Screw Fixation In Cervical Spine Research Articles

Robotic-Assisted and Computer-Assisted Navigation Surgery in the Cervical Spine: Current Experiences, Techniques, and Accuracy

Background: In recent years, the role of robotic-assisted and computer-assisted navigation (RA-CAN) systems has significantly expanded in spine surgery, particularly those performed in the thoracic, lumbar and sacral spine showing higher accuracy in pedicle screw placement and improved surgical efficiency. However, there are few reports on these techniques in the cervical spine. The anatomy of the cervical spine possesses additional challenges such as the close proximity to critical neurovascular structures. Purpose: In this article, we present the existing clinical experience of RA-CAN in the cervical spine and evaluate technical considerations. Cervical spine screw fixation and decompression using RA-CAN are reviewed. Results: This analysis covers various aspects such as techniques, accuracy, and the types of procedures reported in the literature. Recent reports include surgical procedures such as anterior cervical diskectomy and fusion’s, odontoid fracture fixation, C1 lateral mass, C2 pedicle, translaminar, subaxial spine lateral mass, and mid-cervical spine pedicle screw fixation. There is potential for enormous clinical benefit to navigated decompression in cervical CAN procedures also. Future opportunities include further improvements in imaging co-localization, pre-surgical planning software, and mechanization of surgical procedures for instrumentation and decompression. Conclusion: The growth of RA-CAN in spinal surgery has shown significant potential in its application in the cervical spine for fusion procedures as well as decompression. By understanding the potential limitations and techniques reported from early experiences, previous techniques can be improved and provide further benefits for accuracy and less invasive surgery.

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.

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COMPUTER 3D-MODELING OF PATIENT-SPECIFIC NAVIGATIONAL TEMPLATE FOR CERVICAL SCREW INSERTION

Objective. To prove the effectiveness of 3D computer modeling and printing of patient-specific templates for cervical spine screw fixation. Materials and Methods . Based on the MSCT data of three patients, 3D models of cervical vertebrae and guiding templates were produced. The screws were inserted transpedicularly into 3D-printed models of C 2 –C 7 vertebrae and C 1 lateral masses using standard cervical instrumentation. This technology was then clinically tested in a patient with C 2 tumor, in whom posterior stabilization of C 1 –C 3 vertebrae was performed using guiding templates. In the postoperative period, MSCT was performed to monitor the position of screws. Results. When implanting screws into 3D-models, technical difficulties were not revealed. After insertion of screws, a visual assessment of the 3D vertebra model was made. Malpositions in models were not detected. Based on the proven technique, a clinical approbation was performed in a patient with normal cervical spine pattern. MSCT study revealed the deviation of screws relative to the planned trajectory by no more than 2 mm, with no malpositions. Conclusion. The first domestic description of the technique of navigation using guiding templates is presented. Of all the existing methods, this is the most reliable way of screw positioning in the cervical spine. The possible insertion error does not affect the quality of positioning.

Pedicle screw fixation in the lower cervical spine: Case series

Background: Pedicle screw fixation of lower cervical spine is a new technique that provides an alternative to posterior lateral mass plating. Although biomechanical studies suggest the use of pedicle screws to reconstruct the cervical spine, placing screw in small cervical pedicle poses a technical challenge. Penetreation of screw in pedicle is a primary complication associated with screw insertion in the lower cervical spine. Aim and Objective: To manage the cervical spine injuries by pedicle screw presented to department of Orthopaedics, BPKIHS, Dharan. Materials and methods: This is retrospective interventional study done at the department of Orthopaedics, B.P. Koirala Institute of Health Sciences, Dharan, Nepal over a period of 2 years from March 2012 to April 20014. A total of 55 patients with cervical spine injuries were treated by pedicle screw. The patient’s age ranged from 20 to 60 years and the mean follow-up was 12 weeks. Results: The study comprised of 55 patients with cervical spine injuries were treated by pedicle screw The age incidence in this series ranged from 20 years to 60 years. 40 patients were males and 20 was female. All had fractures or fracture dislocation at different levels of lower cervical spine. The mechanism of injury included falls from height (80%), motor vehicle accidents (18%) and sports related injury (2%). Discussion: Pedicle screw insertion into the pedicles in the lower cervical spine is technique that requires a solid knowledge of 3-dimensional anatomy of cervical spine and experience of pedicle screw fixation in thoracolumbar spine. The biomechanical advantages of pedicle screw fixation in cervical spine is obvious, but data are limited. However, safety and role of pedicle screw fixation in reconstruction in the lower cervical spine have not been defined. Conclusion: It is indicated in patients with osteoporotic bone or when rigid internal fixation can not be achieved by conventional techniques.

Successful Treatment of Iatrogenic Vertebral Artery Pseudoaneurysm with Coil Embolization: Case Report

Introduction: Iatrogenic vertebral artery injury (IVAI) is a rare intricacy during cervical spine screw fixation or removal surgery. The overall incidence of vertebral artery (VA) injury related to craniocervical surgery is about 0.2% in literature.Case presentation: We report a case of 52-year-old male who suffered iatrogenic vertebral artery injury (VAI) as a result of surgical removal of C1-2 screw that was successfully fixed at posterior cervical spine on account of traumatic atlantoaxial dislocation four (4) years ago. The surgical removal was on going at a periphery hospital when the patient suffered this intricacy with massive bleeding. He was immediately transferred to our facility. CT angiography done at our facility revealed a pseudoaneurysm measuring about 5.5 cm in diameter at the cervical region.Conclusions: We successfully treated this pseudoaneurysm with coil embolization without any further neurological deficits. Although the occurrence of iatrogenic VAI pseudoaneurysm as a result of the removal of C1-2 screw is extremely rare, it occurrence can be very fetal with very serious neurological deficits or death.

Transpedicular Approach for Subaxial Cervical Spine

Cervical spine decompression, fusion and fixation are required when pathologies like trauma, degeneration, infection or tumor destabilizes the spine or cause compression on neurovascular structures. Many approaches and instrumentation technique have evolved to achieve a stable spine closest to its natural state, preserving the anatomy and the function. Transpedicular approach to cervical spine has been a new addition to the attempt. Here, our experience of the procedure is presented.Total of 38 cases underwent this procedure from 2014 February to 2015 December. Twenty-four cases had unstable spine due to trauma, twelve had severe multilevel spondylotic cord compression and two had dump bell schwannomas. Their age ranged from 24 to 76 years with 22 males and 16 females. The procedures were done under general anesthesia in prone position on Gardner-Wells pins and a horseshoe headrest. After exposing the pedicles, 3.5 mm by 22 mm titanium poly-axial screws where inserted through the pedicles using the technique described by Professor Abumi. The pedicle screws were connected by a connecting rod, which had been bent in accordance with the normal cervical lordosis. Fusion was done using the bones obtained from the spinous process and laminae.There were fifty-six screws which were mis-directed, and had to be immediately corrected. There was no incidence of significant pedicle penetration or injury to neuro-vascular structures. There was temporary weakness of upper limbs postoperatively in seven patients, which recovered fully in two months’ time. There were six deaths due to uncontrolled septicaemia triggered by chest infection. The rest of the patients were discharged between one to six weeks after surgery.Transpedicular fixation of unstable cervical spine provides biomechanically a very rigid and good correction of sagittal alignment with a high-fusion rate and a few surgical complications. After realizing these advantages, transpedicular screw fixation in cervical spine is becoming an increasingly popular spine surgeon's armamentarium.Nepal Journal of Neuroscience 13:11-18, 2016

The feasibility of transpedicular screw fixation of the subaxial cervical spine in the Arab population: a computed tomography-based morphometric study.

BackgroundTranspedicular screw fixation of the cervical spine provides excellent biomechanical stability. The feasibility of inserting a 3.5-mm screw in the pedicle requires a minimum pedicle diameter of 4.5 mm. This diameter allows at least 0.5 mm bony bridge medially and laterally in order to avoid pedicle violation which can result in neurovascular complications. We aim to evaluate the feasibility of this technique in Arab people since no data are available about this population.Materials and methodsThis cross-sectional study involved a retrospective review of computed tomography scans of normal cervical spines of 99 Arab adults. Ten morphometric measurements were obtained. Data were analyzed using a p value of ≤0.05 as the cut-off level of statistical significance.ResultsOur sample included 63 (63.6 %) males and 36 (36.4 %) females, with a mean age of 35.5 ± 16.5 years. The morphometric parameters of C3–C7 spine pedicles were larger in males than in females. The outer pedicle width (OPW) was <4.5 mm in >25 % of all subjects at C3–C6 vertebrae. Statistically significant differences in the OPW between males and females were noted at C3 (p = 0.032) and C6 (p = 0.004).ConclusionsInserting pedicle screws in the subaxial cervical spine is feasible among the majority of Arab people.Level of evidenceLevel 3.

Anterior transpedicular screw fixation of cervical spine: Is it safe? Morphological feasibility, technical properties, and accuracy of manual insertion.

OBJECT Due to lack of construct stability of the current anterior cervical approaches, supplemental posterior cervical approaches are frequently employed. The use of an anterior-only approach with anterior transpedicular screws (ATPSs) has been proposed as a means of providing 3-column fixation. This study was designed to investigate the feasibility of anterior transpedicular screw (ATPS) fixation of cervical spine, to obtain the morphological measurements for technical prerequisites, and to evaluate the accuracy of the ATPS using fluoroscopy. METHODS The study included both radiological and anatomical investigations. The radiological investigations were based on data from cervical spine CT scans performed in 65 patients. Technical prerequisites of ATPS were calculated using OsiriX for Mac OS. In the anatomical part of the study, 30 pedicles (C3-7) from 6 formalin-preserved cadavers were manually instrumented. Measurements obtained included pedicle width (PW), pedicle height (PH), pedicle transverse angle (PTA), distance of the entry point from the midline (DEPM), and distance of the entry point from the superior endplate (DEPSEP). The authors also analyzed screw position in the manually instrumented vertebrae. RESULTS The mean PW and PH values showed a tendency to increase from C-3 to C-7 in both males and females. The means were significantly larger for both PW and PH in males than in females at all levels (p = 0.001). The overall mean PTA value was significantly lower at C-7 (p < 0.0001). The mean value for the distance of entry point from the midline (DEPM) represented a point at the contralateral side of the pedicle for every level except C-7. The mean DEPSEP values showed significant differences between all levels (p < 0.0001). Seven of the 30 screws were identified as breaching the pedicle (23.3%); these screw malplacements were seen at C-3 (3 screws), C-4 (2 screws), and C-5 (2 screws). CONCLUSIONS The morphological measurements of this study demonstrated that ATPS fixation is feasible in selected cases. They indicate that ATPS insertion using a fluoroscopy-assisted pedicle axis view is safe at the C-6 and C-7 levels, but the results at the other levels did not prove the safety of this technique.

Pedicle screw fixation of cervical spine assisted by CT-based navigation system

目的 探讨计算机 CT三维导航系统辅助下进行颈椎椎弓根螺钉内固定的可行性和置钉精确性.方法总结 CT三维导航系统辅助下置入的 159枚颈椎 (C2-7)椎弓根螺钉,术后进行经椎弓根螺钉水平的 CT平扫,观察椎弓根螺钉置入的精确性.同时总结 X线透视引导下 145枚颈椎椎弓根螺钉的置钉准确性,并与 CT三维导航引导组进行对比分析.并对其中 20例患者进行术中导航操作时间和精确性的监测.结果 CT三维导航系统引导组螺钉置入满意率为 97.5% , X线透视引导组螺钉置入满意率为 91.7%,两组满意率差异有显著性意义 (P< 0.05).导航组位置不满意的 4枚螺钉均发生于早期病例,导航系统使用熟练后未再出现置钉不满意病例 .两组病例均未出现明显的神经、血管损伤并发症.术中工具注册和参考点照合时间平均 3.5min( 2～ 8min),位置误差率平均 0.31mm( 0.12～ 0.56mm,导航仪自动计算).每枚椎弓根螺钉定位针置入所需时间平均 2min( 1～ 3.5min).术中只需进行 2次 C型臂 X线机透视印证螺钉定位针和螺钉置入的准确性.结论采用 CT三维导航系统辅助进行颈椎椎弓根螺钉内固定 是可行的,与 X线透视引导相比,能显著提高椎弓根螺钉置入的精确性、安全性.

Morphometric evaluation of lower cervical pedicle and its projection.

This study evaluated the lower cervical pedicle from C3 to C6 to provide information for accurate transpedicular screw fixation in this region. To measure the dimensions of the lower cervical pedicle and to determine the correct location of the pedicle axis on the posterior aspect of the lateral mass. Several anatomic studies and clinical applications of transpedicular screw fixation in the cervical spine have been documented, but little quantitative data concerning the lower cervical pedicle and its projection are available. Forty dry cervical specimens from C3 to C6 (160 cervical vertebrae) were used for this study. Anatomic evaluation included pedicle height, width, effective length, and anguli. The distances from the projection point of the pedicle axis to reference lines related to the lateral edge of the lateral mass (vertical) and the inferior edge of the superior facet (horizontal) also were measured. The means, ranges, and standard deviations were calculated for all of the specimens and separately for male and female spines. Statistically significant differences in dimensions of males and females were found in one linear and one angular measurement, which included the pedicle height of C6 and the pedicle sagittal angle of C4. The greatest variation for males and females was found in the pedicle sagittal angle, with a range of 4.3-9.8 degrees. The distances from the projection point to the horizontal line did not show any real pattern of change from C3 to C6, whereas the distances from the projection point to the vertical line consistently increased from cephalad to caudad. Taking into consideration some variations between individuals, this information, combined with evaluation of results of preoperative axial computed tomography and conventional radiography, may enhance the safety of transpedicular screw fixation in the lower cervical spine.

Pediatric Cervical Spine Instrumentation Using Screw Fixation

From July 1986 to August 1993 we performed 24 pediatric cervical spine screw fixation procedures on 23 patients 16 years of age or less. The types of cervical instrumentation procedures performed were as follows: anterior cervical plates 12, posterior C1-2 screw fixations 8, posterior lateral mass plates 2, odontoid screw fixations 2. The mean age of all patients was 14.2 years (range 6-16). Indications for operation included traumatic instability in 20 cases, congenital instability in 1 case, 2 cases of postoperative swan neck deformity, and one reoperation for early graft and hardware failure. Six of the 23 patients had persistent instability following previous failed fusions (3 with 1 prior surgery, 2 with 2 prior surgeries, and 1 with 3 prior surgeries). Eight patients had improvement of their neurological status following operation and 15 remained at their preoperative level of neurological function. No patient was worse neurologically after their procedure. There were no long-term instrumentation, graft or fusion failures. Two complications occurred. One was the aforementioned graft and hardware failure requiring reoperation, the other was a superficial wound infection treated successfully with antibiotics. We feel that cervical spine fixation techniques have increased our ability to stabilize the pediatric cervical spine and have proven to be safe and effective.