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Background: Congenital craniovertebral deformity, including basilar invagination (BI) and atlantoaxial instability (AAI), are often associated with three-dimensional (3D) deformity, such as C1-2 rotational deformity, craniocervical kyphosis, C1 lateral inclination, among other abnormalities. Effective management of these conditions requires the restoration of the 3D alignment to achieve optimal reduction. Recently, 3D printing technology has emerged as a valuable tool in spine surgery, offering the significant advantage of allowing surgeons to customize the prosthesis design. This innovation provides an ideal solution for precise 3D reduction in the treatment of craniovertebral deformities. Objective: This study aims to describe our approach to individualized computer-simulated reduction and the design of C1-2 intra-articular 3D printed porous titanium alloy cages for the quantitative correction of craniovertebral junction deformities. Methods: A retrospective analysis was conducted on patients with craniovertebral deformities treated at our institution using individualized 3D-printed porous titanium alloy cages. Preoperative CT data were used to construct models for 3D realignment simulations. Cage designs were tailored to the simulated joint morphology following computer-assisted realignment. Preoperative and postoperative parameters were statistically analyzed. Results: Fourteen patients were included in the study, with a total of 28 3D-printed porous titanium alloy cages implanted. There were no cases of C2 nerve root resection or vertebral artery injury. All patients experienced symptom relief and stable implant fixation achieved in all cases. No implant-related complications were reported. Conclusion: The use of individualized computer-simulated reduction and the design of C1-2 intra-articular 3D printed porous titanium alloy cage facilitates precise 3D realignment in patients with craniovertebral deformities, demonstrating effectiveness in symptom relief and stability. [ABSTRACT FROM AUTHOR]

The data on the use of a one- or two-screw technique (1S, 2S) for ventral osteosynthesis of type II dens fractures are contradictory. The aim was to design an apparatus to mimic the physiological conditions and test stability with 1S, 2S, and a headless compression screw (HCS) for osteosynthesis of artificially created type II odontoid fractures. The apparatus was mounted on a Zwick materials testing machine. A total of 18 C1–2 specimens were stratified into three groups (1S, 2S, HCS). Odontoid fractures were artificially created, and osteosynthesis was performed. Each specimen was tested at loads increasing from 1 to 40 N. Screw loosening was observed visually, by fatigue data, and by a camera tracking system. Analysis of the Zwick data and the camera data revealed a significant higher stability after 2S compared to 1S and HCS treatment (Zwick data: p = 0.021, camera data: p < 0.001), while visible screw loosening showed a superiority of the 2S only over HCS (p = 0.038). The developed apparatus allowed the dynamic study of the atlantoaxial joint with a high approximation to physiological conditions. The results demonstrated superiority of the 2S over the 1S and HCS in biomechanical stability in the treatment of type II odontoid fractures. [ABSTRACT FROM AUTHOR]

Background: cervicogenic headaches are common and are believed to be the cause of dysfunction in the upper cervical spine. The mobility and the position of the atlas have been identified as a cause of upper cervical dysfunction. The mobility of the atlas is entirely under the control of the suboccipital muscles. The oblique capitis inferior muscle has a rotatory effect on the atlas when contracted. This study evaluated the immediate effects of a dry needling electrical stimulation-induced contraction of the left oblique capitis inferior muscle on the position and mobility of the atlas in the atlantoaxial joint. Methods: thirty-one subjects participated in this within-subject repeated measure study design. Each subject underwent a pre-measures neck flexion rotation test, palpation of the atlas position, and measurement of the length of the right oblique capitis inferior muscle with musculoskeletal ultrasound imaging. The pre-measures were repeated after two five-second tetanic contractions of the oblique capitis inferior muscle. Results: post-intervention analysis revealed significant changes in the length of the right oblique capitis inferior muscle. This length change correlated with the palpated positional default position immediately after the intervention. Conclusions: two five-second tetanic contractions of the left oblique capitis inferior muscle immediately affected the position of the atlas in the atlantoaxial joint. In our subjects, 90% displayed a positional default in the left rotation, and this was correlated with a change in the neck flexion rotation test. This study supports the notion that suboccipital muscle tonicity can result in mobility dysfunction and, thus, conditions such as cervicogenic headaches. [ABSTRACT FROM AUTHOR]

Key Clinical Message: Traumatic posterior atlantoaxial dislocation combined with Jefferson fracture and odontoid process fracture with vertebral artery injury is rare. The management of such injury raises controversial issues and is still open to debate. A 74‐year‐old Chinese male presented with sustained neck pain and stiffness after falling from height. The patient was neurologically intact. Preoperative radiographs demonstrated a Jefferson burst fracture with a posterior dislocation of the atlantoaxial joints and odontoid process Anderson and D'alonzo type II fracture. A computed tomography angiography (CTA) showed an occluded left vertebral artery. Coil embolization in the proximal portion of the occluded vertebral artery was performed to prevent further cerebral infarction due to distal embolization of the thrombus. Then a second stage occipito‐cervical fusion was performed to reconstruct cervical spine stability. A systematic screening of blunt trauma vertebral artery injuries through CTA is required when dealing with upper cervical fracture. For cases with vertebral artery occlusion secondary to cervical spine injury, endovascular treatment preceding cervical spine surgery is a feasible and a safe treatment. [ABSTRACT FROM AUTHOR]

Objective: Both two‐level anterior cervical corpectomy and fusion (t‐ACCF) and posterior open‐door laminoplasty (ODLP) are effective surgical procedures for the treatment of ossification of the posterior longitudinal ligament (OPLL). Previous studies have identified different effects of different surgical procedures on the upper and subaxial cervical spine (UCS, SCS), however, there are no studies on the effects of t‐ACCF and ODLP on the occipito‐atlantoaxial complex. Therefore, the purpose of this study is to compare the changes in sagittal parameters and range of motion (ROM) of the occipito‐atlantoaxial complex in OPLL patients treated with t‐ACCF and ODLP. Methods: This was a retrospective study that included 74 patients who underwent t‐ACCF or ODLP for the treatment of OPLL from January 2012 to August 2022 at our institution. Preoperative, 3‐month, and 1‐year postoperative cervical neutral, flexion‐extension, and lateral flexion radiographs were taken. Sagittal parameters including Cobb angle of C2‐7, C0‐2, C0‐1, C1‐2, C2 slope, and the ROM were measured. The clinical outcome was assessed using the JOA, VAS, and NDI scores preoperatively and at 3 and 12 months postoperatively. Multiple linear regression was employed to identify factors influencing changes in UCS. Results: In the ODLP group, the SCS (C2‐7) Cobb angle was significantly reduced (12.85 ± 10.0 to 7.68 ± 11.27; p < 0.05), and the UCS (C0‐2) Cobb angle was significantly compensated for at 1 year postoperatively compared with the t‐ACCF group (3.05 ± 4.09 vs 0.79 ± 2.62; p < 0.01). The SCS and lateral flexion ROM of the ODLP group was better maintained than t‐ACCF (14.51 ± 6.00 vs 10.72 ± 3.79; 6.87 ± 4.56 vs 3.81 ± 1.67; p < 0.01). The compensatory increase in C0‐2, C0‐1, and C1‐2 ROM was pronounced in both groups, especially in the ODLP group. The results of multiple linear regression showed that only the surgical procedure was a significant factor influencing UCS. Conclusion: The loss of the SCS Cobb angle was more pronounced in ODLP relative to t‐ACCF, resulting in a significant compensatory increase in UCS and atlantoaxial Cobb angle. The ROM of the UCS, atlantooccipital, and atlantoaxial joints was significantly increased in both groups, this may accelerate degenerative changes in the occipital‐atlantoaxial complex, may leading to poorer outcomes in the long‐term; of these, ODLP should receive more attention. In contrast, t‐ACCF better maintains normal curvature of the SCS and occipito‐atlantoaxial complex but loses more ROM. [ABSTRACT FROM AUTHOR]

In forensic commingled contexts, when the disarticulation occurs uniquely at the atlantoaxial joint, the correct match of atlas and axis may lead to the desirable assembly of the entire body. Notwithstanding the importance of this joint in such scenarios, no study has so far explored three-dimensional (3D) methodologies to match these two adjoining bones. In the present study, we investigated the potential of re-associating atlas and axis through 3D–3D superimposition by testing their articular surfaces congruency in terms of point-to-point distance (Root Mean Square, RMS). We analysed vertebrae either from the same individual (match) and from different individuals (mismatch). The RMS distance values were assessed for both groups (matches and mismatches) and a threshold value was determined to discriminate matches with a sensitivity of 100%. The atlas and the corresponding axis from 41 documented skeletons (18 males and 23 females), in addition to unpaired elements (the atlas or the axis) from 5 individuals, were superimposed, resulting in 41 matches and 1851 mismatches (joining and non-joining elements). No sex-related significant differences were found in matches and mismatches (p = 0.270 and p = 0.210, respectively), allowing to pool together the two sexes in each group. RMS values ranged between 0.41 to 0.77 mm for matches and between 0.37 and 2.18 mm for mismatches. Significant differences were found comparing the two groups (p < 0.001) and the highest RMS of matches (0.77 mm) was used as the discriminative value that provided a sensitivity of 100% and a specificity of 41%. In conclusion, the 3D–3D superimposition of the atlanto-axial articular facets cannot be considered as a re-association method per se, but rather as a screening one. However, further research on the validation of the 3D approach and on its application to other joints might provide clues to the complex topic of the reassociation of crucial adjoining bones. [ABSTRACT FROM AUTHOR]

Background: Salvage revisions of atlantoaxial (AA) joint complex posterior segmental instrumented fusion constructs require careful individualized planning to prevent occipital extension. In this case report, we describe the use of bilateral intrafacet spacer placement as a mobility-sparing bailout option for the revision surgery. Case Report: A 64-year-old male with a history of diffuse idiopathic skeletal hyperostosis, extremely limited baseline cervical mobility, and prior AA posterior segmental instrumented fusion presented with increasing pain at his 6-month follow-up. Imaging showed fusion and hardware failures and dynamic instability. To prevent occipitocervical fixation, AA intra-articular fusion via a DTRAX spinal system (Providence Medical Technology, Inc) was used as an adjunct to a navigated C1 lateral mass and C2 pars screw posterior segmental instrumented fusion construct. The patient had an uneventful postoperative course and was discharged with resolution of symptoms. Three-month postoperative follow-up confirmed persistent resolution of symptoms and absence of complaints, along with successful arthrodesis on imaging. Conclusion: AA posterior segmental instrumented fusion revision is technically challenging, particularly when partial preservation of craniovertebral junction mobility is required. Bilateral intra-articular cages may be used as an adjunct to hardware revision in construct salvage when sturdy arthrodesis is desired without occipital extension and may represent a major potential strength of intra-articular cages. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to investigate the association between unilateral high-riding vertebral artery (HRVA) and morphological changes in the atlantoaxial joint (AAJ) and to determine whether unilateral HRVA is a risk factor for atlantoaxial osteoarthritis (AAOA). Methods: We conducted a retrospective analysis of 2496 patients admitted to our medical center between January 2020 and December 2022 who underwent CT imaging of the cervical spine. Two hundred and seventy-two patients with unilateral HRVA (HRVA group) were identified and a respective 2:1 age- and sex-matched control group without HRVA was built. Morphological parameters, including C2 lateral mass settlement (C2 LMS), C1/2 coronal inclination (C1/2 CI), lateral atlanto-dental interval (LADI), and C1/2 relative rotation angle (C1/2 RRA) were measured. The degree of AAOA was recorded. Risk factors associated with AAOA were identified using univariate and multivariable logistic regression analyses. Results: The study included 61.4% women, and the overall average age of the study population was 48.7 years. The morphological parameters (C2 LMS, C1/2 CI, and LADI) in AAJ were asymmetric between the HRVA and the non-HRVA sides in the HRVA group (p < 0.001). These differences in parameters (d-C2 LMS, d-C1/2 CI, and d-LADI) between the HRVA and the non-HRVA sides, and C1/2 RRA were significantly larger than those in the control group. Eighty-three of 816 patients (10.2%) with AAOA had larger values of d-C2 LMS, d-C1/2 CI, d-LADI, and C1/2 RRA compared with the patients without AAOA (p < 0.05). The multivariable logistic regression analysis indicated that unilateral HRVA [adjusted odds ratio (OR) = 2.6, 95% CI: 1.1–6.3, p = 0.029], age in the sixth decade or older (adjusted OR = 30.2, 95% CI: 16.1–56.9, p < 0.001), women (adjusted OR = 2.1, 95% CI: 1.0–5.6, P = 0.034) were independent risk factors for AAOA. Conclusion: Unilateral HRVA was associated with asymmetric morphological changes of nonuniform settlement of C2 lateral mass, lateral slip of atlas, and atlantoaxial rotation displacement. Besides age ≥ 60 years and females, unilateral HRVA is an independent risk factor for AAOA. [ABSTRACT FROM AUTHOR]

Objective: Muscle dysfunction caused by repetitive work or strain in the neck region can interfere muscle responses. Muscle dysfunction can be an important factor in causing cervical spondylosis. However, there has been no research on how the biomechanical properties of the upper cervical spine change when the suboccipital muscle group experiences dysfunction. The objective of this study was to investigate the biomechanical evidence for cervical spondylosis by utilizing the finite element (FE) approach, thus and to provide guidance for clinicians performing acupoint therapy. Methods: By varying the elastic modulus of the suboccipital muscle, the four FE models of C0-C3 motion segments were reconstructed under the conditions of normal muscle function and muscle dysfunction. For the two normal condition FE models, the elastic modulus for suboccipital muscles on both sides of the C0-C3 motion segments was equal and within the normal range In one muscle dysfunction FE model, the elastic modulus on both sides was equal and greater than 37 kPa, which represented muscle hypertonia; in the other, the elastic modulus of the left and right suboccipital muscles was different, indicating muscle imbalance. The biomechanical behavior of the lateral atlantoaxial joint (LAAJ), atlanto-odontoid joint (ADJ), and intervertebral disc (IVD) was analyzed by simulations, which were carried out under the six loadings of flexion, extension, left and right lateral bending, left and right axial rotation. Results: Under flexion, the maximum stress in LAAJ with muscle imbalance was higher than that with normal muscle and hypertonia, while the maximum stress in IVD in the hypertonic model was higher than that in the normal and imbalance models. The maximum stress in ADJ was the largest under extension among all loadings for all models. Muscle imbalance and hypertonia did not cause overstress and stress distribution abnormalities in ADJ. Conclusion: Muscle dysfunction increases the stress in LAAJ and in IVD, but it does not affect ADJ. [ABSTRACT FROM AUTHOR]

The combination of atlantoaxial joint dislocation accompanied by an odontoid process fracture is exceptionally rare, with only a few cases reported. The estimated frequency of these cases is < 2% of all upper cervical spine injuries. In this report, the authors describe an unusual case of traumatic atlantoaxial dislocation with a type III odontoid fracture in a 44-year-old male patient. Before the diagnosis, the patient had a history of seeking a masseur for a neck massage. Subsequently, the patient underwent occipitocervical stabilization to address the underlying condition. This procedure aims to treat the instability between the skull and cervical spine and should be considered in the treatment planning if the patient's anatomy suits it. [ABSTRACT FROM AUTHOR]

BACKGROUND/AIM: Craniocervical junction (CCJ) can be involved in inflammatory arthritis. We aimed to define types of CCJ involvement in rheumatoid arthritis (RA), spondyloarthritis (SpA), and psoriatic arthritis (PsA) and compare them with patients without inflammatory arthritides. MATERIALS AND METHODS: In this retrospective analysis, cervical CT or MRIs of patients with RA, SpA, or PsA, taken for any reason between 2010 and 2020, according to ICD-10 codes, were scanned. Demographic data of the patients were recorded. CCJ involvements (atlantoaxial, vertical, or subaxial subluxation, odontoid process involvement) were reevaluated by an experienced radiologist. The control group consisted of consecutive patients without inflammatory arthritis. RESULTS: Exactly 459 patients (204 RA, 200 SpA, and 55 PsA) and 78 patients in the control group were included in the study. CCJ involvement was detected in 101 (49.5%) RA, 53 (26.5%) SpA, 10 (18.2%) PsA, and 4 patients (5.1%) in the control group (p < 0.001). The odontoid process was one of the main targets, especially in RA patients (69 (33.8%)), which was significantly higher than in the SpA, PsA, and control groups. Although vertical subluxation (VS) was numerically higher in the RA and SpA groups compared to the control group, VS-related brainstem compression was relatively uncommon: 6 (2.9%) in RA, 1 (0.5%) in AS, and none in the PsA and control groups. CONCLUSION: CCJ involvement can often be detected in patients with inflammatory arthritis, especially in RA and SpA patients. The odontoid process is the main target of inflammation.

Postoperative atlantoaxial rotatory subluxation (AARS) is a rare complication that develops almost exclusively in children following oropharyngeal and otologic surgeries, proposing that oropharyngeal inflammatory responses and excessive head rotation are responsible factors. However, there have been no reports of AARS after excision of a nevus on the head and neck. Here, we present two cases of AARS following limited head rotation during simple nevus excision. Patient 1, a 9-year-old girl, complained of neck pain and limited range of motion after excision of the nevus on the neck. After 2 months, computed tomography and magnetic resonance imaging finally revealed AARS with a ruptured transverse atlantal ligament. A month of halo traction was required for the treatment. Patient 2, an 11-year-old girl, presented with immediate pain and limited neck extension after tissue expander insertion under the upper chest and excision of the nevus on her left cheek. The diagnosis was promptly made using cervical spine radiography. A cervical collar was applied for 1 month. Both patients recovered without any complications after treatment. This report highlights the importance of suspicion for AARS after surgery regardless of surgical duration or amount of head rotation. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Tissue Engineering Research / Zhongguo Zuzhi Gongcheng Yanjiu is the property of Chinese Journal of Tissue Engineering Research and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Tissue Engineering Research / Zhongguo Zuzhi Gongcheng Yanjiu is the property of Chinese Journal of Tissue Engineering Research and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background Osteoarthrosis of the lateral atlanto-axial joint (LAAJ) may be a cause of upper neck pain and headache. Intra-articular injection of steroids may provide only short-lasting relief. For intractable pain, arthrodesis of the joint might be considered. Objective To determine the success rates of arthrodesis of the lateral atlanto-axial joint for relieving neck pain and disability. Design Practice audit. Setting Private practice of senior author. Subjects Prospective series of 23 consecutive patients. Methods Outcomes were measured using a numerical rating scale for neck pain, and the Neck Disability Index for disability. Success rates were calculated for various degrees of improvement of neck pain at long-term follow-up (8–40 months), and for achieving various combinations of improvement of both neck pain and disability. Results Complete relief of pain was achieved in 40% of patients, with a further 40% achieving at least 50% relief. At long-term follow-up, 30% of patients had no neck pain and no disability, and a further 25% had only minimal pain, minimal disability, or both. Conclusions The present study did not corroborate earlier studies that claimed outstanding outcomes for arthrodesis of the LAAJ, but its outcomes are consonant with more recent studies that provided transparent outcome data. These studies provide Pain Physicians with empirical data on success rates and outcomes, upon which they can base their consideration of referral for arthrodesis. [ABSTRACT FROM AUTHOR]

Objective: Spinal involvement in rheumatoid arthritis (RA) is limited to the upper cervical spine, leading to cervical spine instability. This study aimed to evaluate the prevalence of anterior atlantoaxial subluxation (aAAS) and its associated risk factors in patients with RA. Method: This single‐centre cross‐sectional study 240 patients consecutively were recruited. Radiographs of the cervical spine were obtained in the flexion and neutral neck positions and read by two blinded observers. The diagnosis of aAAS was based on the distance between the anterior aspect of the dens and the posterior aspect of the anterior arch of the atlas, which was >3 mm during flexion. Statistical analysis was performed to determine the predictive factors of aAAS. Results: Two hundred and forty patients with a mean ± SD age of 56.4 ± 11.4 years were recruited, and 191 (78%) were female. The mean ± SD duration of the disease was 10.2 ± 8.5 years. Of all 25 cases (10.4%) diagnosed with aAAS, the mean anterior atlantodental interval in patients with AAS was 4.19 ± 1.20 mm. One in three patients with aAAS had no neck pain. Patients with aAAS had longer disease duration, lower age at diagnosis, lower body mass index, higher anti‐cyclic citrullinated peptide autoantibodies (anti‐CCP), more frequent erosion, joint restriction, and joint prostheses. In the multivariate regression model, joint limitation, history of joint prostheses, low BMI, and higher anti‐CCP levels were independent predictors of the aAAS. Conclusion: Thirty‐three percent of patients with cervical involvement do not experience neck pain. Cervical involvement should be considered even without neck pain, particularly in established diseases. [ABSTRACT FROM AUTHOR]

(1) Background: In elderly patients with type II odontoid fractures, accompanying severe atlantoaxial instability (AAI) is discussed as a marker possibly warranting more aggressive surgical therapy. This study aimed to characterize adverse events as well as the radiological and functional outcomes of surgical vs. conservative therapy in patients with odontoid fracture and AAI. (2) Methods: Patients aged 65 years and older with type II odontoid fracture and AAI treated were included. AAI was assumed if the mean subluxation across both atlantoaxial facet joints in the sagittal plane was greater than 50%. Data on demographics, comorbidities, treatment, adverse events, radiological, and functional outcomes were analyzed. (3) Results: Thirty-nine patients were included. Hospitalization time was significantly shorter in conservatively treated patients compared to patients with ventral or dorsal surgery. Adverse events occurred in 11 patients (28.2%), affecting 10 surgically treated patients (35.7%), and 1 conservatively treated patient (9.1%). Moreover, 25 patients were followed-up (64.1%). One secondary dislocation occurred in the conservative group (11.1%) and three in the surgical group (18.8%). (4) Conclusions: Despite the potential for instability in this injury, conservative treatment does not seem to lead to unfavorable short-term results, less adverse events, and a shorter hospital stay and should thus be considered and discussed with patients as a treatment option, even in the presence of severe AAI. [ABSTRACT FROM AUTHOR]

Objective: Cable‐dragged reduction and cantilever beam internal fixation can provide promising results in the treatment of atlantoaxial dislocation or instability. However, bilateral atlantoaxial joints bone autografting has not been conducted in this technique. We aim to evaluate the safety and effectiveness of bilateral atlantoaxial joints bone autografting in posterior cable‐dragged reduction and cantilever‐beam internal fixation. Methods: In this retrospective study, we included 14 patients with a minimum 24‐month follow‐up from December 2019 to September 2020. The granular bone harvested from the iliac crest was packed into the bilateral atlantoaxial joints of 14 patients in posterior cable‐dragged reduction and cantilever‐beam internal fixation. X‐ray imaging and cervical computed tomography (CT) were performed during follow‐up. The time required for bone fusion was recorded. The clinical outcomes were evaluated using the JOA scores, NDI, and VAS scores. Mann–Whitney U test, the chi‐squared test, or the Fisher exact test were used to compare the two groups regarding patient characteristics, clinical outcomes, bone fusion rates, and cervical sagittal alignment. Results: The operations were successfully performed in all patients without any intraoperative complications. The mean operation time was (169.64 ± 20.91) minutes, and the intraoperative blood loss was (130.71 ± 33.62) mL. All patients received satisfactory reductions and firm bony fusion at the final follow‐up. The fusion rates were 64.29% in the atlantoaxial joints and 21.43% in post bone graft area at 3 months postoperatively, and a significant difference was observed (p = 0.022). Besides, the cervical sagittal alignment in all patients was well maintained in the last follow‐up compared to preoperatively. Importantly, a complete bony fusion in the atlantoaxial joints was observed in all patients. Moreover, the JOA, NDI, and VAS scores had improved significantly at the last follow‐up. Conclusion: Bone autografting of the bilateral atlantoaxial joints is a safe and effective technique to increase bone fusion rates, shorten bone fusion time, and reduce complication rates when the cable‐dragged reduction and cantilever beam internal fixation approach is used. Therefore, it is a cost‐effective surgical procedure for treating patients with atlantoaxial dislocation or instability. [ABSTRACT FROM AUTHOR]

Study Design: Retrospective cohort study. Objective: To investigate the effect of HRVA on the intrapedicular accuracy of C2PS placement through the freehand method in patients with BI and analyse the possible risk factors for C2PS malpositioning. Method: A total of 91 consecutive patients with BI who received 174 unilateral C2PS placements through the freehand method were retrospectively included. The unilateral pedicles were assigned to the HRVA and non-HRVA groups. The primary outcome was the intrapedicular accuracy of C2PS placement in accordance with the Gertzbein–Robbins scale. Moreover, the risk factors that possibly affected intrapedicular accuracy were assessed. Results: The rate of intrapedicular accuracy in C2PS placement in patients with BI was 23.6%. Results showed that the non-HRVA group had remarkably higher rates of optimal and clinically acceptable C2PS placement than the HRVA group. Nevertheless, the HRVA group exhibited similar results for grade B classification as the non-HRVA group. Moreover, in the HRVA and non-HRVA groups, the most common direction of screw deviations was the lateral direction. Furthermore, the multivariate analyses showed that the obliquity of the lateral atlantoaxial joint in the sagittal plane ≥15°, and that in the coronal plane ≥ 20°, isthmus height < 4.3 mm, and distance from the skin to the spinous process ≥ 2.8 cm independently contributed to a high rate of screw malpositioning in BI patients. Conclusion: The presence of HRVA in BI patients contributed to the high rate of malpositioning in C2PS placement via the freehand method. However, the rates of intrapedicular accuracy in patients with BI with and without HRVA were considerably low. [ABSTRACT FROM AUTHOR]

Purpose: The treatment of unstable atlas fractures remains a controversial topic. The study aims at assessing the prognosis and efficacy of osteosynthesis for unstable atlas fractures through a review of the current literature and additionally aims to compare outcomes between the transoral and posterior approaches. Methods: A systematic review of databases including PubMed, EMBASE, Cochrane, Web of Science, CNKI, and Wanfang was conducted. Titles and abstracts were screened by two reviewers to identify studies meeting pre-defined inclusion criteria for comprehensive analysis. Results: The systematic review included 28 articles, 19 employing the posterior approach and 9 utilizing the transoral approach. It covered osteosynthesis in 297 patients with unstable atlas fractures, comprising 169 treated via the posterior approach and 128 via the transoral approach. Analysis revealed high healing rates and clinical improvement in both approaches, evidenced by improvements in the visual analog scale, range of motion, atlantodens interval, and lateral displacement distance post-surgery. Conclusion: Osteosynthesis offers effective treatment for unstable atlas fractures. Both transoral and posterior approaches can achieve good clinical outcomes for fracture, and biomechanical studies have confirmed that osteosynthesis can maintain the stability of the occipitocervical region, preserve the motor function of the atlantoaxial and occipito-atlantoaxial joints, and greatly improve the quality of life of patients. However, variations exist in the indications and surgical risks associated with each method, necessitating their selection based on a thorough clinical evaluation of the patient's condition. [ABSTRACT FROM AUTHOR]

PurposeRigid occipitocervical (O-C) instrumentation can reduce the anterior pathology and has a high fusion rate in children with craniovertebral instability. Typically, axis (C2) screw fixation utilizes C1-C2 transarticular screws or C2 pars screws. However, anatomic variation may preclude these screw types due to the size of fixation elements or by placing the vertebral artery at risk for injury. Pediatric C2 translaminar screw fixation has low risk of vertebral artery injury and may be used when the anatomy is otherwise unsuitable for C1-C2 transarticular screws or C2 pars screws.MethodsWe retrospectively reviewed a neurosurgical database at UCSF Benioff Children's Hospital Oakland for patients who had undergone a cervical spinal fusion that utilized translaminar screws for occipitocervical instrumentation between 2002 and 2020. We then reviewed the operative records to determine the parameters of C2 screw fixations performed. Demographic and all other relevant clinical data were then recorded.ResultsTwenty-five patients ranging from 2 to 18 years of age underwent O-C fusion, with a total of 43 translaminar screws at C2 placed. Twenty-three patients were fused (92%) after initial surgery with a mean follow-up of 43 months. Two patients, both with Down syndrome, had a nonunion. Another 2 patients had a superficial wound dehiscence that required wound revision. One patient died of unknown cause 7 months after surgery. One patient developed an adjacent-level kyphosis.ConclusionWhen performing occipitocervical instrumentation in the pediatric population, C2 translaminar screw fixation is an effective option to other methods of C2 screw fixation dependent on anatomic feasibility.

This article explores the surgical treatment of craniovertebral junction anomalies, specifically focusing on C1-C2 fusion in patients with atlantoaxial dislocation and basilar invagination. The importance of identifying vertebral artery anomalies before surgery is emphasized, as they can have serious consequences. A case study is presented, detailing a successful fusion in a patient with an occipitalized atlas and a fenestrated vertebral artery. The article provides a step-by-step description of the surgical procedure, highlighting the use of imaging techniques and surgical tools. The authors stress the significance of preoperative CT angiography for surgical planning and recommend caution during surgery to avoid injuring the vertebral artery. Overall, the article concludes that with careful planning and consideration of the vertebral artery anatomy, a stable and strong fusion of the C1-C2 vertebrae can be achieved. [Extracted from the article]

Purpose: To present the clinical features and treatment strategy of degenerative atlantoaxial subluxation (DAAS). Methods: Patients with DAAS treated in our institution from 2003 to 2020 were retrospectively reviewed. We utilized the Japanese Orthopedic Association (JOA) scale to evaluate the neurologic status and distance of Ranawat et al. (DOR) to measure vertical migration. Results: We recruited 40 patients with > 2 years of follow-up and an average age of 62.3 ± 7.7 years. All the patients had myelopathy; only one patient had moderate trauma before exacerbation of symptoms, and the duration of symptoms was 34 ± 36 months. The most frequent radiological features were vertical migration of C1 (100%), sclerosis (100%), and narrowing of the atlantoaxial lateral mass articulations (100%). Two patients underwent transoral release combined with posterior reduction and fusion, and 38 patients underwent posterior reduction and fusion with C1 lateral mass screws-C2 pedicle screws and plate systems only. Forty cases (100%) achieved a solid atlantoaxial fusion, and 38 cases (95%) achieved anatomic atlantoaxial reduction. The JOA score increased from 9.3 ± 2.6 to 14.8 ± 2.1 (P < 0.01). DOR increased from 14.5 ± 2.5 to 17.8 ± 2.2 mm at the final follow-up (P < 0.01). Loosening of the locking caps was detected in one case, bony fusion was achieved, and harvest-site pain was reported in five patients. Conclusion: DAAS differs from other types of AAS and presents with anterior subluxation combined with vertical subluxation arising from degenerative changes in the atlantoaxial joints. We recommend anatomic reduction as an optimal strategy for DAAS. [ABSTRACT FROM AUTHOR]

Objectives: To propose a surface reconstruction algorithm based on a differential manifold (a space with local Euclidean space properties), which can be used for processing of clinical images and for modeling of the atlantoaxial joint. To describe the ideal anatomy of the lateral atlantoaxial articular surface by measuring the anatomical data. Methods: Computed tomography data of 80 healthy subjects who underwent cervical spine examinations at our institution were collected between October 2019 and June 2022, including 46 males and 34 females, aged 37.8 ± 5.1 years (28–59 years). A differential manifold surface reconstruction algorithm was used to generate the model based on DICOM data derived by Vision PACS system. The lateral mass articular surface was measured and compared in terms of its sagittal diameter, transverse diameter, articular surface area, articular curvature and joint space height. Results: There was no statistically significant difference between left and right sides of the measured data in normal adults (P > 0.05). The atlantoaxial articular surface sagittal diameter length was (15.83 ± 1.85) and (16.22 ± 1.57) mm on average, respectively. The transverse diameter length of the articular surface was (16.29 ± 2.16) and (16.49 ± 1.84) mm. The lateral articular surface area was (166.53 ± 7.69) and (174.48 ± 6.73) mm2 and the curvature was (164.03 ± 5.27) and (153.23 ± 9.03)°, respectively. The joint space height was 3.05 ± 0.11mm, respectively. There is an irregular articular space in the lateral mass of atlantoaxial, and both upper and lower surfaces of the articular space are concave. A sagittal plane view shows that the inferior articular surface of the atlas is mainly concave above; however, the superior articular surface of the axis is mainly convex above. In the coronal plane, the inferior articular surface of the atlas is mostly concave above, with most concave vertices located in the medial region, and the superior articular surface of the axis is mainly concave below, with most convex vertices located centrally and laterally. Conclusion: A differential manifold algorithm can effectively process atlantoaxial imaging data, fit and control mesh topology, and reconstruct curved surfaces to meet clinical measurement applications with high accuracy and efficiency; the articular surface of the lateral mass of atlantoaxial mass in normal adults has relatively constant sagittal diameter, transverse diameter and area. The distance difference between joint spaces is small, but the shape difference of articular surfaces differs greatly. [ABSTRACT FROM AUTHOR]

Complex craniovertebral junction (CVJ) defects account for a considerable proportion of CVJ diseases. Given the heavily assimilated C1, an unfavorable C1-C2 joint orientation, an overriding C2 superior facet, a low-hanging occiput, and an abnormal vertebral artery course with a high-riding vertebral artery, placement of C1 lateral mass screws might be difficult. To address this, a novel technique for placing C1 lateral mass screws that avoid vertebral artery injury, low-hanging occiput, and overriding C2 superior facet was developed in this study. This approach enables firm fixation of C1-C2 even in difficult situations where the placement of the C1 lateral mass is challenging. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Clinical Pediatric Surgery is the property of Journal of Clinical Pediatric Surgery Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Clinical Pediatric Surgery is the property of Journal of Clinical Pediatric Surgery Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This document is a reply to a letter regarding a study on the displacement of the atlantoaxial joint in patients with os odontoideum. The authors respond to the comments made by Fei Ma and co-authors, addressing their concerns about the congenital anomalies in lateral atlantoaxial joints (LAJs) and the correlation between the displacement direction of os odontoideum with atlantoaxial displacement (AAD) and the axial superior facet slope (ASFS). The authors also discuss the potential methods for preventing AAD and preserving atlantoaxial functions in patients without spine syndromes. The document concludes by stating that the study did not receive any funding and the authors have no conflicts of interest. [Extracted from the article]

Study Design: Retrospective cohort. Objective: To radiographically evaluate Craniovertebral junction (CVJ) tuberculosis infection pathogenesis and to propose a modification to the Lifeso classification. Methods: A cohort of patients with radiologically or microbiologically identified CVJ tuberculosis treated at a single tertiary referral center in a TB endemic area was queried for characteristics about clinical presentation, treatment, and radiographic evidence of bone destruction and abscess formation were included. Disease was classified according to the Lifeso grading system and bony lesions were classified as either type 1 (preservation of underlying structure) or type 2 (damage of underlying structure). Results: 52 patients were identified (mean age 28.5 ± 13.4yr, 48% male; 14% with a prior history of tuberculosis). All presented with neck pain at presentation, 29% with rotatory pain, and 37% with myelopathy. Comparison by Lifeso type showed Lifeso III lesions had longer symptom durations (P =.03) and more commonly had periarticular or predental abscess formation (P <.05), spinal cord compression (P <.01), and more commonly involved the C2 body and atlanto-dental joint. Underlying bony destruction was more common for lesions of the lateral atlantoaxial joints and atlanto-dental joints in Lifeso III cases than in either Lifeso I or II (all P <.05). Conclusions: The radiologic findings of the present series suggest CVJ TB infection may originate in the periarticular fascia with subsequent invasion into the adjacent atlanto-dental and lateral atlantoaxial joints in later disease. To reflect this proposed etiology, we present a modified Lifeso classification to describe the radiologic pathogenesis of CVJ TB. [ABSTRACT FROM AUTHOR]

Aim: An estimated 88% of rheumatoid arthritis (RA) patients experience various degrees of cervical spine involvement. The excessive movement of the atlantoaxial joint, which connects the occiput to the upper cervical spine, results in atlantoaxial instability (AAI). AAI stabilization is usually achieved by C1 lateral mass‐to‐C2 pedicle screw‐rod fixation (LC1–PC2 fixation), which is technically challenging in RA patients who often show destructive changes in anatomical structures. This study aimed to analyze the clinical results and operative experiences of C1–C2 surgery, with emphasis on the advancement of image‐guided surgery and augmented reality (AR) assisted navigation. Methods: We presented our two decades of experience in the surgical management of AAI from April 2004 to November 2022. Results: We have performed surgery on 67 patients with AAI, including 21 traumatic odontoid fractures, 20 degenerative osteoarthritis, 11 inflammatory diseases of RA, 5 congenital anomalies of the os odontoideum, 2 unknown etiologies, 2 movement disorders, 2 previous implant failures, 2 osteomyelitis, 1 ankylosing spondylitis, and 1 tumor. Beginning in 2007, we performed LC1–PC2 fixation under C‐arm fluoroscopy. As part of the progress in spinal surgery, since 2011 we used surgical navigation from presurgical planning to intraoperative navigation, using the preoperative computed tomography (CT) ‐based image‐guided BrainLab navigation system. In 2021, we began using intraoperative CT scan and microscope‐based AR navigation. Conclusion: The technical complexities of C1–C2 surgery can be mitigated by CT‐based image‐guided surgery and microscope‐based AR navigation, to improve accuracy in screw placement and overall clinical outcomes, particularly in RA patients with AAI. [ABSTRACT FROM AUTHOR]

Background: The aim of this study was to describe clinical and imaging features of atlantoaxial subluxation (AAS) and the associated risk factors in patients with rheumatoid arthritis (RA). Methods: We conducted a retrospective and comparative study including 51 RA patients with AAS and 51 RA patients without AAS. Atlantoaxial subluxation was defined by the presence of an anterior C1C2 diastasis on the cervical spine radiograph in hyperflexion and/or an anterior, posterior, lateral or rotatory C1C2 dislocation on MRI with/without inflammatory signal. Results: In G1, clinical presentations revealing AAS were mainly neck pain (68.7%) and neck stiffness (29.8%). MRI revealed: diastasis C1C2 (92.5%), periodontoid pannus (92.5%), odontoid erosion (23.5%), vertical subluxation (9.8%) and spinal cord involvement (7.8%). A collar immobilisation and corticosteroid boluses were indicated in 86.3% and 47.1% of cases. C1‐C2arthrodesis was performed in 15.4% of cases. Atlantoaxial subluxation was significantly associated with: age at disease onset (p = 0.009), history of joint surgery (p = 0.012), disease duration (p = 0.001), rheumatoid factor (p = 0.01), anti‐cyclic citrullinated peptide (p = 0.02), erosive radiographic status (p < 0.005), coxitis (p < 0.001), osteoporosis (p = 0.012), extra‐articular manifestations (p < 0.001), and high disease activity (p = 0.001). Multivariate analysis identified RA duration (p < 0.001, OR = 1.022 CI[1.01–1.034]) and erosive radiographic status (p = 0.01, OR = 21.236 CI[2.05–219.44]) as predictive factors of AAS. Conclusion: Our study showed that longer disease duration and joint destruction are the major predictive factors of AAS. Early treatment initiation, tight‐control and regular monitoring of cervical spine involvement are required in these patients. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the biomechanical stability of anterior transarticular crossing screw (ATCS) and compare it with anterior transarticular screw (ATS) which may provide basic evidence for clinical application. Methods: Eight human fresh cadaveric specimens (occiput-C4) were tested with 5 conditions including the intact status, the injury status (type II odontoid fracture), the injury+ATS fixation status (traditional bilateral ATS fixation); the injury+unilateral ATCS fixation status; and the injury+bilateral ATCS fixation status. Specimens were applied to a pure moment of 1.5 Nm in flexion-extension, lateral bending, and axial rotation, respectively. The range of motions (ROMs) and the neutral zones (NZs) of C1 to C2 segment were calculated and compared between 5 status. Results: ATS and ATCS fixations significantly reduced the motions in all directions when compared with the intact and injury statues (p < 0.05). In flexion-extension, the ROMs of ATS, unilateral ATCS, and bilateral ATCS were 4.7° ± 2.5°, 4.1° ± 1.9°, and 3.2° ± 1.2°, respectively. Bilateral ATCS resulted in a significant decrease in ROM in flexion-extension when compared with ATS and unilateral ATCS (p = 0.035 and p = 0.023). In lateral bending and axial rotation, there was no significant difference in ROM between the 3 fixations (p > 0.05). Three fixations resulted in similar NZs in all directions (p > 0.05). Conclusion: ATCS is a biomechanically effective alternative or supplemental method for atlantoaxial instability. [ABSTRACT FROM AUTHOR]

Purpose: The incidence of atlanto-axial injuries is continuously increasing and often requires surgical treatment. Recently, Harati developed a new procedure combining polyaxial transarticular screws with polyaxial atlas massae lateralis screws via a rod system with promising clinical results, yet biomechanical data is lacking. This biomechanical study consequently aims to evaluate the properties of the Harati technique. Methods: Two groups, each consisting of 7 cervical vertebral segments (C1/2), were formed and provided with a dens axis type 2 fracture according to Alonzo. One group was treated with the Harms and the other with the Harati technique. The specimen was loaded via a lever arm to simulate extension, flexion, lateral flexion and rotation. For statistical analysis, dislocation (°) was measured and compared. Results: For extension and flexion, the Harati technique displayed a mean dislocation of 4.12° ± 2.36° and the Harms technique of 8.48° ± 1.49° (p < 0.01). For lateral flexion, the dislocation was 0.57° ± 0.30° for the Harati and 1.19° ± 0.25° for the Harms group (p < 0.01). The mean dislocation for rotation was 1.09° ± 0.48° for the Harati and 2.10° ± 0.31° for the Harms group (p < 0.01). No implant failure occurred. Conclusion: This study found a significant increase in biomechanical stability of the Harati technique when compared to the technique by Harms et al. Consequently, this novel technique can be regarded as a promising alternative for the treatment of atlanto-axial instabilities. [ABSTRACT FROM AUTHOR]

Objectives Anterior atlanto-axial subluxation (AAS), defined as an anterior atlanto-dental interval ≥3 mm, can occur in RA and carries a risk of severe neurological impairments. Our objective was to determine the prevalence and predictors of radiographic aAAS after 12 years' follow-up of patients with early polyarthritis. Methods We studied patients enrolled in the early polyarthritis cohort ESPOIR (Study and Monitoring of Early Undifferentiated Arthritis) between 2002 and 2005 (at least two swollen joints for >6 weeks and <6 months, no other diagnosis than RA, and no previous exposure to glucocorticoids or DMARDs). All patients still in the cohort after 12 years had dynamic cervical-spine radiographs taken then read by two blinded observers. To evaluate how well combinations of tests performed at baseline and 10 years predicted aAAS after 12 years, univariate analysis and multiple logistic regression procedure were applied. Results Of 323 patients followed for 12 years, 15 (4.6%; 95% CI 2.8, 6.4) had aAAS. Among baseline variables, only IgA RFs were associated (P  < 0.05) with aAAS (sensitivity 60%, specificity 75%). Among data collected after 10 years, oral CS therapy during the 10-year interval, treatment by DMARDs, CRP (mg/dl) and positive tests for RFs were associated with aAAS after 12 years, but only CRP and RFs remained in a model of logistic regression (combination predicted aAAS with a sensitivity of 60% for a specificity of 90%). Conclusion In conclusion, the prevalence of aAAS after 12 years was 4.6% in the ESPOIR cohort, with no patients having severe aAAS. Although some factors were found to be statistically associated to AAS, the event is too rare to allow a clinical relevance. [ABSTRACT FROM AUTHOR]

Traumatic cranio-cervical junction injuries in infants are rare and require early surgical stabilization. In view of the unique anatomy of the occipitocervical junction in infants, the creation of a fusion construct that is both safe and biomechanically sound is challenging. A 9-month-old male infant involved in an accident presented with weakness in both upper limbs. Imaging revealed a displaced odontoid synchondrosis fracture with combined occipitocervical and atlantoaxial dissociation. Due to the unstable nature of the injury, occiput to C2 arthrodesis using dual distal radius locking plates and autologous full-thickness parietal region calvarial bone graft was performed. Minerva jacket was applied. Computed tomography (CT) scan obtained at 12 weeks demonstrated evidence of bony fusion. Combined injuries to the occipitocervical and atlantoaxial joint in an infant can be fatal. A thorough assessment of multiple imaging modalities helps to make an early and accurate diagnosis. [ABSTRACT FROM AUTHOR]

ABSTRACT Purpose: This study compared, through biomechanical evaluation under ventral flexion load, four surgical techniques for ventral stabilization of the atlantoaxial joint in dogs. Methods: In total, 28 identical atlantoaxial joint models were created by digital printing from computed tomography images of a dog, and the specimens were divided into four groups of seven. In each group, a different technique for ventral stabilization of the atlantoaxial joint was performed: transarticular lag screws, polyaxial screws, multiple screws and bone cement (polymethylmethacrylate–PMMA), and atlantoaxial plate. After the stabilization technique, biomechanical evaluation was performed under ventral flexion load, both with a predefined constant load and with a gradually increasing load until stabilization failure. Results: All specimens, regardless of stabilization technique, were able to support the predefined load without failing. However, the PMMA method provided significant more rigidity (p ≤ 0.05) and also best resisted the gradual increase in load, supporting a significantly higher maximum force (p ≤ 0.05). There was no statistical difference in flexural strength between the transarticular lag screws and plate groups. The polyaxial screws method was significantly less resistant to loading (p ≤ 0.05) than the other groups. Conclusions: The PMMA technique had biomechanical advantages in ventral atlantoaxial stabilization over the other evaluated methods.

An 11-year-old male neutered Yorkshire Terrier was presented with a cervical mass that developed a draining tract. Aside from the dysphagia reported by the owner, his neurologic exam was normal. Three years prior, the patient was diagnosed with an atlantoaxial subluxation that was ventrally stabilized with polymethylmethacrylate (PMMA) and self-tapping titanium screws. There were no postoperative complications until presenting with the cervical mass and dysphagia. Computerized tomography (CT) of the cervical spine confirmed caudal migration of the PMMA and screws with an abscess surrounding the implant. A surgical explant of the PMMA and screws was performed without complication. The atlantoaxial joint remained normally aligned on postoperative radiographs. Cultures of the implant grew Streptococcus bovis. He was treated with cephalexin (22 mg/kg PO BID) for 30 days. At the time of his one-month recheck, he was swallowing normally with no neurologic deficits. He remains normal at the time of this report (17 months later). This case reports a successful explant of a chronic atlantoaxial implant infection. [ABSTRACT FROM AUTHOR]

Objective To describe the technique, safety profile, and outcome of computed tomography (CT)–guided atlanto-axial lateral articulation injections performed at our institution. Methods Consecutive cases of all CT-guided atlanto-axial injections performed from January 2017 to April 2022 at our institution were searched in the electronic medical records. Patient charts were reviewed for demographics, characterization of pain, potential altered anatomy, pain level before and immediately after the procedure, procedure technique, complications, and follow-up outcomes, if available. Results Forty-five injections in 40 different patients were included. The average age was 67.4 years, and 28 (70%) of the patients were female. Of the 45 injections, 43 (96%) were technically successful. The average change in pain score (0–10) from immediately before to immediately after the injection was –3.36 (SD = 2.87, range = –8 to +3). Of all injections, 14 (31%) had a postprocedural pain score of zero. In 2 cases (4%), patients reported an increase in pain score immediately after the injection. In 3 cases (7%), transient non–vertebral artery vascular uptake of contrast was documented during the procedure, which could be cleared with needle repositioning. There were no complications. Conclusion CT-guided atlanto-axial lateral articulation injection is a safe procedure with a high technical success rate. It allows for direct visualization of vital structures and provides an alternative option to the traditional fluoroscopic guidance, especially in cases of prior technically unsuccessful fluoroscopically guided injection or altered anatomy. [ABSTRACT FROM AUTHOR]

Background: Many techniques for atlantoaxial fixation have been developed. However, the biomechanical differences among various atlantoaxial fixation methods remain unclear. This study aimed to evaluate the biomechanical influence of anterior and posterior atlantoaxial fixation techniques on fixed and nonfixed segments. Methods: An occiput-C7 cervical finite element model was used to construct 6 surgical models including a Harms plate, a transoral atlantoaxial reduction plate (TARP), an anterior transarticular screw (ATS), a Magerl screw, a posterior screw-plate, and a screw-rod system. Range of motion (ROM), facet joint force (FJF), disc stress, screw stress, and bone-screw interface stress were calculated. Results: The C1/2 ROMs were relatively small in the ATS and Magerl screw models under all loading directions except for extension (0.1°–1.0°). The posterior screw-plate system and screw-rod system generated greater stresses on the screws (77.6–1018.1 MPa) and bone-screw interfaces (58.3–499.0 MPa). The Harms plate and TARP models had relatively small ROMs (3.2°–17.6°), disc stress (1.3–7.6 MPa), and FJF (3.3–106.8 N) at the nonfixed segments. Changes in disc stress and FJF of the cervical segments were not consistent with changes in ROM. Conclusions: ATS and Magerl screws may provide good atlantoaxial stability. The posterior screw-rod system and screw-plate system may have higher risks of screw loosening and breakage. The Harms plate and TARP model may more effectively relieve nonfixed segment degeneration than other techniques. The C0/1 or C2/3 segment may not be more susceptible to degeneration than other nonfixed segments after C1/2 fixation. [ABSTRACT FROM AUTHOR]

Simple Summary: Instability between the two uppermost vertebrae (atlantoaxial instability) is a common problem, especially in toy breed dogs, resulting in a variety of neurologic symptoms. In most cases, surgical stabilization is indicated, but all of these procedures have some degree of complication, one of which is recurrent instability due to implant failure/loosening. To reduce this problem, a new augmentation technique involving additional wire/suture fixation through a bone tunnel in the second vertebra was evaluated, and the long-term clinical outcome was analyzed. Ten of the eleven dogs enrolled in the study had good to excellent clinical outcomes with no neurological symptoms. One dog died due to postoperative complications. In conclusion, the augmentation technique may be a valuable and technically feasible addition to the surgical stabilization of atlantoaxial instability in toy breed dogs, hopefully reducing the rate of recurrent postoperative instability. The feasibility of a newly developed augmentation of ventral fixation technique for surgical stabilization of atlantoaxial instability was clinically evaluated in a cohort of eleven dogs, and long-term clinical outcomes were retrospectively analyzed. The new technique combines wire/suture fixation through a transverse hole in the axis anchored by two screws placed in the alae atlantis or at the cranial end of plates used to bridge the atlantoaxial joint ventrally. A previous biomechanical study demonstrated good stability of this technique during shear loading, comparable to the stability achieved with other standard techniques. Ten dogs improved clinically after surgery and returned to a normal life within 3–6 months of surgery. One dog developed aphonia, dysphagia, and died of aspiration pneumonia three days after surgery. The augmentation of conventional ventral atlantoaxial fixation with the transverse bony corridor of the proximal axis body may be a valuable way to enhance stabilization of the atlantoaxial joint. [ABSTRACT FROM AUTHOR]

Key Clinical Message: Craniovertebral junction (CVJ) schwannomas are rare tumors, showing direct involvement of the atlanto‐occipital and atlanto‐axial joints. Microsurgical removal is the standard of care to improve symptoms and local control, but stereotactic radiosurgery (SRS) is an option. Both, surgery, and SRS, may show risks of severe complications. A 41‐year‐old male was referred to our department after incidental finding of a right‐sided C1 tumor. A CT angiogram with 3D reconstructions showed the close relationship between the tumor and the right vertebral artery (VA). A post‐contrast enhancement MRI revealed the presence of an extradural mass, sited at the level of the CVJ, mainly at the level of the right articular mass of C1. After multidisciplinary assessment, involving the gamma‐knife and neurosurgical teams, we performed a microsurgical resection of the tumor. Histology confirmed the diagnosis of schwannoma. At 1 year follow‐up the patient is stable, with no recurrence of the tumor. CVJ schwannoma's current standard of care is surgical resection, but longitudinal studies are required, and should promoted promptly since the recent introduction of the new version of GKSRS that allow the treatment of CVJ's lesions. [ABSTRACT FROM AUTHOR]

Background: The objective of the study was to assess clinical and imaging features of rheumatoid arthritis associated with atlantoaxial dislocation (RA‐AAD) in comparison to RA without AAD (RA‐C) and to identify the associated factors to AAD. Methods: This was a retrospective comparative study including RA patients over 18 years old. The control group of RA‐C was matched according to age (±2 years), gender, and RA duration (±2 years). General data, RA characteristics, AAD features, and treatment modalities were recorded. Statistical analysis was performed to determine the predictive factors of AAD. Results: A total of 120 patients were included (78 RA‐AAD and 42 RA‐C); sex‐ratio was 0.15. Mean age was 58.55 ± 9.14 years (RA‐AAD) versus 60.43 ± 10.78 years (RA‐C), (p = 0.31). Regarding RA features, RA‐AAD patients have significantly a higher rheumatoid factor (RF) rate (p = 0.002), extra‐articular manifestations (p = 0.009) especially osteoporosis (p < 10−3), eye involvement (p = 0.02), coxitis (p < 0.0001), Disease Activity Score (DAS28) (p < 10−3), and global health status scale (HAQ) (p = 0.003). X‐ray analysis showed pathologic PADI (<14 mm) in 51.6% of cases. The AADI was pathological (>3 mm) in 100% of patients with the following distribution: 67.9% between (3–6 mm) and 23.3% between (6–9 mm). Atlantoaxial dislocation (AAD) was presumed anterior (85.4%), lateral (7.3%) and rotatory (7.3%). The abnormalities observed on magnetic resonance imaging (MRI) were: C1–C2 synovitis (61%), confirmed AAD (34.1%) and basilar impression (4.9%). AAD diagnosed by cervical MRI was anterior in 89.8% of cases, lateral (5.3%) and with a double ascending and anterior component in 4.9% of cases. An immobilisation with a type C4 cervical collar was indicated for all the patients and five of them had boluses of corticosteroid (methylprednisolone 1 g/day) for three consecutive days. C1–C2 arthrodesis by trans‐articular screwing was performed in four patients with neurological signs or pathological measurements on cervical MRI. The outcome was favourable in 100% of cases after surgical treatment with improvement in neck pain and neurological condition within a mean decline of 4 ± 3 years [1–7]. Multivariate analysis identified coxitis, osteoporosis, high baseline DAS28, and a high rate of RF positivity as predictive factors of AAD. Conclusion: Our results confirmed that predictive factors of AAD were related to higher disease activity and structural damage. These modifiable factors may be prevented by tight control, early treatment, and educating RA patients to improve treatment adherence. [ABSTRACT FROM AUTHOR]

Purpose: Kashin-Beck disease (KBD) is an endemic osteoarthropathy affecting the epiphyseal growth plate of multiple joints in young and adolescent patients. Previous studies have focused on the visible deformed extremities instead of the spinal radiological features, especially the atlantoaxial joint. The aim of this study was to determine the prevalence and radiographic features of atlantoaxial dislocation (AAD) in adult patients with KBD.Methods: This study was conducted on KBD patients in three typical endemic counties between October 2017 and November 2019. The patients were evaluated by collecting basic information, clinical signs and symptoms. They underwent dynamic cervical radiography, by which AAD was diagnosed. For those patients with confirmed or suspected AAD, computed tomography (CT) imaging was performed to observe the odontoid morphology and degenerative changes in the lateral atlantoaxial joints. Radiographic evaluations were reviewed to determine the prevalence and features of AAD.Results: A total of 39 (14.6%) of 267 KBD patients were diagnosed with AAD. Compared with the non-AAD patients, the detection rate of AAD was associated with a longer disease duration and stage and was not associated with age, sex or BMI. Thirty-two patients had symptoms at the neck or neurological manifestations, while seven had no symptoms. There were three types of morphologies of the odontoid process in AAD patients: separating in 19 cases, hypoplastic in 15 cases and intact in five cases. Anterior dislocation was noted in 29 cases, and posterior dislocation was noted in ten cases. Thirty-four cases were reducible, and five were irreducible. The lateral atlantoaxial joints had different severities of degenerative changes in 17 cases.Conclusions: This study revealed that the prevalence of AAD was 14.6% in adult KBD patients. The radiographic features of AAD include manifestations of odontoid dysplasia and chronic degenerative changes in atlantoaxial joints. KBD patients with severe stages and longer disease duration were more vulnerable to the occurrence of AAD. We postulate that this atlantoaxial anomaly might originate from chondronecrosis of the epiphyseal growth plate of the odontoid process in young and adolescent individuals. This study may provide a clinical reference to help clinicians screen, prevent and treat AAD in adult patients with KBD. [ABSTRACT FROM AUTHOR]

Purpose: To establish reference ranges for four most commonly used diagnostic measures of craniocervical instability (CCI) in three cervical sagittal positions. This necessitated development of a reliable measurement protocol using upright, dynamic MRI (udMRI), to determine differences in the extent of motion between positions, and whether age and sex correlate with these measures. Materials and Methods: Deidentified udMRIs of 50 adults, referred for reasons other than CCI, were captured at three positions (maximal flexion, maximal extension and neutral). Images were analyzed, providing measures of basion-axial interval, basion-axial angle, basion-dens interval (BDI) and the Grabb–Oakes line (GOL) for all three positions (12 measures per participant). All measures were independently recorded by a radiologist and neurosurgeon to determine their reliability. Descriptive statistics, correlations, paired and independent t-tests were used. Mean (± 2 SD) identified the reference range for all four measures at each craniocervical position. Results: The revised measurement protocol produced inter-rater reliability indices of 0.69–0.97 (moderate–excellent). Fifty adults' (50% male; mean age 41.2 years (± 9.7)) reference ranges for all twelve measures were reported. Except for the BDI and GOL when moving between neutral and full flexion, significant extents of movement were identified between the three craniocervical positions for all four measures (p ≤ 0.005). Only a minor effect of age was found. Conclusions: This is the first study to provide a rigorous standardized protocol for four diagnostic measures of CCI. Reference ranges are established at mid and ends of sagittal cervical range corresponding to where exacerbations of signs and symptoms are commonly reported. [ABSTRACT FROM AUTHOR]

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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. [ABSTRACT FROM AUTHOR]

This article discusses the case of a 10-year-old child who presented with acute torticollis and walking difficulty. The child was diagnosed with atlantoaxial rotatory dislocation, which was confirmed through lateral cervical X-ray and magnetic resonance imaging (MRI) of the cervical spine. The MRI also revealed an incompletely ossified odontoid process and narrowing of the spinal canal, which required immediate surgical intervention. The article provides information on the classification and management of atlantoaxial dislocations, emphasizing the importance of considering this condition in pediatric patients with acute torticollis and neck pain, even in the absence of an obvious history of trauma or infection. [Extracted from the article]

Our knowledge about the underlying pathomechanisms of craniocervical junction abnormalities (CCJA) in dogs mostly derives from measurements based on tomographic imaging. These images are static and the positioning of the dogs' head does not reflect the physiological in vivo position of the craniocervical junction (CCJ). Aberrant motion patterns and ranges of motion (ROM) in sound individuals of CCJA predisposed breeds may be a pathogenetic trigger. To further extend our limited knowledge of physiological motion of the CCJ, this prospective, comparative study investigates the in vivo motion patterns and ROM of the CCJ in walk and trot in sound Cavalier King Charles Spaniels and Chihuahuas. The Labrador retriever is used as a reference breed without predisposition for CCJA. This is the first detailed description of CCJ movement of trotting dogs. Biplanar fluoroscopy images, recorded in walking and trotting dogs, were matched to a virtual reconstruction of the skull and cranial cervical spine utilising Scientific Rotoscoping. Kinematic data reveal the same motion patterns among all breeds and gaits with individual temporal and spatial differences in each dog. A stride cycle-dependent lateral rotation of the cranial cervical spine and axial rotation of the atlantoaxial joint in trot in dogs is described for the first time. The ROM of the atlantoaxial and atlantooccipital joints in walk and trot were not statistically significantly greater in the CCJA-predisposed breeds CKCS and Chihuahua. ROM values of all translational and rotational degrees of freedom were larger in walk than trot, although this is only statistically significant for the atlantoaxial joint. Until proven otherwise, a more species-specific than breed-specific general motion pattern of the CCJ in walking and trotting, clinically sound dogs must be assumed. Species-specific anatomic properties of the CCJ seem to supersede breed-specific anatomical differences in clinically sound dogs. [ABSTRACT FROM AUTHOR]