Atlanto-axial joint of atlanto-axial subluxation patients due to rheumatoid arthritis before and after surgery, morphological evaluation using CT reconstruction

Radiological assessment and surgical management of cervical spine involvement in patients with rheumatoid arthritis

The purpose of the present systematic review was to describe the diagnostic evaluation of rheumatoid arthritis in the cervical spine to provide a better understanding of the indications and options of surgical intervention. We performed a literature review of Pub-med, Embase, and Scopus database. Upon implementing specific inclusion and exclusion criteria, all eligible articles were identified. A total of 1878 patients with Rheumatoid Arthritis (RA) were evaluated for cervical spine involvement with plain radiographs. Atlantoaxial subluxation (AAS) ranged from 16.4 to 95.7% in plain radiographs while sub-axial subluxation ranged from 10 to 43.6% of cases. Anterior atlantodental interval (AADI) was found to between 2.5 mm and 4.61 mm in neutral and flexion position respectively, while Posterior Atlantodental Interval (PADI) was between 20.4 and 24.92 mm. 660 patients with RA had undergone an MRI. A pannus diagnosis ranged from 13.33 to 85.36% while spinal cord compression was reported in 0-13% of cases. When it comes to surgical outcomes, Atlanto-axial joint (AAJ) fusion success rates ranged from 45.16 to 100% of cases. Furthermore, the incidence of postoperative subluxation ranged from 0 to 77.7%. With regards to AADI it is evident that its value decreased in all studies. Furthermore, an improvement in Ranawat classification was variable between studies with a report improvement frequency by at least one class ranging from 0 to 54.5%. In conclusion, through careful radiographic and clinical evaluation, cervical spine involvement in patients with RA can be detected. Surgery is a valuable option for these patients and can lead to improvement in their symptoms.

Genetically predicted C-reactive protein mediates the association between rheumatoid arthritis and atlantoaxial subluxation

OBJECTIVE

Investigating the causal relationship between rheumatoid arthritis (RA) and atlantoaxial subluxation (AAS) and identifying and quantifying the role of C-reactive protein (CRP) as a potential mediator.

METHODS

Using summary-level data from a genome-wide association study (GWAS), a two-sample Mendelian randomization (MR) analysis of genetically predicted rheumatoid arthritis (14,361 cases, and 43,923 controls) and AAS (141 cases, 227,388 controls) was performed. Furthermore, we used two-step MR to quantitate the proportion of the effect of c-reactive protein-mediated RA on AAS.

RESULTS

MR analysis identified higher genetically predicted rheumatoid arthritis (primary MR analysis odds ratio (OR) 0.61/SD increase, 95% confidence interval (CI) 1.36-1.90) increased risk of AAS. There was no strong evidence that genetically predicted AAS had an effect on rheumatoid arthritis risk (OR 1.001, 95% CI 0.97-1.03). The proportion of genetically predicted rheumatoid arthritis mediated by C-reactive protein was 3.7% (95%CI 0.1%-7.3%).

CONCLUSION

In conclusion, our study identified a causal relationship between RA and AAS, with a small proportion of the effect mediated by CRP, but a majority of the effect of RA on AAS remains unclear. Further research is needed on additional risk factors as potential mediators. In clinical practice, lesions of the upper cervical spine in RA patients need to be given more attention.

Normal Atlanto-Occipital Interval in Adults of Southeast Nigeria: An Evaluation of the Effect of Age, Sex, and Race

BACKGROUND

Imaging of the craniocervical junction (CCJ) after trauma is crucial for injury detection and description. Of all the anatomic measurements of the CCJ, the normal value of atlanto-occipital interval (AOI) is not yet well established in adults. The aim of our study is to determine the normal values of the AOI in Nigerians aged between 21 and 60 years using multidetector computed tomography (MDCT) scan and to determine racial, age, and sex differences.

METHODS

This was a prospective observational study done at Memfys Hospital for Neurosurgery, Enugu, Nigeria, between May 2016 and April 2017. There were 240 subjects (120 men and 120 women) divided into the following age groups: 21-30, 31-40, 41-50, and 51-60 years. Non-Nigerians and those with preexisting CCJ abnormalities were excluded. Normal values were those within the 95% confidence interval. Results were analyzed for possible sex and age variations and compared with the available literature for racial differences. Ethical approval was obtained for this study.

RESULTS

The measured normal computed tomography value of the AOI in adult Nigerians was 1.181 ± 0.018 mm. The values in the age groups of 21-30, 31-40, 41-50, and 51-60 years were 1.279 ± 0.038, 1.164 ± 0.033, 1.151 ± 0.029, and 1.133 ± 0.033 mm, respectively (P < 0.05). The average normal values in men and women were 1.188 ± 0.025 and 1.174 ± 0.026 mm, respectively. The interobserver reliability test using the Cronbach α was 0.938.

CONCLUSIONS

AOI values in this study were higher than previous MDCT-based values in non-African populations. The AOI decreased linearly with age and did not show any sex difference.

A Comparison of the Long-Term Results of Posterior Transarticular Stand-Alone Screw Instrumentation and Magerl Technique in Patients with Traumatic Atlantoaxial Instability: Mean 5-Year Follow-Up Study with Radiological and Patient-Rated Outcomes Assessments

OBJECTIVE

To perform a radiological analysis of the degeneration of C1-C2 joints after C1-C2 transarticular fixation (TAF) and compare the long-term results of a routine Magerl technique (RMT) to a posterior transarticular C1-C2 stand-alone screw instrumentation (SAS) application.

METHODS

A total of 40 patients (26 men and 14 women) were included in the present retrospective observational cohort study. The mean follow-up period was 61.7 months (range, 11-118). The mean patient age at the baseline examination was 48.4 years (range, 22-82). Of the 40 patients, 11 were included in the RMT group and 29 in the SAS group.

RESULTS

The structure of 80 atlantoaxial joints was analyzed, with grade 4 degenerative changes observed in 57 joints (71.3%). Of the 40 analyzed atlanto-odontoid joints, grade 4 degenerative changes were revealed in 18 joints (45%). C1-C2 bone fusion was observed in 38 patients (95%) and stable fibrous fusion in 2 patients (5%). No cases of C1-C2 nonunion were revealed. No statistically significant differences in the frequency of C1-C2 fracture consolidation or C1-C2 fusion were revealed between the RMT and SAS groups.

CONCLUSIONS

The application of cortical lag screws in TAF might result in stable atlantoaxial joint fusion formation without joint curettage. Atlanto-odontoid joint fusion was also observed after C1-C2 TAF. The application of cortical lag screws for bilateral fixation using the SAS technique resulted in C1-C2 fusion in 93.1% of cases, comparable to the results with the Magerl technique.

Use of Recombinant Human Bone Morphogenetic Protein-2 at the C1-C2 Lateral Articulation without Posterior Structural Bone Graft in Posterior Atlantoaxial Fusion in Adult Patients

BACKGROUND

Posterior atlantoaxial fusion is an important armamentarium for neurosurgeons to treat several pathologies involving the craniovertebral junction. Although the potential advantages of recombinant human bone morphogenetic protein-2 (rhBMP-2) are well documented in the lumbar spine, its indication for C1-C2 fusion has not been well characterized. In our institution, we apply rhBMP-2 to the C1-C2 joint either alone or with hydroxyapatite, locally harvested autograft chips, and/or morselized allogenic bone graft for selected cases-without conventional posterior structural bone graft. We report the clinical outcomes of the surgical technique to elucidate its feasibility.

METHODS

We performed a single-center, retrospective review of data from 2008 to 2016 and identified 69 patients who had undergone posterior atlantoaxial fusion with rhBMP-2. The clinical records of these patients were reviewed, and the baseline characteristics, operative data, and postoperative complications were collected and statistically analyzed.

RESULTS

The average age of the 69 patients was 60.8 ± 4.5 years, and 55.1% were women. With an average follow-up period of 21.1 ± 4.2 months, the C1-C2 fusion rate was 94.3% (65 of 69), and the average time to fusion was 11.4 ± 2.6 months (range, 5-23). The overall reoperation rate was 10.1% (7 of 69), with instrumentation failure in 7 patients (10.1%), adjacent segment disease in 2 (2.9%), and postoperative dysphagia and dyspnea in 2 patients (2.9%). No ectopic bone formation or soft tissue edema developed.

CONCLUSIONS

Although retrospective and from a single center, our study has shown that rhBMP-2 usage at the C1-C2 joint without posterior structural bone grafting is a safe and reasonable surgical option.

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.

Is It the Age at Disease Onset or the Disease Radiological Severity That Affects Cervical Spine Involvement in Patients With Rheumatoid Arthritis?

Background:

Cervical spine involvement in patients with rheumatoid arthritis (RA) can cause pain and disability, with a variety of neurologic signs and symptoms.

Objectives:

To investigate the relationship between structural cervical spine involvement in patients with RA with the age at disease onset and the degree of radiologic severity of RA measured by Larsen scoring.

Patients and methods:

This cross-sectional study included 50 adult patients with RA. Patients who complained or not complained from symptoms of cervical spine involvement in RA were included; we did X-ray of the cervical spine, hands, and feet; Larsen scoring method; disease activity score (DAS28); and Neck Disability Index.

Results:

The results revealed that patients with cervical involvement tend to be younger at their disease onset than those with no cervical involvement, as detected by cervical X-ray. The relation was significant P < .05 regarding all cervical involvements except for basilar invagination. Disease radiological severity (measured by Larsen score) significantly increases the risk for subaxial subluxation, P = .040. All other cervical complications of RA tend to have nonsignificant relation with disease severity. Using univariate binary regression analysis for risk factors for cervical involvement showed that the only probable risk factor for cervical involvement (detected by X-ray) in patients with RA is age at disease onset.

Conclusions:

The early age at disease onset tends to affect cervical spine involvement in patients with RA more than the disease radiological severity.

Treatment of atlanto-axial subluxation secondary to rheumatoid arthritis by short segment stabilization with polyaxial screws

OBJECTIVE

The main aim of this study was to analyse the compex clinical and radiographic findings in a group of RA patients with atlanto-axial slip (AAS) treated with free-hand short C1 lateral mass and C2 trans-pedicular screw fixation. The surgical technique used and the pathology treated were the same in all patients, producing a very homogeneous cohort of patients This allowed the study and measurement of radiographic parameters and fusion process.

METHODS

Twenty-nine patients (21 female, 8 male, mean age 54.9 years, duration of RA 17.3 years) with AAS and without CS were treated by short C1/2 fixation. Mean follow-up was 4.5 years. Pain intensity was monitored using VAS. Radiographic assessment consisted of lateral cervical radiographs in neutral and dynamic views, MR and CT of the cervical spine. The AADI, PADI, AAA, sub-axial cervical Cobb angle and canal-clivus angle (CCA) were measured pre-operatively and during the follow-up.

RESULTS

Significant malposition was recorded in 4 (3.4%) out of 116 inserted screws. AADI, PADI, AAA and CCA values changed significantly after surgery and remained stable during follow-up. The Cobb C angle value showed no significant change after surgery. There was a significant decrease of the VAS after the surgery. Fusion or a stable situation was achieved in all patients at 2-year follow-up. Pannus regression was observed in the vast majority of patients; only in two cases was rheumatic tissue detected on MR at 2 years post-operatively.

CONCLUSION

C1 lateral mass and C2 trans-pedicular fixation with polyaxial screws followed by an autograft between C1 and C2 lamina allowed, with an acceptable complication rate and favourable clinical results, adequate slip reposition, introduction of optimal sagittal alignment in terms of the final AAA with no radiographic consequences for the sub-axial cervical spine and assurance of long-term stability.

Reference ranges for atlantodental interval in adults and its variation with age and gender in a large series of subjects on multidetector computed tomography

BACKGROUND

The atlanto-dental interval measurement in the cervical spine in young adults has been reported on multidetector computed tomography (MDCT), but has not been systematically assessed in all ages.

PURPOSE

To evaluate the reference ranges for the atlanto-dental interval (ADI) in a large sample of adult patients on MDCT and to analyze the relationships of these measurements with gender and age of the patients as well as inter-observer performance.

MATERIAL AND METHODS

First, a consecutive series of 700 Chinese patients aged over 18 years undergoing an upper cervical MDCT scan were divided equally into seven age groups. Second, the mid-sagittal image of the atlanto-dental joint was chosen for measurement and ADI was defined as the distance intercepted from the segment line linking the center of anterior atlas tubercle with that of posterior tubercle. Third, the correlation of ADI with age and gender was analyzed using linear regression analysis. Finally, the inter-observer performance was assessed using Bland and Altman's limits of agreement.

RESULTS

The ADI was 1.77 ± 0.39 mm, 1.61 ± 0.37 mm, 1.58 ± 0.36 mm, 1.41 ± 0.29 mm, 1.31 ± 0.29 mm, 1.34 ± 0.28 mm, and 1.06 ± 0.47 mm in the age groups 18-24 years, 25-29 years, 30-39 years, 40-49 years, 50-59 years, 60-69 years, and older than 70 years, respectively. The range of ADI was 0.85-3.12 mm in the age group 18-39 years, 0.71-2.55 mm in the age group 40-59 years, and 0.00-2.37 mm in the age group older than 60 years. There was no difference between gender and ADI (r = 0.00, P = 1.000). ADI decreased linearly with age (r = -0.511, P = 0.000). The inter-observer performance was reliable.

CONCLUSION

ADI measurements on MDCT linearly decrease with increasing age, and these are not affected by gender in adult patients. Different reference values might be used at different ages when diagnosing atlantoaxial anterior dislocation or subluxation.

Tomographic analysis for C2 screw placement in rheumatoid arthritis patients

Objective

A morphological analysis of the bone structure of C2 in patients with rheumatoid arthritis in order to enhance the security of the stabilization procedures for this vertebra.

Methods

We retrospectively analyzed 20 CT scans of the cervical spine performed in patients with rheumatoid arthritis; the following parameters were measured: spinolaminar angle, thickness and length of C2 lamina.

Results

The mean values are: 5.92mm and 5.87mm for thickness of right and left laminae retrospectively, 27.75mm for right lamina length and 27.94mm for left lamina length, and 44.7º for spinolaminar angle.

Conclusion

The values obtained are consistent with studies in normal subjects published by other groups, with no apparent need for change in the screw placement technique. Level of Evidence IV, Case Series.

Morphological and volumetric analysis of the development of atlantoaxial vertical subluxation in rheumatoid arthritis

BACKGROUND

Cervical disorders in rheumatoid arthritis (RA) patients have been an important problem for a long time. Although the recent progression of the treatment strategies for RA might change the progression of atlantoaxial vertical subluxation (VS) in RA patients, to reveal the risk factors for VS progression should be important at present. Osteoporosis (OP) and RA share the same risk factors. The purposes of this study were to identify the progression of VS in RA, and to evaluate the relationship between the VS development and OP.

METHODS

Eighty female patients with RA and 18 female patients with OP were retrospectively analyzed. The RA patients were divided into VS (10 patients) and non-VS groups (70 patients). Morphological parameters on coronal reconstructed computed tomography images were evaluated. Three-dimensional analysis was used to measure volumes and volumetric bone mineral densities (vBMDs) at the upper cervical spine (UCS).

RESULTS

The VS group had higher age, longer RA symptom duration, and lower BMD at the lumbar spine compared to the non-VS group. Volumes and vBMDs at the UCS in RA group were greater than those in the OP group. In accordance with VS development, the lateral masses at the UCS became shorter, the C1 facet angle became sharper, and the volumes at the UCS decreased. However, there was no statistically significant relationship between vBMDs at the UCS and the VS development.

CONCLUSION

The C1 facet angle became sharper with VS progression. Although 3-dimensional analysis revealed that decreases in the volumes at the UCS were associated with VS development, no significant relationship between OP and the VS development was observed.

Effect of a reduction of the atlanto-axial angle on the cranio-cervical and subaxial angles following atlanto-axial arthrodesis in rheumatoid arthritis

PURPOSE

We retrospectively investigated the radiographic findings in patients with atlanto-axial subluxation (AAS) due to rheumatoid arthritis, and clarified the effect of reduction of the atlanto-axial angle (AAA) on the cranio-cervical and subaxial angles.

METHODS

Forty-one patients, consisting of 29 females and 12 males, with AAS treated by surgery were reviewed. The average patient age at surgery was 61.0 years, and the average follow-up period was 4.0 years. We investigated the AAA at the neutral position in lateral cervical radiographs before surgery and at the last follow-up. In addition, we also investigated the clivo-axial angle (CAA) and the subaxial angle (SAA) at the neutral position before and after surgery.

RESULTS

Due to pre-operative AAA, the patients were classified into three groups as follows: (1) the kyphotic group (K group), (2) the neutral group (N group), and (3) the lordotic group (L group). The average AAA values at the neutral position in the K group before and after surgery were 6.0° and 18.1°, respectively (P < 0.001). In the N group 19.7° and 21.7°, respectively (P < 0.05), and in the L group 31.6° and 27.0°, respectively (P < 0.01). However, no significant differences in the average CAA values were found before and after surgery in all groups. Furthermore, no significant differences in the SAA values were seen before and after surgery in all groups.

CONCLUSIONS

A proper reduction of the AAA did not affect the cranial angles or induce kyphotic malalignment of the subaxial region after atlanto-axial arthrodesis. However, if we can obtain a significant and large reduction of AAA in patients showing kyphosis before surgery, then this reduction will be offset in the atlanto-occipital joint and we should therefore pay special attention to its morphology after surgery.

Characteristics of idiopathic atlanto-axial subluxation: a comparative radiographic study in patients with an idiopathic etiology and those with rheumatoid arthritis

OBJECTIVE

Atlanto-axial subluxation (AAS) is caused by multiple conditions; however, idiopathic AAS patients without RA, upper-cervical spine anomalies or any other disorder are rarely encountered. This study retrospectively investigated the radiographic findings in idiopathic AAS patients, and clarified the differences between those AAS patients and those due to RA.

METHODS

Fifty-three patients with AAS treated by transarticular screw fixation were reviewed. The subjects included 8 idiopathic patients (ID group) and 45 RA patients (RA group). The study investigated the atlanto-dental interval (ADI) value and space available for spinal cord (SAC) at the neutral and maximal flexion position.

RESULTS

The average ADI value at the neutral position in the ID and RA groups before surgery was 7.8 and 7.2 mm, respectively (p > 0.74). The average ADI value at the flexion position in the two groups was 10.3 and 11.7 mm, respectively (p > 0.06). The average SAC value at the neutral position in the two groups was 12.0 and 17.1 mm, respectively (p < 0.01). Finally, the average SAC value at the flexion position in the two groups was 10.7 and 13.5 mm, respectively (p < 0.01).

CONCLUSIONS

The SAC value at both the neutral and flexion positions in idiopathic AAS patients was significantly smaller than those values in RA-AAS patients. This may be because the narrowing of the SAC in the idiopathic group easily induces cervical myelopathy. Furthermore, surgery was often recommended to RA patients, because of the neck pain induced by RA-related inflammation of the atlanto-axial joint, regardless of any underlying myelopathy.

Is external cervical orthotic bracing necessary after posterior atlantoaxial fusion with modern instrumentation: meta-analysis and review of literature

BACKGROUND

No guidelines exist regarding external cervical orthoses (ECO) after atlantoaxial fusion. We reviewed published series describing C1-2 posterior instrumented fusions with screw-rod constructs (SRC) or transarticular screws (TAS) and compared rates of fusion with and without postoperative ECO.

METHODS

Online databases were searched for English-language articles between 1986 and April 2011 describing ECO use after posterior atlantoaxial instrumentation with SRC or TAS. Eighteen studies describing 947 patients who had SRC (± ECO: 254 of 693 patients), and 33 studies describing 1424 patients with TAS (± ECO: 525 of 899 patients) met inclusion criteria. Meta-analysis techniques were applied to estimate rates of fusion with and without ECO use.

RESULTS

All studies provided class III evidence, and no studies directly compared outcomes with or without ECO use. There was no significant difference in the proportion of patients who achieved successful fusion between patients treated with ECO and without ECO for SRC or TAS patients. Point estimates and 95% confidence intervals (CI) for rates of fusion ± ECO were 97.4% (CI: 95.2% to 98.6%) versus 97.9% (CI: 93.6% to 99.3%) for SRC and 93.6% (CI: 90.7% to 95.6%) versus 95.3% (CI: 90.8% to 97.7%) for TAS. There was no correlation between duration of ECO treatment and fusion (dose effect).

CONCLUSIONS

After C1-2 fusion with modern instrumentation, ECO may be unnecessary (class III). Some centers recommend ECO use with patients with softer bone quality (class IV). Prospective, randomized studies with validated radiographic and clinical outcome metrics are necessary to determine the utility of ECO after C1-2 fusion and its impact on patient comfort and cost.

Atlantoaxial fusion with transarticular screws: meta-analysis and review of the literature

OBJECTIVE

To review published series describing C1-2 posterior instrumented fusions and summarize clinical and radiographic outcomes of patients treated with transarticular screw (TAS) fixation.

METHODS

Online databases were searched for English-language articles published between 1986 and April 2011 describing posterior atlantoaxial instrumentation with C1-2 TAS fixation. There were 45 studies including 2073 patients treated with TAS that fulfilled inclusion criteria. Meta-analysis techniques were used to calculate outcomes.

RESULTS

All studies provided class III evidence. The 30-day perioperative mortality rate was 0.8%, and the incidence of neurologic injury was 0.2%. The incidence of clinically significant malpositioned screws was 7.1% (confidence interval [CI], 5.7%-8.8%), the incidence of vertebral artery injury was 3.1% (CI, 2.3%-4.3%), and the rate of fusion with the TAS technique was 94.6% (CI, 92.6%-96.1%).

CONCLUSIONS

TAS fixation is a safe and effective treatment option for C1-2 instability with high rates of fusion (approximately 95%). Screw malposition and vertebral artery injury occurred in approximately 5% of patients. The successful insertion of TAS requires a thorough knowledge of atlantoaxial anatomy.