Augmented Reality in Spine Surgery: A Case Study of Atlantoaxial Instrumentation in Os Odontoideum.

Despite advancement in surgical innovation, C1-C2 fixation remains challenging due to risks of screw malposition and vertebral artery (VA) injuries. Traditional image-based navigation, while useful, often demands that surgeons frequently shift their attention to external monitors, potentially causing distractions. In this article, we introduce a microscope-based augmented reality (AR) navigation system that projects both anatomical information and real-time navigation images directly onto the surgical field. In the present case report, we discuss a 37-year-old female who suffered from os odontoideum with C1-C2 subluxation. Employing AR-assisted navigation, the patient underwent the successful posterior instrumentation of C1-C2. The integrated AR system offers direct visualization, potentially minimizing surgical distractions. In our opinion, as AR technology advances, its adoption in surgical practices and education is anticipated to expand.

Atlantoaxial posterior screw fixation using intra-operative spinal navigation with three-dimensional isocentric C-arm fluoroscopy.

PURPOSE: Intra-operative image acquisition coupled with navigation aims to increase screw placement accuracy, and it is particularly helpful in complex spinal procedures. The aim of this study is to analyze the accuracy and reliability of posterior atlanto-axial fixation using spinal navigation combined with intra-operative 3D isocentric C-arm. METHODS: We retrospectively reviewed all patients presenting with C1-C2 instability and treated by posterior atlanto-axial fixation in our center between December 2016 and September 2018. Screw positioning was guided by intra-operative navigation, registered with surface matching procedure on a previously obtained CT scan and controlled by intra-operative 3D isocentric C-arm. Age, sex, pre- and post-operative neurological status, duration of surgery, presence/absence of vertebral artery injury, and screw placement were retrospectively collected from patients' records. All patients underwent clinical and radiological follow-up at three months after surgery. Radiological assessment of screw positioning was performed by an independent radiologist using the Gertzbein and Robbins grading. RESULTS: N = 11 (7F, 4 M) consecutive patients were included, with a mean age of 72 years (range from 51 to 85). N = 44 navigated screws were inserted and controlled with intra-operative 3D fluoroscopy at the end of the procedure. An acceptable screw positioning (Gertzbein-Robbins grade A and B) was obtained in all cases (100%). No vertebral artery injury was observed. Mean operating time was 123 minutes. At three months, no screw loosening or displacement was observed. CONCLUSION: In our experience, spinal navigation coupled with intra-operative 3D fluoroscopy proved to be reliable and safe for C1-C2 screw placement.

Minimally invasive posterior percutaneous transarticular C1-C2 screws: how I do it.

BACKGROUND: Transarticular C1-C2 screw fixation, first described by Magerl, is a widely accepted used technique for C1-C2 instability with a good biomechanical stability and fusion rate. METHOD: We present a 69-year-old woman, who was diagnosed with a C2 Odontoid fracture type III and primarily treated with conservative treatment and collar. During first 2 weeks of follow-up, the patient developed cervical pain associated with C1-C2 instability. A minimally invasive posterior C1-C2 transarticular screw instrumentation with a percutaneus approach was performed. RESULTS AND CONCLUSION: Minimally invasive approach with tubular transmuscular approach for C1-C2 transarticular screws instrumentation is safe and effective for C1-C2 instability.

Traumatic atlantoaxial rotatory fixation in an adult patient.

INTRODUCTION: Atlantoaxial rotational fixation (AARF) is a rare entity in adults, with only a few cases reported in the English literature and often associated with a traumatic mechanism. It is an underdiagnosed condition that must be taken into account in the initial assessment of all craniocervical trauma. Both diagnostic and therapeutic delay may be a potential cause of severe neurological damage or even death of the patient. The therapeutic management is controversial given the difficulty of achieving optimum stability and permanent reduction. METHODS AND RESULTS: A 28-year-old woman was involved in a traffic accident a week before coming to the emergency with rotation and irreducible cervical flexion from trauma and severe neck pain. CT and MRI column were performed and showed a cervical spinal AARF with transverse and alar ligaments intact and preserved atlantoaxial distance (Fielding I). The patient was treated by progressive cervical traction with 5 kg and manual reduction was completed in 24 h. Subsequently, an external immobilization was performed by cervical rigid collar for 16 weeks. The clinical course was good, with the patient regaining full mobility with cervical neck pain improvement. CONCLUSIONS: The purpose of this paper is to show a case of a young woman with a posttraumatic AARF successfully treated conservatively. This case delineates the difficulties in diagnosing this pathology, as well as the challenges encountered in its management.

Anterior transarticular C1-C2 fixation with contralateral screw insertion: a report of two cases and technical note.

PURPOSE: Anterior transarticular fixation of the C1-C2 vertebrae is a well-known technique that involves screw insertion through the body of the C2 vertebra into the lateral masses of the atlas through an anterior transcervical approach. Meanwhile, contralateral screw insertion has been previously described only in anatomical studies. METHODS: We describe two case reports of the clinical application of this new technique. RESULTS: In Case 1, the patient was diagnosed with an unstable C1 fracture. The clinical features of the case did not allow for any type of posterior atlantoaxial fusion, Halo immobilization, or routine anterior fixation using the Reindl and Koller techniques. The possible manner of screw insertion into the anterior third of the right lateral mass was via a contralateral trajectory, which was performed in this case. Case 2 involved a patient with neglected posteriorly dislocated dens fracture who could not lie in the prone position due to concomitant cardiac pathology. Reduction of atlantoaxial dislocation was insufficient, even after scar tissue resection at the fracture, while transdental fusion was not possible. Considering the success of the previous case, atlantoaxial fixation was performed through the small approach, using the Reindl technique and contralateral screw insertion. CONCLUSIONS: These two cases demonstrate the potential of anterior transarticular fixation of C1-C2 vertebrae in cases where posterior atlantoaxial fusion is not achievable. This type of fixation can be performed through a single approach if one screw is inserted using the Reindl technique and another is inserted via a contralateral trajectory.

Long-Term Influence of C1-C2 Pedicle Screw Fixation on Occipitoatlantal Angle and Subaxial Cervical Spine in the Pediatric Population.

OBJECTIVE: The goal of this study was to evaluate the impact of C1-C2 pedicle screw fixation on the occipitoatlantal angle and subaxial cervical spine for a pediatric population, and the clinical efficacy and adjacent-segment degeneration after C1-C2 pedicle screw fixation with a minimum of 2 years of follow-up. METHODS: Twenty-two pediatric patients with atlantoaxial dislocation who were enrolled in this study underwent atlantoaxial pedicle screw fixation. The correlation between C0-C1, C2-C7, and C1-C2 pre- and postoperative sagittal angles was assessed using plain radiographs, and adjacent-segment degeneration (ASD) and JOA scores (Japanese Orthopaedic Association scores) were evaluated after atlantoaxial pedicle screw fixation. RESULTS: The C1-C2 angle increased from 16.1 ± 13.37 to 28.1 ± 5.1° (p < 0.01). The pre- and postoperative C1-C2 angles were negatively correlated with the pre- and postoperative C0-C1 and C2-C7 angles, respectively. In accordance with the optimal atlantoaxial fusion angle (25-30°) obtained from the literature, postoperative JOA scores were greater in the groups with angles of more than 30° and less than 25°, although the difference in ASD was not statistically significant. Postoperative JOA scores were not relevant to the postoperative C1-C2 angle; however, there was a positive correlation between JOA improvement rate and the change of the C1-C2 angle postoperatively. CONCLUSION: Atlantoaxial pedicle screw fixation can be used easily to reduce atlantoaxial dislocation in the pediatric population; however, outside the range of the optimal atlantoaxial fusion angle it can change the occipitoatlantal angle and subaxial alignment, which induces ASD and influences the clinical efficacy. It is necessary to achieve an optimal atlantoaxial angle when using atlantoaxial pedicle screw fixation.

Bicortical facet screws as a new option for posterior C2 fixation: anatomical study and clinical experience.

PURPOSE: C2 fixation is a demanding procedure, particularly in patients with variants of C1-C2 anatomy. The inferior articular process (IAP) of the axis can be an alternative for screw placement. We report the results of a CT study of C2 IAP anatomy and we present the clinical experience of 28 patients operated with this technique. METHODS: Anatomical study: 50 CT angiographies of the vertebral arteries (VA) were used for this study and, therefore, 100 IAPs were considered. We measured on the axial and sagittal planes the length, height and width of the facet, the distance between the anterior cortex and the VA and the distance between the screw entry point and the VA. We also measured the angle between the sagittal plane and the external tangent line of the VA. CLINICAL REPORT: 28 patients were treated with C2 IAP screws at the Spine Surgery Department of the University Hospital in Lyon, France, from January 2014 to January 2016. RESULTS: Anatomical study: the mean length of C2 IAP was 12 ± 2 mm, the mean distance between the anterior cortical layer and the VA was 5.2 ± 1.4 mm, and the mean angle we found was 0.2° ± 5.3°. CLINICAL REPORT: 16 of the 28 patients presented post-traumatic C1-C2 instability, 8 patients presented degenerative disease, 1 patient was treated for pseudoarthrosis, 1 for tumour, 1 for OPLL and 1 for rheumatoid arthritis. All the screws were correctly positioned and there was no VA injury. CONCLUSION: IAP screws can represent a safe alternative option for C2 fixation.

Combined Anterior Odontoid Screw Fixation and C1-C2 Jefferson Fracture Anterior Fixation: A Step-by-Step Technical Note.

BACKGROUND: Combined triple atlas (C1)-axis (C2) fixation has been described in previous literature as a safe, effective, and minimally invasive procedure for complex atlas and odontoid fractures that allows for a greater range of motion compared with posterior approaches and atlanto-occipital fusion. However, it is rarely performed due to the occipital-cervical diastasis resulting from often-fractured C1 joint masses. No evidence-based consensus has been reached regarding the treatment of complex atlantoaxial fractures, and the choice of surgical strategy is based only on clinical experience. METHODS: We report the combined triple C1-C2 fixation technique with manual reduction of the joint masses during patient positioning on the operating table, which allowed for effective stabilization during a single surgical session. We describe our experience in the management of a 75-year-old patient presenting with an acute complex type II fracture of C1, which also involved 1 lateral mass, combined with a type II odontoid fracture and occipital-cervical diastasis. RESULTS: We provide a step-by-step guide for combined triple C1-C2 anterior fixation with manual fracture reduction and describe the clinical case of an acute complex type II fracture of C1, which also involved 1 lateral mass, combined with a type II odontoid fracture and occipital-cervical diastasis. CONCLUSIONS: Combined triple C1-C2 fixation represents a safe and efficient minimally invasive anterior approach for complex type II fractures of C1 with type II odontoid fractures. Manual reduction of the joint masses during patient positioning allows for effective stabilization in a single surgical session.

Immediate postoperative resolution of syrinx post-C1/C2 fixation in an operated case of foramen magnum decompression for Chiari malformation: Is Goel's procedure a rescue surgery or a gold standard?

Chiari malformation (CM) is a common neurological disorder with foramen magnum decompression (FMD) as a commonly accepted treatment. The authors present a case of CM-1 wherein there was no radiological instability preoperatively and FMD was done as a treatment, after which the patient improved transiently only to deteriorate further. Atlantoaxial fixation was done as a second-stage procedure, after which the patient improved clinically and radiologically. The knowledge of this case and surgical entity should be borne in mind before the formulation of a treatment plan. It is important that the solution is to identify and treat the underlying pathology rather than to decompress and directly manipulate the tonsils.

Evaluation of Craniometric Parameters and Efficacy of Posterior Surgical Intervention Types in Basilar Invagination Patients.

OBJECTIVE: Basilar invagination is one of the most frequently observed abnormalities at the craniovertebral junction, in which the odontoid process of C2 prolapses into the foramen magnum. METHODS: The current study included 27 patients who underwent surgery for basilar invagination between October 2013 and January 2023. The study group was divided into 2 groups according to basilar invagination types; type I (the presence of type A atlantoaxial instability and instability is the main pathology) and type II (the presence of type B and C atlantoaxial instability and skull base dysgenesis is the main pathology). Craniometric parameters included in the study were atlantodental interval, posterior atlantodental interval, Chamberlain's line violation, clivus-canal angle, Welcher's basal angle, and Boogaard angle. RESULTS: The mean age of the patients was 24.30 ± 14.36 years (5-57 years). Fourteen patients (51.9%) were female, and 13 patients (48.1%) were male. Ten patients (37%) had type I basilar invagination, and 17 patients (63%) had type II basilar invagination. Preoperative and postoperative atlantodental interval and Boogaard angle were significantly higher in type I basilar invagination, as preoperative and postoperative posterior atlantodental interval and clivus-canal angle were significantly higher in type II basilar invagination. There was a positive strong correlation between Chamberlain's line violation and Boogaard angle. Postoperative Chamberlain's line violation was significantly higher in occipitocervical fixation (P = 0.035). C1 lateral mass screw fixation was found more successful in Chamberlain's line violation correction than occipital plates. Occipitocervical fixation was found to be associated with higher postoperative Nurick scores (P = 0.015) and complication rates (P = 0.020). Cages applied to the C1-C2 joint space were found to be associated with higher fusion rates (P = 0.023) and lower complication rates (P = 0.024). CONCLUSIONS: In the present study, it was found that C1-C2 fixation was more successful in correcting craniometric parameters and had lower complication rates than occipitocervical fixation. In appropriate patients, it was determined that cage application increased the success rates of the operations.

Successful Cases of Closed Reduction of Chronic Traumatic Atlantoaxial Rotatory Dislocation: A Report of Two Cases.

We report two cases of children with atlantoaxial rotatory dislocation (AARD) post-trauma with a chronic history of persistent neck pain and torticollis. The neurological examinations were normal. The dislocation reduction was challenging; however, cases with such delayed presentation, treated with closed reduction and external stabilization, are rare. After reduction, a serial CT scan during follow-up showed no recurrence.

C1 lateral mass reduction screws for treating atlantoaxial dislocations: Bringing ease by modification.

Objective: The C1-C2 fixation technique revolutionized the management of complex craniovertebral junction (CVJ) anomalies. Presently used polyaxial screw and rod systems have inadvertent technical difficulties in rod fitting and reduction of atlantoaxial dislocations (AAD) requiring forceful joint handling. The purpose of this study is to analyze the use of a specially designed "reduction screw" in C1 lateral mass in C1-C2 fixation for treating AAD with or without basilar invagination (BI). Study Design: This is a retrospective cohort study in which long lateral mass reduction screws were used for C1-C2 fixation. Materials and Methods: Eighteen patients diagnosed with congenital AAD with or without BI treated with C1-C2 fixations using C1 reduction lateral mass were included in the study. The outcome was measured clinically by the modified Japanese Orthopedic Association score and radiologically by conventional craniometric indices. Results: Among all cases included in the study, 72% (13/18) are males and 18% (5/18) are females with average age at presentation of 33.5 years. Among 18 cases of AAD, 84% (15/18) of patients have BI, 22% (4/18) have Chiari Type 1 malformation, and one patient has Klipple-Feil syndrome. Symptomatic improvement is noted in all patients following surgery. Adequate reduction of AAD with normalization of radiological indices was also achieved in all 18 (100%) patients. Conclusion: C1 lateral mass reduction screw in C1-C2 fixation helps in reduction of AAD and BI (Type A) even in difficult cases of CVJ anomalies with intraoperative technical ease, reduced operative time, no need for special instruments or complex maneuvers, and avoiding potential neurological injury.

An experience with Goel-Harms C1-C2 fixation for type II odontoid fractures.

Objective: Type II odontoid fractures need surgical stabilization for disabling neck pain and instability. Anterior odontoid screw fixation is a well-known technique. However, certain patients require posterior fixation. We present our surgical results and experiences with nine cases managed by the Goel-Harms technique. Materials and Methods: This is a retrospective review of nine patients operated on between January 2019 and December 2021 for Type II odontoid fractures with posterior fixation technique. Their clinical profile was collected from case files. The radiological data were retrieved from radiology archives. The indications for surgery were instability and refractory neck pain. The surgical decision for posterior fixation was guided by fracture morphology. Results: The mean age of presentation was 37.22 ± 9.85 years. Seven patients had Type II, and two had Type IIa odontoid fracture. All patients presented with unbearable neck pain. One patient had a quadriparesis. The fracture line was anterior-inferior sloping in six, posterior-inferior sloping in two, and transverse in one case. The anterior-posterior displacement of fracture ranged from 0 to 7 mm (mean 2.44 ± 2.18 mm). Partial transverse ligament tear without the Atlanto Axial Dislocation was present in three patients. The C1-C2 joint distraction was required in five cases. C1-C2 joint spacer was required in two cases. Following surgery, neck pain was relieved in all cases. Complete fracture alignment was achieved in eight patients. There were no postoperative complications. At the mean follow-up of 16.22 ± 9.61 months, there was no implant failure. Conclusions: Posterior C1-C2 fixation by the Goel-Harms technique is an excellent alternative to anterior fixation in selected cases.

Efficacy and Safety of Goel-Harms Technique in Upper Cervical Spine Surgery: A Systematic Review and Meta-Analysis.

OBJECTIVE: The main purpose of this systematic review and meta-analysis was to estimate the incidence of implant-associated complications and fusion rates for the Goel-Harms technique (GHT) and to show potential factors affecting the complications and nonunion development. METHODS: A systematic search of the PubMed database according to PRISMA guidance was performed. The main inclusion criteria comprised description of fusion rate and/or implant-associated complications rate. RESULTS: This systematic review included 86 articles focused on the results of surgery in 4208 patients. The rate of screw-related complications was as follows: 1) vertebral artery (VA) injury, 2.8%; 2) screw malposition in the direction of the VA, 5.8%; and 3) C2 nerve root irritation, 6.1%. The nonunion rate was 4.2%. Transpedicular screw insertion to the C1 and C2 vertebrae were the safest regarding VA injury and correlated with lower blood loss. For C1-C2 fusion, there was no statistical difference for the different bone graft localization. C2 nerve root irritation rate did not depend on screw insertion technique. The use of a freehand technique did not correlate with a high rate of screw-related complications. CONCLUSIONS: The Goel-Harms technique is a promising method of C1-C2 fusion, with a relatively low nonunion and VA injury rate. It can be performed safely without C-arm or navigation system assistance. Transpedicular screw insertion trajectories to the C1 and C2 vertebrae were safest regarding VA injury and blood loss volume. Further comparative studies of various C1-C2 stabilization methods with a high level of significance should be carried out to identify the optimal approach.

Accuracy of Axis Drill Guides in the Cases of Atlantoaxial Instabilities Associated With High-Riding Vertebral Arteries, Narrow Pedicles, and Complex Deformities: Comparison of 3 Fixation Methods.

OBJECTIVE: To contrast the accuracy of C2 navigation template-assisted versus freehand pedicle and/or pars screw fixation in high-risk cases where a high-riding vertebral artery (VA) or narrow pedicle and complex deformities were associated. METHODS: In our hospital, computed tomography (CT) data of 30 patients with pathology on C0-1-2, who had risk factors for VA injury, that were complex cervical deformities, atlantoaxial instabilities with narrow C2 pedicle and/or HRVA variations were retrospectively reviewed. Using computer-aided design software and desktop printer we printed 3 sets of high cervical models per case. We divided them into 3 groups using 3 different C2 screw fixation techniques: the freehand pars screw fixation group, the freehand pedicle screw fixation group, and the navigation template-assisted pedicle screw fixation group. After 180 screw placements were finished, the parts underwent a CT scan. Then the breach rates on postoperative scans were measured. RESULTS: Our results showed that the accurate placement rate is not noticeably different between navigation template-assisted and freehand pedicle screws, where the high-riding vertebral artery and narrow pedicles were associated, but was better in the navigational template group with complex deformities. Pars screws were found to be superior in terms of accuracy. CONCLUSIONS: The current study suggests that navigational template-assisted pedicle screws are risky for high-risk individuals with abnormal anatomy, such as those with a high-riding vertebral artery, a narrow pedicle, and complex abnormalities, and alternative C2 pars screws may be a reliable option for such individuals.

The enigma of acute worsening after a latent interval in post-operative patients of craniovertebral junction instability.

OBJECTIVE: For reasons that are poorly understood and still undocumented, few patients of craniovertebral junction (CVJ) anomalies with instability/atlantoaxial dislocation (AAD) in our practice have been seen to suffer unprecedented acute neurological deterioration with respiratory compromise about 48-72 h post-surgery. This has been specifically observed after an uneventful, stable clinical condition in the immediate postoperative period. This study attempts to elucidate the factors and outcomes related to such latent worsening. PATIENTS AND METHODS: The 4-year surgical data of 268-patients with CVJ instability (AAD/basilar-invagination) who underwent C1-C2 fixation were retrospectively studied. The relevant factors of 17 patients who showed such deterioration were compared with that of the remaining in a multivariate model. RESULTS: Seventeen patients had acute neurological worsening with respiratory arrest after a latent period. Ten improved at follow-up. Contrary to the general expectation, poor preoperative neurological score or severe dislocation that needed considerable manipulation did not influence such worsening. Dural injury in patients with associated Chiari malformation and vertebral arterial (VA) injury emerged as independent factors (p < 0.01) associated with this pattern of delayed neurological decline. CONCLUSIONS: We report our management and outcomes of a unique subset of AAD with neurological worsening in the postoperative period after 48-72 h. Such a subgroup was not previously identified in literature. Dural lacerations in AAD with Chiari, and VA injury seem to predispose to such complications and should be prevented at best. Close observation, and caution regarding early extubation (<72 h) is recommended in this subset despite an apparently uneventful immediate postoperative neurological status.

Posterior percutaneous transarticular stand-alone screw instrumentation of C1-C2 with endoscopic assistance: A report of two cases.

We present two cases of minimally invasive posterior transarticular screw fixation of C1-C2. The points for screw insertion were visualized by endoscopy via the instrumental port. A patient with a type III odontoid fracture with subluxation underwent a minimally invasive posterior stand-alone transarticular screw fixation. Despite the application of compression screws, for technical reasons, only minimal compression on the anterior third of the C1-C2 lateral joint was achieved. However, complete fracture fusion was achieved with stable fibrous C1-C2 fusion 2.5 years postoperatively. A second patient with a chronic type II odontoid fracture underwent percutaneous C1-C2 fixation by the same method. After 2 years, fracture fusion and C1-C2 lateral mass ankylosis were achieved. The use of a tubular retractor and endoscopy in stand-alone screw fixation of C1-C2 allows direct visualization of the screw entry point and decreases surgical trauma. This procedure might be an alternative to other methods of transarticular instrumentation.

Atlantoaxial Stabilization by Posterior C1 and C2 Screw-Rod Fixation for Various Pathologies: Case Series and Comprehensive Review of Literature.

We retrospectively analyzed atlantoaxial dislocation (AAD) of various pathologies, namely, rheumatoid arthritis (RA), os odontoideum, and trauma. Various techniques were discussed in relation to C1-C2 stabilization. The study aims to share our clinical experience in a series of six cases of C1-C2 instability that underwent posterior C1-C2 fusion, with free hand technique and limited fluoroscopy. The clinicoradiological presentation for each patient is described. We reviewed different literatures related to our case vividly and focused on the basic neuroanatomy involved in the atlantoaxial joint. All patients of AAD had evidence of severe canal compromise and chronic compressive spinal cord changes. In our study, the patients age ranged from 28 to 52 years. The study included four males and two females. Out of six patients of AAD, three had history of trauma, two had os odontoideum, and one had chronic inflammatory condition (RA). From our case series, we concluded that the Goel-Harms technique is the most versatile and surgeon friendly technique for C1-C2 fixation. Early recognition and surgical intervention of atlantoaxial joint instability is essential to prevent catastrophic neurological complications.

Supplementation of Screw-Rod C1-C2 Fixation With Posterior Arch Femoral Head Allograft Strut.

BACKGROUND: Numerous C1-C2 fixation techniques exist for the treatment of atlantoaxial instability. Limitations of screw-rod and sublaminar wiring techniques include C2 nerve root sacrifice and dural injury, respectively. We present a novel technique that utilizes a femoral head allograft cut with a keyhole that rests posteriorly on the arches of C1 and C2 and straddles the C2 spinous process, secured by sutures. OBJECTIVE: To offer increased fusion across C1-C2 without the passage of sublaminar wiring or interarticular arthrodesis. METHODS: A total of 6 patients with atlantoaxial instability underwent C1-C2 fixation using our method from 2015 to 2016. After placement of a C1-C2 screw/rod construct, a cadaveric frozen femoral head allograft was cut into a half-dome with a keyhole and placed over the already decorticated dorsal C1 arch and C2 spinous process. Notches were created in the graft and sutures were placed in the notches and around the rods to secure it firmly in place. RESULTS: The femoral head's shape allowed for creation of a graft that provides excellent surface area for fusion across C1-C2. There were no intraoperative complications, including dural tears. Postoperatively, no patients had sensorimotor deficits, pain, or occipital neuralgia. 5 patients demonstrated clinical resolution of symptoms by 3 mo and radiographic (computed tomography) evidence of fusion at 1 yr. One patient had good follow-up at 1 mo but died due to complications of Alzheimer disease. CONCLUSION: The posterior arch femoral head allograft strut technique with securing sutures is a viable option for supplementing screw-rod fixation in the treatment of complex atlantoaxial instability.

Cirq® Robotic Assistance for Minimally Invasive C1-C2 Posterior Instrumentation: Report on Feasibility and Safety.

BACKGROUND: Accurate screw placement remains very challenging especially in the upper cervical spine. OBJECTIVE: To present our first experience of a percutaneous posterior C1-C2 fixation for a traumatic fracture. METHODS: This is a case report of a non-neurological patient, harboring a type II odontoid fracture. She underwent a posterior percutaneous fixation using Cirq® Robotic Assistance coupled to the AIRO® intraoperative computed tomography (iCT)-scan and BrainLab® navigation system (all by BrainLab AG). Routine CT was performed on postoperative day 2 to evaluate pedicle screw placement. The effective dose was calculated. RESULTS: The C1-C2 posterior percutaneous fixation was performed with cannulated VERTEX® Reconstruction System (Medtronic). Overall, 4 screws were placed. All of them were rated as acceptable (100%). Radiation dose received by the patient was 4.13 mSv. Radiation dose received by the surgical staff was 0 mSv. Postoperative course was excellent. CONCLUSION: Posterior percutaneous fixation using Cirq® Robotic Assistance coupled with iCT navigation system is a major innovation that can improve pedicle screw positioning's accuracy with acceptable patient radiation and reduced surgical team exposure.