its clinical application range continuously expanding. This article provides a comprehensive review of relevant literature on spinal surgery robots over the past decade, summarizing recent advancements in screw placement techniques such as cervical, thoracic, and lumbar pedicle screws; cortical bone trajectory (CBT) screws; cervical lateral mass screws; and S2 sacroiliac (S2AI) screws. It also discusses RA-guided targeted puncture and endoscope placement through intervertebral foramen as well as decompressive laminectomy procedures. Furthermore, this article systematically analyzes the advantages and disadvantages of RA technology while elucidating its accuracy, safety, and practicality. We believe that this article will help clinicians to gain a deeper understanding of the current clinical application status of spinal surgery robots while promoting further enhancements and wider adoption of RA technology to ultimately benefit more patients.

Infinity: A Prospective Trial for Safety and Accuracy of Navigated Posterior Cervical and Thoracic Instrumentation in long-segment Fusions.

Unblinded single-arm prospective clinical trial. Evaluate safety and accuracy of navigation for placement of posterior cervicothoracic instrumentation. Computer assisted stereotactic navigation for placement of spinal instrumentation has been widely studied and implemented in the thoracic and lumbar spine. However less literature exists regarding the use of computer assisted navigation for posterior cervical instrumentation, particularly with lateral mass fixation. Here we present the first prospective study of navigated cervical lateral mass screw placement for cervicothoracic fusion. Patients who met indications for posterior cervical fusion were screened, consented, and enrolled preoperatively for instrumentation with Medtronic Infinity Occipital-Cervical-Thoracic implants, with use of intraoperative O-arm and stereotactic Stealth navigation. Postoperative CTs of the instrumented levels were obtained during the same hospital admission. Primary outcome of the trial was safety. Secondary outcomes were screw accuracy assessed by Gertzbein-Robbins grade, neurologic exams, and patient reported outcomes on the PROMIS 29 questionnaire. A total of 50 patients underwent surgery, and 557 screws were placed. There were no adverse events related to the use of navigation or screw malposition. Gertzbein-Robbins grade A or B placement comprised 95% of navigated screws. There was a decrease in positive Hoffmann sign rate postoperatively, and sensory and motor exams remained stable. There was improvement in patient reported pain and sleep domains. Navigation for cervicothoracic instrumentation is safe overall and leads to high rates of accurately placed screws. Longer term follow up could provide more insight to whether the use of this technology results in durable improvement in spinal alignment parameters and patient reported outcomes. 3.

Successful Rectification of Cervical Nerve Root Irritation with Sequential Surgical Maneuvers during Posterior Cervical Instrumentation

AbstractPosterior cervical instrumentation is used to treat a variety of cervical pathologies, including cervical spondylotic myelopathy, severe canal stenosis, and degenerative diseases. A 55-year-old man with severe cervical canal stenosis underwent a C3–C6 laminectomy and lateral mass screw fixation under general anesthesia. After lateral mass screw fixation and rod placement on the right side, raw electromyography (EMG) revealed irritative discharges in the right biceps brachii muscle. Following a suspicion of irritation/mechanical stretching of the C5–C6 nerve root, a posterior foraminotomy was performed on the right side as a rescue measure. The amplitude of raw EMG irritative discharges in the right biceps brachii muscle decreased significantly after posterior foraminotomy. Following rod reapplication with decreased rod lordosis, the irritative EMG discharges were eliminated. Before implementing further measures, posterior foraminotomy can be a crucial initial intervention for minimizing nerve root irritation due to mechanical factors after cervical lateral mass screw fixation.

Feasibility of Using Intraoperative Neurophysiological Monitoring for Detecting Bone Layer of Cervical Spine Surgery.

Intraoperative neurophysiological monitoring (IONM) as a guide to bone layer estimation was examined during posterior cervical spine lamina grinding. To explore the feasibility of IONM to estimate bone layer thickness. Cervical laminoplasty is a classic operation for cervical spondylosis. To increase safety and accuracy, surgery-assistant robots are currently being studied. It combines the advantages of various program awareness methods to form a feasible security strategy. In the field of spinal surgery, robots have been successfully used to help place pedicle screws. IONM is used to monitor intraoperative nerve conditions in spinal surgery. This study was designed to explore the feasibility of adding IONM to robot safety strategies. Chinese miniature pig model was used. Electrodes were placed on the lamina, and the minimum stimulation threshold of DNEP for each lamina was measured (Intact lamina, IL). The laminae were ground to measure the DNEP threshold after incomplete grinding (Inner cortical bone preserved, ICP) and complete grinding (Inner cortical bone grinded, ICG). Subsequently, the lateral cervical mass screw canal drilling was performed, and the t-EMG threshold of the intact and perforated screw canals was measured and compared. The threshold was significantly lower than that of the recommended threshold of DENP via percutaneous cervical laminae measurement. The DNEP threshold decreases with the process of laminae grinding. The DNEP threshold of the IL group was significantly higher than ICP and ICG group, while there was no significant difference between the ICP group and the ICG group. There was no significant relationship between the integrity of the cervical spine lateral mass screw path and t-EMG threshold. It is feasible to use DENP threshold to estimate lamina thickness. Cervical lateral mass screw canals by t-EMG showed no help to evaluate the integrity.

Spine Surgical Robotics: Current Status and Recent Clinical Applications.

With the development of artificial intelligence and the further deepening of medical-engineering integration, spine surgical robot-assisted (RA) technique has made significant progress and its applicability in clinical practice is constantly expanding in recent years. In this review, we have systematically summarized the majority of literature related to spine surgical robots in the past decade, and not only classified robots accordingly, but also summarized the latest research progress in RA technique for screw placement such as cervical, thoracic, and lumbar pedicle screws, cortical bone trajectory screws, cervical lateral mass screws, and S2 sacroiliac screws; guiding targeted puncture and placement of endoscope via the intervertebral foramen; complete resection of spinal tumor tissue; and decompressive laminectomy. In addition, this report also provides a detailed evaluation of RA technique's advantages and disadvantages, and clarifies the accuracy, safety, and practicality of RA technique. We consider that this review can help clinical physicians further understand and familiarize the current clinical application status of spine surgical robots, thereby promoting the continuous improvement and popularization of RA technique, and ultimately benefiting numerous patients.

A Novel Semi-Cannulated Screw Enhanced Bone Cement Augmentation and Pullout Strength in Posterior Cervical Lateral Mass Screw Fixations: An In Vitro Biomechanical and Morphological Study.

To develop a novel semi-cannulated lateral mass screw (SC-LMS) for cervical posterior fixations and compare the fixation stability and safety of SC-LMS with regular solid lateral mass screw (S-LMS) in bone cement augmentation and pullout strength using fresh cadaveric cervical vertebrae. The conventional multiaxial screw for cervical lateral mass fixation was modified to a cannulated screw with two lateral holes, used for bone cement injection in situ. Eight fresh human cervical vertebrae (C3, C4, and C5) were collected and used. μCT scan was performed to evaluate the bone quality of the lateral masses, including bone mineral density (BMD), trabecular thickness (Tb.Th), and trabecular separation (Tb.Sp). SCLMS or S-LMS were randomly inserted into the paired cervical vertebrae and pulled out as a screw loosening model. These screws were reinserted in with bone cement augmentation, scanned by μCT to obtain the bone cement distribution along the screws, and pulled out to test the screw purchase strength. Fmax values exhibited strong positive correlations with the local BMD (𝑟 = 0.8640, p < 0.0001) and Tb.Th (𝑟 = 0.6795, p = 0.0038), whereas a negative correlation with Tb.Sp (𝑟 = -0.5567, p = 0.0251). A significant difference was observed between the Fmax before and after PMMA injection on the SC-LMS side (p = 0.019). The SC-LMS exhibited lower risk of cement leakage than S-LMS after PMMA injection, and a positive correlation was observed between 𝐹max and the distribution volumes on the SC-LMS side. The novel SC-LMS provides more robust fixation stability and is safer than the S-LMS for PMMA augmentation, which may be related to the cement-screw-cement-bone complex formation.

Comparison between cervical lateral mass screw and cervical pedicle screw surgery

Comparison between cervical lateral mass screw and cervical pedicle screw surgery

Spinal navigation with preoperative computed tomography

Safe placement of posterior cervical-sacral pedicle screws, S2-Ala-iliac screws, iliac screws, transarticular screws C1/2, translaminar screws C2 or cervical lateral mass screws under the guidance of spinal navigation. All posterior spinal instrumentations with screws: instabilities and deformities of rheumatic, traumatic, neoplastic, infectious, iatrogenic or congenital origin; multilevel cervical spinal stenosis with degenerative instability or kyphosis of the affected spinal segment. There are no absolute contraindications for spinal navigation. Cervical spine: Prone position on agel mattress, rigid head fixation, e.g., with Mayfield tongs; if appropriate, closed reduction under lateral image intensification; thoracic + lumbar spine: prone position on acushioned frame; midline posterior surgical approach at the level of the segments to be instrumented; if necessary, open reduction; insertion of the cervical/upper thoracic screws under the guidance of spinal navigation; if necessary, posterior decompression; instrumentation longitudinal rods; if fusion is to be obtained, decortication of the posterior bone elements with ahigh-speed burr and onlay of cancellous bone or bone substitutes. In stable instrumentations, no postoperative immobilization with orthosis is necessary, removal of drains (if used) 2-3days postoperatively (postop), removal of the sutures 14days postop, clinical and x‑ray controls 3and 12months postop or in case of clinical or neurological deterioration. Numerous studies showed that the use of spinal navigation significantly reduces implant malplacement rates, complications, and revision surgery. Furthermore, intraoperative radiation exposure to the operation team can be reduced by up to 90%.

Insertional torque in cervical lateral mass screw with Magerl technique

Insertional torque in cervical lateral mass screw with Magerl technique

Cervical lateral mass screw length analysis in men versus women.

Posterior fixations with lateral mass screws have become popular. The Roy-Camille and the Magerl techniques have been established and screw length was identified as a particularly important element. Sex and ethnicity are significant factors in cervical spine morphology, but few studies have been performed for screw length. We performed measurements using computed tomography (CT) images of adult patients hospitalized for surgery of the cervical spine, with targeted 3D data analysis. The final number of patients was 47 (33 men, 14 women) and 235 vertebrae. With the Roy-Camille technique, the screw length was longest at C3 (men: 13.0 mm ± 1.9 mm, women: 13.0 mm ± 1.9 mm) and smallest at C7 (men: 10.8 mm ± 1.8 mm, women: 9.4 mm ± 1.2 mm). With the Magerl technique, the screw length was smallest at C3 (men: 14.8 mm ± 1.6 mm, women: 14.3 mm ± 1.6 mm) and longest at C7 for men (16.8 mm ± 2.8 mm), and at C6 for women (15.4 mm ± 3.0 mm). To differ from spinal canal or pedicle, cervical lateral mass showed no obvious morphological differences from that of subjects of other ethnicity. The placement of a standard lateral mass screw would not cause complications in Japanese patients, even with the use of devices designed in North America or Europe. However, the anatomical background is essential because it is important to optimize the selection for each patient to avoid complications considering sex and individual differences.

Versatile Usage of the Modified Lateral Mass Screw as an Alternative to Cervical Pedicle Screw Fixation.

Posterior subaxial cervical screw fixation is commonly performed using the cervical pedicle screws (CPS) and lateral mass screws (LMS); however, their compatibility is low. Modified lateral mass screws (mLMS, also called paravertebral foramen screw) fixation was introduced as a salvage technique for LMS fixation and has features of both LMS and CPS techniques. In the present study, the use of mLMS as an alternative to CPS was analyzed based on clinical results. Seventy-eight screws (38 CPSs and 40 mLMSs) were inserted into 12 patients. The misplacement of the screws was evaluated by computed tomography (CT). The failure of instrumentation and instability were evaluated using plain radiographs. The total number of CPS misplacements was 3 (10.5%); however, neurologic complications were not observed. mLMSs were used in the middle segments of the fusion in 10 patients and 2 patients had mLMS fixation for single-level fusion. An additional bridging implant was not required for connecting both CPSs and mLMSs. Instability was not observed during the observation period (4-51 months). Complete fusion was seen in 10 patients. The alternative mLMS fixation can decrease the risk of screw misplacement compared with CPS fixation alone and achieves adequate stability leading to fusion.

Posterior hemivertebra resection and short-segment fusion with lateral mass screws in congenital scoliosis: a novel strategy for the resource-limited setting

BackgroundPosterior hemivertebra resection and short-segment fusion with pedicle screws are an established treatment in congenital scoliosis, which require pediatric-specific instrumentation. The purpose of this study was to report the results of utilizing cervical lateral mass screws instead of pedicle screws in the treatment of congenital scoliosis in children younger than 5 years old.MethodsIn an IRB-approved retrospective chart review study, patients <5 years old with congenital scoliosis who underwent posterior hemivertebra resection and fusion with lateral mass screws from 2013 to 2017 were included. Demographic information, pre- and post-operative radiographs, complications, and outcomes were extracted from the charts.ResultsTwenty-three patients were included in the final analysis with a mean age of 40 months, of which 14 were female. Patients were followed for a mean of 51.3±13.2 months. The mean blood loss was 210ml, and patients were hospitalized for a mean of 4 days post-operatively. The correction rate of the main coronal curve, compensatory cranial curve, compensatory caudal curve, and segmental sagittal curve was 74.8%, 68%, 65.2%, and 68.9%, respectively. Three complications were observed: one intra-operative pedicle fracture, one case of implant failure, and one deep surgical-site infection, all of which were successfully managed.ConclusionsOur findings suggest that adult lateral mass screws can be used for transpedicular fixation of the thoracic and lumbar vertebrae in low-resource settings where pediatric-specific pedicle instruments are not readily available. The correction rate, outcomes, and complications are similar and comparable to pediatric-specific pedicle screws, in addition to being low-profile and less bulky compared to adult implants.

Clinical and Radiological Evaluation of Cervical Spondylotic Myelopathy Operated With Posterior Decompression and Lateral Mass Fixation- a Retrospective Review with Minimum Two Years Follow-Up

Objective: There is controversy in surgical management of cervical spondylotic myelopathy (CSM); a few group encourage only laminectomy or laminoplasty while the others emphasize on lateral mass fixation along with laminectomy. Cervical lordosis is an important factor for maintaining posture neck and preventing postoperative axial neck pain. Literature has reported that cervical lordosis less than -20 degrees is often responsible for neck pain. The purpose of this study was to evaluate clinical outcome and radiological parameters after posterior cervical laminectomy and fixation in CSM. Material and Methods: This retrospective study included 37 patients operated with posterior cervical decompression and lateral mass screw fixation with minimum two-year follow-up. All patients were operated for CSM. All were operated by a single surgeon and followed up at six weeks, twelve weeks, six months, one year and yearly afterwards. Clinical outcome and radiological parameters were analyzed for clinical improvement [European Myelopathy Score (EMS)] and cervical lordotic angle. Results: Average age 68±8.3 years. The cervical lordotic angle of -23.02±4.19 degrees was maintained in patients operated with lateral mass screw fixations along with laminectomy at final follow-up. The EMS and VAS score showed significant improvement postoperatively from 15.7 to 13.6 (p&lt;0.05) and 8.1 to 1.5 (p&lt;0.05), respectively. Three patients had postoperative C5 palsy that recovered completely within three months. Two patients expired within a few months after surgery due to acute myocardial infarction and respiratory arrest, respectively. There were three patients who had postoperative C5 palsy, which recovered completely within three months postoperatively. There was no permanent postoperative neurological deficit noticed in the series. Conclusion: Posterior cervical lateral mass screw fixation for CSM gives satisfactory clinical outcome and maintains cervical lordosis. Lateral mass fixation with

Evaluation of free-hand screw placement in cervical, thoracic, and lumbar spine by neurosurgical residents

BackgroundKnowledge of free-hand screw technique remains critical to adequately train neurosurgical residents. The purpose of this study was to evaluate the accuracy of screw placement via the free-hand technique in lumbar, thoracic, and cervical spine by neurosurgical residents completing an enfolded spine fellowship. MethodsMedical records of all patients who underwent free-hand screw placement at all spinal levels over a 6-month period by senior neurosurgical residents enrolled in an in-folded spine fellowship were retrospectively reviewed. Postoperative CT images were assessed for presence and direction of cortical breach. ResultsTwenty-six patients underwent 162 free-hand screw placements. The most commonly placed screws were cervical lateral mass screws (n = 69), thoracic (n = 41), and lumbar pedicle screws (n = 41). The most common indication for surgery was deformity (n = 22), followed by infection (n = 2) and trauma (n = 2). Fifty-five breaches were identified in 44 (27 %) screws placed in 21 patients (81 %). Anterior breach was identified in 22 cases (40.0 %), lateral in 12 (23.6 %), superior in 7 (12.7 %), and inferior in 7 (12.7 %), and medial in 6 (10.9 %). The most common level of breach was observed in cervical lateral mass screws (n = 19, 43 %) and least common in C2 pars screws (n = 1, 2%). With an average length of follow up of 12.1 ± 7.7 months of follow-up, no clinical sequalae of screw breach was observed. ConclusionsDespite the high prevalence of screw breach using the free-hand technique by neurosurgical residents, the absence of clinical sequelae implies safety and emphasizes the importance of early exposure to this technique during neurosurgical residency training.

Simple Technique to Place the Lateral Mass Screws in the Revision Surgery after Cervical Laminoplasty for Ossification of the Posterior Longitudinal Ligament.

A lateral mass screw (LMS) is one of the standard anchor screws in posterior cervical fixation. Although the advantage of cervical LMS is that it is easier and safer to place than pedicle screw, it is sometimes difficult for surgeons to confirm the exact point for screw entry and accurate angle in cases of revision surgery. When LMS fixation is performed as revision surgery after cervical laminoplasty or laminectomy, it might be complicated to secure safe placement of the LMSs. We present a simple but practical technique involving a caliper and angle device for revision surgery after cervical laminoplasty for ossification of the posterior longitudinal ligament. In this technique, the distance between the bilateral entry points is ascertained using preoperative CT. Insertion of the screw is guided using the angle device set to 25 degrees. The technique presented here is easy and allows accurate placement of the LMSs in the posterior cervical spine, and is practical even for revision surgery.

Canadian Spine SocietyPresentation CPSS1: Spinal insufficiency fracture in the geriatric pediatric spinePresentation CPSS2: The clinical significance of tether breakages in anterior vertebral body growth modulation: a 2-year postoperative analysisPresentation CPSS3: Anterior vertebral body growth modulation for idiopathic scoliosis: early, mid-term and late complicationsPresentation CPSS4: Ovine model of congenital chest wall and spine deformity with alterations of respiratory mechanics: follow-up from

Canadian Spine SocietyPresentation CPSS1: Spinal insufficiency fracture in the geriatric pediatric spinePresentation CPSS2: The clinical significance of tether breakages in anterior vertebral body growth modulation: a 2-year postoperative analysisPresentation CPSS3: Anterior vertebral body growth modulation for idiopathic scoliosis: early, mid-term and late complicationsPresentation CPSS4: Ovine model of congenital chest wall and spine deformity with alterations of respiratory mechanics: follow-up from

3-Dimensional printing templates guiding versus free hand technique for cervical lateral mass screw fixation: A prospective study

ObjectiveIn this randomized, single blind and controlled study, the feasibility and precision of 3-dimensional printing templates for cervical lateral mass screw insertion was evaluated. MethodsA total of 6 patients (72 screws), who were diagnosed with cervical spondylotic myelopathy (CSM) and developmental cervical spinal stenosis, were randomly divided into A and B two groups. All subjects underwent modified posterior surgery with using cervical lateral mass screws insertion (C4–C6). Group A underwent surgeries with screw insertion assisted by the guidance of 3-dimensional printing templates and Group B underwent surgeries with screw insertion by freehand. The criteria of the accuracy of screw placement were set as the main evaluation indicators. ResultsThere was no significant difference between the 2 groups in age, improvement rate of JOA, operation time and blood loss. According to Bayard’s criteria, 32 screws (88.9%) were described as “acceptable” in group A and 22 screws (61.1%) were described as “acceptable” in Group B (P < 0.05). Based on our criteria, the “excellent and good” rate of screws was 83.3% in group A and 47.2% in Group B, respectively (P < 0.05). The precision of screws’ location in Group A was superior to that in Group B. Conclusions3-Dimensional printing screw insertion templates may achieve (1) comprehensive visualization of the cervical vertebrae and lateral mass and the individual surgical planning using the 3-dimensional model preoperatively. (2) increasing the accuracy of cervical lateral mass screw insertion.

Risk Factor Analysis of Facet Fusion Following Cervical Lateral Mass Screw Fixation with a Minimum 1-Year Follow-up: Assessment of Maximal Insertional Screw Torque and Incidence of Loosening.

Posterior stabilization is a common surgical procedure, which aims for rigid stabilization by facet fusion. Facet non-union has a potential risk of the screw loosening and malalignment. Although some authors have reported the influencing factors about screw loosening in the lumbar spine, there are few reports about the risk factor contributing to the facet non-union in the cervical spine. In all, 22 patients (78 facets and 122 screws) with degenerative cervical kyphosis or spondylolisthesis who underwent decompression and lateral mass screw (LMS) fixation were analyzed. Age, gender, smoking, bone mineral density (BMD), the degree of facet decortication with bone packing, and screw loosening were investigated as risk factors contributing to the facet non-union at each segmental fused level. Facet fusion rate was 85.9% (67/78 facets) and the incidence of loosening was 4.9% (6/122 screws, 4 patients). Insufficient facet decortication with bone packing is a significant risk factor of facet non-union (p <0.05, odds ratio: 26.5). All six loosened screws were associated with bony non-union of the facet and were located in the uppermost or lowermost vertebrae. Comparing loosened screws and stable screws, the average maximal insertional screw torque (MIT) was 9.8 cNm and 39.5 cNm, respectively (p <0.05). Additionally, the length of the stable screws was significantly longer versus the loosened screws (p <0.05). Lower MIT and shorter screw length located near the ends of the lateral mass may predict loosening, which can lead to facet non-union. Sufficient facet decortication with bone packing is one of the important factors contributing to the facet fusion.

Progress in the application of posterior cervical lateral mass screw fixation

Posterior cervical lateral mass screw fixation refers to the surgical procedure for treating cervical vertebrae disease by inserting a needle into the lateral side of the cervical vertebra and achieving internal fixation to the cervical vertebrae by screws, connecting plates and the like. In view of the high degree of cervical vertebra activity and complex structure, adjacent to the cervical spinal cord and multiple nerves and blood vessels, the cervical spine is difficult to place and has a certain degree of risk, and the posterior cervical lateral mass screw fixation can effectively reduce the incidence of injuring the nerves and vessels. In recent years, the clinical research on the posterior approach of the cervical spine is more and more abundant. In order to facilitate the clinician to better understand the advantages and disadvantages of the procedure and the development direction of the new technology of dynamic tracking. Now, a review of the application of this technique in recent years is reviewed. Key words: Cervical vertebrae; Spinal canal; Decompression, surgical; Lateral mass screws fixation

174. Analysis of radiological accuracy among different intraoperative imaging systems for screw fixation in cervicothoracic region

BACKGROUND CONTEXT Surgical techniques for posterior fixation of cervicothoracic pathologies are challenged by the great variation in pedicle dimension and angulations as well as the risky neurovascular anatomy with the proximity of the spinal cord, nerve roots, and vertebral artery. Intraoperative computed tomography navigation promises improved accuracy of spinal navigation with the benefit of increased visualization of a pedicle's trajectory. Even though multiple studies have demonstrated improved accuracy using navigated instrumentation, it remains a debate how useful iCT imaging is for posterior pedicle and lateral mass screw implantation in the subaxial cervicothoracic spine. PURPOSE The aim of this study was to compare the accuracy of posterior subaxial cervicothoracic fixation using three different techniques: intraoperative computed tomography (iCT-AIRO) scanner-guided navigation, 3D- (O-arm) based spinal navigation and fluoroscopy based posterior stabilization. STUDY DESIGN/SETTING Retrospective analysis of the accuracy of cervicothoracic screw placement in posterior fixation in 3 groups of patients. PATIENT SAMPLE In the period between August 2007 and October 2018, a total of 495 screws were implanted in 67 patients with cervicothoracic instability who underwent posterior fixation. A total of 163 screws were inserted with the use of the iCT based spinal navigation (group A); 310 screws were implanted using the O-arm navigation system (group B), while 22 screws were inserted under the guidance of fluoroscopy (group C). OUTCOME MEASURES Screw positions were evaluated using postoperative CT scans according to the Neo et al (cervical pedicles) and Gertzbein and Robbins (thoracic) classifications. The screws in the cervical lateral mass were evaluated according to a new classification created by the authors. METHODS The assessment of the screw placement was retrospectively done and graded by an independent observer. Accurate positioning was defined then as screws correctly placed completely within the pedicle as well as screws with a breach of less than 2 mm or screws correctly placed within the lateral mass as well as screws with incomplete perforation of the cortex. RESULTS Intraoperative computed tomography-based navigation has permitted a more accurate intraoperative evaluation of the implanted screws and has allowed the immediate correction of misplaced screws. With the use of the iCT, the accuracy rate has reached 97.55% with a much better resolution of the images acquired, while with the O-arm navigation, the accuracy rate has reached 90%. In cervicothoracic posterior stabilizations done with the aid of fluoroscopy, the intraoperative accuracy was not determined and only a final accuracy rate was measured which reached 90%. The most significant difference in accuracy was in the positioning of cervical pedicle screws. Our results have demonstrated an accuracy of 96% with iCT compared to an accuracy of 64% with the O-Arm. The accuracy rates in positioning the cervical lateral mass screws and the thoracic pedicle screws with both the iCT or the O-Arm were almost the same. CONCLUSIONS In subaxial cervicothoracic posterior fixation especially of pedicle screws, the use of iCT-based spinal navigation has demonstrated higher accuracy rates as well as higher quality images allowing more accurate evaluation than with the O-arm-based spinal navigation or fluoroscopy-based systems. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.