C1-C2 posterior fixation: are 4 screws better than 2?

Prevalence of anatomical variations at the suboccipital (V3) segment of the vertebral artery: a systematic review

BACKGROUND AND OBJECTIVE

A recent meta-analysis on the incidence of iatrogenic injury to the VA has revealed that patients with variant anatomy are more prone to iatrogenic injury. Therefore, this review is designed to investigate the incidence of variations in the suboccipital component of the vertebral artery in different population groups according to the available literature.

METHODS

This systematic review was conducted according to PRISMA guidelines (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). The review is based on a comprehensive and extensive search of PubMed, Google Scholar, and ResearchGate. The following search terms were used: "vertebral artery" AND "suboccipital segment" AND "anomalies/anatomical variations of the V3 segment." Reference lists of all extracted articles were also extensively searched for references to any further relevant publications.

RESULTS

A total of 17 papers met the inclusion criteria. The 17 studies corresponded to a total of 10,820 patients. A persistent first intersegmental artery was registered in 1.8% (197 out of 10,820) of the patients. Extradural PICA origin was observed in 1.6% (175 out of 10,820) of the patients. Fenestration was detected in 0.7% (72 out of 10,820) of the patients.

CONCLUSION

The authors summarize the incidence of vascular variation at the suboccipital segment of the VA in different population groups across the Asian, European, American, and African continents. Awareness of the extent of possible anatomical variation will help interpret radiographs, which will enhance the identification of vascular pathologies and reduce the risk of iatrogenic injury.

Geriatric Odontoid Fractures: Treatment Algorithms of the German Society for Orthopaedics and Trauma Based on Expert Consensus and a Systematic Review

STUDY DESIGN

Systematic review/expert consensus.

OBJECTIVES

Fractures of the axis represent the most frequent injury of the spine in elderly patients. Both, operative and non-operative treatment are associated with a high rate of complications and mortality. The aim of this article was to summarize the current literature on the management of odontoid fractures in geriatric patients and to weigh it based on an expert consensus process.

METHODS

In a joint consensus process, members of the Spine Section of the German Orthopaedic and Trauma Society (DGOU) aimed to formulate recommendations for the diagnostic workup and treatment of odontoid fractures in geriatric patients. Based on the previously published recommendations, this article is an updated version with incorporating a systematic review of the recent literature.

RESULTS

Based on the new data available, the recommendations established in the initial consensus process were adapted.

CONCLUSIONS

Computed tomography represents the diagnostic standard for patients with suspected injuries of the upper cervical spine. Anderson/D'Alonzo odontoid fractures type 1, non-displaced type 2, and type 3 can be treated conservatively. Even non-unions do not necessarily result in poor clinical outcome. In Anderson/D'Alonzo type 2 fractures, surgical therapy offers the advantage of relatively safe osseous healing with no increased complication rate even in elderly patients and can thus be recommended. In very high aged patients, however, a case-by-case decision should be made. When surgical stabilization of osteoporotic odontoid fractures is indicated, posterior techniques are biomechanically advantageous and can be considered the standard.

The Comparison Between Transarticular Screw Fixation and Segmental Screw-Rod Fixation for Posterior Fusion of the C1-2 Segment: A Systematic Review and Meta-Analysis

OBJECTIVE

Both transarticular screw fixation (TAS) and segmental screw-rod fixation (SF) have been widely performed for C1-2 fusion; however, just only small clinical studies and a few meta-analyses comparing the 2 surgical techniques for C1-2 posterior fusion have been reported.

METHODS

We searched the Cochrane, Embase, and Medline databases for articles comparing the intraoperative and postoperative outcomes of TAS and SF for C1-2 posterior fusion with April 14, 2022, as the publication cutoff date. The odds ratio (OR) and standardized mean difference were used to analyze differences in outcomes between the 2 abovementioned surgical techniques. A P value < 0.05 was considered statistically significant.

RESULTS

A total of 5101 publications were assessed, and 6 studies were finally included in the study. In terms of the fusion rate, SF produced significantly better outcomes than TAS did (OR = 2.96, P = 0.02). With respect to surgical outcomes, blood loss and operation times were significantly lower in the TAS group than those in the SF group (P = 0.008 and P < 0.00001, respectively). The rate of vertebral artery injury was significantly lower in the SF group than that in the TAS group (OR = 3.95, P = 0.04). However, other complications, such as screw malposition, infection, hardware failure, and nonunion, were not significantly different between the 2 groups.

CONCLUSIONS

SF showed a greater fusion rate and lower risk of vertebral artery injury than TAS did, but TAS showed less blood loss and lower operation times than SF.

Patient-rated outcome after atlantoaxial (C1-C2) fusion: more than a decade of evaluation of 2-year outcomes in 126 patients

INTRODUCTION

Various surgical techniques have been introduced for atlantoaxial (C1-C2) fusion, the most common being Magerl's (transarticular) or the Harms/Goel screw fixation. Common indications include degenerative osteoarthritis (OA), trauma or rheumatoid arthritis (RA). Only few, small studies have evaluated patient-reported outcomes after C1-C2 fusion. We investigated 2-year outcomes in a large series of consecutive patients undergoing isolated C1-C2 fusion.

METHODS

We analysed prospectively collected data (2005-2016) from our Spine outcomes database, collected within the framework of EUROSPINE's Spine Tango Registry. It included 126 patients (34 (27%) men, 92 (73%) women; mean (SD) age 67 ± 19 y) who had undergone first-time isolated C1-C2 fusion (61% Magerl, 39% Harms(-Goel)) at least 2 years ago for OA (83 (66%)), RA (20 (16%)), fracture (15 (12%)) or other (8 (6%)). Patients completed the multidimensional Core Outcome Measures Index (COMI; 0-10) and various single item outcomes.

RESULTS

Questionnaires were returned by 118/126 (94%) patients, 2 years post-operative. Mean COMI scores showed a significant reduction from baseline: 6.9 ± 2.4 to 2.7 ± 2.5 (p < 0.0001). Overall, 75% patients achieved the MCIC of ≥ 2.2 points reduction in COMI and 88% reported a good global outcome. 91% patients were satisfied/very satisfied with their care. Self-reported complications were declared by 16% patients and further surgery at the same segment, by 2.5%.

CONCLUSION

In this large series with almost complete follow-up, C1-C2 fusion showed extremely good results. Despite the complexity of the intervention, outcomes surpassed those typically reported for simple procedures such as ACDF and lumbar discectomy, suggesting reservations about the procedure should perhaps be reviewed.

Fluoroscopic landmarks and trajectories for safe posterior percutaneous transarticular C1-C2 screw insertion: a CT-based simulation study

PURPOSE

To determine the safe screw trajectory for posterior transarticular fixation of C1-C2 without direct visualisation of C2 lateral masses and by using fluoroscopic landmarks only.

METHODS

Fluoroscopic models of the craniovertebral region in frontal and sagittal planes were reconstructed using 1-mm interval computed tomography scans of the cervical spine in 30 patients. The imitation model of the screw trajectory was then applied with verification of the exact screw localisation using multiplanar reconstruction. Twenty-seven trajectories for 60 oblique C1-C2 reformations were tested.

RESULTS

In the frontal plane, all correct trajectories passed through the medial waistline point (WstP) of C3 and through the middle of the lateral mass of C1. In the lateral plane, the posterior spinal process-lateral mass (SpLM) point-middle C1 anterior tuberculum point (ATP), middle SpLM-upper ATP, and lower SpLM-odontoid point (ODP)-had relatively low rates of vertebral artery (VA) injury (2.3%, 4.6%, and 7%, respectively) and other screw malpositions (6.9%, 4.6%, and 4.6%, respectively). In cases of an isthmus height exceeding 8 mm, there were no incidences of VA injury. Patients with an isthmus width greater than 7 mm had a lower risk of screw malposition.

CONCLUSION

We identified potentially safe trajectories for percutaneous posterior transarticular fixation of C1-C2. Using SpLM, ATP, and ODP landmarks in the lateral plane, and WstP and C1 middle landmarks in the frontal plane, it is possible to achieve an acceptable screw position without direct visualisation of the C2 lateral mass.

A possible novel technique for intraoperative imaging of the vertebral artery during arthrodesis of the upper cervical spine

In elderly, the fractures in C1-C2 are a common entity. Poor bone quality and wide range of motion hamper the natural bone fusion, thus making surgery often the only possible way to deal with the underlying pathology. The proximity to important neurovascular structures represents the stabilization in this segment a challenge to the surgical team. There are two major techniques, which are used to achieve a dorsal fusion in the C1-C2 Segment: Goel/Harms and Magerl techniques. The reported risk for damaging the vertebral artery in both techniques lies between 8% and 9,5% using a C-Arm. In Goel/Harms technique lateral mass screws in C1 and pedicle screws in C2 are placed. A transarticular screw is placed on both sides C1-C2 in Magerl technique in order to achieve stabilization of the C1-C2 Segment. By using the new navigational methods for a better imaging of the bony structures (O-Arm), this risk could be reduced further down. The risk for injury of the vertebral artery using the O-Arm navigation depends on the pathology, which is operated, ranging from 0, 3% to 2%. A further problem represents the anatomical variations of the vertebral artery, of which the high-riding vertebral artery being the most important one, reported between 10 and 14,5% of the cases according to the literature review. The novel technique for intraoperative imaging of the vertebral artery represents a fusion between an intraoperative O-Arm and intraoperative application of contrast, thus intraoperatively seeing the exact way of the vertebral artery. Also, after the insertion of the screws, a second CT scan with the O-Arm could be performed, yet again with contrast, to see whether the perfusion of both vertebral arteries is preserved. The significance of this method could bring the injuries of the vertebral artery to 0% independently on the technique, which has been used. This method could be used not only for craniocervical stabilization but also for removal of complex tumors in craniocervical junctions, whereas the vertebral artery is encompassed.

Potential intraoperative factors of screw-related complications following posterior transarticular C1-C2 fixation: a systematic review and meta-analysis

PURPOSE

This study aimed to evaluate the impact of several factors, including patients' intraoperative position, intraoperative visualization technique, fixation method, and type of screws and their parameters, on the frequency of intraoperative screw-associated complications in posterior transarticular C1-C2 fixation.

METHODS

A systematic review of the PubMed database between January 1986 and March 2018 was performed. The key inclusion criteria comprised detailed descriptions of the surgical technique and post-operative screw-associated complications.

RESULTS

The initial search resulted in 1041 abstracts, and a total of 54 abstracts were included in the present study. The overall number of operated patients was 2306. In this group, 4439 screws were inserted. The rate of screw-associated complications during the different time periods was estimated upon meta-analysis. Statistical analysis of the screw malposition rate, vertebral artery injury rate, screw breakage rate based on patients' intraoperative position, intraoperative visualization technique, fixation method, and type of implants and their parameters was also performed.

CONCLUSIONS

The factors that help reduce the rate of screw-associated complications include the intraoperative application of biplanar fluoroscopy or neuronavigation system, the use of 4 mm or thicker lag screws, and screw insertion through contraincisions using cannulated ported instruments. On the other hand, the potential risk factors of screw-associated complications include inadequate intraoperative head fixation using skeletal traction, uniplanar fluoroscopy-guided screw insertion, screw insertion using the posterior midline approach, and the use of 3.5 mm or thinner full-threaded screws. These slides can be retrieved under Electronic Supplementary Material.

Screw Placement Accuracy and Outcomes Following O-Arm-Navigated Atlantoaxial Fusion: A Feasibility Study

Study Design Case series of seven patients. Objective C2 stabilization can be challenging due to the complex anatomy of the upper cervical vertebrae. We describe seven cases of C1-C2 fusion using intraoperative navigation to aid in the screw placement at the atlantoaxial (C1-C2) junction. Methods Between 2011 and 2014, seven patients underwent posterior atlantoaxial fusion using intraoperative frameless stereotactic O-arm Surgical Imaging and StealthStation Surgical Navigation System (Medtronic, Inc., Minneapolis, Minnesota, United States). Outcome measures included screw accuracy, neurologic status, radiation dosing, and surgical complications. Results Four patients had fusion at C1-C2 only, and in the remaining three, fixation extended down to C3 due to anatomical considerations for screw placement recognized on intraoperative imaging. Out of 30 screws placed, all demonstrated minimal divergence from desired placement in either C1 lateral mass, C2 pedicle, or C3 lateral mass. No neurovascular compromise was seen following the use of intraoperative guided screw placement. The average radiation dosing due to intraoperative imaging was 39.0 mGy. All patients were followed for a minimum of 12 months. All patients went on to solid fusion. Conclusion C1-C2 fusion using computed tomography-guided navigation is a safe and effective way to treat atlantoaxial instability. Intraoperative neuronavigation allows for high accuracy of screw placement, limits complications by sparing injury to the critical structures in the upper cervical spine, and can help surgeons make intraoperative decisions regarding complex pathology.

Comparative Experimental Study of Custom Made Plate for Anterior Stabilization and Dorsal Fixation Systems at C1-C2 Vertebrae Level

Experimental study on the evaluation of strength of fixation with metal constructions at the level of C1-C2 vertebrae was performed on the basis of test laboratory for orthopaedic and traumatologic products. Experiments were performed on the cadaver block preparation (4) and plastic models (8) of craniovertebral spine. Authors’ custom made plate, hook system, screw systems by Magerl and Harms were used as fixators. First step was the imitation of the turning of the head to the right (“twisting”), second step - imitation of head tilting forward (“three point pressure”). It was shown that by its strength and stability of craniovertebral segment the elaborated metal plate was not inferior to dorsal fixation systems.

Percutaneous atlantoaxial anterior transarticular screw fixation combined with mini-open posterior C1/2 wire fusion for patients with a high-riding vertebral artery

CONTEXT/OBJECTIVE

To describe the technique and clinical results of percutaneous atlantoaxial anterior transarticular fixation combined with limited exposure posterior C1/2 arthrodesis in patients with a high-riding vertebral artery.

DESIGN SETTING

Zhejiang Spine Center, China.

PARTICIPANTS

Five patients with a high-riding vertebral artery and an upper cervical fracture.

INTERVENTIONS

Percutaneous atlantoaxial anterior transarticular screw fixation combined with limited exposure posterior C1/2 wire fusion.

OUTCOME MEASURES

Computed tomography scans were used to assess the high-riding vertebral artery and feasibility of anterior transarticular screw fixation preoperatively. A Philadelphia collar was used to immobilize the neck postoperatively. Anteroposterior (open-mouth) and lateral views were obtained at pre/postoperation and at the follow-up.

RESULTS

The operation was performed successfully on all of the patients, and no intraoperative operation-related complications such as nerve injury, vertebral artery, and soft tissue complications occurred. The mean follow-up period was 33.8 months (range: 24 to 58 months). No screw breakage, loosening, pullout, or cutout was observed. Bone union was achieved in all patients at the last follow-up.

CONCLUSIONS

Our small case series results suggested that percutaneous anterior transarticular screw fixation combined with mini-open posterior C1/2 wire fusion is a technically minimally invasive, safe, feasible, and useful method to treat patients with a high-riding vertebral artery.

C2 nerve dysfunction associated with C1 lateral mass screw fixation

The C1 lateral mass screw technique is widely used for atlantoaxial fixation. However, C2 nerve dysfunction may occur as a complication of this procedure, compromising the quality of life of affected patients. This is a review of the topic of C2 nerve dysfunction associated with C1 lateral mass screw fixation and related research developments. The C2 nerve root is located in the space bordered superiorly by the posterior arch of C1 , inferiorly by the C2 lamina, anteriorly by the lateral atlantoaxial joint capsule, and posteriorly by the anterior edge of the ligamentum flavum. Some surgeons suggest cutting the C2 nerve root during C1 lateral mass screw placement, whereas others prefer to preserve it. The incidence, clinical manifestations, causes, management, and prevention of C2 nerve dysfunction associated with C(1) lateral mass screw fixation are reviewed. Sacrifice of the C2 nerve root carries a high risk of postoperative numbness, whereas postoperative nerve dysfunction can occur when it has been preserved. Many surgeons have been working hard on minimizing the risk of postoperative C2 nerve dysfunction associated with C1 lateral mass screw fixation.

Comparison between Bilateral C2 Pedicle Screwing and Unilateral C2 Pedicle Screwing, Combined with Contralateral C2 Laminar Screwing, for Atlantoaxial Posterior Fixation

Study Design

A retrospective study.

Purpose

To compare clinical and radiological outcomes between bilateral C2 pedicle screwing (C2PS) and unilateral C2PS, combined with contralateral C2 laminar screwing (LS), for posterior atlantoaxial fixation.

Overview of Literature

Posterior fixation with C1 lateral mass screwing (C1LMS) and C2PS (C1LMS-C2PS method) is an accepted procedure for rigid atlantoaxial stabilization. However, conventional bilateral C2PS is not always allowed in this method due to anatomical variations of C2 pedicles and/or asymmetry of the vertebral artery. Although unilateral C2PS plus contralateral LS (C2PS+LS) is an alternative in such cases, the efficacy of this procedure has not been evaluated in controlled studies (i.e., with bilateral C2PS as a control).

Methods

Clinical and radiological records of patients who underwent the C1LMS-C2PS method, using unilateral C2PS+LS (n=9), and those treated using conventional bilateral C2PS (n=10) were compared, with a minimum two years follow-up.

Results

Postoperative complications related to the unilateral C2PS+LS technique included one case of spontaneous spinous process fracture of C2. A C1 anterior arch fracture occurred after a fall in one patient, who underwent bilateral C2PS and C1 laminectomy. No significant differences were seen between the groups in reduction of neck pain after surgery or improvement of neurological status, as evaluated using the Japanese Orthopaedic Association score. A delayed union occurred in one patient each of the groups, with the final fusion rate being 100% in both groups.

Conclusions

Clinical and radiological outcomes of unilateral C2PS+LS were comparable with those of the bilateral C2PS fixation technique for the C1LMS-C2PS method.

C1-2 posterior arthrodesis technique with a left segmental and right transarticular fixation. A hybrid novel (Kotil) technique

INTRODUCTION

The most commonly used techniques for C1-C2 posterior arthrodesis are Goel and Magerl fixation techniques. Due to the anatomical variations of the region, the prior determination of the surgical technique might be hard. Right side Magerl, left side Goel's C1-C2 posterior arthrodesis case is presented as a new surgical combination technique used due to anatomical difficulties.

MATERIALS AND METHODS

Posterior C1-C2 arthrodesis operation was indicated for a 56-year-old female patient for the treatment of atlanto-axial subluxation caused by os odontoideum. First it was fixed from the nondominant arterial side (right vertebral artery) with Magerl (transarticular) technique. The left side was not suitable for the anatomical transarticular fixation, and the contralateral Goel fixation technique (segmental) was performed. Eventually, right side transarticular left side segmental fixation techniques were combined in one patient for the first time and C1-C2 fusion combination technique was presented.

RESULTS

Both Goel and Magerl techniques of C1-C2 posterior fusion techniques were successfully used simultaneously. The operation was initiated with Magerl technique with one screw on the nondominant side. The contralateral side was not suitable for Magerl technique therefore we changed to Goel's technique. Although, fluoroscopy was used 3 times as much during the introduction of the Drill with Magerl technique, twice as much operative time was spent during hemostasis and bleeding, preparation of the C1 entry point, and the reconstruction of polyaxial screws for Goel technique. No neurovascular complications were occurred during both procedures.

DISCUSSION

Combination of two C1-C2 posterior fusion techniques, Goel and Magerl, in suitable cases caused by anatomical or other reasons appears to be an alternative surgical procedure that protects the patient from complications. For a collection of better data, other studies that include large numbers of patients with high evidential value should be conducted.

The surgical management of the rheumatoid spine: Has the evolution of surgical intervention changed outcomes?

Context:

Surgery for the rheumatoid cervical spine has been shown to stabilize the unstable spine; arrest/improve the progression of neurological deficit, help neck pain, and possibly decelerate the degenerative disease process. Operative intervention for the rheumatoid spine has significantly changed over the last 30 years.

Aims:

The purpose of this study was to review all cases of cervical rheumatoid spine requiring surgical intervention in a single unit over the last 30 years.

Materials and Methods:

A prospectively-maintained spine database was retrospectively searched for all cases of rheumatoid spine, leading to a review of indications, imaging, Ranawat and Myelopathy Disability Index measures, surgical morbidity, and survival curve analysis.

Results:

A total of 224 cases were identified between 1981 and 2011. Dividing the data into three time-epochs, there has been a significant increase in the ratio of segment-saving Goel-Harms C1-C2: Occipitocervical fixation (OCF) surgery and survival has increased between 1981 and 2011 from 30% to 51%. Patients undergoing C1-C2 fixation were comparatively less myelopathic and in a better Ranawat class preoperatively, but postoperative outcome measures were well-preserved with favorable mortality rates over mean 39.6 months of follow-up. However, 11% of cases required OCF at mean 28 months post-C1-C2 fixation, largely due to instrumentation failure (80%).

Conclusion:

We present the largest series of surgically managed rheumatoid spines, revealing comparative data on OCF and C1-C2 fixation. Although survival has improved over the last 30 years, there have been changes in medical, surgical and perioperative management over that period of time too confounding the interpretation; however, the analysis presented suggests that rheumatoid patients presenting early in the disease process may benefit from C1 to C2 fixation, albeit with a proportion requiring OCF at a later time.

Disappearance of degenerative, non-inflammatory, retro-odontoid pseudotumor following posterior C1-C2 fixation: case series and review of the literature

PURPOSE

Retro-odontoid pseudotumor, not related to inflammatory or traumatic conditions, is an uncommon pathology. Atlanto-axial instability has been advocated to explain the pathophysiology of retro-odontoid pseudotumor's formation and growth. Despite pseudotumor direct removal through transoral or lateral approach represented the main surgical strategy for a long time, in the last decade several authors highlighted the possibility to treat retro-odontoid pseudotumor by occipito-cervical or C1-C2 fixation without removal of the intracanalar tissue. The goal of this study is to analyze the data collected in a series of patients suffering from cervical myelopathy due to non-inflammatory, degenerative retro-odontoid pannus and treated by posterior C1-C2 fixation. The relevant literature is also reviewed.

METHODS

Five patients, not suffering from inflammatory diseases, were treated between 2009 and 2012. Abnormalities of cranio-cervical junction and/or lower cervical spondylotic degeneration were observed in all patients. No evidence of atlanto-axial instability was demonstrated. Clinical and radiological evaluation included pre- and post-operative Nurick score as well as pre- and post-operative X-rays, CT and MRI. In one case, CT scan highlighted an eggshell calcification of the pannus. All patients underwent either a C1-C2 fixation (C1 lateral mass and C2 isthmus-pedicle screws) or occipito-cervical fixation (2 patients) in cases of C0-C1 fusion.

RESULTS

Follow-up ranges from 22 to 45 months (mean 32) in four patients. One patient died of surgery-unrelated disease. Nurick score changes suggest a clinical improvement in four cases. Neuro-radiological evaluation shows a progressive but incomplete reduction of thickness of retro-odontoid pseudotumor in one patient, and its disappearance in the other three cases. A second-stage transoral or posterior lateral approach was not required.

CONCLUSION

Although the etiopathogenesis of non-inflammatory, i.e., degenerative, retro-odontoid pseudotumor is still controversial, our series (the second largest on degenerative retro-odontoid pannus in the literature) confirms that a posterior approach may be sufficient and transoral surgery is not required.