Cervical Pedicle Research Articles

Optimal screw positioning in cervical pedicles to avoid complications.

Cervical instability can be caused by a variety of factors, including trauma, tumors, or infection. The cervical transpedicular screw (CPS) is one of the most modern procedures for treating cervical instability. Despite the fact that numerous innovative techniques for CPS have been proposed, the appropriate screw entry points and screw directions have yet to be thoroughly established. The aim of this study is to determine the screw insertion angles and screw entry point distances based on reference points, pedicle axis lengths, and pedicle axis intersections for each vertebra from cervical (C) C2 to C7 in both right and left by gender and age groups. In this study, computed tomography (CT) images of patients who underwent cervical examination for any reason were evaluated retrospectively. A total of 100 patients (59 men and 41 females), ranging in age from 18 to 79 years (mean 43 years), were randomly selected for the study. Patients with a history of cervical pathology or surgery were excluded. CT images turned into 3D reconstructed images and density settings were made so that bone tissue could be best observed using OsiriX software. Pedicle axis length (PAL), pedicle transverse angle (PTA), pedicle sagittal angle (PSA), distance of screw entry point to lateral notch (DLN), distance of screw entry point to inferior articular process (DIAP), and pedicle axis intersections were measured. According to our findings, the optimal entry point should be 2-4 mm medial to the lateral notch and 8-12 mm superior to inferior articular process. PTA ranges between 30 to 45°, while PSA ranges between 11 to 15°. Except for the C2 pedicles, which were slightly shorter, the pedicle axis lengths (PAL) were similar from C3 to C7 in the total group. The intersection of the right and left pedicle axes was determined to be the most in C4 (51.21% in females and 72.88% in males). This study has shown that intersections of the pedicle axis must be considered in both genders, especially in C4. Standardizing optimal entry points and trajectories is crucial for improving the CPS technique's safety and effectiveness.

Comparison between O-arm Navigation and Conventional Fluoroscopic Guidance in Corrective Posterior Fixation for Cervical Spinal Injury.

Purpose : To compare the effectiveness of O-arm navigation with that of conventional fluoroscopic guidance in corrective posterior fixation for cervical spinal injury. Methods : This retrospective comparative study involved 11 consecutive patients who underwent corrective posterior fixation using O-arm navigation or conventional fluoroscopy for cervical spinal injury between February 2016 and May 2021. Patient-specific characteristics (age and sex), number of screws, number of pedicle screws, accuracy of pedicle screw insertion, number of vertebral bodies fixed, operating time, and length of hospital stay were analyzed using the t-test. A P-value < 0.05 was considered statistically significant. Results : Corrective posterior fixation was performed under O-arm navigation in 5 patients and under conventional fluoroscopic guidance in 6. A significantly greater number of pedicle screws was used in the O-arm group (6.4 vs 2.7, P = 0.046). According to the Neo classification for pedicle screw placement, there were no grade 2 or 3 breaches. No other items showed a significant difference between the groups (P > 0.05). Conclusion : O-arm navigation can improve the accuracy of cervical pedicle screw insertion. Its introduction could expand the indications for use of pedicle screws in posterior fixation of cervical spinal injury beyond those that are possible using conventional fluoroscopy. J. Med. Invest. 69 : 273-277, August, 2022.

Accuracy and safety of free-hand pedicle screw placement in cervical injury patients

Objectives: The purpose of this study was to describe the free hand method of pedicle screw placement without intraoperative imaging monitors and to evaluate the accuracy of the screw placement in quadriplegics patients. Methods: A free hand screw was inserted in the eleven cervical injury patients with quadriplegia. We studied the preoperative pedicle dimension in all the patients and assessed the clinical and radiological outcome and accuracy of the screw placement. Results: A total of 44 screws were inserted in the cervical pedicles of eleven patients. The postoperative images showed that 28 of the 44 screws had perforated the pedicles but none of them had breached the spinal canal. Among them 16 screws were grade 2 and 12 screws were grade 3. All the screws had penetrated the lateral wall. There were no neurovascular complications related to any malpositioned screw and there was no screw loosening or instrumentation failure in the patients. Conclusion: The free hand screw placement without intraoperative image guidance seems to be safe and effective method of fixation. But this technique requires sound knowledge of the cervical anatomy and experience and is useful in the places where navigation system are not available.

The accuracy of cervical pedicle screw placement with O-arm-based navigation: A comparison of medial and lateral approaches

The accuracy of cervical pedicle screw placement with O-arm-based navigation: A comparison of medial and lateral approaches

Morphometric Computed Tomography-Based Analysis of Cervical Pedicle and Facet Joints in South Indian Population

Title: Morphometric CT based analysis of cervical pedicle and facet joints in South Indian population.&#x0D; Aim: To evaluate individual morphometric variations of the cervical spine pedicles and facet joints by computed tomography among patients attending a tertiary care centre.&#x0D; Methodology: A retrospective cross-sectional study was carried out among 25 patients undergoing CT study of the cervical spine at Saveetha Medical College and Hospitals, Thandalam. Various measurements of the cervical pedicles and cervical facet joints were obtained and analysed as mean, standard deviation, and range using Statistical Package for the Social Sciencessoftware.&#x0D; Results: Among the 25 subjects, 56% were males and 44% were females with mean age of 59.9 and 55.2 respectively. Pedicle length (PL) and Pedicle height (PH) was comparatively smaller in women than in men. Pedicle isthmus (PI) and Lateral pedicle distance (LPD) of C7 was the greatest in both genders. Pedicle axial length (PAL) was equal in both genders with left side being more than the right. Maximum Superior Pedicle distance (SPD) was found to be at C5 level in both genders. Sagittal angulation showed lesser values in females and the Transverse angulation was the lowest at C7 level in both genders. Facet tropism showed a decreasing pattern from C3 to C7 in both genders.&#x0D; Conclusion: This study helps the surgeon to understand variations in the morphometrics of the study population and will be useful in the determination of a safe treatment modality.

Benefits and Pitfalls of O-Arm Navigation in Cervical Pedicle Screw

Cervical pedicle screw (CPS) with O-arm-based intraoperative navigation has demonstrated satisfactory results in recent studies. In this article, we introduce our experience and discuss important considerations for CPS placement with O-arm navigation. We retrospectively reviewed the data of 51 patients with 156 pedicle screws who underwent O-arm navigated CPS from July 2020 to October 2021. The accuracy of each screw placement was evaluated at the initial screw location using intraoperative 3D reconstructed O-arm images and the final screw location using postoperative computed tomography (CT). The screw accuracy was assessed in the axial image. The initial accuracy of screws on intraoperative 3D reconstructed O-arm images was 93.6% (146 of 156). The accuracies of the mid-cervical level (C3, C4, C5) were relatively low (83.3%-85.0%) compared with those of C2, C6, and C7 (93.3%-100.0%) at the initial screw due to the rotation of the vertebral body. Among 10 violated screws, 5 were converted to lateral mass screws or removed intraoperatively, and the other 5 were retained because the violations were minimal. After converting the screw, the final accuracy of the screws in postoperative CT was 96.7% (146 of 151). CPS with O-arm navigation showed relatively low accuracy at the mid-cervical level due to vertebral rotation. However, the opportunity to convert the screw from intraoperative 3D reconstructed O-arm images is the advantage of the O-arm navigation, and it showed excellent accuracy.

Letter to the Editor Regarding “Traumatic Brain Injury–Related Pediatric Mortality and Morbidity in Low- and Middle-Income Countries: A Systematic Review”

Cervical pedicle screws (CPS) in the subaxial cervical spine (C3-C6) are faced with high incidence of perforating the lateral pedicular cortex endangering the vertebral artery (VA). The present study analyzes the pedicle width (PW) from C3 to C6 and defines the relation of VA with regard to pedicle and transverse foramen (TF) to determine the safety margin in cases of lateral pedicular breach.Computed tomography angiograms of 500 patients were retrospectively studied to identify the pedicle width (PW), VA area, TF area, and the lateral pedicle to vertebral artery distance (LPVA). Occupancy ratio (OR; the percentage area of transverse foramen occupied by VA) and safety margin (SM; permissible displacement of VA in TF), along with LPVA were considered to be protective parameters against VA injury if lateral pedicle breach happens.PW was 4.7 mm at C3, 4.83 mm at C4, 5.26 mm at C5 and 5.41 mm at C6. Mean LPVA at different levels was between 0.97 mm and 1.15 mm, OR was around 20% at all levels, and mean SM was between 2.34 mm and 2.92 at various levels. Sex differences were statistically significant for PW but not for LPVA, SM, or OR.This study gives us an idea about the various parameters in placement of cervical pedicle screw in subaxial cervical spine and the probable reasons there are few vertebral artery injuries despite high incidence of cervical pedicle breach. LPVA, safety margin, and OR may explain why even very significant CPS misplacement does not lead to vascular injury or neurologic deficit.

Cervical Spine Pedicle Screw Accuracy in Fluoroscopic, Navigated and Template Guided Systems-A Systematic Review.

Background: Pedicle screws provide excellent fixation for a wide range of indications. However, their adoption in the cervical spine has been slower than in the thoracic and lumbar spine, which is largely due to the smaller pedicle sizes and the proximity to the neurovascular structures in the neck. In recent years, technology has been developed to improve the accuracy and thereby the safety of cervical pedicle screw placement over traditional fluoroscopic techniques, including intraoperative 3D navigation, computer-assisted Systems and 3D template moulds. We have performed a systematic review into the accuracy rates of the various systems. Methods: The PubMed and Cochrane Library databases were searched for eligible papers; 9 valid papers involving 1427 screws were found. Results: fluoroscopic methods achieved an 80.6% accuracy and navigation methods produced 91.4% and 96.7% accuracy for templates. Conclusion: Navigation methods are significantly more accurate than fluoroscopy, they reduce radiation exposure to the surgical team, and improvements in technology are speeding up operating times. Significantly superior results for templates over fluoroscopy and navigation are complemented by reduced radiation exposure to patient and surgeon; however, the technology requires a more invasive approach, prolonged pre-operative planning and the development of an infrastructure to allow for their rapid production and delivery. We affirm the superiority of navigation over other methods for providing the most accurate and the safest cervical pedicle screw instrumentation, as it is more accurate than fluoroscopy and lacks the limitations of templates.

Determination of Availability of Safety Margin for Placement of C3-C6 Pedicle Screw on CT Angiography

Cervical pedicle screws (CPS) in the subaxial cervical spine (C3-C6) are faced with high incidence of perforating the lateral pedicular cortex endangering the vertebral artery (VA). The present study analyzes the pedicle width (PW) from C3 to C6 and defines the relation of VA with regard to pedicle and transverse foramen (TF) to determine the safety margin in cases of lateral pedicular breach. Computed tomography angiograms of 500 patients were retrospectively studied to identify the pedicle width (PW), VA area, TF area, and the lateral pedicle to vertebral artery distance (LPVA). Occupancy ratio (OR; the percentage area of transverse foramen occupied by VA) and safety margin (SM; permissible displacement of VA in TF), along with LPVA were considered to be protective parameters against VA injury if lateral pedicle breach happens. PW was 4.7 mm at C3, 4.83 mm at C4, 5.26 mm at C5 and 5.41 mm at C6. Mean LPVA at different levels was between 0.97 mm and 1.15 mm, OR was around 20% at all levels, and mean SM was between 2.34 mm and 2.92 at various levels. Sex differences were statistically significant for PW but not for LPVA, SM, or OR. This study gives us an idea about the various parameters in placement of cervical pedicle screw in subaxial cervical spine and the probable reasons there are few vertebral artery injuries despite high incidence of cervical pedicle breach. LPVA, safety margin, and OR may explain why even very significant CPS misplacement does not lead to vascular injury or neurologic deficit.

Ten-year clinical and radiographic results of computer-assisted cervical pedicle screw fixation combined with laminoplasty

ObjectiveCervical pedicle screw (CPS) fixation is widely used for the treatment of cervical spinal instability from various causes; however, there are few reports on the long-term outcomes of this procedure. The present study evaluated the 10-year results of CPS fixation for cervical instability. MethodsThe medical records of 13 consecutive patients who underwent computer-guided CPS fixation for cervical instability were reviewed. The mean observation period was 153 months. Evaluated items included Japanese Orthopaedic Association (JOA) score and C2-7 lordotic angle before surgery and at 5 and 10 years afterwards. Visual analog scale (VAS) scores for neck pain and radiological evidence of adjacent segment degeneration (ASD) at 10 years of follow-up were also assessed. ResultsMean JOA score significantly improved from 9.4 points before surgery to 13.2 points at 5 years after surgery (p < 0.001), followed next by a slight reduction to 11.6 points at 10 years postoperatively. C2-7 lordotic angle tended to decrease from 7.9° preoperatively to 5.3° at 10 years after surgery. No clinically significant complications, such as neurovascular injury caused by screw misplacement, were observed. The mean VAS score for neck pain was 31.7 points at the study endpoint, and ASD rate was 23.1%. ConclusionsAt 10 years after CPS fixation, mean JOA score was improved without symptoms indicative of cervical myelopathy recurrence. Our long-term results confirm that computer-assisted CPS fixation is useful for treating cervical instability.

The comparative accuracy and safety of fluoroscopic and navigation-based techniques in cervical pedicle screw fixation: systematic review and meta-analysis.

The goal of this study was to evaluate the comparative accuracy and safety of navigation-based approaches for cervical pedicle screw (CPS) placement over fluoroscopic techniques. A systematic search of the literature published between January 2006 and December 2019 relating to CPS instrumentation and the comparative accuracy and safety of fluoroscopic and intraoperative computer-based navigation techniques was conducted. Several databases, including the Cochrane Library, PubMed, and EMBASE, were systematically searched to identify potentially eligible studies. Data relating to CPS insertion accuracy and associated complications, in particular neurovascular complications, were extrapolated from the included studies and summarized for analysis. A total of 17 studies were identified from the search methodology. Eleven studies evaluated CPS placement under traditional fluoroscopic guidance and 6 studies addressed outcomes following navigation-assisted placement (3D C-arm or CT-guided placement). Overall, a total of 4278 screws were placed in 1065 patients. Misplacement rates of CPS were significantly lower (p < 0.0001) in navigation-assisted techniques (12.51% [range 2.5%-20.5%]) compared to fluoroscopy-guided techniques (18.8% [range 0%-43.5%]). Fluoroscopy-guided CPS insertion was associated with a significantly higher incidence of postoperative complications relating to neurovascular injuries (p < 0.038), with a mean incidence of 1.9% compared with 0.3% in navigation-assisted techniques. This systematic review supports a logical conclusion that navigation-based techniques confer a statistically significantly more accurate screw placement and resultant lower complication rates.

Cervical Spine Navigation and Enabled Robotics: A New Frontier in Minimally Invasive Surgery.

Background: Robotic-assisted and computer-assisted navigation (CAN) systems utilization has been rapidly increasing in recent years. Most existing data using these systems are performed in the thoracic, lumbar, and sacral spine. The unique anatomy of the cervical spine maybe where these technologies have the greatest potential. To date, the role of navigation-enabled robotics in the cervical spine remains in its early stages of development and study. Purpose: This review article describes the early experience, case descriptions and technical considerations with cervical spine screw fixation and decompression using CAN and robotic-assisted surgery. Methods: Representative cervical cases with early surgical experience with cervical and robotic assisted surgery with CAN. Surgical set up, technique considerations, instrumentation, screw accuracy and screw placement were elevated and recorded for each representative cervical case. Results: Existing robotic assisted spine surgical systems are reviewed as they pertain to the cervical spine. Method for cervical reference and positioning on radiolucent Mayfield tongs are presented. C1 lateral mass, odontoid fracture fixation, C2 pedicle, translaminar, subaxial lateral mass, mid cervical pedicle, navigated decompression and ACDF cases and techniques are presented. Conclusion: In conclusion, within the last several years, the use of CANs in spinal surgery has grown and the cervical spine shows the greatest potential. Several robotic systems have had FDA clearance for use in the spine, but such use requires simultaneous intraoperative fluoroscopic confirmation. In the coming years, this recommendation will likely be dropped as accuracy improves.

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.

Subaxial Cervical Pedicle Screw Placement With Direct Visualization of Pedicle Borders: 2-Dimensional Operative Video.

Pedicle screws provide superior fixation of the subaxial cervical spine to other techniques. However, a high degree of accuracy is required for safe placement given the proximity of pedicles to critical neurovascular structures. A variety of techniques are described to maximize accuracy, including freehand, fluoroscopy-guided, and neuronavigation-based methods. We present a technique for the placement of pedicle screws in the subaxial cervical spine using direct visualization of the pedicle in a patient who required an occipito-cervical fusion construct in the setting of a C2 chordoma. A laminotomy or laminectomy is performed laterally to allow for visualization of the medial, superior, and inferior walls of the pedicle. The entry point for screw placement is determined based on pedicle anatomy and is typically 1 to 2 mm lateral to the midpoint of the lateral mass, just below the base of the superior articulating process. Screw trajectory is determined by visualizing the pedicle borders and is aimed at the junction of the medial pedicle wall, with the posterior vertebral body down the pedicle axis. Tactile feedback (loss of resistance) is used to assess for a breach while drilling. The cannulation is then tapped, and the screw is placed in a standard fashion. Direct visualization of pedicle anatomy can be a useful adjunct to guide the safe placement of subaxial pedicle screws when superior fixation is required or when normal anatomy is distorted. The technique may be combined with fluoroscopic or navigation-based techniques to provide real-time anatomic guidance during screw placement. The patient provided informed, written consent for this procedure before surgery. Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

Comparative evaluation of screw accuracy and complications of new C-arm free O-arm navigated minimally invasive cervical pedicle screw fixation (MICEPS) with conventional cervical screw fixation

Study designRetrospective comparative study. ObjectiveComparative study of C-arm free O-arm navigated minimally invasive cervical pedicle screw (MICEPS) fixation with conventional cervical pedicle screw fixation. MethodsTwenty-five patients with different cervical spine pathologies were operated with MICEPS with O-arm navigation (group M; 18 patients) and conventional pedicle screw (group C; 7 patients) from June 2017 to January 2020. Operative time, blood loss were recorded. Preoperative and postoperative radiograms, CT scans and MRI were evaluated. Postoperatively screw position accuracy and angulation was determined on CT. Breach rate was evaluated on CT scan and classified according to Neo grading. Complications if any were noted. ResultsThe average blood loss in group M and group C was 129 ml and 329 ml, respectively. The average operative time in group M and group C was 77.4 min and 82.3 min, respectively. A total of 148 screws were inserted. In group M, no patient showed grade 2 and 3 breach while in group C, grade 0 and 1 breach was found in 85.7% screws and grade 2 in 14.3% screws. Mean screw medial angulation was 45.2 degrees in group M and 33.4 degrees in group C. There was one dural tear and two C5 palsies in each group. ConclusionWith C -arm free O-arm navigated MICEPS fixation operative time and blood loss are less though not statistically significant. It has less pedicle breach rate, less incidence of neurovascular complications than conventional technique. There is no radiation exposure to operating surgeon and staff.

Using the lamina nutrient foramen as the entry point for posterior cervical pedicle screw placement

Study designA prospective study and technique description. ObjectiveThis study introduced a method for posterior cervical pedicle screw placement by using the bilateral posterior lamina nutrient foramens as the entry point. MethodsFirstly, 30 dry C3-C7 vertebrae specimens were harvested for measurement. The lamina nutrient foramens were used as the entry points for posterior cervical pedicle screw placement and four linear and two angle parameters were obtained from a computed tomography scan(CT). Then, 60 patients who underwent C3–C7 pedicle screw fixation using this method were included, linear and angle parameters were obtained from a postoperative CT. ResultsThe average incidences of lamina nutrient foramen on the C3–C7 specimens were 88.3%, 90.0%, 95.0%, 95.0%, and 96.7%, respectively. The distances from the entry point to the pedicle screw tip (OD), the pedicle transverse angles (α), and the pedicle sagittal angles (β) measure for the entry points from C3–C7 were 28.74 ± 3.45–30.15 ± 2.01 mm, 26.88 ± 6.89° to 32.72 ± 5.91°, and 12.48 ± 9.31° to 19.71 ± 8.45°, respectively, with no significant differences between the left and right sides. In the 60 patients who underwent surgery, the lengths of the pedicle screws (PL) were 28.34 ± 2.25–30.15 ± 2.31 mm, the pedicle transverse angles (α) were 26.89 ± 6.86° to 32.36 ± 5.65°, and the pedicle sagittal angles (β) were 12.49 ± 9.11° to 20.06 ± 8.91°. The new method had a 96.8% (454/469) success rate among these patients, with no screws penetrating the spinal canal or signs of vertebral artery injury. ConclusionEntry at the bilateral lamina nutrient foramen represents an alternative posterior cervical pedicle screw placement technique that is feasible and safe.

3D PLANNING IN ORTHOPAEDICS: AN ESSENTIAL TOOL FOR COMPLEX SURGERY

Abstract INTRODUCTION In orthopedic surgery, the appearance of three-dimensional digital reconstructions represented a clear before and after in the planning of highly complex surgeries. However, these reconstructions only allow to improve the visualization of the lesion. In recent years, new techniques have been incorporated, such as 3D printing of bone reconstructions, improving the understanding of the anatomy of each patient, allowing the simulation of possible treatments, and even their intraoperative manipulation. MATERIAL AND METHODS A 3D impression was made in surgical resin of a reconstruction of a CT of the cervico-thoracic spine, with a metastatic lesion in T2, in order to study the possible viability of an en-bloc vertebrectomy and the simulation of pedicle paths. RESULTS The feasibility of vertebrectomy was verified thanks to a better estimation of the available window size. Simulations were performed in the cervical pedicle paths, obtaining the best possible orientation according to the anatomy. Manipulation of the model in the surgical field allowed an in situ comparison with the exposed area, and optimized the result. CONCLUSIONS Planning and 3D printing in Orthopaedics is an indispensable tool when performing complex surgery. It allows to improve the understanding of the particular anatomy of each patient and simulate different treatments to obtain the best possible result.

Morphometric Analysis of Subaxial Cervical Spine Pedicles in a Middle Eastern Population.

Pedicle screw instrumentation of the posterior cervical spine is the most secure form of fixation available to surgeons. It has not achieved widespread use yet in the Middle East, mostly due to concerns regarding its feasibility in the target population. A detailed morphometric analysis of the lower cervical spine pedicles using computerized tomography (CT) was proposed to address this issue. Two hundred and seventy patients were enrolled in the study. CT scans were reviewed by two experienced assessors, and measurements of pedicle width (PW), height (PH), and transverse angle (TA) were recorded for all patients. Interobserver and intraobserver reliability were calculated using the kappa statistic. Sex differences were also recorded and analyzed. The t test was used to assess for any significant differences in measurements due to sex (P < .05). The mean PW varied from 4.4 mm in C3 to 6.1 mm in C7. The mean PH was 6.4 mm in C3 and 6.8 mm in C7. Pedicle TA varied from 42 to 51 degrees between the different levels. Sex differences were observed and were statistically significant for PW and PH. Interobserver reliability was high for PW and PH, but was low for TA. Intraobserver reliability was 0.99 for both assessors. This study provides reliable PW and PH measurements and demonstrates that cervical pedicle screw instrumentation is feasible in our local population. Significant variability exists, however, and each patient must be addressed individually for best results. 3. This study shows that the morphology of the subaxial cervical pedicle permits instrumentation in a majority of cases of our target population.

Validation of Freehand Cervical Pedicle Screw Placement in Subaxial Spine Using the "Burcev Technique": A Cadaveric Study.

The present study attempted to validate the “Burcev freehand method” based on anatomical observations in Indian cadavers. The study was conducted on 32 cervical pedicle screws (CPSs) that were placed in four cadavers by the authors according to the “freehand technique,” described by Burcev et al, without the aid of fluoroscopy and the trajectory verified by computed tomography scans. The screws were designated as satisfactory, permissible, or unacceptable. Descriptive variables were represented in number and percentages, continuous variables were represented as mean ± standard deviation (SD). Of the 32 CPSs placed, 24 (75%) exhibited a satisfactory position, 1 (3%) exhibited a permissible position, and 7 (22%) exhibited an unacceptable position. Of the seven CPSs in the unacceptable group, four exhibited a lateral breach and three exhibited a medial breach, whereas the CPS in the permissible group exhibited a medial breach. The overall angle with contralateral lamina in the horizontal plane in terms of mean ± SD was 175.43 ± 2.82, 169.49, and 169.65 ± 6.46 degrees in the satisfactory, permissible, and unacceptable groups, respectively. In the sagittal plane, the screws exhibited an angle of 88.15 ± 3.56 degrees. No breach was observed superiorly or inferiorly. The “Burcev technique” is replicable with similar results in cadavers. Further studies must be conducted in a clinical setting to ensure its safety.

Robotic Assistance for Minimally Invasive Cervical Pedicle Instrumentation: Report on Feasibility and Safety

Accurate screw placement remains challenging, especially in the cervical spine. We present our first experience of minimally invasive posterior cervical and upper thoracic pedicle screw fixation in the lower cervical spine. This study reports a case series of patients, undergoing posterior percutaneous pedicle fixation using Cirq robotic assistance coupled to the Airo intraoperative computed tomography scan and Brainlab navigation system. Routine computed tomography was performed on postoperative day 2 to evaluate pedicle screw placement. The effective dose was calculated. Between February 2020 and December 2020, 7 patients (4 men and 3 women) were treated. The mean age was 58.8 years (range, 29-75 years). Fixation was performed with a cannulated PASS OCT Reconstruction System (Medicrea). Overall, 28 screws were placed within cervical and upper thoracic pedicles. According to the Neo and Heary classification, 85.7% were rated as acceptable and 14.3% as poor. The radiation dose received by the patient was 9.1 mSv (range, 7.7-10.6 mSv). The radiation dose received by the surgical staff was 0 mSv. The postoperative course was excellent. Posterior miniopen fixation using Cirq robotic assistance coupled with an intraoperative computed tomography navigation system is a major innovation that can improve the accuracy of pedicle screw positioning, with acceptable patient radiation and reduced surgical team exposure.