Search

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., (© 2024. The Author(s).)

Objective: Patients with instability because of congenital craniovertebral anomalies often have complex C1-C2 osseovascular anomalies. C2 nerve root sacrifice has been described to address such difficult anatomy during posterior C1-C2 fixation and has its own downsides. Its preservation as a recent alternative poses greater surgical challenge, and the considerations differ from other causes of craniovertebral junctional instability; the pertaining outcomes have been scarcely studied. The objective of this study was to prospectively determine the feasibility and outcomes related to C2 nerve root preservation in patients with congenital atlantoaxial dislocation (CAAD) after posterior C1-C2 fixation., Methods: In this observational study, 63 patients (126 nerve roots) with CAAD after posterior fixation were prospectively assessed. Underlying osseovascular anomalies affecting the feasibility of C2 nerve root preservation, and C2 nerve-related dysfunction at 12 months follow-up were analyzed., Results: The overall C2 nerve root preservation rate was 89.7%. Even in the presence of extreme joint obliquity/spondyloptosis and anomalous vertebral artery, it was feasible in about three fourths. After preservation, 28.3% patients developed new-onset C2 nerve root dysfunction: neuralgia in 2, dysesthesia in 6, and hypoesthesia/paresthesia in 9. The symptoms were not disabling in most patients., Conclusions: In most patients with CAAD, C2 nerve root preservation is feasible despite an aberrant bony and vascular anatomy. A few patients after nerve root preservation develop related symptoms that are conservatively manageable, with no significant adverse consequences. Given the controversy in the literature on C2 nerve sacrifice-related outcomes, we favor an attempt at C2 nerve root preservation., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Craniocervical injuries (CCJs) account for 10% to 30% of all cervical spine trauma. An increasing number of patients are surviving these injuries due to advancements in automobile technology, resuscitation techniques, and diagnostic modalities. The leading injury mechanisms are motor vehicle crashes, falls from height, and sports-related events. Current treatment with urgent rigid posterior fixation of the occiput to the cervical spine has resulted in a substantial reduction in management delays expedites treatment of CCJ injuries. Within CCJ injuries, there is a spectrum of instability, ranging from isolated nondisplaced occipital condyle fractures treated nonoperatively to highly unstable injuries with severely distracted craniocervical dissociation. Despite the evolution of understanding and improvement in the management of cases regarding catastrophic failure to diagnose, subsequent neurologic deterioration still occurs even in experienced trauma centers. The purpose of this article is to review the injuries that occur at the CCJ with the accompanying anatomy, presentation, imaging, classification, management, and outcomes., Competing Interests: Disclosure The authors have nothing to disclose., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Objective: To investigate the characteristics of transverse fractures of the C2 axis body diagnosed on sagittal computed tomography (CT) and to propose new classification and appropriate treatment strategies., Methods: A retrospective study was performed by enrolling 49 patients (26 men and 23 women) with transverse fractures of the C2 axis body who were treated at four national trauma centers of tertiary university hospitals from January 2000 to December 2017. The mean age of the patients was 60.8 years (ranging from 21 to 90 years). We classified 49 transverse fractures of the C2 body into three types based on fracture trajectories involving superior articular facet (SAF) and lateral cortex (LC) of the C2 body on coronal CT as follows: Type 1, involvement of C2 SAF on both sides; Type 2, unilateral involvement of C2 SAF on one side and LC on the other side; Type 3, involvement of LC on both sides. The characteristics, treatment methods, and results of 49 transverse fractures of the C2 body were analyzed. Mean follow-up was 12.6 months (ranging from 12 to 26 months)., Results: Twenty-six (53.1%) patients were Type 1, 21 (42.9%) were Type 2, and 2 (4.0%) were Type 3. Correlation coefficients for intra-observer and inter-observer reliabilities of classification were 0.723 and 0.598 (both, P < 0.001), respectively. About 40.8% (7 Type 1 and 13 Type 2) of the patients had fracture displacement >3 mm; Incidence of fracture displacement >3 mm was higher in Type 2 than Type 1 (61.9% vs 26.9%, P < 0.05). About 79.6% (20 Type 1, 17 Type 2 and 2 Type 3) of the patients were treated conservatively, and 20.4% (6 Type 1 and 4 Type 2) underwent surgery. At last follow-up, 47 out of 49 patients achieved fusion; overall fusion rate was 95.9%. All conservatively treated Type 1 and Type 3 patients achieved fusion. Out of 17 conservatively treated Type 2 patients, 15 achieved fusion but two developed nonunion; however, two nonunion patients opted not to undergo surgery. Subgroup analysis showed that Philadelphia brace caused nonunion significantly in fracture displacement >3 mm compared to Minerva brace/Halovest (100% vs 0%, P < 0.05). All surgically treated Type 1 and 2 patients achieved fusion. In terms of clinical outcomes, neck pain visual analog scale and neck disability index were significantly improved (both, P < 0.01). According to Odom's criteria, 93.9% (46/49) of the patients achieved satisfactory outcomes. No major complications occurred., Conclusions: The majority of transverse fractures of C2 body can be treated conservatively. However, surgery or rigid Minerva brace/Halovest should be considered for Type 2 transverse fractures of the C2 body with fracture displacement >3 mm., (© 2021 The Authors. Orthopaedic Surgery published by Chinese Orthopaedic Association and John Wiley & Sons Australia, Ltd.)

Background: The preoperative assessment of C2 morphology is important for safe instrumentation. Sclerotic changes are often seen in C2 pedicles. Evaluating the diameter measurements solely might not accurately assess the safety of screw insertion. We have proposed a novel grading system of the C2 pedicle that includes sclerosis and evaluated the predictive value of this grading system with the surgeon's safety evaluation., Methods: We reviewed and measured the dimensional values in 220 cervical computed tomography angiograms. Additionally, we used a grading system that divides the findings into 5 grades according to the width measurement and degree of sclerosis in the C2 pedicle. Two spine surgeons independently classified the pedicles as follows: safe (minimal risk of pedicle violation), caution needed (caution to minimize pedicle violation), or dangerous (a high risk of pedicle violation). Finally, we compared the measurements and the surgeons' safety assessments., Results: A total of 411 pedicles of 203 patients (mean age, 69.5 years; 49.5% women) were included. Of the 411 C2 pedicles, 170 were classified as high risk by ≥1 surgeon. Between the dimensional measurements and grading system, the sclerotic grade showed the best predictive value., Conclusions: We have introduced a novel tool to evaluate the safety of C2 pedicle screw placement. Our results suggest that our pedicle width-sclerosis grading system is reproducible and predicts the surgeon's assessment of safe screw placement better than C2 pedicle diametrical measurements alone., (Copyright © 2021. Published by Elsevier Inc.)

Objective: 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)., Methods: 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., Results: 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., Conclusions: 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., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: Occipitocervical fusion is an important surgical procedure to treat instability of the upper cervical and craniocervical junction. Fixation to the dense cortical bone of the occiput, contemporaneously typically accomplished with a plate and screws, is known to be strong and durable, but there are many competing methods used to secure an adequate number of fixation points of sufficient strength at the cervical end. Extension of hardware to the midcervical region to acquire additional fixation points, however, results in loss of subaxial motion segments and additional potential morbidity. The C2 vertebra is unique in that its morphology and dimensions permit fixation with longer screws than are typically possible to place in the midcervical lateral masses. Translaminar and pars screw techniques, both commonly used to achieve C2 fixation, are not mutually exclusive, as their respective trajectories are considerably different and engage different portions of the bony anatomy., Methods: We describe a novel, 4-point C2 fixation technique for OC fusion that may avoid the need to extend fusion to the subaxial spine., Results: This technical note illustrates how 4-point C2 fixation can be employed in occiptocervical fusion., Conclusions: 4-point fixation of C2 combining translaminar and pars screw placement is technically feasible and may be a suitable strategy to spare subaxial motion segments in OC fusion procedures. Futher investigation may establish its applicability to additional surgical procedures., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Chondrosarcoma, a malignant bone tumor, is rarely encountered in the cervical spine. This article describes a patient whose neck pain and dysphagia were caused by an expansive, destructive lesion with calcification that was located in the body of the axis (C2 vertebra), the first time a chondrosarcoma has been reported in this location.

Purpose: A skeleton named Iuzu has been unearthed from an exceptional middle Holocene burial in Toca dos Coqueiros site, in Serra da Capivara National Park (UNESCO World Heritage Site, Piauí State, Brazil). During a bioarchaeological analysis of its remains, we discovered that Iuzu was suffering from rare vertebral malformations. A double foramen transversaria, the agenesis of a foramen on the atlas and the hypoplasia of the transverse process of the axis have been highlighted. We aimed to deduce the clinical consequences of the malformation on the patient's health., Methods: We proceeded to macroscopic observation and radiography of the bones, then we search for other examples of such a pathology in archaeological litterature., Result: The malformation caused vascular insufficiency that may have led to neurological lesions leading to various pains and troubles. The very rare malformations Iuzu presented have not been found on a paleoindian skeleton from South America so far., Conclusion: This case allowed us to examine the conditions of selection of individuals buried in southern Piauí during the Middle Holocene, during which time this rite does not seem to predominate.

Background: Mobilization of intraosseous course of vertebral artery for safe screw insertion into pedicle of axis in cases with high riding vertebral artery is discussed., Objective: To show drilling, exposure, and mobilization of the "high-riding" vertebral artery loop during its course in relationship with superior facet/pedicle of C2 vertebra can provide safety to techniques of atlantoaxial fixation that involve insertion of screws in the pars/pedicle/facet of C2., Methods: During the period June 2016 to April 2018, 15 patients operated for atlantoaxial stabilization underwent vertebral artery exposure and mobilization using the technique discussed. The ages of the patients ranged from 6 to 48 yrs. Four patients had mobile and reducible atlantoaxial dislocation. Seven patients had basilar invagination. Four patients had os-odontoideum. Gentle and precise drilling of bone that covers the "high-riding" vertebral artery can lead to its safe and wide surgical exposure. The arterial loop can then be either completely or partially mobilized out of the vertebral artery groove such that C2 screw insertion can be conducted under direct surgical visualization of the vertebral artery., Results: During the average follow-up period of 14 mo, there have been no complications related to the surgical procedure, metal implant, or vertebral artery., Conclusion: Vertebral artery exposure and mobilization is rather simple and safe procedure and is remarkably effective in providing a space for C2 screw implantation., (Copyright © 2019 by the Congress of Neurological Surgeons.)

Purpose: Os odontoideum is a rare anatomical and morphological variation of the odontoid process and associated with a range of symptoms such as spinal cord and vertebral artery injuries. This study aimed to evaluate the frequency of os odontoideum in Turkish cases by sagittal/coronal cervical magnetic resonance imaging (MRI) and computed tomography (CT) and analyze the relationship with age, gender and related symptoms., Methods: The incidence of os odontoideum was retrospectively diagnosed by sagittal/coronal cervical CT and MRI out of 16,122 subjects aged 20-70 years (mean 46) in the period between 2014 and 2018. The relationship of os odontoideum with age, gender, and symptoms was recorded., Results: The statistical analysis of the study was performed by the χ² test and two-way mixed ANOVA. Os odontoideum was detected in 18 (0.11%) (11 males; 7 females) out of 16,122 patients. The mean age was 47.5 ± 1.4 years in the females and 43.5 ± 2.5 years in the males (p < 0.05). 6 odontoideum were detected out of 6467 (3756 males, mean 48 ± 0.7, 2711 females, mean 46 ± 1.2) subjects by CT and 12 odontoideum were detected out of 9655 patients (5607 males and 4048 females) by MRI., Conclusion: Neck pain was the most frequent symptom. The prevalence of os odontoideum especially round type is more frequent in older male patients over 40 years old with head and neck pain or atlantoaxial instability, and is less common in Turkish subjects when compared to various ethnic groups.

Objective: To elucidate the imaging manifestations of os odontoideum, establish the diagnosis and guide surgical therapy., Methods: Clinical and imaging data, including X-ray, CT and MR of 24 patients with os odontoideum, were retrieved and reviewed retrospectively., Results: Os odontoideum with intact cortex was divided into round, conical and blunt tooth types. Four cases of orthotopic and 20 cases of dystopic os odontoideum were included. There was anterior displacement of the base of the dens in six cases, posterior displacement in nine cases and no displacement in nine cases. A widening of anterior atlanto-axial space was shown in 14 patients with varying degrees. Thickening of the soft tissue posterior to the dens was observed in 19 patients, spinal canal stenosis in 21 patients, cervical myelopathy in 10 patients and craniocervical junction malformation in 9 patients. Posterior C1-C2 pedicle screw fixation and fusion was performed in 12 patients and 4 patients underwent posterior occipito-cervical fixation and fusion., Conclusion: Radiographically, os odontoideum is defined as an independent ossicle of variable size with smooth circumferential cortical margins separated from the axis. Imaging can be used to assess atlanto-axial instability, associated normal or abnormal anatomical structures and guide surgical therapy.

Objective: The aim of this study was to report an experience with 190 cases of os odontoideum over 20 years. The management outcome following atlantoaxial fixation was analyzed., Methods: From January 2000 to September 2018, 190 patients with os odontoideum were surgically treated. There were 113 male patients and 77 female patients; average age was 24 years (range, 2-68 years).The patients were divided into 3 groups depending on the nature of atlantoaxial dislocation (group 1, mobile and partially or completely reducible atlantoaxial dislocation; group 2, fixed or irreducible atlantoaxial dislocation; group 3, presence of basilar invagination). There were 65 pediatric patients (<18 years old). All patients underwent atlantoaxial joint manipulation and lateral mass plate and screw fixation. The goal of surgery was segmental atlantoaxial arthrodesis. No transoral or posterior foramen magnum bone decompression was done. Occipital bone was not included in the fixation construct., Results: On direct bone handling and observation, atlantoaxial joint pathologic hyperactivity related instability was identified in all patients. Atlantoaxial segmental stabilization resulted in clinical symptomatic and neurologic improvement in 100% of patients., Conclusions: Os odontoideum signifies chronic or long-standing atlantoaxial instability. Segmental atlantoaxial fixation is a reliable form of surgical treatment. Bone decompression is not necessary. Inclusion of occipital bone and subaxial vertebrae in the fixation construct is not necessary., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Os odontoideum is a rare entity of the second cervical vertebra, characterized by a circumferentially corticated ossicle separated from the body of C2. The ossicle is a distinct entity from an odontoid fracture or a persistent ossiculum terminale. The diagnosis may be made incidentally on imaging obtained for the workup of neck pain or neurologic signs and symptoms. Diagnosis usually can be made with plain radiographs. MRI and CT can assess spinal cord integrity and C1-C2 instability. The etiology of os odontoideum is a topic of debate, with investigative studies supporting both congenital and traumatic origins. A wide clinical range of symptoms exists. Symptoms may present as nondescript pain or include occipital-cervical pain, myelopathy, or vertebrobasilar ischemia. Asymptomatic cases without evidence of radiologic instability are typically managed with periodic observation and serial imaging. The presence of atlantoaxial instability or neurological dysfunction necessitates surgical intervention with instrumentation and fusion for stability.

Os odontoideum is a rare anomaly of the second cervical vertebra. The odontoid process is separated by a wide gap from the vertebral body in this anomaly. It can be associated with atlantoaxial instability.

Competing Interests: Competing interests: None declared.

Purpose: Because of the complex cervical vertebral embryology and some normal variations, the atlantoadental interval (ADI) was not suitable for the evaluation of the anatomic relationship between the atlas and axial in children less than 2 years old. And the influence of the age and gender on the anatomic relationship between atlas and axial in children was still unclear. Two novel parameters, atlas-axis anteroposterior distance (AAAD) and atlas-axis lateral distance (AALD), were invented to evaluate the anatomic relationship between the atlas and axis in the children no more than 8 years old with different age and gender., Methods: Cross-sectional computed tomography (CT) scans of the atlantoaxial joint for 140 randomly selected pediatric patients no more than 8 years old were analyzed. On the ideal CT reconstruction images, AAAD, AALD, atlantoaxial lateral bending angle (AALB), and atlantoaxial rotation angle (AARA) were measured., Results: There was no statistically significant difference between the mean AAAD in different age and gender groups. The 99% confidence interval for AAAD was 7.12-7.82 mm. There was no significant correlation between AAAD and AALB/AARA and AALD and AALB/AARA., Conclusion: The AAAD was less than 7.12 mm or much than 7.82 mm that suggested a possible instability in the atlantoaxial joint and could help the diagnosis of the atlantoaxial instability in children no more than 8 years old. There was no difference between the mean AAAD of pediatric patients no more than 8 years old in different age and gender groups.

Study Design: Retrospective case series., Objectives: To describe the indications and outcomes of cervical fixation using modern instrumentation in a case series of pediatric Down syndrome (DS) patients., Summary of Background Data: Cervical instability is the major cervical spine concern in children with DS. Although fixation techniques have advanced over the past quarter-century, the outcome of fixation with modern instrumentation for upper cervical instability in DS patients has not been thoroughly investigated., Methods: We searched the orthopedic database at our institution for patients with a diagnosis of DS who had undergone a cervical spine fusion between 2006 and 2017. Patient demographics, diagnoses, surgical indications, surgical details, and complications were recorded. Preoperative imaging was reviewed to determine atlanto-dens intervals and spinal cord signal changes. Postoperative radiographs or CT scans were reviewed to determine union., Results: Twelve DS patients met our inclusion criteria. The mean age at surgery was 9.3 years (range 3.8-18.8 years). Patients with secondary causes of instability included 7 patients with os odontoideum and 1 patient with a pars fracture. Three patients (25%) were identified on asymptomatic screening, with none of these having cord signal changes on magnetic resonance imaging (MRI). Modern implants (screws, plates, cages) were used in every patient in our series. The mean number of levels fused was 1.9 (range 1-5). The overall complication rate was 41.7% (5/12). Four patients required repeat surgery for nonunion. All patients with adequate radiographic follow-up demonstrated union (11/11, 100%). One patient was lost to follow-up., Conclusions: Fixation for cervical instability is a critical component of the management of DS. A minority of patients receiving surgery were identified through asymptomatic screening. There was a high complication risk associated with surgery in our study; however, the addition of rigid fixation has lessened the complication rate compared with previous studies., Level of Evidence: Level IV., (Copyright © 2019 Scoliosis Research Society. Published by Elsevier Inc. All rights reserved.)

Objective: Pannus formation in the atlanto-axial joint is a well-recognized complication of rheumatoid arthritis (RA). Occasionally, atlanto-axial pannus is reported when patients without a history of RA undergo magnetic resonance imaging (MRI) of the cervical spine. We sought to further characterize these patients., Methods: The Partners HealthCare Research Patient Data Registry was free-text searched for "atlanto-axial" AND "pannus" in cervical spine MRI reports from 2001 to 2015. Cases with MRI reports describing pannus were reviewed. Clinical data were extracted by chart review in cases with confirmed atlanto-axial pannus (n = 105)., Results: Twenty-nine patients (27.6%) had RA, all of whom except one carried this diagnosis at the time of the MRI scan. Only 1 of 77 patients without a history of RA was subsequently diagnosed with RA (1.3%, 95% CI 0.1-7.0%, median followup 3.6 yrs). Non-RA patients were significantly older (median age 79 vs 63 yrs, p < 0.0001), less frequently female (55% vs 86%, p = 0.0032), and more likely to have undergone prior cervical spine surgery (18% vs 0%, p = 0.016) compared with RA patients. Thirty-four non-RA patients (44.7%) either had a clinical diagnosis of calcium pyrophosphate dihydrate disease (CPPD) or imaging evidence for tissue calcification. There were no significant differences in age or sex between the CPPD subgroup and other non-RA patients. Twenty-eight patients (26.7%) underwent cervical spine surgery., Conclusion: Patients without RA diagnosis and incidental atlanto-axial pannus on cervical spine MRI are unlikely to have previously unrecognized RA. Degenerative disease and tissue calcification may contribute to pannus formation in these patients.

Background: Os odontoideum is a smooth, independent ossicle separated from a hypoplastic odontoid process located cranially in the expected position of the odontoid tip. The pathogenesis of os odontoideum remains controversial, and several etiological theories have been suggested for congenital, developmental, and traumatic origins., Case Description: We have reported symptomatic familial cases of dystopic os odontoideum in 2 elderly sisters who denied any traumatic history of the head and neck. Both patients were treated surgically, with successful outcomes achieved., Conclusions: When examining the etiology of os odontoideum, checking for the existence of a traumatic history is important. However, a more important matter is to consider morphological segmentation abnormalities of the proatlas. Segmentation abnormalities of the proatlas could be closely connected to the development of familial os odontoideum., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Objective: The aim of this study is to present a unique case of a patient who presented to our Emergency Department with evidence of a chronic traumatic spondylolisthesis of the axis with severe displacement treated with anterior cervical discectomy and fusion (ACDF) of C2-C3 as well as and posterior cervical fusion (PCF) of C1-C3., Methods: One patient with an untreated traumatic spondylolisthesis of the axis with Levine type II injury pattern and 1.2 cm of anterior subluxation underwent ACDF C2-C3 and PCF C1-C3., Results: The patient recovered well, radiographs demonstrated reduction of the anterior subluxation, and the patient reported a neck disability index (NDI) score of 20 at 6-month follow-up with full neurologic function intact. The patient was then lost to follow-up., Conclusion: In this report, we present an alcoholic patient with a history of many falls who presented with a Levine type II traumatic spondylolisthesis of the axis with signs of chronicity seen on magnetic resonance imaging (MRI). We were able to partially reduce the anterior displacement with traction, but needed both anterior and posterior cervical approaches to achieve adequate reduction and stabilization of the injury.

Background: We present 3 case reports to share our experience and explore the safety and efficacy of treating huge teardrop fracture of the axis (HTDFA)., Case Description: Case 1: A 47-year-old man suffered from generalized pain after falling from a height. Case 2: A 39-year-old woman suffered facial contusions and lacerations during a car accident, and her neck was sore. Case 3: A 51-year-old woman was hit in the face during a car accident, and her neck was sore. These 3 patients had limited neck movement and no nerve injury, and their radiographs showed HTDFA. The patients were treated with Zero-Profile (Zero-P) implant placement combined with miniscrew fixation., Conclusions: The treatment of HTDFA by Zero-P implant placement combined with miniscrew fixation is effective and stable. The last follow-up examination of the patients showed that fusion had been achieved, and their neck pain had disappeared. Anterior reduction, diskectomy, and Zero-P implantation combined with miniscrew fixation can be used to treat HTDFA. Both avulsed teardrop fragment removal and C2-3 bone grafting lead to bone healing. This method is effective, safe, and simple for the treatment of HTDFA., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Objective: Fracture of the odontoid process is a critical injury to diagnose and often treat. The aim of this anatomic study was to present a comprehensive understanding of this part of the C2 vertebra., Methods: We used 20 C2 vertebrae. Samples underwent imaging (computed tomography [CT] with and without three-dimensional reconstruction, micro-CT, 1.5T magnetic resonance imaging) and sagittal and coronal sectioning using a bone saw. Sectioned specimens were imaged under a digital handheld microscope, and transillumination of the bone was used to highlight its internal trabecular pattern. Three samples underwent infusion of the odontoid process with a hardening substance and were then decalcified., Results: Internal trabecular patterns of the odontoid process of all specimens were discernible. In sagittal and coronal sections, trabecular patterns were highlighted with transillumination, but the patterns were much clearer using the digital microscope. Magnetic resonance imaging and CT provided the least detail of the imaging methods, but the trabecular patterns could be identified. Three-dimensional reconstruction of CT data was the preferred imaging method over magnetic resonance imaging and CT without three-dimensional reconstruction. The most distinct trabecular and cortical patterns were seen using micro-CT. Osteoporosis was seen in 2 specimens (10%). Five specimens (25%) were found to have a subdental synchondrosis. For most specimens, the trabeculae were found throughout the odontoid process., Conclusions: Improved knowledge of the anatomy, structural composition, and variations within the C2 vertebra may allow for better treatment options and patient care., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Bony anomaly of axis (C2) vertebra is well known. However, expansion of the posterior element is less documented. We describe a case of additional bony ring attached to the posterior spinous process in a 10-year-old male who presented with the complaint of progressive swelling at the upper cervical region. On physical examination a firm swelling approximately 8 × 5 cm was present at the back of the neck just below the hair line. There was no focal neurologic deficit. Computed tomography scan of the cervical spine showed an additional bony arch attached to the spinous process of the C2 vertebra. Magnetic resonance imaging revealed a soft tissue mass within the additional bony ring without involvement of neural structures. Complete surgical excision of the mass was done. Anomalous expansion of the spinous process of the C2 vertebra may remain silent. Surgery may be necessary for cosmetic purposes., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Objective: To investigate the efficacy and safety of ixekizumab in patients with active radiographic axial spondyloarthritis (SpA) and prior inadequate response to or intolerance of 1 or 2 tumor necrosis factor inhibitors (TNFi)., Methods: In this phase III randomized, double-blind, placebo-controlled trial, adult patients with an inadequate response to or intolerance of 1 or 2 TNFi and an established diagnosis of axial SpA (according to the Assessment of SpondyloArthritis international Society [ASAS] criteria for radiographic axial SpA, with radiographic sacroiliitis defined according to the modified New York criteria and ≥1 feature of SpA) were recruited and randomized 1:1:1 to receive placebo or 80-mg subcutaneous ixekizumab every 2 weeks (IXEQ2W) or 4 weeks (IXEQ4W), with an 80-mg or 160-mg starting dose. The primary end point was 40% improvement in disease activity according to the ASAS criteria (ASAS40) at week 16. Secondary outcomes and safety were also assessed., Results: A total of 316 patients were randomized to receive placebo (n = 104), IXEQ2W (n = 98), or IXEQ4W (n = 114). At week 16, significantly higher proportions of IXEQ2W patients (n = 30 [30.6%]; P = 0.003) or IXEQ4W patients (n = 29 [25.4%]; P = 0.017) had achieved an ASAS40 response versus the placebo group (n = 13 [12.5%]), with statistically significant differences reported as early as week 1 with ixekizumab treatment. Statistically significant improvements in disease activity, function, quality of life, and spinal magnetic resonance imaging-evident inflammation were observed after 16 weeks of ixekizumab treatment versus placebo. Treatment-emergent adverse events (AEs) with ixekizumab treatment were more frequent than with placebo. Serious AEs were similar across treatment arms. One death was reported (IXEQ2W group)., Conclusion: Ixekizumab treatment for 16 weeks in patients with active radiographic axial SpA and previous inadequate response to or intolerance of 1 or 2 TNFi yields rapid and significant improvements in the signs and symptoms of radiographic axial SpA versus placebo., (© 2018 The Authors. Arthritis & Rheumatology published by Wiley Periodicals, Inc. on behalf of American College of Rheumatology.)

Objective: Posterior C1-2 dislocation secondary to fracture of the dens or os odontoideum is uncommon. Little is known about posterior dislocations in which close reduction fails, requiring intraoperative maneuvers. The objective of this retrospective study was to analyze clinical presentations, factors causing irreducibility, and nuances in the achievement of intraoperative reduction., Methods: The clinicoradiological features of 10 patients with irreducible posterior C1-2 dislocation were studied. Six were posttraumatic, with odontoid fractures, and 4 had os odontoideum. The radiologic images were studied to analyze the cause of irreducibility, and the operative management of these cases was discussed., Results: The patients with traumatic dislocation had persistent neck pain (n = 6) and early onset (n = 1) or delayed onset (n = 4) myelopathy. The fracture line was oblique, extending anterosuperiorly to posteroinferiorly in all except 1 patient, with fracture fragments distracted in 4 and interlocked in 2. There was associated lateral translation in 2. All patients had facet locking. Intraoperative reduction was achieved in all by unlocking the facets, intrafracture reduction, or both. All 4 patients with congenital posterior dislocations had retrolisthesis of dens with lateral translation. They presented with neck tilt (n = 4) and severe myelopathy (n = 3). They were easier to reduce intraoperatively, but the improvement lesser in comparison with the traumatic fractures., Conclusions: The posterior C1-2 dislocation associated with fracture of the dens or os-odontoideum is a distinct entity. Lateral translation is often seen with retrolisthesis of the os odontoideum and occasionally in traumatic posterior dislocations. It is necessary to address the cause of irreducibility and achieve multiplanar realignment for a good outcome., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Objective: Atlantoaxial stabilization procedures in high-riding vertebral artery (HRVA) cases are challenging. C2 translaminar screws are rigid and pose no risk to the vertebral artery. The aim of this study was to present clinical outcomes of atlantoaxial dislocation combined with HRVA using C2 translaminar screws., Methods: Cases of atlantoaxial dislocation combined with HRVA surgically treated in our institution from 2007 to 2015 were retrospectively reviewed. Atlantodental interval and clivus-axial angle were measured. The Japanese Orthopaedic Association scale was used to evaluate neurologic status., Results: There were 58 patients enrolled: 15 with instability and 43 with dislocation, 13 of which were irreducible. Incidence of bilateral HRVA was 5.2%. C1-C2 fixation was performed in 26 cases; atlantodental interval decreased from 9.9 ± 3.7 mm to 1.0 ± 1.7 mm (P < 0.05). C0-C2 fixation was performed in 32 cases; clivus-axial angle increased from 125° ± 13° to 150°± 15° (P < 0.05). Preoperative and postoperative Japanese Orthopaedic Association scores of 56 patients with myelopathy were 11.9 ± 2.8 and 14.6 ± 2.4, respectively (P < 0.05). Fusion rate was 93.1% (54/58) and at 4-month follow-up was 81% (47/58). In 14 cases of redislocation, final fusion was achieved; 3 of 14 required odontoidectomy. Four cases lacking bony fusion also required revision surgery. Redislocation rate was 31% (18/58), and reoperation rate was 12.1% (7/58)., Conclusions: Surgical results of C2 translaminar screws are unsatisfactory, with high redislocation and reoperation rates in atlantoaxial dislocation cases. New treatment methods should be investigated to facilitate clinical outcomes. Extending fixed segments should be considered., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background: Vocal cord dysfunction resulting from recurrent laryngeal nerve palsy (RLNP) is a known complication following anterior cervical discectomy and fusion. RLNP occurs typically secondary to neurapraxia caused by intraoperative compression or traction on the nerve and less commonly from direct nerve injury intraoperatively in the setting of anterior cervical spine surgery. Patients with RLNP typically present with hoarseness immediately after surgery owing to unilateral vocal cord paralysis. In rare cases, there is late-onset, progressive development of RLNP that may potentially lead to permanent vocal cord paralysis or respiratory failure., Case Description: A 75-year-old woman presented with myeloradiculopathy and chronic urinary incontinence. Imaging showed severe foraminal and central stenosis with T2 cord signal change. A C4-7 anterior cervical discectomy and fusion was successfully performed without immediate complications following surgery. The patient had a normal voice and was tolerating a regular diet well. On postoperative day 3, the patient developed new hoarseness and dysphagia. An otolaryngologist was consulted, and flexible nasolaryngoscopy showed left vocal cord paralysis consistent with left RLNP. The patient was treated with a course of steroids, and her hoarseness and dysphagia had resolved at the 6-month follow-up visit., Conclusions: To our knowledge, this is the first report of delayed RLNP in patients undergoing anterior cervical discectomy and fusion. This rare complication should be discussed during preoperative patient counseling. Previous literature indicates the underlying pathophysiology for delayed onset of RLNP may be small vessel ischemia, vasospasm, or viral resurgence that leads to recurrent laryngeal nerve dysfunction., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Aim: To evaluate anatomical data of the bony structures during exploration of the C1-C2 complex., Material and Methods: This study included six formalin-fixed cadaveric head and neck specimens. Radiological images and anatomical measurements included: C1-C2 distance, bony distance between C1 anterior tubercle-nares and superior incisors, height of C1 anterior arch, and height and width of odontoid articular surface., Results: The mean distance between C1 anterior tubercle-nares and superior incisors on maxilla were 96.16 ± 8.07 mm and 84.14 ± 9.16 mm, respectively. The mean height of C1 anterior arch was 13.89 mm. The meandistance between medial borders of right-left C1 lateral masses was 19.10 ± 1.80 mm. The mean distance between medial border of lateral midline on mass right and left sides were 9.43 ± 0.88 mm and 9.68 ± 0.97 mm, respectively. The mean height of C1 anterior arch at midline was 13.89 ± 2.48 mm, and the mean distance between ventral surface of anterior arch and ventral joint of odontoid at midline was 6.43 ± 1.29 mm. The anteroposterior, horizontal diameters of odontoid on its base were 12.12 ± 0.38 mm, and 11.12 ± 0.94 mm, respectively. The angles of transoral and transnasal approaches to C1 were 32.67 ± 4.59° and 32.00 ± 2.10°, respectively., Conclusion: A safe transoral or transnasal odontoidectomy requires accurate measurements and imaging regarding ventral C1-C2 relationships, distances of odontoid, lateral mass and midline.

Over the past century, atlantoaxial stabilization techniques have improved considerably. To our knowledge there has been a scarcity of articles published that focus specifically on the history of atlantoaxial stabilization. Examining the history of instrumentation allows us to evaluate the impact of early influences on current modern stabilization techniques. It also provides inspiration to further develop the techniques and prevents repetition of mistakes. This paper reviews the evolution of C1-C2 instrumentation techniques over time and provides insights into the future of these practices.We did an extensive literature search in PubMed, Embase and Google Scholar, using the following search terms: 'medical history', 'atlantoaxial', 'C1/C2', 'stabilization', 'instrumentation', 'fusion', 'arthrodesis', 'grafting', 'neuroimaging', 'biomechanical testing', 'anatomical considerations' and 'future'.Many different entry zones have been tested, as well as different constructs, from initial attempts with use of silk threads to use of hooks and rod-wire techniques, and handling of bone grafts, which eventually led to the development of the advanced screw-rod constructs that are currently in use. Much of this evolution is attributable to advancements in neuroimaging, a wide range of new materials available and an improvement in biomechanical understanding in relation to anatomical structures.

Background: Screw diameters currently available are based on the literature available. No data are available for the safety margin available for C2 pedicle screw placement. The objective of this study was to define the average pedicle size available for placing C2 pedicle screws and to quantify the safety margin available in case of lateral breach of screw., Methods: Computed tomography angiograms of 259 patients (161 men, 98 women) were analyzed to calculate the C2 pedicle width, the area of the transverse foramen (TF) and the vertebral artery (VA), and the occupation ratio (OR) of the VA within the TF. The VA was classified into groups based on its lie within the TF (anteromedial, anterolateral, posteromedial, posterolateral, central, ectatic). The distance which the pedicle screw can breach without encountering the VA was calculated (lateral pedicle to vertebral artery distance [LPVA]). The diameters of the VA and the TF were estimated, and their difference gives the safety margin in case of breach of the lateral cortex of the C2 pedicle., Results: The mean mediolateral diameter of the pedicle isthmus, perpendicular to the pedicle axis, in women was 5.3 mm and in men it was 5.8 mm. This difference was statistically significant. In 53.9% (122/226) of patients, the VA was dominant on the left side. The overall mean OR at the C2 vertebral level was found to be 37.3%. The mean LPVA was 0.9 mm, and the average overall safety margin available was 2.5 mm (range, 0.4-5.3 mm)., Conclusions: This study describes the relationship of the VA in the C2 TF and the relative risk during pedicle screw fixation., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Objective: We sought to develop a new posterior fusion technique composed of bilateral C1 titanium cables and C2 pedicle screw-rods for treatment of atlantoaxial instability not suitable for C1 screw placement., Methods: A study was conducted of 18 patients with atlantoaxial instability who had C1 broken screw trajectory or anatomic anomalies. All patients underwent posterior fixation with bilateral C1 titanium cables and C2 pedicle screws. The follow-up period was a minimum 1 year. Clinical outcomes measurements included visual analog scale score for neck pain assessment, the American Spinal Injury Association Impairment Scale and Japanese Orthopaedic Association score for neurologic status and function. According to preoperative computed tomography (CT) reconstruction and CT angiography, the patients selected in this study were not suitable for C1 screw placement. Postoperative plain radiographs and CT reconstruction were performed to evaluate the reduction, bony fusion, and implant position. All outcomes were evaluated at each follow-up., Results: The average clinical follow-up period was 24 months (range 12-36 months). All patients had complete neck pain relief at postoperative 6 months. Their neurologic symptoms had improved significantly at 1-year follow-up. Radiologic outcomes indicated good bony fusion and construction stability in all patients without implant failure at the last follow-up. No neural or vascular complications related to this technique were observed., Conclusions: Posterior atlantoaxial fixation using C1 titanium cables and C2 pedicle screw-rod construct appears to be an effective and safe technique for treatment of atlantoaxial instability, which could be an alternative method for cases unsuitable for C1 screw placement when using C1-C2 screw fixation., (Copyright © 2018 Elsevier Inc. All rights reserved.)

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

Background: This study aimed to investigate whether the presence of low bone mineral density (BMD) in patients with axial spondyloarthritis (axSpA) predicts formation of new syndesmophytes over 2 years., Methods: One hundred and nineteen patients fulfilling the imaging arm of the Assessment of SpondyloArthritis International Society axSpA criteria were enrolled. All patients were under 50 years of age. The modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS) was assessed by two trained readers blinded to the patients' data. BMD (lumbar spine, femoral neck or total hip) at baseline was assessed using dual-energy absorptiometry. Low BMD was defined as Z score ≤ - 2.0. Spinal radiographic progression was defined as worsening of the mSASSS by ≥ 2 points over 2 years. Logistic regression analyses were performed to identify predictors associated with development of new syndesmophytes and spinal radiographic progression., Results: At baseline, 19 (16%) patients had low BMD. New syndesmophytes had developed in 22 (21%) patients at 2-year follow-up. New syndesmophyte formation after 2 years occurred more in patients with low BMD than in those with normal BMD (p = 0.047). In the multivariable analysis, current smoking, existing syndesmophytes and low BMD at baseline were associated with spinal radiographic progression (OR (95% CI) 3.0 (1.1, 7.7), 4.6 (1.8, 11.8) and 3.6 (1.2, 11.2), respectively). The presence of syndesmophytes at baseline and low BMD were predictors of new syndesmophytes over the following 2 years (OR (95% CI) 5.5 (2.0, 15.2) and 3.6 (1.1, 11.8), respectively)., Conclusions: Low BMD and existing syndesmophytes at baseline were independently associated with the development of new syndesmophytes in young axSpA patients.

Background: In the present study, we investigated bone geometry, microstructure, and volumetric bone mineral density (vBMD) in a cohort of patients with nonradiographic axial spondyloarthritis (nr-axSpA) in order to define the early bone changes occurring in axial spondyloarthritis (axSpA) and to define potential factors for deterioration of bone microstructure., Methods: Patients with axSpA (n = 107) and healthy control subjects (n = 50) of similar age and sex were assessed for geometric, volumetric, and microstructural parameters of bone using high-resolution peripheral quantitative computed tomography (HR-pQCT) at the radius. Additionally, demographic and disease-specific characteristics of patients with axSpA were recorded., Results: Patients with nr-axSpA and control subjects were comparable in age, sex, and body mass index. Geometric and microstructural analysis by HR-pQCT revealed a significantly reduced cortical area (p = 0.022) and cortical thickness (p = 0.006) in patients with nr-axSpA compared with control subjects. Total and cortical vBMD were significantly reduced in patients with nr-axSpA (p = 0.042 and p = 0.007, respectively), whereas there was no difference in trabecular vBMD. Patients with a short disease duration (< 2 years; n = 46) also showed significant reduction of cortical thickness and cortical area compared with control subjects. Patients with disease duration > 2 years (n = 55) additionally developed a decrease of cortical and total vBMD. Multiple regression models identified male sex to be associated with lower cortical vBMD and female sex to be associated with lower trabecular vBMD., Conclusions: Bone microstructure in patients with nr-axSpA is characterized primarily by deterioration of cortical bone. Cortical bone loss starts early and is evident within the first 2 years of the disease.

Objective: The study used a 3D digitizer to determine three-dimensional motion analysis of the 2nd cervical (C2) spinous process at end range cervical rotation with the scapula in different positions., Methods: 30 healthy adults participated in this study. Different scapula positions were adopted bilaterally and positioned passively at normal resting, depression, adduction, and abduction. Under each scapula position, bilateral end range cervical rotation and displacement of the C2 spinous process were analyzed by a 3D digitizer., Results: Displacement of the C2 spinous process relative to the occiput was significantly correlated with range of cervical rotation under all scapular positions (p<0.05). However, there were no significant differences between end range cervical rotation and displacement of the C2 spinous process relative to the occiput in any scapular position., Conclusion: These results suggest that measurement of upper cervical mobility using the 3D digitizer is a reliable method that holds promise in the evaluation of people with cervical spine disorders.

VA anomalies in extra- and intraosseous regions of the craniovertebral junction (CVJ) is considered very carefully during the posterior screw fixation for the atlantoaxial instability (AAI). This study aims to compare the incidence and variations of VA anomalies, isthmus and pedicle size of C2 in 100 patients with AAI due to congenital skeletal anomaly (CSA) and acquired disease by using three-dimensional CT angiograms (3D CTA) before surgery. The CSA group contained 48 patients and the acquired disease group consisted of 52. In the CSA group, Os odontoideum was the major cause with 43 patients. The causes of acquired disease were RA in 16 patients and OA in 36 patients. Five patients had the anomalous VA in only CSA group; fenestration 2 patients and persistent first intersegmental (PFIS) artery 3 patients. Between CSA and acquired disease groups, no significant differences were found in the isthmus height, internal height, and pedicle width of C2 except the right internal height that is bigger in CSA group. The high-riding VA (isthmus height <4 mm or internal height <2 mm) had no significant difference between CSA group (27.1%) and acquired disease group (34.6%). However, in acquired disease group, patients with rheumatoid arthritis had smaller left internal height (4.21 ± 1.63 vs. 5.51 ± 1.83 mm) and pedicle width (4.11 ± 1.05 vs. 5.05 ± 1.66 mm) of C2 than those of patients with degenerative osteoarthritis. Therefore, in the case of atlantoaxial fusion, we should contemplate VA anomaly and the high-riding VA, especially in patients with CSA and RA., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Case: A 35-year-old man was involved in a motor-vehicle collision and sustained multiple thoracoabdominal and extremity injuries. A high injury burden and a normal neurologic examination contributed to a delay in diagnosing a ligamentous, combined atlanto-occipital dissociation (AOD) and vertical atlantoaxial injury (AAI). Additional imaging revealed the combined injury, and the patient underwent an occipitocervical fusion., Conclusion: To our knowledge, this is the first case of a simultaneous traumatic AOD and AAI without fracture in a neurologically intact patient. Knowledge of reliable and easily applied radiographic relationships is important to expeditiously diagnose potentially lethal yet easily overlooked occipitocervical injuries.

Background: Axis (C2) screw fixation has been shown to be effective in treating disorders that necessitate cervical stabilization. Although translaminar C2 screws have demonstrated clinical efficacy in adults, this technique has not yet been thoroughly investigated in children. This study describes the indications, technique, and results of translaminar C2 screw fixation in a case series of pediatric cervical spine disorders., Methods: We searched the orthopaedic database at our institution for patients who had undergone a cervical spinal fusion that encompassed C2 between 2007 and 2017. Operative records were reviewed to determine if C2 screw fixation was performed and, if so, the type of C2 screw fixation. Clinical data with regard to patient age at surgery, diagnosis, procedure details, intraoperative complications, and postoperative complications were recorded. Preoperative and postoperative computer tomographic scans were reviewed to determine laminar measurements and containment, respectively., Results: In total, 39 C2 translaminar screws were placed in 23 patients that met our inclusion criteria. The mean age was 12.6 years (range, 5.2 to 17.8 y) with a mean of 2 levels fused (range, 1 to 6). Diagnoses included 7 patients with instability related to skeletal dysplasia, 6 os odontoideum, 4 congenital deformities, 3 basilar invaginations, 2 cervical spine tumors, and 1 fracture. Indications for C2 translaminar screws included 14 cases with distorted anatomy favoring C2 translaminar screws, 6 cases without explicit reasoning for translaminar screw usage in the patient records, and 3 cases with intraoperative vertebral artery injury (1 sacrificed secondary to tumor load and 2 others injured during exposure because of anomalous anatomy). The vertebral artery injuries were not due to placement of any instrumentation. There were no screw-related intraoperative or postoperative complications and no neurological injuries. All patients demonstrated clinical union or healing on follow-up with no episodes of nonunion., Conclusions: Translaminar C2 screw fixation can be reliably used in the pediatric population. Our series contained no screw-related complications, no neurological injuries, and all patients demonstrated clinical union or healing., Level of Evidence: Level IV-Case series.

Purpose: There are two theories about the origin of os odontoideum: traumatic or congenital. However, most studies favor the hypothesis of traumatic theory. To emphasize the congenital theory, we report a pair of identical twins both with atlantoaxial dislocation and os odontoideum, which is believed to be a congenital defect., Methods: We present two 14-year-old identical twins with atlantoaxial dislocation and os odontoideum. Neither of the twins had history of trauma in head nor cervical spine. We reviewed and compared the cervical radiographs of the identical twins. Posterior atlantoaxial reduction, pedicle screw fixation and atlantoaxial fusion were performed for the two twins., Results: Radiological examination showed the identical twins had typical atlantoaxial dislocation and os odontoideum. The twins had high similarity in the appearance of atlantoaxial dislocation and os odontoideum. The etiology of the os odontoideum in the twins is believed to be congenital. Both the twins had improvement in neurological function after surgery., Conclusion: Although a great number of cases with os odontoideum have been reported to be traumatic, there are some cases believed to be congenital.

Objective: Fixation with the axis vertebra (C2) using pedicle screws is commonly used to treat an unstable occipitocervical junction; however, it is accompanied by a risk of vertebral artery injury. The occiput-C2 (OC2) crossing translaminar screw fixation technique may avoid this risk, but rod implantation is difficult. Offset connectors can help facilitate this construct. This study aimed to evaluate the stability of a technique for OC2 crossing translaminar screw fixation using offset connectors (C2LAM + OF) in comparison with other methods., Patients and Methods: Six fresh-frozen human cadaveric occipital-cervical spines were tested intact under flexion, extension, lateral bending, and axial rotation. These were then made into a type II odontoid fracture model, instrumented with an occipital plate, and tested in the following modes: C2 bilateral pedicle screws (C2P), a single C2 pedicle screw and bilateral C3 lateral mass screws (C2P + C3M), C2 crossing translaminar screws (C2LAM), and C2LAM + OF. The OC2 range of motion (ROM) for each construct was obtained and compared using a repeated-measures analysis., Results: The ROM of the C2LAM + OF construct was found not to be significantly different from that of the C2P and C2P + C3M fixations in every direction (p > 0.05). However, the C2LAM + OF construct was superior to the C2LAM construct in axial rotation (p < 0.05)., Conclusions: OC2 crossing translaminar screw fixation using offset connectors offers similar stability to C2 pedicle screw fixation and is an effective alternative method for treating an unstable occipitocervical junction., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Introduction: Paediatric cervical spine injuries are uncommon. Traumatic spondylolisthesis of the axis (TSA) is commonly encountered in the trauma setting. The management of TSA may be surgical or non-surgical. Decision making is quite challenging depending on patient presentation and nature of injury, and even more so in the paediatric age group., Objectives: To present a case report highlighting the challenges in the management of TSA., Methods: We present an 8 year old male, who sustained a bilateral C2 pars fracture with associated unusual C2-C3 posterior subluxation., Results: Neuroradiological studies identified the fracture/subluxation of C2-C3 and revealed an intact but posteriorly displaced C2-C3 disc causing cord compression. An Extension Halter traction was initially commenced. This seemed to have worsened the patient's neck pains, and caused motor weakness and autonomic dysfunction. An anterior cervical discectomy and fusion was finally decided on and performed after evaluation and brainstorming by our spinal Unit. Intra-operative findings revealed separation of the C2-C3 disc from the C3 superior end plate which probably explains the unusual nature of the subluxation., Conclusion: The case shows that surgical intervention as a primary management for TSA even in the paediatric age group is safe and also avoids risks inherent in conservative management.

Objective: The demographic change in the population leads to a rising number of patients presenting with fractures of the cervical spine, especially C-2, due to falls. With an increase of co-morbidities in these elder patients, the risk for intra- and postoperative complications is increased likewise. Thus, an alternative strategy instead of operative management of these fractures should be taken into account whenever possible. Conservative management of dens fractures in the elderly is still a subject of great controversy despite numerous studies on this topic. The aim of this study was to analyze the rate of successful osseous consolidation of C-2 fractures with conservative treatment by wearing a semi-rigid collar or halo thoracic vest without further surgical intervention., Patients and Methods: We analyzed the medical records and CT-scan of the cervical spine of 254 patients with C-2 fractures retrospectively, who were admitted to our department between January 1990 and September 2015. Fractures were diagnosed by CT-scan of the cervical spine and classified according to the Anderson - D`Alonzo classification. 183 patients were submitted to surgery as treatment of choice. In 71 patients a conservative management with external immobilization was chosen. The latter group was subjected to study analysis., Results: 71 patients (mean age 74.08 years ± 16.06 years) were diagnosed with C-2 fractures (Typ I: 4; Typ II 36; Typ III: 31) and treated conservatively using a Philadelphia collar (n = 57), or a halo-thoracic vest (n = 14), respectively. 12 patients were lost to follow up and excluded from further analysis. Conservative treatment of the fractures was deemed successful when a bony consolidation of the fracture in follow-up CT scans was seen (45 of 59 patients; 76.3%). 20 patients with a Type II fracture (20/28, 71.4%) showed a successful ossification. In 14 patients (overall 23.7%; Typ I: 1 (7.14%), Typ II: 8 (57.14%), Typ III: 5 (35.71%)) external immobilization failed to achieve primary stability. These patients were submitted to consecutive surgery., Conclusion: From our data it can be concluded that elderly patients, presenting with non-dislocated Type II fractures of the axis without accompaining neurological deficits, will have a more than 70% chance for a bony consolidation by conservative management. Consolidation rates may be estimated even higher in Type I and III fractures. Therefore, we suggest that external immobilization might be a valuable option to treat elderly patients with these fractures under certain circumstances., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Objective: We report our experience with surgery in 50 patients with C2 neurinomas. The anatomic subtleties of these discrete forms of tumors and their surgical implications are analyzed., Methods: During the period 2006-2016, we operated on 50 patients with 55 C2 neurinomas. Type A tumors were located within the spinal canal, type B tumors were located in the lateral gutter, and type C tumors had a paraspinal extension. By working within the dural confines of the tumor and appropriately angulating the microscope, the entire tumor bulk extending into 1 or all 3 compartments was resected. Follow-up duration ranged from 3 months to 10 years (mean 68 months)., Results: This series included 36 male and 14 female patients. Age range of patients was 14-70 years (mean age 36 years). Progressive symptoms of myelopathy were present in 41 patients. There were 16 type A + B tumors, 27 type B tumors, 10 type B + C tumors, and 2 type A + B + C tumors. All patients experienced symptom improvement after surgery and were able to resume their normal lifestyle., Conclusions: C2 neurinomas arise in the region of the C2 ganglion, and despite the fact that some achieve a large size, they remain confined within the dura. Radical tumor resection can be achieved by working within the layers of the dural cover. Bone removal and opening of spinal dura for tumor exposure and resection can be avoided., (Copyright © 2017 Elsevier Inc. All rights reserved.)