Atlantoaxial Research Articles

Does fracture-extension into the pars interarticularis alter outcomes in odontoid failure? a technical note on pars interarticularis osteotomy and atlantoaxial distraction arthrodesis.

Odontoid process fractures can extend rostral into the C2 arch. We investigated the clinical impact of a concurrent fracture of the pars interarticularis on odontoid failure. To overcome the surgical challenges related to the morphology of these fractures, we describe a novel surgical strategy using atlantoaxial joint distraction arthrodesis. We conducted a single centre cohort study of 13 consecutive patients with odontoid fractures extending into the pars treated between June 2016 and June 2018. Criteria for a stable fibrous non-union were: Atlanto-Dens Interval (ADI) < 3mm, Posterior Atlanto-Dens Interval (PADI) > 14mm and lack of symptomatic motion at the fracture site. Atlantoaxial instability was defined as greater than 50% subluxation across the C1-C2 joint. Return to pre-injury performance status was considered a satisfactory clinical outcome. The mean age of the patient population was 77.2years (SD 11.9). The mean follow-up time was 15months (SD 5.2). 69% had an associated atlantoaxial instability (P-value 0.0005). Cervical orthosis treatment was associated with a high non-union rate (70%) (P-value 0.04) although it did not affect the overall clinical outcome. 2 cases presented with cord compression were treated surgically with pars interarticularis osteotomy and atlantoaxial distraction arthrodesis. Odontoid fracture with extension into the pars interarticularis often present with atlantoaxial instability and may result in stable fibrous non-union if treated non-operatively. The C1-C2 segment can be stabilised with atlantoaxial distraction arthrodesis achieved through an osteotomy of the pars interarticularis.

The Feasibility Study of C1 Posterior Arch Crossing Screw Fixation in Adult Thai Population: A Computed Tomographic Morphometric Analysis Study

Objective: Atlantoaxial instability can be caused by various etiologies and surgical fixation is often required. Various methods have been described for atlantoaxial fixation. Screw fixation is associated with an increased risk of vertebral artery injury especially in patients with an anomalous vertebral artery location or abnormal bony anomalies. A new C1 posterior arch crossing screw fixation technique was proposed to reduce the risk of vertebral artery injury. The present study aimed to assess morphometric CT analysis of atlas for C1 posterior arch crossing screw fixation in Thai people. Materials and Methods: The present research was an observational study that reviewed 150 computed tomography (CT) scans of the patients who had neck trauma or any other complaint requiring craniocervical investigations. Atlantoaxial articulation deformities due to trauma, infections, neoplasm, congenital anomaly, inflammatory disease, incomplete CT scan analysis, and history of surgical intervention of the cervical spine were excluded. All the images were measured for the height of the posterior tubercle, the width of the posterior arch was measured bilaterally in three parts on the axial plane, part 1: medial of the VA groove, where the arch transforms into the VA groove, part 2: the middle part between the posterior tubercle and medial of the VA, and part 3: posterior tubercle, length of the screw, and the screw projection angle was calculated. Results: Out of the 139 CT scans analyzed, the mean measurement of posterior arch height was 7.45±1.03 mm, wherein 73.3% exceed 7 mm. The mean width of the left posterior arch in part 1, 2, and 3 was 4.50±0.70 mm, 4.90±0.70 mm, and 5.70±0.80 mm, respectively, and the width of the right posterior arch in part 1, 2, and 3 was 4.50±0.70 mm, 4.80±0.70 mm, and 5.60±0.80 mm, respectively. The mean crossing screw length of the Left and Right was 17.02±3.04 mm and 17.37±2.75 mm, respectively. The mean angle of screw of the Left and Right was 24.62±3.38 degrees and 24.78±3.57 degrees, respectively. There were no significant differences in these variables between gender or sides (p&gt;0.05) except the mean angle of the screw between gender (p&lt;0.05). Conclusion: C1 posterior arch screw fixation is feasible in the adult Thai population. Preoperative thin-cut CT is essential for planning successful posterior arch crossing screws placement. Keywords: C1 posterior arch, Computed tomography, Crossing screw fixation

A Clinical Study to Assess the Efficacy of Anterior Transarticular C1-C2 Screw Fixation for Stabilization of AtlantoAxial Instability

Introduction: The upper cervical spine includes the atlas (C1) and Axis (C2). The anatomy of upper twovertebrae is unique from each other. Atlanto-axial articulation is the most unique, mobile segment of spine,which largely depends on ligamentous supports based on integrity of odontoid for its stability. Historically,atlanto-axial subluxation was treated by reduction and fusion of C1-C2 joint. However, High riding vertebralartery precludes the placement of posterior trans-articular screw, which is liable to injury during screwplacement. Socomputed tomography scans can be used to evaluate the risk of “high riding” vertebral arteryduring the management of atlanto-axial subluxation. Hence, anterior trans-articular screw fixation techniqueavoids the course of high riding vertebral artery.Material and Method: Nine patients underwent NCCT cervical spine with 3-D reconstruction and clinicalevaluation of pain was done by recording the VAS score done pre operatively and after surgery.Results: All surgical cohorts underwent anterior C1-C2 fixation with an average follow up for 24 months.All patients were assessed as per fixed protocol of our local hospital guidelines of orthopaedics department.Pain score was clinically evaluated by VAS score before and after surgery yielding 90% excellent result.Conclusion: Anterior Trans-articular C1-C2 screw fixation isa minimally invasive technique with less bloodloss, shorter skins car and faster post-operative recovery. It is an appropriate technique for stabilization ofAtlanto-Axial instabilities.

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

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

Rheumatoid pannus presenting as a large epidural mass in the subaxial cervical spine: A case report

Rheumatoid arthritis (RA) is a debilitating inflammatory condition characterised by joint damage that affects the cervical spine most commonly at the atlantoaxial joint resulting in neck pain and myelopathy. The pathogenesis of RA involves the formation of a hyperplastic synovial tissue, termed pannus, which invades the local bone and causes osseous erosion. Here, we describe a case of rapid onset quadriparesis due to spinal cord compression at C5–C6 secondary to vertebral subluxation and mass effect from a large inflammatory pannus in the subaxial spine. Surgical decompression and resection of the subaxial pannus were performed, and the patient regained strength in all extremities. Histopathologic evaluation of the resected tissue confirmed the diagnosis of pannus over other more common epidural masses. Pannus formation commonly occurs in the peri-odontoid region; however, its presentation as a large soft tissue mass in the subaxial spine is not described in the current literature. Therefore, pannus should be considered in the differential diagnosis of epidural masses in the spine of RA patients. We use this case to discuss the pathology and radiological findings relevant to rheumatoid pannus formation in the subaxial cervical spine, as well as emphasise the importance of treatment in the context to severe degenerative disease.

Geometric model of reduction in basilar invagination with atlantoaxial dislocation and its clinical application

Objectives: To establish a geometric model of the atlantoaxial dislocation and basilar invagination reduction,and examine its value for clinical application. Methods: A retrospective analysis of 35 patients with atlantoaxial dislocation and basilar invagination admitted to the Department of Neurosurgery,First Affiliated Hospital of Chongqing Medical University from May 2018 to May 2020 was conducted.There were 5 males and 30 females,aged (48±15) years(range: 19 to 69 years). The geometric model of the atlantoaxial reduction was established based on the mid-sagittal section of the cervical spine. The relevant data were calculated according to the geometric model before operation,and the fusion cage of the corresponding height was placed into C1-2 facet joint of patient for quantitative reduction. The theoretical reset value, actual reset value, postoperative symptoms and complications were collected. The paired t-test was used to compare the difference between theoretical and actual reset value to verify the reliability of the geometric model. Results: The theoretical vertical reduction distance of all patients was (5.79±2.96) mm(range:1.52 to 10.96 mm),and the actual vertical reduction distance was (7.43±2.96)mm(range: 1.40 to 12.77 mm),and there was no statistical difference between them(t=-1.96,P=0.069).The theoretical reduction angle was (10.80±2.24)°(range: 7.09 to 14.86°), the actual reduction angle was (10.64±7.00)°(range: 3.50 to 20.50°),and there was no statistical difference between them (t=0.09, P=0.933). At 6 months follow-up, 35 patients achieved satisfactory atlanto-axial joint fusion, and the symptoms were relieved. No internal fixation system displacement, fracture, wound infection and other complications occurred. Conclusion: This geometric model can estimate the vertical reduction distance and the reduction angle of the axial before operation,and provide a reference for the height of the fusion cage so as to avoid under or over-reduction.

Biologic Agents Preserve the C-2 Pedicle in Patients with Rheumatoid Arthritis: A Comparative Imaging Study Using Three-Dimensional Computed Tomography

To investigate whether biologic agents (BAs) reduce a narrow C-2 pedicle screw trajectory, which is often a key stabilizer in surgical treatment, in patients with rheumatoid arthritis (RA). A total of 100 patients with RA treated with and without BAs (BA [+] group [n= 50] and BA [-] group [n= 50]), respectively, were included in the present study. Computed tomography (CT) images of their cervical spine, including C-2, were analyzed. The maximum screw diameter at C-2 that could be inserted without breaching the cortex, measured on 3-dimensional images using a CT-based navigation system, was compared between the groups with and without BA administration. Furthermore, the destruction of the atlantoaxial joint was examined using CT images. The risk factors for a narrow C-2 pedicle were elucidated among the patients treated with BAs. The pedicle in the BA (+) group had a significantly larger C-2 maximum screw diameter than the BA (-) group (6.00 mm vs. 5.13 mm, P < 0.001), with less destruction of the atlantoaxial joint. Among the BA (+) group, a longer period until the initial administration of BAs and RA disease duration were associated with a narrow C-2 pedicle. This study suggests that BAs can maintain the trajectory for C-2 pedicle screws, which acts as a key stabilizer in surgical management for the rheumatoid cervical spine, by halting the destruction of the atlantoaxial joint. Early introduction of BAs can be especially important to prevent the narrowing of the C-2 pedicle.

Tophaceous gout of the atlantoaxial joint: a case report

BackgroundTo report the occurrence of tophaceous gout in the cervical spine and to review the literature on spinal gout.Case presentationThis report details the occurrence of a large and clinically significant finding of tophaceous gout in the atlantoaxial joint of the cervical spine in an 82-year-old Caucasian man with a 40-year history of crystal-proven gout and a 3-month history of new-onset progressive myelopathy. The patient's American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) criteria score was 15.0.ConclusionSpinal gout is more common than previously thought, and it should be considered in patients who present with symptoms of myelopathy. Diagnosis can be made without a tissue sample of the affected joint(s) with tools like the ACR/EULAR criteria and the use of the “diagnostic clinical rule” for determining the likelihood of gout. Early conservative management with neck immobilization and medical management can avoid the need for surgical intervention.

Teaching and use of cervical high-velocity, low-amplitude manipulation at colleges of osteopathic medicine.

Despite the documented effectiveness of high-velocity, low-amplitude (HVLA) treatment of the cervical spine, concerns about patient safety potentially limit didactic instruction and use in clinical practice. Understanding how cervical HVLA is taught and employed is of interest to osteopathic educators and clinicians. To characterize the perspectives of osteopathic manipulative medicine/osteopathic principles and practices (OMM/OPP) departments within colleges of osteopathic medicine (COMs) in the US regarding patterns of teaching and practice of HVLA treatment of the cervical spine. A questionnaire was distributed on April 11, 2019 in paper format to OMM/OPP department chairs or designated faculty member attendees at the Educational Council on Osteopathic Principles biannual meeting. If the department chair was not available, the survey was provided to the faculty member designated to represent the Chair of the institution at ECOP. All respondents in this category returned the survey in paper before they left the meeting. The OMM/OPP department chairs who did not attend or send representatives to the ECOP meeting were sent the survey by email on April 11, 2019 and given three opportunities over 6weeksat 2-week intervals to reply to this voluntary online survey. The survey was given or sent to a total of 51 OMM/OPP department chairs or representatives. Six questions elicited demographic information pertaining to status, age, gender, ethnicity, board-certified specialty, and COM affiliation. Nine questions examined perspectives related to the instruction of cervical HVLA manipulation and treatment. Of the 51 OMM/OPP department chairs surveyed, 38 (74.5%) responded, 32 to the paper survey at the ECOP meeting and six to the digital survey. Respondents were primarily dual Board-certified in Family Medicine and Neuromuscular Medicine (55.3%). At over 90% (35) of the COMs for which department chairs responded to the survey, cervical HVLA instruction occurs in the curriculum primarily during program years 1 and 2. Instruction in cervical HVLA to the 2nd through 7th cervical vertebral levels occurred in 97% (37), while 11% (4) of the COMs excluded the occipital-atlanto (OA) and atlanto-axial (AA) joints. A high percentage (81.6%; 31) of the OMM/OPP department chairs or representatives reported employing cervical HVLA techniques within their practice. Among the respondents, 40.5% (15) reported that 0-25% of their school's medical school class could perform cervical HVLA competently upon graduation, whereas 27% (10) said that 51-75% of their class could perform cervical HVLA. A majority of COMs provide education in their curricula related to cervical HVLA primarily in the first 2 years of medical education. However, instruction often excludes cervical HVLA to the upper regions of the cervical spine. At COMs where HVLA to the cervical spine is not taught, that decision is because the techniques are thought to be too difficult and the attendant medicolegal risk perceived to be too high. OMM/OPP department chairs expressed confidence in only a small proportion of their graduates having the ability to competently apply HVLA to the cervical spine immediately after completing their predoctoral medical training.

Vascularized Occipital Bone Grafting: Indications, Techniques, Clinical Outcomes, and Alternatives

Successful arthrodesis at the craniocervical junction and atlantoaxial joint can be more challenging than in other segments of the cervical spine. Different techniques for spinal fixation in this region have been well described, along with auxiliary methods to improve fusion rates. The occipital vascularized bone graft is a novel technique that can be used to augment bony arthrodesis in the supra-axial cervical spine. It provides the benefits of a vascularized autologous graft, such as accelerated healing, earlier fusion, and increased strength. This technique can be learned with relative ease and may be particularly helpful in cases with high risk of nonunion or pseudoarthrosis in the upper cervical spine.

A novel 3D-printed locking cage for anterior atlantoaxial fixation and fusion: case report and in vitro biomechanical evaluation

BackgroundTreatment of atlantoaxial dislocation is aimed at reduction and stabilization of the atlantoaxial joint. 3D printing refers to a process where additive manufacturing is achieved under precise computer control. Literature on its utilization in anterior atlantoaxial fixation and fusion is rare. This study is the first report on a 3D-printed locking cage used in the anterior procedure for atlantoaxial dislocation.MethodsA middle-aged male in his 40s presented with weakness and numbness of his extremities for 3 years and could only walk slowly with assistance. Imaging studies revealed severe anterior migration of C1, irreducible atlantoaxial dislocation, and severe cervical-medullary compression. A preoperative plan consisting of trans-oral soft tissue release and fixation using tailor-designed 3D-printed cages was devised. Following fluoroscopic confirmation of reduction of the atlantoaxial joints, two customized 3D-printed cages made of titanium alloy were inserted into the bilateral facet joints, which were then locked by six screws into the lateral masses of C1 and C2. The microstructure of the inserted cages was optimized for improved biomechanical stability and enhanced osseo-integration, without the need for bone grafting. In addition, a biomechanical test was performed on seven human cadaveric specimens comparing the novel implant with the conventional C1 lateral mass-C2 pedicle screw construct in three modes of motion (flexion-extension, lateral bending, axial rotation).ResultsImprovement of neurologic function in the patient was evident immediately after surgery. He was able to walk independently 1 month post-operatively. At the 12-month follow-up, coronal reconstruction of CT demonstrated properly-positioned 3D-printed cages, evidence of osseo-integration at the bone-implant interface, and no subsidence or displacement of the implant. Eighteen months out of surgery, the mJOA score improved to 15, and lateral X-ray confirmed reduction of atlanto-axial dislocation. Additionally, the new construct provided strong fixation comparable to that conferred by conventional constructs as there was no significant difference observed between the two groups in all three directions of motion.ConclusionsThe novel implant represents a new option in the treatment of irreducible atlantoaxial dislocation. It can provide strong anterior support for solid fixation and fusion with a low profile and a microstructure that obviates the need for bone grafting.

A Case Report of Complete Dislocation of Atlantoaxial Joint due to a Traumatic and Pathological Axial Lesion.

Atlantoaxial dislocation usually results in sudden death. The patient had never found any axial lesion before, and the atlantoaxial joint dislocation was caused by rotation of the neck due to discomfort of the neck. The patient was given surgical treatment after the rescue of respiratory and cardiac arrest during transportation, which was extremely rare and rarely reported. A 62-year-old male patient presented with limited cervical mobility after a violent rotation of the neck due to neck discomfort. X-ray and computed tomography (CT) scan suggested atlantoaxial dislocation. Sudden respiratory and cardiac arrest during transportation was immediately followed by continuous cranial traction and successful occipital and neck fusion operation. After the successful rescue of endotracheal intubation, the patient was given continuous cranial traction. After the completion of CT scan, the patient was given occipital neck fusion, and 6 days after the surgery, the patient wore the skull-neck-thorax brace and walked freely. Continuous cranial traction and posterior occipitocervical fusion are effective methods for treating axial pathological fracture with atlantoaxial dislocation. 5.

Calcium Pyrophosphate Deposition Disease in the Craniovertebral Junction: An Unusual Cause of Neck Pain

Crowned Dens Syndrome (CDS) is a rare manifestation of Calcium Pyrophosphate Deposition (CPPD) disease characterised by calcification around the odontoid process in the atlantoaxial joint. It manifests as intense neck pain with signs of systemic inflammation, including elevated acute phase reactants. Thus, it can simulate other causes of neck pain and diagnosis can be challenging. Moreover, CPPD disease can be asymptomatic and observed as radiological finding. Here in, two cases of spinal CPPD disease with distinct presentations are reported. The first of 83-year-old woman describes CDS that was misdiagnosed as Polymyalgia Rheumatica (PMR) whereas in the second case of 70-year-old female calcification around the odontoid process was incidentally found in a patient with acute cervical spine fracture. These two reported cases highlight the spectrum of manifestations of spinal CPPD disease and support the notion that careful discrimination of the cause of neck pain is essential for improving outcomes.

Three cases of typical polymyalgia rheumatica with effusion of the atlantoaxial joint found on MRI

Three cases of typical polymyalgia rheumatica with effusion of the atlantoaxial joint found on MRI

Posterior Arthrodesis of Atlantoaxial Joint in Congenital Atlantoaxial Instability Under 5 Years of Age: A Systematic Review.

Posterior Arthrodesis of Atlantoaxial Joint in Congenital Atlantoaxial Instability Under 5 Years of Age: A Systematic Review.

“Crossed C1 Lateral Mass–C2 Subfacetal Screw and Rod Construct” for Atlantoaxial Fixation in Patients with High-Riding Vertebral Artery: A Technical Note

Background: Goel–Laheri's posterior C1/C2 fixation technique is the gold standard procedure for atlantoaxial dislocation (AAD) and basilar invagination. Coexisitng vertebral artery anomalies such as high-riding vertebral arteries pose an increased risk of vertebral artery injury during instrumentation. Alternate technique for avoiding vertebral artery injury in such cases like translaminar screw fixation had been associated with a high chance for screw pull out, resulting in an unstable construct. This case report introduces a novel, cost-effective technique of atlantoaxial fixation with a “bilateral crossed C1 lateral mass-C2 subfacetal screw and rod construct” in patients with atlantoaxial subluxation with high-riding vertebral arteries.Case Presentation: A 63-year-old male presented with complaints of neck pain and difficulty in walking. On physical examination, he had features of high cervical myelopathy. Imaging revealed AAD with bilateral high-riding vertebral arteries. He was treated with “Crossed C1 lateral mass-C2 subfacetal screw and rod fixation” without evidence of vertebral artery injury or neurological deficits. Postoperatively, the patient showed significant improvement in pain and Nurick score.Conclusions: This technique has the uniqueness of providing a stable, rigid fixation of the atlantoaxial joint with screws inserted into the C2 body providing good bone purchase and at the same time avoid vertebral artery injury in high riding cases. The surgical technique is demonstrated in a detailed manner in this technical note.

Cervical Spinal Cord Surgical Stabilization in a Sheep

Background: Trauma is the main cause of spinal fractures and dislocations in humans and large animals. Clinical signs present with acute onset and vary according to the location and severity of the spinal cord injury. The treatment of fractures in large animals depends on economic value, cost of procedures, prognosis, location and type of fracture. However, although spinal fractures in large animals are not uncommon, the literature about their clinical aspects and treatment is scanty. Therefore, the purpose of this report is to describe a surgical stabilization of atlantoaxial subluxation, fracture of the third cervical vertebra and C2-C3 subluxation.Case: An approximately 2-year-old Île-de-France sheep, weighing 101 kg, with a history of cervical trauma and non-ambulatory tetraparesis was treated at the Veterinary Hospital of the Institution (UNIPAMPA). During physical examination, the animal presented good general physical condition and heart rate, respiratory rate and temperature was according to physiological parameters for the species. The animal remained in lateral decubitus, with minimal head and limb movements, and exhibited deep pain sensitivity. Clinical treatment with dexamethasone, limb physiotherapy and change in lateral decubitus position were employed, but failed to improve the animal’s condition. After five days of unresponsive to clinical treatment, the patient was referred to the neurology department, where it underwent neurological examination and radiographic examination of the cervical region was performed under general anesthesia. The radiographic examination revealed atlantoaxial subluxation, by displacement of the odontoid process into the vertebral canal, fracture of the third cervical vertebra and C2-C3 vertebral subluxation. The surgical planning aimed cervical vertebral instability repair using atlantoaxial arthrodesis associated the stabilization of C1-C2 and C2-C3 vertebrae with Schanz pins and bone cement, due facility and versatility this association. The postoperative radiographic examination showed incomplete insertion of the Schanz pin into the left Atlas wing and a cervical collar was recommended. The clinical evaluation was performed daily, and after 23 days of surgery the animal could crawl in lateral decubitus besides assisted walking ability. However, the animal died 36 days after surgery due to severe dyspnea. A necropsy revealed pulmonary edema and hepatic lipidosis, besides hepatic septic thrombus. Moreover, the vertebral canal of C1-C2 and C2-C3 segments stayed realigned and stabilized, without spinal cord injury and trachea compression.Discussion: Non-ambulatory tetraparesis, and minimal head and limb movements confirm severe spinal cord injury. The failure of clinical treatment, craniocervical instability in C1-C2 and C2-C3 and the high economic and genetic value of patients was definite for the surgical indication, besides reserved prognosis. The surgical treatment aim is recovery motor function from spinal cord decompression, vertebral canal realignment and the stabilization of vertebral instability. The cervical collar was placed on the patient after the surgery was intended to prevent rotation of the atlantoaxial joint, aiding vertebral stability. It is believed that the recovery of large animals with spinal cord injuries like in this case report is slower due to their heavy weight and the difficulty in managing such patients. This case report confirms that the techniques employed here achieved the proposed objectives of spinal canal alignment and spinal stabilization, showing improvement of clinical signs and recovery of the animal’s limb and neck movements.

Comparison of MR Ultrashort Echo Time and Optimized 3D-Multiecho In-Phase Sequence to Computed Tomography for Assessment of the Osseous Craniocervical Junction.

To assess changes of the craniocervical junction (CCJ), computed tomography (CT) is considered the reference standard. Recent advances in bone depiction on magnetic resonance imaging (MRI) enable high-quality visualization of osseous structures. Consequently, MRI may serve as an alternative to CT, without the use of ionizing radiation. To compare two MRI sequences optimized for bone visualization to the CT reference standard in the assessment of the osseous CCJ. Prospective. Twenty-seven decedents and five healthy volunteers. 3T/ultrashort-echo time gradient echo (UTE) and optimized 3D-multiecho in-phase gradient echo sequences (FRACTURE). All decedents were scanned with both MRI sequences and CT. Three observers rated degeneration to obtain a score for the upper (atlanto-dental and left/right atlanto-occipital joint) and for the lower part of the CCJ (left and right atlanto-axial joint). Two reader rated the following quantitative parameters: basion-axial-interval, atlanto-dental-interval, atlanto-occipital-interval, Powers-ratio, and signal/contrast-to-noise-ratio. As a proof of concept, five healthy volunteers were scanned with both MRI sequences. Degeneration was assessed on a Likert scale by three independent observers. Interrater and intermodality reliability were calculated using an intraclass correlation coefficient. To compare distance measurements between examination methods, a Friedman test, between-degenerative ratings, and a Kruskal-Wallis test were performed. Degenerative ratings of the CCJ between MRI sequences and CT showed a good interrater and intermodality agreement. MRI sequences tended to underestimate the degree of degeneration compared to CT, and this became more marked with increasing degeneration severity. There were no significant relationships between distance measurements and the degree of degeneration (PCT = 0.62, PUTE = 0.64, PFRACTURE = 0.67). The in vivo examination proved the feasibility of both MRI methods in a clinical setting. Quantitative and qualitative ratings on MR images were comparable to CT images; thus, MRI may be a valid alternative to CT assessing the CCJ. 1. 3.

Morphometric Analysis of the Lateral Atlantoaxial Joints in Patients with an Old Type II Odontoid Fracture and Atlantoaxial Dislocation: A Study Based on CT Analysis.

The morphological features of the lateral atlantoaxial joints (LAJs) in patients with old type II odontoid fractures and atlantoaxial dislocation have not been fully analyzed. Our study found the changes in morphological features of the LAJs in some patients, and revealed the causes and consequences of the changes in morphological features of the LAJs.

Results of Conservative and Surgical Management in Children with Idiopathic and Nonidiopathic Os Odontoideum

The outcomes of conservative and operative treatment of os odontoideum in children remain unclear. Our objective was to study the outcomes of conservative and surgical treatment of idiopathic os odontoideum in children and compare these outcomes in age- and treatment-matched nonidiopathic children with os odontoideum. A retrospective multicenter review identified 102 children with os odontoideum, of whom 44 were idiopathic with minimum 2-year follow-up. Ten patients were treated conservatively, and 34 underwent spinal arthrodesis. Both groups were matched with nonidiopathic patients by age and type of treatment. Cervical arthrodesis was recommended for patients with increased atlantoaxial distance or reduced space available for the cord in flexion-extension radiographs. All 20 children undergoing conservative treatment remained asymptomatic during follow-up, but 1 nonidiopathic patient developed cervical instability. The idiopathic group had significantly less severe radiographic cervical instability and less neurologic complications than the nonidiopathic group (P < 0.05 for all comparisons). Thirty-three (97%) patients in the idiopathic group and 32 (94%) patients in the nonidiopathic group (94%) had spinal fusion at final follow-up (P= 0.55). The risk of complications (15% vs. 41%; odds ratio 0.234, 95% confidence interval 0.072-0.757, P= 0.015) and nonunion (6% vs. 24%; odds ratio 0.203, 95% confidence interval 0.040-0.99, P= 0.040) were significantly lower in the idiopathic than in the nonidiopathic group. Idiopathic children undergoing rigid fixation achieved spinal fusion. Idiopathic patients with stable atlantoaxial joint at presentation remained asymptomatic and intact during conservative treatment. Idiopathic children with os odontoideum undergoing spinal arthrodesis had significantly fewer complications and nonunion than nonidiopathic children. III.