Atlanto-axial fusion with transarticular screw fixation

Posterior Temporary C1-2 Pedicle Screws Fixation for the Treatment of Unstable C1-2 Complex Fractures: Minimum of 2-Year Follow-Up

STUDY DESIGN

Retrospective.

OBJECTIVES

To present rarely reported complex fractures of the upper cervical spine (C1-C2) and discuss the clinical results of the posterior temporary C1-2 pedicle screws fixation for C1-C2 stabilization.

METHODS

A total of 19 patients were included in the study (18 males and 1 female). Their age ranged from 23 to 66 years (mean age of 39.6 years). The patients were diagnosed with complex fractures of the atlas and the axis of the upper cervical spine and underwent posterior temporary C1-2 pedicle screws fixation. The patients underwent a serial postoperative clinical examination at approximately 3, 6, 9 months, and annually thereafter. The neck disability index (NDI) and the range of neck rotary motion were used to evaluate the postoperative clinical efficacy of the patients.

RESULTS

The average operation time and blood loss were 110 ± 25 min and 50 ± 12 ml, respectively. The mean follow-up was 38 ± 11 months (range 22 to 60 months). The neck rotary motion before removal, immediately after removal, and the last follow-up were 68.7 ± 7.1°, 115.1 ± 11.7°, and 149.3 ± 8.9° (P < 0.01). The NDI scores before and after the operation were 42.7 ± 4.3, 11.1 ± 4.0 (P < 0.01), and the NDI score 2 days after the internal fixation was removed was 7.3 ± 2.9, which was better than immediately after the operation (P < 0.01), and 2 years after the internal fixation was removed. The NDI score was 2.0 ± 0.8, which was significantly better than 2 days after the internal fixation was taken out (P < 0.001).

CONCLUSIONS

Posterior temporary screw fixation is a good alternative surgical treatment for unstable C1-C2 complex fractures.

Anterior Transarticular Crossing Screw Placement for Atlantoaxial Instability in Children: Computed Tomography-Based Study

OBJECTIVE

The feasibility of anterior transarticular crossing screw (ATCS) fixation for atlantoaxial instability was confirmed in adults. However, atlantoaxial instability is more common in children. Therefore this study was aimed to ascertain the pediatric morphometric characteristics of ATCS in C1-2.

METHODS

Morphometric analysis was conducted on computed tomography scan in 87 pediatric patients who were divided into groups based on ages (1-6 years, 7-10 years, and 11-16 years). Measurements were taken in sagittal and axial planes of computed tomography imaging to determine the range of screw lateral angles, incline angles, and screw lengths.

RESULTS

The overall screw lengths were relatively longer in males than females. For those aged 1-6 years, the screw lengths were 25.5-32.8 mm in males and 24.2-31.3 mm in females, respectively. The screw lengths showed no difference in the 7- to 10-year group between sexes, while the incline angle was larger in females than males. And the screw lengths were 33.5-43.2 mm in males and 31.2-40.4 mm in females in the 11- to 16-year group. The screw lengths were increased with age, yet the lateral angles were decreased. We also found that the epiphyseal closure of odontoid reached 93.6% when the age was older than 7 years old. Therefore ATCS was recommended for children older than 7 years.

CONCLUSIONS

The overall screw lengths and lateral angles of ATCS were larger in male children than those in females, but the incline angles were larger in females. ATCS is feasible in children, particularly those aged 7 years or older.

The limitations of fully threaded screws in isolated percutaneous transarticular screw fixation of C1/C2

Demographic aging accompanied by increased falls inevitably leads to an increased incidence of atlantoaxial instabilities (AAI). Minimally invasive surgical procedures decrease the perioperative risk and regarding the treatment of AAI, percutaneous transarticular screw fixation of C1/C2 was more frequently considered in the past. This study aims to investigate the outcome of patients treated for AAI by isolated percutaneous transarticular screw fixation of C1/C2 (IPTSFC1/C2) using 3.5 mm fully threaded screws to identify its chances and limitations. In this retrospective study, data from patients who underwent IPTSFC1/C2 were analyzed. 23 patients (17 females and 6 males) with an average age of 73.1 years (y) were included. Mean VAS decreased significantly from preoperative 3.9 ± 1.8 to the last follow-up 2.6 ± 2.5 (p = 0.020) and neurological functions were preserved. In the radiological follow-up, we saw a single malposition of an inserted screw (2.27%) and one single bony fusion (4.54%). However, in 6 of 7 patients (85.71%), there was a loosening of the inserted screws due course. We demonstrated that the use of 3.5 mm fully threaded screws for IPTSFC1/C2 results in low rates of osseous fusions between C1 and C2. Therefore, their use in IPTSFC1/C2 is not suitable, especially for geriatric patients with impaired bone status.

The association between atlantoaxial instability and anomalies of vertebral artery and axis

BACKGROUND CONTEXT

A screw-rod system is the most widely used technique for atlantoaxial instability (AAI). However, neglecting anomalies of the vertebral artery and axis could lead to fatal complications. Whether or not the presence of AAI is associated with a more complicated anatomy for instrumentation is unclear.

PURPOSE

To analyze the association between AAI and anomalies of the vertebral artery and axis in patients with and without AAI.

STUDY DESIGN

A retrospective comparative study.

PATIENT SAMPLE

One hundred and twenty patients who underwent preoperative 3-dimensional computed tomography with vertebral angiography of the cervical spine at our institution from 2012 to 2020.

OUTCOME MEASURES

The C2 isthmus height, internal height of the C2 lateral mass, and C2 pedicle width were radiologically assessed.

METHODS

A case control study with matched cohort analysis was conducted. One hundred and twenty patients were divided into 2 groups according to presence of AAI, and the presence of high-riding vertebral artery (HRVA) and a narrow pedicle for insertion of the C2 pedicle screw was assessed, as was the prevalence of extraosseous vertebral artery anomaly.

RESULTS

The C2 isthmus height, C2 internal height, and C2 pedicle width were significantly narrower in the AAI group (p<.01, <.01, and <.01, respectively). A significantly greater proportion of patients with AAI had HRVA and a narrow pedicle than those without (p<.01 and < 0.01, respectively). Among patients with AAI, the C2 internal height was significantly narrower in patients with rheumatoid arthritis (p<.01). Five patients (8.3%) with AAI had vertebral artery anomaly (3 fenestration, 2 persistent first intersegmental artery), while there were no vertebral artery anomalies in patients without AAI (p<.01).

CONCLUSIONS

Vertebral artery anomalies are more common in patients with AAI. Furthermore, posterior instrumentation in patients with AAI has a narrower safe zone compared to that in patients without AAI, which may be caused by a long-lasting deformity rather than a congenital deformity. Therefore, more thorough preoperative evaluation of the anatomy should be performed in these patients.

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.

Reducible Nonunited Type II Odontoid Fracture with Atlantoaxial Instability: Outcomes of Two Different Fixation Techniques

Displaced nonunited type II odontoid fracture can result in atlantoaxial instability, causing delayed cervical myelopathy. Both Magerl's C1-C2 transarticular screw fixation technique and Harms-Goel C1-C2 screw-rod segmental fixation technique are effective techniques to provide stability. This study aimed to demonstrate the results of two surgical fixation techniques for the treatment of reducible nonunited type II odontoid fracture with atlantoaxial instability. Medical records of patients with reducible nonunited type II odontoid fracture hospitalized for spinal fusion between April 2007 and April 2018 were reviewed. For each patient, specific surgical fixation, either Magerl's C1-C2 transarticular screw fixation technique augmented with supplemental wiring or Harms-Goel C1-C2 screw-rod fixation technique, was performed according to our management protocol. We reported the fusion rate, fusion period, and complications for each technique. Of 21 patients, 10 patients were treated with Magerl's C1-C2 transarticular screw fixation technique augmented with supplemental wiring, and 11 were treated with Harms-Goel C1-C2 screw-rod fixation technique. The bony fusion rate was 100% in both groups. The mean time to fusion was 69.7 (95%CI 53.1, 86.3) days in Magerl's C1-C2 transarticular screw fixation technique and 75.2 (95%CI 51.8, 98.6) days in Harms-Goel C1-C2 screw-rod fixation technique. No severe complications were observed in either group. Displaced reducible, nonunited type II odontoid fracture with cervical myelopathy should be treated by surgery. Both fixation techniques promote bony fusion and provide substantial construct stability.

Anthropometric evaluation for surgical feasibility of C1-C2 transarticular screw stabilization in Indian population

Study Design:

This study was a radiographic observational study for C1–C2 anthropometry.

Purpose:

The purpose of the study was to understand the anatomic relationship of C1–C2 in view of transarticular screw (TAS) fixation, to overcome the difficulties related with TAS placement, and to minimize the technique-related complications.

Materials and Methods:

It was an anthropometric observational study with retrospectively obtained anatomical data of randomly selected 116 patients from a single center. The anatomical measurements such as pars width, pars height, screw trajectory, and length were evaluated on the axial, sagittal, and three-dimensional reconstructed cervical CT scan using the radiant DICOM viewer software by the two fellowship trained spine surgeons which were blind to the study group details. The intra- and interobserver reliability with regard to the measured parameters was statistically analyzed.

Results:

The mean age of male and female was 28 and 29 years. The average BMI was calculated to be 23.5 and 25 for males and females, respectively. The mean right pars width in males was 5.78 ± 0.93 (range: 3.1–6.5 mm), while in female, it was 5.84 ± 0.95 (range: 3.1–6.5). The mean left pars width in males was 5.95 ± 1.13 (range: 3.8–8.1 mm), while in females, it was 5.70 ± 1.18 (range: 3.7–8.1 mm). Right side mean pars height in males was 5.90 ± 1.2 (range: 3.7–9.4 mm), and in females, it was 6.11 ± 1.04 (range: 3.8–9.3 mm). Left-sided mean pars height in males was 6.0 ± 1.1 (range: 3.2–9.4 mm) as compared to females, in which it was 5.77 ± 1.23 (range: 4.1–9.3 mm). The mean lateral angulation angle in males was 9.99° ± 1.70° (8.1°–15°), while in females, it was 10.15° ± 1.73° (8.1°–15°). The mean sagittal angulation in males was 26.33° ± 3.32° (21.0°–32.80°), while in females, it was 27.18 ± 3.05 (21.0°–32.10°). The average screw length in males was 41.74 ± 5.63 (34–54.8 mm), whereas in females, it was 41.35 ± 4.77 (34–54.8 mm).

Conclusion:

This study provides a morphometric database which is characteristic of the C1–C2 vertebrae in the normal Indian population with regard to the anatomic feasibility of the TAS fixation for various C1–C2 pathologies. The C2 pars width and height measured in the current study can guide the selection of TAS screws in the Indian population. This study could serve in providing the baseline anatomic parameters assessed in the healthy individuals to design and develop customized screws and related implant assembly which might provide wider clinical applicability.

Pediatric Spine Trauma: A Brief Review

Pediatric spinal trauma is a broad topic with nuances specific to each anatomic region of the spinal column. The purpose of this report is to provide a brief review highlighting the most important and common clinical issues regarding the diagnosis and management of pediatric spine trauma. Detailed descriptions of imaging findings along with specific operative and nonoperative management of each fracture and dislocation type are beyond the scope of this review.

Morphometry of the C2 Pedicle and Lamina in Thai Patients

Background

Traumatic upper cervical spine leads to instability and neurological deficit. At present, C2 (axis) pedicle or lamina screws for fixation are popular because further external immobilization is not needed. However, these techniques demand experience inserting the screws and carry the risk of vertebral artery or spinal cord injury. In some patients, the C2 screws cannot be inserted because of limited C2 size.

Objective

To determine the width, length, height, and angle in the C2 pedicle and lamina in the Thai population.

Materials and Methods

Patient data were collected from the Picture Archiving and Communication System at the Faculty of Medicine, Prince of Songkla University from January 2016 to December 2017. The C2 parameters, i.e., width, length, height, and angle of the pedicle and lamina were recorded.

Results

The CT C-spine scans of 270 patients were enrolled. The mean Thai C2 pedicle dimensions were width 5.51 mm, length 23.78 mm, angle 39.04°, and height 8.64 mm. The mean C2 lamina dimensions were width 5.88 mm, length 32.17 mm, angle 49.46°, and height 12.27 mm. Twenty-four patients from the 270 patients (8.8%) had a pedicle width <3.5 mm but all patients had a lamina width ≥3.5 mm.

Conclusion

In the Thai samples, 8.8% had a C2 pedicle width <3.5 mm which would not allow insertion of screws; however, they could be replaced with lamina screws since the lamina width was ≥3.5 mm. In this study, all of the patients who could not be inserted pedicle can be replaced with lamina screws inserted.

Cervical Myelopathy in Patients Suffering from Rheumatoid Arthritis-A Case Series of 9 Patients and A Review of the Literature

Cervical myelopathy occurs in approximately 2.5% of patients suffering from rheumatoid arthritis (RA) and is associated with notable morbidity and mortality. However, the surgical management of patients affected by cervical involvement in the setting of RA remains challenging and not well studied. To address this, we conducted a retrospective analysis of our clinical database between May 2007 and April 2017, and report on nine patients suffering from cervical myelopathy due to RA. We included patients treated surgically for cervical myelopathy on the basis of diagnosed RA. Clinical findings, treatment and outcome were assessed and reported. In addition, we conducted a narrative review of the literature. Four patients were male. Mean age was 64.8 ± 20.5 years. Underlying cervical pathology was anterior atlantoaxial instability (AAI) associated with retrodental pannus in four cases, anterior atlantoaxial subluxation (AAS) in two cases and basilar invagination in three cases. All patients received surgical treatment via posterior fixation, and in addition two of these cases were combined with a transnasal approach. Preoperative modified Japanese orthopaedic association scale (mJOA) improved from 12 ± 2.4 to 14.6 ± 1.89 at a mean follow-up at 18.8 ± 23.3 months (range 3-60 months) in five patients. In four patients, no follow up was available, and the mJOA of these patients at time of discharge was stable compared to the preoperative score. One patient died two days after surgery, where a pulmonary embolism was assumed to be the cause of mortality, and one patient sustained a temporary worsening of his neurological deficit postoperatively. Surgery is generally an effective treatment method in patients with inflammatory arthropathies of the cervical spine. Given the nature of the RA and potential instability, fixation in addition to cord decompression is generally required.

Radiologic Characteristics of Anterior Transarticular Crossing Screw Placement for Atlantoaxial Joint Instability

OBJECTIVE

The feasibility of anterior transarticular crossing screws (ATCS) was confirmed in cadaveric specimens and it has been used in clinic. However, no study has documented the morphometric characteristics of ATCS. This study seeks to determine the morphometric characteristics of ATCS in C1-C2 fixation.

METHODS

A total of 100 patients without abnormality of C1-2 were enrolled. The range of screw lateral angles (LAs) and the screw lengths of ATCS on coronal images were measured on multiplanar computed tomography images, as well as the screw incline angles (IAs) in the sagittal plane. The ideal trajectory was designed as toward to the posterosuperior points of the opposite C1 lateral mass, which had the longest screw.

RESULTS

The LAs were relatively small in men (31.4°-45.3°) compared with women (32.6°-46.0°). In the sagittal plane, the IAs were ranged from 41.0° to 68.4° in men and from 44.4° to 68.1° in women. The overall screw lengths were longer in men (34.7-44.8 mm) than in women (32.2-39.6 mm). In the ideal path, the LA and IA were 38.4° and 41.0° in men and 39.6° and 44.4° in women, and the screw lengths were 44.8 mm in men and 39.6 mm in women.

CONCLUSIONS

This study provides the range of screw angles and lengths of ATCS, which will help surgeons to perform ATCS safely and accurately.

Does isolated atlantoaxial fusion result in better clinical outcome compared to occipitocervical fusion?

BACKGROUND

The C0 to C2 region is the keystone for range of motion in the upper cervical spine. Posterior procedures usually include a fusion of at least one segment. Atlantoaxial fusion (AAF) only inhibits any motion in the C1/C2 segment whereas occipitocervical fusion (OCF) additionally interferes with the C0/C1 segment. The purpose of our study was to investigate clinical outcome of patients that underwent OCF or AAF for upper cervical spine injuries.

METHODS

Over a 5-year period (2010-2015), consecutive patients with upper cervical spine disorders were retrospectively identified as having been treated with OCF or AAF. The Numeric Pain Rating Scale (NPRS) and the Neck Disability Index (NDI) were used to evaluate postoperative neck pain and health restrictions. Demographics, follow-up, and clinical outcome parameters were evaluated. Infection, hematoma, screw malpositioning, and deaths were used as complication variables. Follow-up was at least 6 months postoperatively.

RESULTS

Ninety-six patients (male = 42, female = 54) underwent stabilization of the upper cervical spine. OCF was performed in 44 patients (45.8%), and 52 patients (54.2%) were treated with AAF. Patients with OCF were diagnosed with more comorbidities (p = 0.01). Follow-up was shorter in the OCF group compared to the AAF group (6.3 months and 14.3 months; p = 0.01). No differences were found related to infection (OCF 4.5%; AAF 7.7%) and revision rate (OCF 13.6%; AAF 17.3%; p > 0.05). Regarding bother and disability, no differences were discovered utilizing the NDI score (AAF 21.4%; OCF 37.4%; p > 0.05). A reduction of disability measured by the NDI was observed with greater follow-up for all patients (p = 0.01).

CONCLUSION

Theoretically, AAF provides greater range of motion by preserving the C0/C1 motion segment resulting in less disability. The current study did not show any significant differences regarding clinical outcome measured by the NDI compared to OCF. No differences were found regarding complication and infection rates in both groups. Both techniques provide a stable treatment with comparable clinical outcome.

Odontoid Fractures: A Critical Review of Current Management and Future Directions

Odontoid fractures represent one of the most common and controversial injury types affecting the cervical spine, being associated with a high incidence of nonunion, morbidity, and mortality. These complications are especially common and important in elderly patients, for which ideal treatment options are still under debate. Stable fractures in young patients maybe treated conservatively, with immobilization. Although halo-vest has been widely used for their conservative management, studies have shown high rates of complications in the elderly, and therefore current evidence suggests that the conservative management of these fractures should be carried out with a hard cervical collar or cervicothoracic orthosis. Elderly patients with stable fractures have been reported to have better clinical results with surgical treatment. For these and for all patients with unstable fractures, several surgical techniques have been proposed. Anterior odontoid fixation can be used in reducible fractures with ideal fracture patterns, with older patients requiring fixation with 2 screws. In other cases, C1-C2 posterior fixation maybe needed with the best surgical option depending on the reducibility of the fracture and vertebral artery anatomy. In this paper, current evidence on the management of odontoid fractures is discussed, and an algorithm for treatment is proposed.

Fusion rates for odontoid fractures after treatment by anterior odontoid screw versus posterior C1-C2 arthrodesis: a meta-analysis

OBJECTIVE

For odontoid fractures, surgical treatment approaches including anterior odontoid screw fixation approach and the posterior C1-C2 arthrodesis approach are generally adopted in practice. However, the choice of different surgical procedures remains controversial. In addition to surgical technique, the fusion rate is an important factor contributing to the clinical efficacy. Therefore, this study was aimed to investigate the discrepancy in fusion rate between these two surgical approaches through synthesizing the currently available evidence on the topic.

METHODS

A computerized search of Ovid, Medline, Embase, and the Cochrane library up to December 2017 for literature on the complication rate during odontoid fracture treatment was conducted. Risk ratio (RR) with its 95% confidence interval (CI) was pooled to assess fusion rates after surgical treatments, including anterior odontoid screw fixation approach or posterior C1-2 arthrodesis procedure, for patients with odontoid fractures.

RESULTS

Thirteen studies were enrolled in the meta-analysis. Results show that no significant difference was found in the overall fusion rate (RR = 0.96, 95% CI 0.90-1.01). There was no significant heterogeneity among the studies (p value = 0.60). As to age- and economic-level subgroups, there was no statistical evidence to suggest an association of the patient age and economy development level with the choice of surgical approach. However, it is shown that better fusion rates of patients (≥ 60 years) in developed countries received a better fusion rates after posterior fixation compared with anterior group using the fixed-effect model (RR = 0.88, 95% CI 0.79-0.98).

CONCLUSION

Elderly patients (≥ 60 years) underwent posterior C1-2 arthrodesis fixation shows higher fusion rates in developed countries comparing with patients who underwent anterior odontoid screw fixation. Overall, there is no significant discrepancy between these two surgical approaches. However, the conclusion should be verified by further study enrolling larger sample size.

Safe and bloodless exposure of the third segment of the vertebral artery: a step-by-step overview based on over 50 personal cases

Craniovertebral junction surgery usually requires the exposure of the third segment of the vertebral artery (V3). However, the complexity of musculature, a relatively high incidence of anomalies in the course of the vertebral artery (VA), and the presence of a rich venous plexus in this region make the V3 exposure challenging with a high risk of serious complications while taking down the suboccipital muscles in a single layer. A muscle dissection in interfascial layers, however, overcomes the drawbacks inherent in a blind dissection of the V3 as each of the muscles represents substantial landmark aiding subsequent step of the procedure and thus helping identify underlying anatomical structure early and safely. Moreover, along with a bloodless VA dissection off its surrounding venous plexus, it permits a safe and comfortable V3 exposure during the surgically demanding procedures.

Hypoglossal Nerve Palsy as a Cause of Severe Dysphagia along with the Oropharyngeal Stenosis due to Occipitocervical Kyphosis

Hypoglossal nerve palsy (HNP) is a potential cause of dysphagia. A 66-year-old man presented to our hospital with dysphagia and neck pain. One year prior to his first visit, he had been diagnosed with upper cervical tuberculosis and had undergone posterior C1-2 fixation. The physical examination led to the diagnosis of dysphagia with HNP, and he had severe weight loss. Radiographic examination revealed that the O-C kyphosis had been exacerbated and that the deformity was likely the primary cause of HNP. To restore the swallowing function, O-C fusion surgery was performed. Postoperatively, the patient showed immediate improvement of dysphagia with gradual recovery of hypoglossal nerve function. In the last follow-up evaluation, swallowing function was confirmed with no signs of HNP. Our results indicate that HNP could be more prevalent in cases with severe cervical kyphosis, being underdiagnosed due to the more apparent signs of the oropharyngeal narrowing.

Axis screws: results and complications of a large case series

OBJECTIVE

To present the surgical results of patients who underwent axis screw instrumentation, discussing surgical nuances and complications of the techniques used.

METHODS

Retrospective case-series evaluation of patients who underwent spinal surgery with axis instrumentation using screws.

RESULTS

Sixty-five patients were included in this study. The most common cause of mechanical instability was spinal cord trauma involving the axis (36 patients - 55.4%), followed by congenital craniocervical malformation (12 patients - 18.5%). Thirty-seven (57%) patients required concomitant C1 fusion. Bilateral axis fixation was performed in almost all cases. Twenty-three patients (35.4%) underwent bilateral laminar screws fixation; pars screws were used in twenty-two patients (33.8%), and pedicular screws were used isolated in only three patients (4.6%). In fourteen patients (21.5%), we performed a hybrid construction. There was no neurological worsening nor vertebral artery injury in this series.

CONCLUSION

Axis screw instrumentation proved to be a safe and efficient method for cervical stabilization. Laminar and pars screws were the most commonly used.

Clinical and radiological outcomes of image guided posterior C1-C2 fixation for atlantoaxial osteoarthritis (AAOA)

Background

Atlantoaxial (C1-C2) osteoarthritis (AAOA) causes severe suboccipital pain exacerbated by lateral rotation. The pain is usually progressive and resistant to conservative therapy. Posterior fusion surgery is performed to stabilise the C1-C2 segment. This is the first Australian study reporting the outcome of posterior atlantoaxial fixation including hybrid fixations performed for AAOA.

Methods

All patients who underwent posterior atlantoaxial fixation surgery for AAOA from 2005 to 2015 at our institutions were enrolled (N=23). Patient demographics and surgical technique were recorded. These techniques included transarticular screw (TAS) fixation using image guidance with iliac crest bone graft and supplemental posterior Sonntag wiring, or C1-C2 lateral mass fixation (Harms technique). Some patients required a combination of fixation due to anatomical variation. Primary outcome measures including patient satisfaction, pain, disability scores and range of motion were recorded for all patients pre- and post-operatively. Post-operative assessment was supplemented with CT and X-ray imaging.

Results

Twenty-three patients (19 women, 4 males, mean age 71.8±6.3 years) underwent surgical fixation. Eight underwent TAS fixation, 8 had Harms fixation, and 7 had a hybrid fixation. All patients reported statistically significant improvement in pain scores [Visual Analogue Scale (VAS) 9.4 pre-op compared to 2.9 post-op, P<0.005]. Disability scores [Neck Disability Index (NDI)] were statistically significantly reduced from 72.2±12.9 pre-operatively to 18.9±11.9 post-operatively, P<0.005. Mean follow-up was 55.3±36.1 months. Results did not vary according to the construct type. Ninety-five point five percent of patients showed radiographic evidence of fusion. Ninety-one percent of patients said they would undergo the surgery again.

Conclusions

Posterior atlantoaxial fixation with TAS and Harms constructs are highly effective for the surgical treatment of intractable neck pain secondary to atlantoaxial lateral mass osteoarthritis (AAOA). Surgery offers a high rate of symptom relief. If anatomical variability exists, both transarticular and pedicle screw fixation could be safely used in the same patient.

Posterior Sublaminar Wiring and/or Transarticular Screw Fixation for Reducible Atlantoaxial Instability Secondary to Symptomatic Os Odontoideum: A Neglected Technique?

Study Design

Retrospective case analysis.

Purpose

We retrospectively evaluated the clinical and radiological outcomes of posterior sublaminar wiring (PSLW) and/or transarticular screw fixation (TASF) for reducible atlantoaxial instability (AAI) secondary to os odontoideum.

Overview of Literature

Limited information is available about the surgical outcomes of symptomatic os odontoideum with AAI.

Methods

We examined 23 patients (12 women and 11 men) with os odontoideum and reducible AAI. The average age of the patients at the time of the operation was 44.2 years. The average follow-up duration was 4.5 years. Thirteen patients with anterior AAI underwent PSLW alone, while 10 patients with combined (anterior+posterior) AAI underwent PSLW and TASF. An autogenous iliac bone graft was used for all patients. Nine patients complained of neck or suboccipital pain, and 14 complained of myelopathy.

Results

Angulational instability (preoperative 18.7°±8.9° vs. postoperative 2.1°±4.6°, p<0.001), translational instability (16.3±4.9 mm vs. 1.8±2.2 mm, p<0.001), and segmental angle of the C1–C2 joint (23.7°±7.2° vs. 28.4°±3.8°, p<0.05) showed significant improvement postoperatively. Neck Visual Analog Scale score (6.2±2.4 vs. 2.5±1.8, p<0.05) and the modified Japanese Orthopedic Association (9.1±3.1 vs. 13.2±2.6, p<0.05) score also improved, with a recovery rate of 51.8%. Among the three patients who developed nonunion and/or wire breakage, one underwent revision surgery with repeat PSLW and was finally able to achieve fusion. The final fusion rate was 91.3%.

Conclusions

PSLW and/or TASF provided satisfactory clinical and radiological outcomes in reducible AAI secondary to os odontoideum without significant neurological complications. Our results suggest that PSLW and/or TASF can be considered a viable surgical option over segmental fixation in highly selected cases of os odontoideum with reducible AAI.

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.

Posterior temporary C1-2 fixation for 3-part fractures of the axis (odontoid dens and Hangman fractures)

Case series study.To report the clinical outcomes of posterior temporary C1-2 fixation for 3-part fracture of the axis (Type II odontoid fracture according to Grauer classification combined with Hangman fracture).The 3-part fracture of the axis is rare and the treatment is controversy.A total of 8 patients with 3-part fracture of the axis were included in this study. X-rays, CT, and MRI prior to surgery were used to evaluate the cervical spine injury. Grauer classification, fracture angulation, and fracture translation were used to evaluate the fracture of dens. The neck disability index (NDI) and range of neck rotary motion were used to assess the neck function.The preoperative fracture angulation and fracture translation were 4.6 ± 1.3° and 2.4 ± 0.6 mm, respectively. The average operation time and blood loss were 109 ± 27 minutes and 49 ± 15 mL. No infection, vascular injuries or neural structure injuries was observed. All patients acquired bone healing at 5.9 ± 2.0 months. The temporary instrumentation was removed at 10.8 ± 1.3 months. The average NDI before and 2 days after removal of instrumentation were 10.1 ± 4.0 and 7.1 ± 3.0, respectively. At 1-year follow-up after instrumentation removal, the NDI was 1.8 ± 0.7, which was much better than immediate NDI after instrumentation removal. The neck rotary motion (left rotation + right rotation) before and 2-day after instrumentation removal were 70.4 ± 6.3° and 119.6 ± 13.1°, respectively. At 1-year follow-up, the average neck rotary motion was 153.1 ± 9.1°, which had significant different with rotary motion 2-day after the removal of temporary instrumentation.With regard to the high fracture fusion rates, low complications, and excellent predictable outcomes in patients treated with posterior temporary C1-2 pedicle screw fixation, the technique may be a suitable choice for 3-part fracture of the axis.

Radiographic and clinical outcomes of C1-C2 intra-articular screw fixation in patients with atlantoaxial subluxation

Background

The Magerl and Goel-Harms techniques have been reported to produce excellent treatment outcomes in cases of atlantoaxial subluxation, but they also carry a risk of vertebral artery injuries. In order to completely prevent such injuries, we developed a surgical procedure, involving bone grafting between the C1 posterior arch and C2 lamina with clamp- or hook-and-rod-based fixation combined with the insertion of an interference screw into the posterior atlantoaxial joint.

Methods

This was a retrospective single-center study. The subjects were 58 patients in whom atlantoaxial subluxation was treated with the abovementioned procedure after 1995 (33 patients with rheumatoid arthritis (RA group) and 25 patients without rheumatoid arthritis (non-RA group)). The clinical outcomes and imaging findings of anterior subluxation at ≥ 2 years after surgery were compared between the RA and non-RA groups.

Results

No vertebral artery injuries occurred during surgery. Seven and two patients died during the follow-up period in the RA and non-RA groups, respectively, but none of these deaths were associated with surgery. At ≥ 2 years after surgery, the visual analogue scale score, Japanese Orthopaedic Association score, and Ranawat classification had significantly improved in both groups (p < 0.001). Radiologically, bone fusion was noted in all patients. Significant changes in the atlas-dens interval (ADI) were seen immediately after surgery in both groups (p < 0.001). In the non-RA group, significant changes in the corrected atlantoaxial height were observed immediately after surgery (p < 0.01), and loss of correction was seen at the final follow-up, but it was not significant (p = 0.1965). No significant changes were noted in any other parameter. Regarding the postoperative alignment of the cervical spine, lordosis tended to decrease, but additional surgery was only performed in one patient, who had developmental stenosis at the mid-lower level and belonged to the RA group. No reoperations due to fused adjacent segmental disease or exacerbated curvature were required.

Conclusion

In the present study, no vertebral artery injuries occurred during surgery, and no major perioperative complications developed. Favorable clinical outcomes were observed at ≥ 2 postoperative years although the patients’ diseases varied. This procedure produced superior outcomes, especially in terms of spinal correction and the maintenance of the ADI.

Can the position of the vertebral artery be predicted on a lateral view X-ray of the craniovertebral junction? A radiological anatomy study

Background

The most feared complication while inserting C2 screws is vertebral artery injury. This article proposes predicting the position of the vertebral artery on a true lateral X-ray of the axis vertebra from the background information acquired from the computed tomography (CT) scan utilizing fluoroscopy.

Methods

Spiral CT scans of 33 C2 vertebrae were performed utilizing a 16-slice CT scanner lateral X-rays of C2 were then obtained before and after painting the vertebral artery grooves with barium. The space available for transarticular and C2 pedicle screw insertion above the vertebral artery groove in the isthmus was then calculated as a ratio for both X-rays and CT scans.

Results

There was no statistically significant difference between the (mean) ratios calculated by CT scan and X-rays regarding the space available for transarticular and C2 pedicle screw insertion (left side: 0.3894 vs 0.3897; right side: 0.3892 vs 0.3925; P > 0.05). The Kappa test revealed that CT scan and X-ray findings were in agreement in majority of the bones (left side: n = 24, 72.7%, right side: n = 22, 73.3%; P < 0.05).

Conclusion

A thorough understanding of a true lateral view X-ray based on background information extracted from three dimensional CT scans helps predict the highest point of the vertebral artery groove. This proves useful for placement of C2 transarticular and pedicle screws during regular "open" and "minimally invasive" spine surgery.

Anatomical variations of vertebral artery and C2 isthmus in atlanto-axial fusion: Consecutive surgical 100 cases

VA anomalies in extra- and intraosseous regions of the craniovertebral junction (CVJ) is considered very carefully during the posterior screw fixation for the atlantoaxial instability (AAI). This study aims to compare the incidence and variations of VA anomalies, isthmus and pedicle size of C2 in 100 patients with AAI due to congenital skeletal anomaly (CSA) and acquired disease by using three-dimensional CT angiograms (3D CTA) before surgery. The CSA group contained 48 patients and the acquired disease group consisted of 52. In the CSA group, Os odontoideum was the major cause with 43 patients. The causes of acquired disease were RA in 16 patients and OA in 36 patients. Five patients had the anomalous VA in only CSA group; fenestration 2 patients and persistent first intersegmental (PFIS) artery 3 patients. Between CSA and acquired disease groups, no significant differences were found in the isthmus height, internal height, and pedicle width of C2 except the right internal height that is bigger in CSA group. The high-riding VA (isthmus height <4 mm or internal height <2 mm) had no significant difference between CSA group (27.1%) and acquired disease group (34.6%). However, in acquired disease group, patients with rheumatoid arthritis had smaller left internal height (4.21 ± 1.63 vs. 5.51 ± 1.83 mm) and pedicle width (4.11 ± 1.05 vs. 5.05 ± 1.66 mm) of C2 than those of patients with degenerative osteoarthritis. Therefore, in the case of atlantoaxial fusion, we should contemplate VA anomaly and the high-riding VA, especially in patients with CSA and RA.

The relationship between the degree of displacement of the atlas to axis and the clinical data in atlanto-axial subluxation due to rheumatoid arthritis

INTRODUCTION

The most common type of anatomical cervical spine involvement is atlanto-axial subluxation (AAS) in rheumatoid arthritis (RA). The purpose of this study was to clarify the relationship between the displacement of the atlas to axis and the clinical data obtained in patients with AAS due to RA.

METHODS

Fifty patients with AAS due to RA that were treated by surgery are herein reviewed. Based on the findings of preoperative lateral cervical radiographs in the neutral position, the patients were classified into two groups as follows: a 10 + group with an atlanto-dental interval (ADI) of ≧ 10 mm, and a 10 - group with an ADI < 10 mm.

RESULTS

Preoperative lateral cervical radiographs demonstrated 15 cases to belong to the 10 + group, while 35 cases belonged to the 10 - group. In the preoperative MR imaging, an intramedullary high signal intensity was observed in seven cases that belonged to the 10 + group and in four cases belonging to the 10 - group. Regarding the neurological severity, the 10 + group included significantly more cases showing severe neurological deficits before surgery; however, there was no significant difference between the two groups regarding the presence of severe deficits even after surgery.

CONCLUSIONS

The severe displacement group included significantly more cases showing an intramedullary high signal intensity in the preoperative MR images. Our results also suggest that a severe displacement before surgery affected the presence of neurological deficits before surgery; however, it did not affect the neurological recovery from such severe neurological deficits.

Comparison of Cervical Alignment and Clinical Outcomes in Patients with Os Odontoideum versus Non-Os Odontoideum after Atlantoaxial Fixation

OBJECTIVE

The purpose of this study was to compare the effect of atlantoaxial fixation on cervical alignment and clinical outcomes in patients with os odontoideum (OO) versus non-os odontoideum (non-OO).

METHODS

A total of 119 patients who underwent atlantoaxial fixation for instability were identified between January 1998 and January 2014. Inclusion criteria included age more than 21 years and diagnosis of OO and non-OO. There were 22 OO patients, and 20 non-OO patients. Measuring the Oc-C1 Cobb angle, C1-2 Cobb angle, C2-7 Cobb angle, and C2-7 sagittal vertical axis (SVA) was assessed. Clinical outcome was assessment of suboccipital pain was determined using a visual analogue scale (VAS), and Japanese Orthopedic Association (JOA) scores were obtained in all patients pre- and postoperatively.

RESULTS

The preoperative C1-2 angle in the OO group (26.02°±10.53°) was significantly higher than the non-OO group (p=0.04). After C1-2 fixation, the OO group had significantly higher kyphotic change in the C1-2 angle (ΔC1-2) (3.2°±7.3° [OO] vs. -1.46°±7.21° [non-OO]) (p=0.04), and higher decrease in postoperative C2-7 SVA (ΔC2-7 SVA) (5.64±11.56 mm [OO] vs. -0.51± 6.57 mm [non-OO]) (p=0.04). Both groups showed improvements in the health related quality of life (HRQOL) after surgery based on the VAS and JOA score (p<0.001).

CONCLUSION

After fixation, kyphotic angular change in atlantoaxial joint and decrease C2-7 SVA were marked in the OO group. Both the OO and non-OO groups improved in neurological function and outcome after surgery.

Most Cited Publications in Cervical Spine Surgery

PURPOSE

The purpose of this study is to perform a citation analysis on the most frequently cited articles in the topic of cervical spine surgery and report on the top 100 most cited publication in this topic.

METHODS

We used the Thomson Reuters Web of Science to search citations of all articles from 1945 to 2015 relevant to cervical spine surgery and ranked them according to the number of citations. The 100 most cited articles that matched the search criteria were further analyzed by number of citations, first author, journal, year of publication, country and institution of origin.

RESULTS

The top 100 cited articles in the topic of cervical spine surgery were published from 1952-2011. The number of citations ranged from 106 times for the 100th paper to 1206 times for the top paper. The decade of 1990-1999 saw the most publications. The Journal of Spine published the most articles, followed by Journal of Bone and Joint Surgery America. Investigators from America authored the most papers and The University of California contributed the most publications. Cervical spine fusion was the most common topic published with 36 papers, followed by surgical technique and trauma.

CONCLUSION

This article identifies the 100 most cited articles in cervical spine surgery. It has provided insight to the history and development in cervical spine surgery and many of which have shaped the way we practice today.

A Retrospective Analysis of Subaxial Subluxation After Atlanto-axial Arthrodesis in Patients With Rheumatoid Arthritis Based on Annual Radiographs Obtained for 5 Years

STUDY DESIGN

Retrospective study.

OBJECTIVE

The purpose of this study was to investigate the incidence of subaxial subluxation (SAS) after atlanto-axial arthrodesis in rheumatoid arthritis (RA) patients using annual radiographs obtained for 5 years and clarify the characteristics of SAS after surgery.

SUMMARY OF BACKGROUND DATA

Rheumatoid SAS has been reported to occur after atlanto-axial arthrodesis. Many authors have noted that excessive correction of the atlanto-axial angle (AAA) results in a decrease in subaxial lordosis, thereby inducing SAS; therefore, we paid special attention to acquiring a suitable AAA in patients with atlanto-axial arthrodesis.

METHODS

Twenty-five patients with AAS treated with surgery were reviewed. In all patients, lateral cervical radiographs were obtained in neutral, maximal flexion, and maximal extension positions every year for 5 years after surgery. We investigated the occurrence and progression of SAS using these annual radiographs.

RESULTS

There were no significant differences between preoperative and postoperative value in AAA and subaxial angle (SAA), respectively. Before surgery, SAS was found in 10 patients. The occurrence and progression of SAS after surgery was found in 12 cases (SAS P+ group). There were no significant differences in age, sex, or the duration of RA between the SAS P+ group and the remaining 13 cases. We also found no differences in the preoperative and postoperative AAA and SAA between the 2 groups.

CONCLUSIONS

Although SAA was maintained after atlanto-axial arthrodesis in RA-AAS patients, 12 of 25 patients (48%) with AAS developed SAS after atlanto-axial fusion. Further surgery was not needed for SAS up to 5 years after the initial surgery. We did not find any relationship between the occurrence of SAS and the AAA and SAA before and after surgery. Therefore, our findings suggest that proper reduction of AAA in patients with atlanto-axial arthrodesis does not affect the occurrence of SAS at 5 years after surgery.

The clinical outcomes of atlanto-axial arthrodesis in patients with rheumatoid arthritis - Assessment according to the Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ)

PURPOSE

The purpose of this study was to evaluate the clinical outcomes of atlanto-axial arthrodesis in rheumatoid arthritis (RA) patients with cervical myelopathy using the Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ).

METHODS

Twenty patients who underwent surgery to treat atlanto-axial subluxation (AAS) were reviewed.

RESULTS

The rates of success rates for each domain were as follows: cervical spine function, 11 of 18 patients (61.1%); upper extremity function, 3 of 15 patients (20%); lower extremity function, 8 of 18 patients (44.4%); bladder function, 5 of 13 patients (38.5%); and quality of life, 3 of 20 patients (15%). Significant differences of success rate were found between the following domains: cervical spine function and upper extremity function, cervical spine function and the quality of life, and lower-extremity function and quality of life. There were significant differences in the pre- and post-surgery visual analogue scale (VAS) scores for pain or stiffness in the neck or shoulders, and pain or numbness in the arms and hands.

CONCLUSION

Atlanto-axial arthrodesis in RA patients provided a better outcome for cervical spine function, with improvement in VAS scores for pain or stiffness in the neck or shoulders. This surgery provided improvement of pain or numbness of the upper extremities but not of upper-extremity function. In contrast, the surgery achieved a relatively good recovery in lower-extremity function but little improvement of pain or numbness of the lower extremities. The success rate with regard to quality of life was found to be significantly lower than the success rates observed for cervical spine function and lower-extremity function.

Hypoglossal Nerve Palsy After Cervical Spine Surgery

STUDY DESIGN

Multi-institutional retrospective study.

OBJECTIVE

The goal of the current study is to quantify the incidence of 2 extremely rare complications of cervical spine surgery; hypoglossal and glossopharyngeal nerve palsies.

METHODS

A total of 8887 patients who underwent cervical spine surgery from 2005 to 2011 were included in the study from 21 institutions.

RESULTS

No glossopharyngeal nerve injuries were reported. One hypoglossal nerve injury was reported after a C3-7 laminectomy (0.01%). This deficit resolved with conservative management. The rate by institution ranged from 0% to 1.28%. Although not directly injured by the surgical procedure, the transient nerve injury might have been related to patient positioning as has been described previously in the literature.

CONCLUSIONS

Hypoglossal nerve injury during cervical spine surgery is an extremely rare complication. Institutional rates may vary. Care should be taken during posterior cervical surgery to avoid hyperflexion of the neck and endotracheal tube malposition.

Accurate and Simple Screw Insertion Procedure With Patient-Specific Screw Guide Templates for Posterior C1-C2 Fixation

STUDY DESIGN

Prospective clinical trial of the screw insertion method for posterior C1-C2 fixation utilizing the patient-specific screw guide template technique.

OBJECTIVE

To evaluate the efficacy of this method for insertion of C1 lateral mass screws (LMS), C2 pedicle screws (PS), and C2 laminar screws (LS).

SUMMARY OF BACKGROUND DATA

Posterior C1LMS and C2PS fixation, also known as the Goel-Harms method, can achieve immediate rigid fixation and high fusion rate, but the screw insertion carries the risk of injury to neuronal and vascular structures. Dissection of venous plexus and C2 nerve root to confirm the insertion point of the C1LMS may also cause problems. We have developed an intraoperative screw guiding method using patient-specific laminar templates.

METHODS

Preoperative bone images of computed tomography (CT) were analyzed using three-dimensional (3D)/multiplanar imaging software to plan the trajectories of the screws. Plastic templates with screw guiding structures were created for each lamina using 3D design and printing technology. Three types of templates were made for precise multistep guidance, and all templates were specially designed to fit and lock on the lamina during the procedure. Surgery was performed using this patient-specific screw guide template system, and placement of the screws was postoperatively evaluated using CT.

RESULTS

Twelve patients with C1-C2 instability were treated with a total of 48 screws (24 C1LMS, 20 C2PS, 4 C2LS). Intraoperatively, each template was found to exactly fit and lock on the lamina and screw insertion was completed successfully without dissection of the venous plexus and C2 nerve root. Postoperative CT showed no cortical violation by the screws, and mean deviation of the screws from the planned trajectories was 0.70 ± 0.42 mm.

CONCLUSION

The multistep, patient-specific screw guide template system is useful for intraoperative screw navigation in posterior C1-C2 fixation. This simple and economical method can improve the accuracy of screw insertion, and reduce operation time and radiation exposure of posterior C1-C2 fixation surgery.

LEVEL OF EVIDENCE

3.

Outcomes Following Arthrodesis for Atlanto-Axial Osteoarthritis

STUDY DESIGN

Retrospective analysis.

OBJECTIVE

We set out to evaluate the radiographic and patient-reported outcomes following C1-C2 arthrodesis for atlantoaxial osteoarthritis (AAOA) using modern instrumentation and techniques.

SUMMARY OF BACKGROUND DATA

Few studies have evaluated outcomes following C1-C2 arthrodesis for AAOA using modern surgical fixation techniques.

METHODS

Retrospective analysis of all patients following C1-C2 arthrodesis with recalcitrant AAOA from a single center, single surgeon from 2002 to 2012. Preoperative, immediate and final follow-up postoperative radiographic images were evaluated. Patient-reported outcomes scores were assessed preoperative, 1-year, and final postoperative follow-up.

RESULTS

We found a total of 14 patients (13 female, 1 male) with average follow-up of 2.96 ± 2.26 years and mean age at surgery of 71.8 ± 9.3 years old. The most common construct was posterior C1-C2 bilateral screw-rod construct (SRC) (n = 9), and there were 3 patients with transarticular screw (TAS) constructs, and 2 patients with hybrid fixation (unilateral SRC and contralateral TAS). Mean change from baseline to final follow-up for Numeric Pain Rating Scale (NRS) was -4.7 ± 2.1, and Neck Disability Index (NDI) was -21.0 ± 13.6, with 11 (78.6%) patients demonstrated a substantial clinical benefit (change in NDI ≥ 10). There were no differences from baseline to all follow-up time points for SF-12 Physical and Mental Component Scores. All patients had evidence of solid C1-C2 arthrodesis and stable fixation at final follow-up, with no significant change in subaxial sagittal alignment. There were no perioperative or postoperative complications.

CONCLUSION

We report one of the largest series evaluating patient-reported outcomes in patients following arthrodesis for AAOA using modern C1-C2 fixation techniques. Our study found C1-C2 arthrodesis for AAOA to be safe and effective, with a significant improvement in patient-reported pain and neck disability and most patients reporting substantial clinical benefit.

LEVEL OF EVIDENCE

4.

Posterior arch C-1 screw technique: a cadaveric comparison study

OBJECTIVE

Posterior atlantoaxial stabilization and fusion using C-1 lateral mass screw fixation has become commonly used in the treatment of instability and for reconstructive indications since its introduction by Goel and Laheri in 1994 and modification by Harms in 2001. Placement of such lateral mass screws can be challenging because of the proximity to the spinal cord, vertebral artery, an extensive venous plexus, and the C-2 nerve root, which overlies the designated starting point on the posterior center of the lateral mass. An alternative posterior access point starting on the posterior arch of C-1 could provide a C-2 nerve root–sparing starting point for screw placement, with the potential benefit of greater directional control and simpler trajectory. The authors present a cadaveric study comparing an alternative strategy (i.e., a C-1 screw with a posterior arch starting point) to the conventional strategy (i.e., using the lower lateral mass entry site), specifically assessing the safety of screw placement to preserve the C-2 nerve root.

METHODS

Five US-trained spine fellows instrumented 17 fresh human cadaveric heads using the Goel/Harms C-1 lateral mass (GHLM) technique on the left and the posterior arch lateral mass (PALM) technique on the right, under fluoroscopic guidance. After screw placement, a CT scan was obtained on each specimen to assess for radiographic screw placement accuracy. Four faculty spine surgeons, blinded to the surgeon who instrumented the cadaver, independently graded the quality of screw placement using a modified Upendra classification.

RESULTS

Of the 17 specimens, the C-2 nerve root was anatomically impinged in 13 (76.5%) of the specimens. The GHLM technique was graded Type 1 or 2, which is considered “acceptable,” in 12 specimens (70.6%), and graded Type 3 or 4 (“unacceptable”) in 5 specimens (29.4%). In contrast, the PALM technique had 17 (100%) of 17 graded Type 1 or 2 (p = 0.015). There were no vertebral artery injuries found in either technique. All screw violations occurred in the medial direction.

CONCLUSIONS

The PALM technique showed statistically fewer medial penetrations than the GHLM technique in this study. The reason for this is not clear, but may stem from a more angulated ”up-and-in” screw direction necessary with a lower starting point.

Top 50 most-cited articles on craniovertebral junction surgery

Background:

Craniovertebral junction is a complex anatomical location posing unique challenges to the surgical management of its pathologies. We aimed to identify the fifty most-cited articles that are dedicated to this field.

Methods:

A keyword search using the Thomson Reuters Web of Knowledge was conducted to identify articles relevant to the field of craniovertebral junction surgery. The articles were reviewed based on title, abstract, and methods, if necessary, and then ranked based on the total number of citations to identify the fifty most-cited articles. Characteristics of the articles were determined and analyzed.

Results:

The earliest top-cited article was published in 1948. When stratified by decade, 1990s was the most productive with 16 articles. The most-cited article was by Anderson and Dalonzo on a classification of odontoid fractures. By citation rate, the most-cited article was by Herms and Melcher who described Goel's technique of atlantoaxial fixation using C1 lateral mass screws and C2 pedicle screws with rod fixation. Atlantoaxial fixation was the most common topic. The United States, Barrow Neurological Institute, and VH Sonntag were the most represented country, institute, and author, respectively. The significant majority of articles were designed as case series providing level IV evidence.

Conclusion:

Using citation analysis, we have provided a list of the most-cited articles representing important contributions of various authors from many institutions across the world to the field of craniovertebral junction surgery.

Migration of titanium cable into spinal cord and spontaneous C2 and C3 fusion: Case report of possible causes of fatigue failure after posterior atlantoaxial fixation

INTRODUCTION

Atlantoaxial instability is a common and serious injury of the upper cervical spine. Brooks' procedure is widely used to reconstruct the unstable atlantoaxial joint. The migration into spinal cord of titanium cable and spontaneous fusion between C2 and C3 has been little reported and the management of such a patient is difficult. We describe an unusual case of fatigue failure of posterior titanium atlantoaxial cable fixation with migration into the spinal cord and spontaneous fusion between C2 and C3.

CASE REPORT

A 16-year-old girl complained of cervico-occipital pain with numbness and weakness of extremities 3 months ago. The girl underwent posterior C1-C2 arthrodesis with titanium cables and autogenous iliac crest bone grafting when she was 6 years old. When presented to our emergency department, imaging revealed the cracked titanium atlantoaxial cable and the spontaneous fusion between C2 and C3. Computed tomography demonstrated a broken wire with anterior migration of the cable into the spinal cord. The patient underwent posterior approach cervical spinal surgery to remove the broken cables. She remains neurologically intact a year following the posterior approach cervical spine surgery.

CONCLUSIONS

Brooks' posterior stabilization could not effectively control rotation at the atlantoaxial articulation, so surgeons must be aware of the potential of fatigue failure of cables as well as the possibility of its migration into the spinal cord when using Brooks' posterior stabilization. Bilateral C1 lateral mass and C2 pedicle screw fixation or transarticular screw fixation are recommended by the authors in the event of rotatory instability.

A novel method of C1-C2 transarticular screw insertion for symptomatic atlantoaxial instability using a customized guiding block: A case report and a technical note

Atlantoaxial instability treated with the C1-2 transarticular screw fixation is biomechanically more stable; however, the technique demanding and the potential risk of neurovascular injury create difficulties for clinical usage, and there is still lack of clinical experience till now.We reported an adult female patient with symptomatic atlantoaxial instability due to rheumatoid arthritis that was successfully treated with a bilateral C1-C2 transarticular screw fixation using a customized guiding block. We preoperatively determined the trajectories for bilateral C1-C2 transarticular screws on a 3-dimensional reconstruction model from the computed tomography (CT) and self-developed computer software, and designed a rapid prototyping customized guiding block in order to offer a guide for the entry point and insertion angle of the C1-C2 transarticular screws.The clinical outcome was good, and the follow-up period was >3 years. The accuracy of the screws is good in comparison with preoperative and postoperative CT findings, and no neurovascular injury occurred.The patient was accurately and successfully treated with a bilateral C1-C2 transarticular screw fixation using a customized guiding block.

Short isthmic versus long trans-isthmic C2 screw: anatomical and biomechanical evaluation

INTRODUCTION

The Harms technique is now considered as the gold standard to stabilize C1-C2 cervical spine. It has been reported to decrease the risk of vertebral artery injury. However, the risk of vascular injury does not totally disappear, particularly due to the proximity of the trans-isthmic C2 screw with the foramen transversarium of C2. In order to decrease this risk of vertebral artery injury, it has been proposed to use a shorter screw which stops before the foramen transversarium.

OBJECT

The main objective was to compare the pull-out strength of long trans-isthmic screw (LS) versus short isthmic screw (SS) C2 screw. An additional morphological study was also performed.

METHOD

Thirteen fresh-frozen human cadaveric cervical spines were included in the study. Orientation, width and height of the isthmus of C2 were measured on CT scan. Then, 3.5-mm titanium screws were inserted in C2 isthmus according to the Harms technique. Each specimen received a LS and a SS. The side and the order of placement were determined with a randomization table. Pull-out strengths and stiffness were evaluated with a testing machine, and paired samples were compared using Wilcoxon signed-rank test and also the Kaplan-Meier method.

RESULTS

The mean isthmus transversal orientation was 20° ± 6°. The mean width of C2 isthmus was less than 3.5 mm in 35 % of the cases. The mean pull-out strength for LS was 340 ± 85 versus 213 ± 104 N for SS (p = 0.004). The mean stiffness for the LS was 144 ± 40 and 97 ± 54 N/mm for the SS (p = 0.02).

DISCUSSION

The pull-out strength of trans-isthmic C2 screws was significantly higher (60 % additional pull-out resistance) than SSs. Although associated with an inferior resistance, SSs may be used in case of narrow isthmus which contraindicates 3.5-mm screw insertion but does not represent the first option for C2 instrumentation.

LEVEL OF EVIDENCE

Level V.

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.

C1 Lateral Mass Screw Migration Causing a Delayed Unilateral Hypoglossal Nerve Lesion: A Case Report

CASE

We present the case of a fifty-eight-year-old woman who was initially treated with a C1 to C7 anterior-posterior cervical decompression and fusion for an epidural abscess and returned two years postoperatively with four days of progressive dysphagia and tongue deviation. She was diagnosed with a unilateral hypoglossal nerve (cranial nerve XII) palsy secondary to compression from a C1 lateral mass screw.

CONCLUSION

This is the first reported case that we are aware of describing a delayed cranial nerve palsy secondary to cutout and cephalad migration of a C1 lateral mass screw resulting in a neurologic deficit due to impingement on the hypoglossal nerve.

Distal Junctional Disease after Occipitothoracic Fusion for Rheumatoid Cervical Disorders: Correlation with Cervical Spine Sagittal Alignment

Study Design Retrospective radiographic study. Objective We have performed occipitothoracic (OT) fusion for severe rheumatoid cervical disorders since 1991. In our previous study, we reported that the distal junctional disease occurred in patients with fusion of O-T4 or longer due to increased mechanical stress. The present study further evaluated the association between the distal junctional disease and the cervical spine sagittal alignment. Methods Among 60 consecutive OT fusion cases between 1991 and 2010, 24 patients who underwent O-T5 fusion were enrolled in this study. The patients were grouped based on whether they developed postoperative distal junctional disease (group F) or not (group N). We measured pre- and postoperative O-C2, C2-C7, and O-C7 angles and evaluated the association between these values and the occurrence of distal junctional disease. Results Seven (29%) of 24 patients developed adjacent-level vertebral fractures as distal junctional disease. In group F, the mean pre- and postoperative O-C2, C2-C7, and O-C7 angles were 12.1 and 16.8, 7.2 and 11.2, and 19.4 and 27.9 degrees, respectively. In group N, the mean pre- and postoperative O-C2, C2-C7, and O-C7 angles were 15.9 and 15.0, 4.9 and 5.8, and 21.0 and 20.9 degrees, respectively. There were no significant differences between the two groups. The difference in the O-C7 angle (postoperative angle - preoperative angle) in group F was significantly larger than that in group N (p = 0.04). Conclusion Excessive correction of the O-C7 angle (hyperlordotic alignment) is likely to cause postoperative distal junctional disease following the OT fusion.

Retrospective review of 22 surgically treated adults with congenital anomalies of the upper cervical spine: a clinical and radiological review

PURPOSE

The purpose of this study was to clarify the characteristics of adult cases with instability due to upper cervical spine anomalies who needed fusion surgery regarding the clinical and radiological findings.

METHODS

Twenty-two consecutive patients with instability due to upper cervical spine anomaly in adult cases were reviewed. The congenital anomalies included idiopathic atlanto-axial subluxation in nine cases, os odontoideum in seven cases, occipitalization of the atlas in four cases, atlanto-occipital subluxation in one case and AAS with another anomaly in one case. We evaluated the severity of neurological symptoms before surgery and at the last follow-up. We also observed MR images before and 1 year after surgery.

RESULTS

Before surgery, the 22 patients included seven Ranawat Grade I cases, ten Ranawat Grade II cases, and five Ranawat Grade IIIa cases. Regarding the neurological status after surgery, those included eighteen Ranawat Grade I cases, three Ranawat Grade II cases, and one Ranawat Grade IIIa case. Preoperative T2-weighted MR images demonstrated intramedullary high signal intensity (IHSI) in 12 cases. IHSI group did not include significantly more Ranawat Grade IIIa cases compared to the remaining 10 cases. In postoperative MR images (nine cases), the regression or disappearance of IHSI was demonstrated in only three cases.

CONCLUSIONS

In adult cases with instability due to upper cervical spine anomalies, we acquired favorable clinical outcomes after surgery. Regarding the neurological severity before surgery, there was no relationship with the IHSI on T2-weighted MR image. Moreover, the regression or disappearance of IHSI after surgery was not frequently demonstrated.

Comparison of fusion rates between rod-based laminar claw hook and posterior cervical screw constructs in Type II odontoid fractures

BACKGROUND

This study was aimed (i) to compare the fusion rates of rod-based laminar claw hook constructs to that of posterior C1/C2 screw constructs in odontoid fractures, and (ii) to evaluate any complications associated with claw hook/rod constructs. To our knowledge, no study in contemporary literature has presented the effects of using modern rod-based laminar claw hooks for treating odontoid fractures. Unlike laminar clamps from the 1980s, contemporary laminar hook-rod instrumentation systems provide better immobilisation of the cervical spine and allows for building reliable frame-like constructs similar to cervical screw-rod systems.

METHODS

A retrospective review of a series of 167 consecutive odontoid fractures from a single-institution was conducted. 30 cases from the series were treated using posterior atlantoaxial fusion, 12 using C1/C2 posterior screws (control group), and 18 with rod-based laminar claw hooks (study group). Hooks were mounted bilaterally in a claw manner on each individual lamina and were rigidly fixed to perpendicular rods with a transverse connector whenever feasible. The minimum follow-up period was one year. Bony union was determined using computed tomography (CT) scan, while stability at the fusion site was assessed using dynamic radiograms.

RESULTS

The study group had an overall fusion rate of 89% (non-geriatric 93% while geriatric subgroup 75%) with a 100% stability rate at the fusion site in all cases. In the control group fusion rate was 100%. There were no major complications in both control and study groups. Four minor complications, three in the control and one in the study group, were noted in 3 patients.

CONCLUSION

Preliminary results of this study suggest that laminar claw hook-rod systems are useful alternatives to posterior screw techniques. Moreover, the fusion rate in non-geriatric patients is comparable to that of posterior screws. Importantly, they are devoid of the disadvantages and complications posed by screw constructs. Further studies are necessary to confirm these promising results.