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Case: Odontoid fractures with atlantoaxial dislocations are rare injuries. We report a case of a 41-year-old man with a Type 2 odontoid fracture with locket facet and posterolateral dislocation. He underwent single-stage C1-C4 posterior fixation and fusion, and at 2-year follow-up, he is symptom-free without any residual pain. Follow-up radiograph and CT scan show healed odontoid fracture with posterior fusion., Conclusion: This case highlights successful management of a complex odontoid fracture by a single-stage posterior surgery. Closed reduction is usually unsuccessful, and open reduction using posterior approach is preferable., Competing Interests: Disclosure: The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJSCC/C422)., (Copyright © 2024 by The Journal of Bone and Joint Surgery, Incorporated.)

Study Design: Retrospective study., Objective: To classify surgical failures following atlantoaxial dislocation, present strategies for revisions, and evaluate the clinical results of revision surgery., Summary of Background Data: With the increase in atlantoaxial dislocation surgery, the number of surgical failures has gradually risen. However, current reports on atlantoaxial surgical revision are limited in scope. There remains a lack of summary regarding the causes of surgical failure, a detailed classification system, and no proposed strategy for revision surgery., Materials and Methods: A total of 109 cases of failed surgery following atlantoaxial dislocation were classified according to the reduction immediately after surgery and the fusion status before revision. The reduction, decompression, fusion status, and outcomes following revision surgery were evaluated by x-ray, computed tomography, magnetic resonance imaging, and the Japanese Orthopaedic Association score. The data were analyzed statistically with a paired-samples t test and multivariable logistic regression analysis., Results: The 109 patients were classified into three categories of failure: nonreduction with nonfusion (NR-NF, 73 cases), nonreduction with fusion (NR-F, 19 cases), and reduction with nonfusion (R-NF, 17 cases). Sixty-four patients underwent anterior revision, 21 posterior revision, and 24 anteroposterior revision. Postoperative complications were the primary cause of early revisions. After revision, complete decompression was achieved in all cases, anatomical reduction in 89 cases, significant improvement of Japanese Orthopaedic Association score in 77 cases, and fusion achieved in 86 cases. Twelve cases experienced surgical complications and three underwent a second revision., Conclusions: The authors found that NR-NF was the most common type of failure following surgery for atlantoaxial dislocation. Revision strategies can be guided according to the descriptive classification of failure, and revision surgery should focus on achieving adequate reduction, appropriate fixation, and reliable fusion to optimize postsurgical outcomes., Competing Interests: The authors report no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Background: The clinical diagnosis of atlantoaxial joint subluxation (AJS) in traditional Chinese medicine (TCM) is characterized by an unequal distance between the lateral mass of the atlas and the odontoid process on imaging, resulting in neck pain accompanied by symptoms such as dizziness, headache, and limited cervical mobility. In Shanghai, Shi cervical rotational manipulation (SCRM) is a commonly employed TCM manual therapy for treating this condition. Nevertheless, there is a lack of evidence-based medical information regarding the clinical efficacy and safety of this technique., Objective: The principal aim of this study is to evaluate the efficacy and safety of SCRM in patients diagnosed with AJS., Methods: This study is a prospective randomized controlled clinical trial that will be conducted at a single center and that has a follow-up period of 24 weeks. A total of 96 patients diagnosed with AJS will be recruited from outpatient and inpatient clinics at Shanghai Baoshan Hospital of Integrated Traditional Chinese and Western Medicine. These patients will be randomly assigned to either the experimental group (SCRM) or the comparison group (basic cervical manipulation [BCM]). Treatment sessions consisting of SCRM or BCM will be administered twice a week for a duration of 4 weeks. Clinical monitoring indicators include the presence or absence of clinical symptoms as recorded on a symptom recording form, cervical imaging examination findings using cervical computed tomography, degree of neck pain measured by a visual analog scale (VAS), cervical range of motion assessed through cervical mobility measurement, degree of vertigo evaluated using the Vertigo Symptoms Scale-Chinese Version (VSS-C), and adverse events that may occur during the follow-up period. The time points for data collection and follow-up are baseline and postintervention (weeks 4, 8, 12, 16, 20, and 24)., Results: This paper presents an overview of the reasoning and structure of a prospective randomized controlled trial with the objective of investigating the clinical efficacy and safety of SCRM in patients with AJS by assessing improvements in clinical symptoms, neck pain severity, and vertigo severity and evaluating changes in cervical imaging findings. Recruitment was started in March 2023. By the end of May 2024, 76 patients were included in this project. The last follow-up data are predicted to be collected by the end of February 2025., Conclusions: This investigation will yield dependable evidence regarding the efficacy and safety of SCRM in patients with AJS., Trial Registration: Chinese Clinical Trial Registry ChiCTR2300068510; https://www.chictr.org.cn/showprojEN.html?proj=186883., International Registered Report Identifier (irrid): DERR1-10.2196/57865., (©Deng Zhen, Shang Haibin, Ai Youli, Yuan Weian, Wang Huihao, Zhan Hongsheng, Li Guozhong, Ding Ren, Shen Zhibi. Originally published in JMIR Research Protocols (https://www.researchprotocols.org), 13.08.2024.)

Purpose: To evaluate the clinical feasibility of atlantoaxial intra-articular cage (AIC) fusion via intermuscular approach for treating reducible atlantoaxial dislocation (AAD)., Methods: An analysis was conducted on the data of 10 patients who underwent C1-C2 segmental fixation and AIC fusion for AAD by unilateral intermuscular approach and contralateral open approach. Outcome assessments included Japanese Orthopaedic Association score (JOA) and Visual Analog Scale Score for Neck Pain (VASSNP). The duration of surgical exposure, screw insertion and cage insertion, and postoperative drainage volume were also compared between two approaches. Bone fusion was evaluated through computed tomography (CT) reconstruction. Postoperative paravertebral tissue edema was evaluated by paravertebral tissue cross-sectional area (CSA) and signal intensity on T2 weighted sequence of magnetic resonance imaging (MRI) at 3 days postoperatively., Results: The intermuscular approach exhibited a longer exposure time but lower drainage postoperatively compared to the open approach (P < 0.05). After operation, JOA scores significant improved (P < 0.05), while VASSNP scores significantly decreased (P < 0.05). There was no significant difference in preoperative CSA between two approaches (P > 0.05). However, compared to the open approach, the intermuscular approach exhibited less CSA (P < 0.05) and lower T2 signal intensity on MRI postoperatively, indicating less invasive to the paravertebral tissues., Conclusions: AIC fusion by intermuscular approach is an effective and safe technique in the treatment of reducible AAD. Intermuscular approach could reduce the postoperative drainage volume and the extent of paravertebral tissue edema compared to open approach., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Study Design: This is a narrative review and case report., Objective: To review the literature concerning Grisel syndrome physiopathology, diagnosis, and surgical reports, highlighting the decision-making for treatment and its timing. We describe the role of intraoperative US in the management of 2 cases of GS of the adult., Summary of Background Data: GS is a rare nontraumatic post inflammatory C1-C2 rotatory instability usually affecting children; adult cases are even rarer, and the role of surgical treatment is not well defined., Case Discussion: Case 1: A 72-year-old man with upper cervical pain and no neurological deficit; radiologic examination revealed C1-C2 spondylitis and epidural abscess. After antibiotic therapy, the patient developed cervical instability. Hence, surgical decompression and C1-C2 stabilization were performed. Case 2: An 82-year-old woman with progressive right hemiparesis. CT and MRI showed C1-C2 spondylitis with retro-odontoid epidural abscess. Atlanto-axial rotatory instability was evident so surgery was achieved. In both cases, intraoperative US was useful for localizing retro-odontoid abscess and allowing safe puncture of the collection, leading to its remarkable radiologic reduction., Conclusion: GS in adults remains a challenge: Patients should be closely monitored concerning neurological and inflammatory status. We describe the successful use of intraoperative US for draining retro-odontoid abscess for the first time, with satisfactory postoperative outcome without need of circumferential approach., Competing Interests: The authors declare no conflict of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Background: This is a report of a series of 14 patients who presented with a range of "atypical" cranial, spinal, and systemic symptoms that started after they suffered a relatively severe injury to the head and/or neck several months or years before surgical treatment. The implications of diagnosing and treating central or axial atlantoaxial dislocation (CAAD) is discussed. Also, the role of dynamic rotatory and lateral head tilt imaging in the diagnosis and treatment is analyzed., Methods: Of the 14 patients, 7 were men and 7 were women, with an age range of 21-64 years (average, 42 years). Due to the severity of the presenting neurological and non-neurological symptoms, all the patients had lost their occupation and were heavily dependent on painkillers and/or antidepressant drugs. In addition to other characteristic clinical and radiological evidence, CAAD was diagnosed made based on the facet alignments on lateral profile imaging in the neutral head position. Dynamic head flexion-extension, lateral head tilt, and neck rotation imaging findings confirmed and subclassified CAAD. All 14 patients underwent atlantoaxial fixation surgery., Result: A personalized self-assessment clinical scoring parameter and the World Health Organization Disability Assessment Schedule 2.0 was used to evaluate the outcome. One patient did not follow-up after surgery. At a minimum follow-up of 6 months after atlantoaxial fixation surgery, the remaining 13 patients experienced relief from all major symptoms., Conclusions: Diagnosing and treating CAAD can have major therapeutic implications for patients presenting with progressively worsening disabling clinical symptoms following relatively severe head and/or neck trauma., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The paper discusses a case of a 58-year-old male suffering from a destructive process affecting the cranial bone and craniovertebral junction. A pathological fracture of the axial vertebrae led to a progressing atlantoaxial dislocation combined with pain syndrome and orthopedic disturbances. After symptom assessment, he was diagnosed to have developed the Gorham-Stout disease (GSD), a rare syndrome accompanied by massive osteolysis. The paper considers GSD etiology and observes the main pathogenetic theories.

Objective: To develop posterior reduction forceps for atlantoaxial dislocation and evaluate the preliminary clinical application of this forceps in assisting simple posterior screw-rod system reduction and fixation in the treatment of irreducible atlantoaxial dislocation., Methods: Based on the posterior atlantoaxial screw-rod system, posterior reduction forceps was developed to assist simple posterior screw-rod system for the treatment of irreducible atlantoaxial dislocation. From January 2021 to October 2022, 10 cases with irreducible atlantoaxial dislocation were treated with this technique. The Japanese Orthopaedic Association (JOA) score was applied before and after surgery to evaluate the neurological status of the patient, and the Atlanto-dental interval (ADI) was measured before and after surgery to evaluate the atlantoaxial reduction. X-ray and CT were performed to evaluate internal fixation, atlantoaxial sequence and bone graft fusion during regular follow-up. MRI was performed to evaluate the status of atlantoaxial reduction and spinal cord compression after surgery., Results: All 10 patients were successfully operated, and there were no complications such as spinal nerve and vascular injury. Postoperative clinical symptoms were significantly relieved in all patients, and postoperative JOA score and ADI were significantly improved compared with those before surgery (P < 0.05)., Conclusions: The developed posterior reduction forceps for atlantoaxial dislocation can assist the simple posterior screw-rod system in the treatment of irreducible atlantoaxial dislocation to avoid the release in anterior or posterior approach and reduce the difficulty of surgery. The preliminary results of this technique are satisfactory and it has a good application prospect., (© 2024. The Author(s).)

Purpose: To evaluate the efficacy of calvarial graft (CG) in craniovertebral fusion procedures in children at a single single center., Methods: Paediatric patients in whom CG had been used as the sole construct, or to augment a semi-rigid construct were identified from a prospective operative database. Age, underlying diagnosis and clinical presentation were obtained from review of the electronic patient record. The primary outcome was bony fusion confirmed on CT. Additional outcome measures were donor site morbidity and need for further surgery., Results: From 82 paediatric CVJ procedures, CG was used in 15 patients with a mean age of 4.1 (± 3.52) years. Aetiology comprised skeletal dysplasia (n = 12), congenital anomaly of segmentation (n = 1) and cervical trauma (n = 2). Myelopathy was the most common clinical finding (9/15), followed by cervical pain (3/15). The indications for surgery comprised atlanto-axial subluxation (8/15), basilar invagination with compression (2/15), and cervicomedullary compression without instability but deemed at risk of instability following decompression (4/15). CG was used in three scenarios: (i) CG + wire only (n = 10); (ii) CG + semirigid instrumentation (n = 3); (iii) CG to augment rigid instrumented fixation (n = 2). In 13 patients a Halo-body Jacket was used peri-operatively. At a mean time of 4.4 months following surgery, 80% of cases had radiological evidence of fusion., Conclusion: Full thickness calvarial bone graft is readily available, has good structural integrity and is associated with minimal donor site morbidity. CG should be considered for use as a sole construct, or to augment semi-rigid constructs when instrumented fixation is precluded., (© 2024. Crown.)

Objective: To investigate (1) lateral atlantoaxial articulation (LAA) morphology in patients with basilar invagination (BI) with atlantoaxial dislocation (AAD) and healthy individuals and its relationship with the severity of dislocation and (2) the effect of the LAA morphology on reduction degree (RD) after surgery., Methods: In this retrospective propensity score matching case-control study, imaging and baseline data of 62 patients with BI and AAD from 2011 to 2022 were collected. Six hundred thirteen  participants without occipitocervical junctional deformity served as controls. Logistic regression and receiver operating characteristic (ROC) curve were used for analysis., Results: The age, BMI and sex did not differ significantly between the two groups after propensity score matching. Sagittal slope angle (SSA) and coronal slope angle (CSA) was lower and greater, respectively, in the patient group than in the control group. A negative SSA value usually indicates anteverted LAA. Regression analysis revealed a significant negative correlation between SSA and severity of dislocation. However, no relationship was found between CSA and the severity of dislocation. The multivariate logistic regression analysis revealed that minimum-SSA emerged as an independent predictor of satisfactory reduction (RD ≥ 90%). The ROC curve demonstrated an area under the curve of 0.844, with a cut-off value set at -40.2., Conclusion: SSA in patients group was significantly smaller and more asymmetric than that in the control group. Dislocation severity was related to SSA but not to CSA. Minimum-SSA can be used as a predictor of horizontal RD after surgery., (© 2024. The Author(s).)

Traumatic posterior atlantoaxial dislocation (PAAD) without detection of a fracture of the upper cervical spine is a very rare injury that usually occurs in younger patients and in most cases leads to immediate death due to distraction of the spinal cord. In contrast, the present case describes this injury in a female geriatric patient at the age of 75 years. In the literature there are also clinical case reports, where traumatic PAAD without a fracture did not result in neurological deficits and where initially existing neurological deficits were completely reversible through closed or open reduction and internal fixation., (© 2024. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

In 1994, the use of interfacet spacer placement was for joint distraction, reduction, and fusion to supplement atlantoaxial or occipitocervical fixation. Here, we present a unique case of bilateral atlantoaxial interfacet fixation using cervical facet cages (CFC) in a pediatric patient with basilar invagination. In addition, we review the literature on atlantoaxial facet fixation. We present a 12-year-old boy with Wiedemann-Steiner syndrome who presented with multiple episodes of sudden neck jerking, described as in response to a sensation of being shocked, and guarding against neck motion, found to have basilar invagination with cervicomedullary compression. He underwent an occiput to C3 fusion with C1-C2 CFC fixation. We also conducted a literature review identifying all publications using the following keywords: "C1" AND "C2" OR "atlantoaxial" AND "facet spacer" OR "DTRAX." The patient demonstrated postoperative radiographic reduction of his basilar invagination from 6.4 to 4.1 mm of superior displacement above the McRae line. There was a 4.5 mm decrease in the atlantodental interval secondary to decreased dens retroflexion. His postoperative course was complicated by worsening of his existing dysphagia but was otherwise unremarkable. His neck symptoms completely resolved. We illustrate the safe use of CFC for atlantoaxial facet distraction, reduction, and instrumented fixation in a pediatric patient with basilar invagination. Review of the literature demonstrates that numerous materials can be safely placed as a C1-C2 interfacet spacer including bone grafts, titanium spacers, and anterior cervical discectomy and fusion cages. We argue that CFC may be included in this arsenal even in pediatric patients., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: Surgical treatment for atlantoaxial instability in pediatric patients is challenging. We report our experience with posterior intra-articular distraction technique in treating this disorder., Methods: This is a retrospective descriptive study which included 15 patients of atlantoaxial instability whose age was less than 16 years at the time of clinical presentation. All patients underwent anterior soft tissue released through a posterior-only approach, followed by intra-facet cage implantation, cantilever correction, and instrumentation. Clinical results were measured using the Japanese Orthopedic Association (JOA) scale and radiographic measurements including the atlantodental interval (ADI), posterior atlantodental interval (pADI), the distance of odontoid tip above Chamberlain's line, clivuscanal angle (CCA), and triangular area (TA) of craniovertebral junction., Results: The follow-up period ranged from 18 to 72 months, with an average of 41.2 ± 15.2 months. The JOA score increased from 13.6 ± 2.3 to 16.6 ± 0.8. ADI decreased from 4.31 ± 2.37 to 1.85 ± 1.09 mm, and TA decreased from 261.96 ± 107.99 to 197.12 ± 72.37 mm2. pADI increased from 12.89 ± 3.52 to 18.25 ± 3.89 mm, and CCA improved from 132.19 ± 16.34 to 144.35 ± 13.91°. All changes in measurements showed statistically significant. There were no evidence of surgery-related complications or iatrogenic secondary cervical deformity during follow-up. Radiological evaluation showed satisfactory corrections and bony fusions of C1-2 facet joint in all cases., Conclusion: Posterior intra-articular distraction followed by cage implantation and cantilever correction can be one of the safe and effective ways to solve atlantoaxial instability in pediatric patients., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Study Design: Multicenter case-control study., Objective: To identify imaging characteristics of the cervical spine in patients with retro-odontoid pseudotumor (ROP) without rheumatoid arthritis (RA) and determine the pathogenesis of ROP., Background: ROP results from proliferative changes in the soft tissue of the atlantoaxial junction surrounding the region of the transverse ligament, and is commonly seen in RA patients. However, the pathogenesis of ROP caused by mechanical instability of the upper cervical spine in patients without RA is yet to be explained., Materials and Methods: We collected imaging data [preoperative radiographs, magnetic resonance imaging (MRI), and computed tomography (CT)] of patients who underwent surgery between April 2011 and March 2022 at the three university hospitals for ROP (cases) and cervical spondylotic myelopathy (as age, sex, and institution matched controls). The two groups were compared for different parameters on cervical dynamic radiographs, MRI, and CT., Results: The ROP group consisted of 42 patients, and the control group comprised 168 patients. C2-C7 range of motion was significantly smaller in the ROP group (25.8 ± 2.6°) compared with the control group (33.0 ± 1.0°). C2-C7 sagittal vertical axis was significantly larger in the ROP group than the control group (39.3 ± 3.6 vs. 32.2 ± 1.3 mm). MRI and CT assessment showed progressive degeneration at all intervertebral levels in the ROP group. A significant positive correlation was observed between the thickness of the soft tissue posterior to the dental process and the atlantodental interval in the flexion position ( r = 0.501)., Conclusions: The development of ROP was associated with degeneration of facet joints and intervertebral disks in the middle and lower cervical spine. Our findings suggest that decreased mobility of the middle and lower cervical spine may cause instability in the upper cervical spine, leading to the formation of ROP., Competing Interests: The authors report no conflicts of interest., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc.)

Objective: Autologous iliac bone is commonly used as a bone graft material to achieve solid fusion in craniocervical junction (CVJ) surgery. However, the developing iliac bone of children is less than ideal as a bone graft material. The matured rib bone of children presents a potential substitute material for iliac bone. The aim of this study was to evaluate the efficacy of autologous rib grafts for craniocervical junction surgery in children., Methods: The outcomes of 10 children with abnormalities of the craniocervical junction who underwent craniocervical junction surgery between January 2020 and December 2022 were retrospectively reviewed. All patients underwent posterior fusion and internal fixation surgery with autologous rib grafts. Pre- and post-operative images were obtained and clinical follow-ups were conducted to evaluate neurological function, pain level, donor site complications, and bone fusion rates., Results: All surgeries were successful. During the 8- to 24-month follow-up period, all patients achieved satisfactory clinical results. Computed tomography at 3-6 months confirmed successful bone fusion and regeneration of the rib defect in all patients with no neurological or donor site complications., Conclusion: Autologous rib bone is a safe and effective material for bone grafting in craniocervical junction fusion surgery for children that can reduce the risks of donor site complications and increase the amount of bone graft, thereby achieving a higher bone fusion rate., (© 2024. The Author(s).)

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).)

Background Context: Studies have shown biomechanical superiority of cervical pedicle screw placement over other techniques. However, accurate placement is challenging due to the inherent risk of neurovascular complications. Navigation technology based on intraoperative 3D imaging allows highly accurate screw placement, yet studies specifically investigating screw placement in patients with traumatic atlantoaxial injuries are scarce. The aim of this study was to compare atlantoaxial screw placement as treatment of traumatic instabilities using iCT-based navigation or fluoroscopic-guidance with intraoperative 3D control scans., Methods: This was a retrospective review of patients with traumatic atlantoaxial injuries treated operatively with dorsal stabilization of C1 and C2. Patients were either assigned to the intraoperative navigation or fluoroscopic-guidance group. Screw accuracy, procedure time, and revisions were compared., Results: Seventy-eight patients were included in this study with 51 patients in the navigation group and 27 patients in the fluoroscopic-guidance group. In total, 312 screws were placed in C1 and C2. Screw accuracy was high in both groups; however, pedicle perforations > 1 mm occurred significantly more often in the fluoroscopic-guidance group (P = 0.02). Procedure time was on average 23 min shorter in the navigation group (P = 0.02)., Conclusions: This study contributes to the available data showing that navigated atlantoaxial screw placement proves to be feasible as well as highly accurate compared to the fluoroscopic-guidance technique without prolonging the time needed for surgery. When comparing these data with other studies, the application of different classification systems for assessment of screw accuracy should be considered., (© 2024. The Author(s).)

Purpose: This study aimed to investigate the association between unilateral high-riding vertebral artery (HRVA) and morphological changes in the atlantoaxial joint (AAJ) and to determine whether unilateral HRVA is a risk factor for atlantoaxial osteoarthritis (AAOA)., Methods: We conducted a retrospective analysis of 2496 patients admitted to our medical center between January 2020 and December 2022 who underwent CT imaging of the cervical spine. Two hundred and seventy-two patients with unilateral HRVA (HRVA group) were identified and a respective 2:1 age- and sex-matched control group without HRVA was built. Morphological parameters, including C2 lateral mass settlement (C2 LMS), C1/2 coronal inclination (C1/2 CI), lateral atlanto-dental interval (LADI), and C1/2 relative rotation angle (C1/2 RRA) were measured. The degree of AAOA was recorded. Risk factors associated with AAOA were identified using univariate and multivariable logistic regression analyses., Results: The study included 61.4% women, and the overall average age of the study population was 48.7 years. The morphological parameters (C2 LMS, C1/2 CI, and LADI) in AAJ were asymmetric between the HRVA and the non-HRVA sides in the HRVA group (p < 0.001). These differences in parameters (d-C2 LMS, d-C1/2 CI, and d-LADI) between the HRVA and the non-HRVA sides, and C1/2 RRA were significantly larger than those in the control group. Eighty-three of 816 patients (10.2%) with AAOA had larger values of d-C2 LMS, d-C1/2 CI, d-LADI, and C1/2 RRA compared with the patients without AAOA (p < 0.05). The multivariable logistic regression analysis indicated that unilateral HRVA [adjusted odds ratio (OR) = 2.6, 95% CI: 1.1-6.3, p = 0.029], age in the sixth decade or older (adjusted OR = 30.2, 95% CI: 16.1-56.9, p < 0.001), women (adjusted OR = 2.1, 95% CI: 1.0-5.6, P = 0.034) were independent risk factors for AAOA., Conclusion: Unilateral HRVA was associated with asymmetric morphological changes of nonuniform settlement of C2 lateral mass, lateral slip of atlas, and atlantoaxial rotation displacement. Besides age ≥ 60 years and females, unilateral HRVA is an independent risk factor for AAOA., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Nablus mask-like facial syndrome (NMFLS) is an extremely rare genetic syndrome characterized by facial dysmorphia as well as developmental delay. In the present report we describe a potential association between non-traumatic atlanto-occipital dislocation and NMFLS in an 11-year old female lacking typical facial features of NMFLS., Case Description: An 11-year-old female with autism presented with symptoms of persistent headache and vomiting as well as neck stiffness. Further investigation and CT imaging revealed congenital malformation of the skull base and craniocervical junction with complete posterior subluxation of the left occipital condyle. MRI findings later corroborated the findings on CT., Conclusions: The patient was successfully treated with occipitocervical fusion. The findings in this case suggest the possibility that atlanto-occipital instability and generalized occipitocervical may be associated with NMFLS., Competing Interests: Declaration of Competing interest report no conflicts of interest. The authors alone are responsible for the content and writing of the article., (Copyright © 2024 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

We report the case of a 3-year-old child with Loeys-Dietz syndrome, a rare genetic connective tissue disorder. The young girl had concurrent cervical kyphosis, atlantoaxial dislocation (AAD), and spinal cord compression. Posterior occipitocervical fusion was performed. Postoperative examination and clinical manifestations confirmed that all pedicle screws were satisfactorily placed, cervical kyphosis and AAD were corrected, and spinal cord compression was relieved. At the 1-year postoperative follow-up, the patient had recovered well, indicating that our operation was successful. To the best of our knowledge, this is the first reported surgical case of cervical kyphosis and AAD caused by Loeys-Dietz syndrome., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Objetive: This study aims to introduce the unilateral biplanar screw-rod fixation (UBSF) technique (a hybrid fixation technique: 2 sets of atlantoaxial screws were placed on the same side), which serves as a salvage method for traditional posterior atlantoaxial fixation. To summarize the indications of this technique and to assess its safety, feasibility, and clinical effectiveness in the treatment of odontoid fractures., Methods: Patients with odontoid fractures were enrolled according to special criteria. Surgical duration and intraoperative blood loss were documented. Patients were followed up for a minimum of 12 months. X-ray and computerized tomography scans were conducted and reviewed at 1 day, and patients were asked to return for computerized tomography reviews at 3, 6, 9, and 12 months after surgery until fracture union. Recorded and compared the Neck Visual Analog Scale and Neck Disability Index presurgery and at 1 week and 12 months postsurgery., Results: Between January 2016 and December 2022, our study enrolled 7 patients who were diagnosed with odontoid fractures accompanied by atlantoaxial bone or vascular abnormalities. All 7 patients underwent successful UBSF surgery, and no neurovascular injuries were recorded during surgery. Fracture union was observed in all patients, and the Neck Visual Analog Scale and Neck Disability Index scores improved significantly at 1 week and 12 months postoperative (P < 0.01)., Conclusions: The UBSF technique has been demonstrated to be safe, feasible, and effective in treating odontoid fractures. In cases where the atlantoaxial bone or vascular structure exhibits abnormalities, it can function as a supplementary or alternative approach to the conventional posterior C1-2 fixation., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Introduction: Down syndrome is the most common chromosomal abnormality associated with intellectual impairments. Unexpected deaths are common with this disease. There are certain difficulties in clarifying the cause of death because the manifestations may be quite diverse and involve many organ systems. Atlantoaxial subluxation is a dangerous complication of Down syndrome, as it may lead to cervical cord-medullary compression., Case Presentation: Herein, we present a case of Down syndrome in a patient who completely recovered from cardiac arrest due to atlantoaxial subluxation. The neck was immobilized during post-cardiac arrest care, and the patient underwent surgery after 14 days. The patient could walk independently and was discharged 3 months later. At the last follow-up 5 years after surgery, the patient's general condition was good., Discussion: Physicians should be aware that atlantoaxial instability can cause cardiac arrest in patients with genetic syndromes., (© 2024. The Author(s), under exclusive licence to International Spinal Cord Society.)

Purpose: This study presents an abnormality of the musculus rectus capitis posterior minor (RCPmi) as a new etiological factor for nontraumatic sagittal plane instability in the C0-C1-C2-complex, with a focus on identifying the absence or atrophy of RCPmi on both sides., Methods: A 36-year-old male patient presented with recurring neck pain (VAS 8/10) and tingling paresthesia in the entire left hand over a six-month period, without significant neurological deficits. Radiated arm pain was not reported. Imaging examinations revealed sagittal plane instability in the C0-C1-C2-complex, spinal canal stenosis (SCS), and myelopathy at the C1 level. Subsequently, a dorsal C0-1 reposition and fusion with laminectomy were performed., Results: The congenital absence or atrophy of RCPmi, leading to the lack of cephalad-rearward traction on the C1-tuberculum-posterius, induced a developmental failure of the C1 posterior arch. Consequently, the oblate-shaped C1 posterior arch lost support from the underlying C2 posterior arch and the necessary cephalad-rearward traction throughout the patient's 36-year life. This gradual loss of support and traction caused the C1 posterior arch to shift gradually to the anterior side of the C2 posterior arch, resulting in a rotational subluxation centered on the C0/1 joints in the sagittal plane. Ultimately, this led to SCS and myelopathy. Traumatic factors were ruled out from birth to the present, and typical degenerative changes were not found in the upper cervical spine, neck muscles, and ligaments., Conclusion: In this case, we not only report the atrophy or absence of RCPmi as a new etiological factor for nontraumatic sagittal plane instability in the C0-C1-C2-complex but also discovered a new function of RCPmi. The cephalad-rearward traction exerted by RCPmi on the C1 posterior arch is essential for the development of a normal C1 anterior-posterior diameter., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: To evaluate the difficulty of reduction of congenital atlantoaxial dislocation with or without os odontoideum or basilar invagination based on computed tomography (CT) quantitative analysis., Methods: From March 2018 to December 2022, the CT features of 108 patients with atlantoaxial dislocation with or without os odontoideum or basilar invagination were analyzed. Quantitative scores were defined according to imaging features, including sloping of the lateral mass; osteophyte between the lateral mass joint; ball-and-socket deformity of the lateral mass joint; vertical interlocking of the lateral mass joint; callus between the lateral mass joint; and atlanto-odontoid joint hyperplasia, blocking, or fusion. Grades were calculated according to the sum of points of the atlanto-odontoid joint and lateral mass joints, as follows: I, 0-1 points; Ⅱ, 2-3 points; Ⅲ, 4-6 points; IV, 7-10 points. After 1 week of bidirectional cervical traction, CT scans were performed, and atlantodens interval and vertical distance from dens to Chamberlain line were measured. The vertical reduction rate, horizontal reduction rate, and overall reduction rate of atlantoaxial dislocation were calculated., Results: The vertical distance from dens to Chamberlain line values after traction were significantly reduced compared with before traction, including grades I, II, III, and IV. The overall reduction rates were 85.1% ± 11.8%, 65.8% ± 8.3%, 45.0% ± 8.5%, and 38.4% ± 13.0% respectively, after 1 week of bidirectional cervical traction., Conclusions: The CT quantitative score system is an effective noninvasive evaluation to judge the reduction difficulty of atlantoaxial dislocation with or without os odontoideum or basilar invagination., (Copyright © 2023. Published by Elsevier Inc.)

Purpose: We evaluate the efficacy, safety and indications of single stage posterior release, reduction, and fixation of basilar invagination (BI) with irreducible atlantoaxial dislocation (IAAD)., Materials and Methods: Seventeen patients with BI and IAAD consecutively underwent one-stage release, reduction, and fixation by a posterior approach from July 2000 to June 2015 were followed up for at least 12 months. There were 8 males. Mean age was 56 35.2 ± 13.8 years (range 12-56). The clinical symptoms and signs of the patients were recorded. Pre- and postoperative imaging examinations were performed. Neurological function was assessed using the Japanese Orthopedic Association (JOA) and Ranawat scores., Results: Average follow-up time was 47.4 months (12-97 months). The JOA score increased from preoperative 4-10 (8.06 ± 2.52) to postoperative 13-16 (15.20 ± 0.62). The preoperative Chamberlain line, McRae line, Wackenheim line, atlantodens interval, and cervico medullary angle were 12.52 ± 5.17 mm, 6.59 ± 3.04 mm, 6.96 ± 4.32 mm, 9.88 ± 1.93 mm, and 115.35 ± 12.40°, respectively. The postoperative values were 2.0 ± 3.67 mm, -3.06 ± 1.85 mm, -1.76 ± 2.88 mm, 1.17 ± 1.18 mm, and 136.76 ± 11.44°, respectively., Conclusion: One-stage release, reduction, and fixation for patients with BI and IAAD through a posterior approach is safe and efficient.

Objective: Cable-dragged reduction and cantilever beam internal fixation can provide promising results in the treatment of atlantoaxial dislocation or instability. However, bilateral atlantoaxial joints bone autografting has not been conducted in this technique. We aim to evaluate the safety and effectiveness of bilateral atlantoaxial joints bone autografting in posterior cable-dragged reduction and cantilever-beam internal fixation., Methods: In this retrospective study, we included 14 patients with a minimum 24-month follow-up from December 2019 to September 2020. The granular bone harvested from the iliac crest was packed into the bilateral atlantoaxial joints of 14 patients in posterior cable-dragged reduction and cantilever-beam internal fixation. X-ray imaging and cervical computed tomography (CT) were performed during follow-up. The time required for bone fusion was recorded. The clinical outcomes were evaluated using the JOA scores, NDI, and VAS scores. Mann-Whitney U test, the chi-squared test, or the Fisher exact test were used to compare the two groups regarding patient characteristics, clinical outcomes, bone fusion rates, and cervical sagittal alignment., Results: The operations were successfully performed in all patients without any intraoperative complications. The mean operation time was (169.64 ± 20.91) minutes, and the intraoperative blood loss was (130.71 ± 33.62) mL. All patients received satisfactory reductions and firm bony fusion at the final follow-up. The fusion rates were 64.29% in the atlantoaxial joints and 21.43% in post bone graft area at 3 months postoperatively, and a significant difference was observed (p = 0.022). Besides, the cervical sagittal alignment in all patients was well maintained in the last follow-up compared to preoperatively. Importantly, a complete bony fusion in the atlantoaxial joints was observed in all patients. Moreover, the JOA, NDI, and VAS scores had improved significantly at the last follow-up., Conclusion: Bone autografting of the bilateral atlantoaxial joints is a safe and effective technique to increase bone fusion rates, shorten bone fusion time, and reduce complication rates when the cable-dragged reduction and cantilever beam internal fixation approach is used. Therefore, it is a cost-effective surgical procedure for treating patients with atlantoaxial dislocation or instability., (© 2024 The Authors. Orthopaedic Surgery published by Tianjin Hospital and John Wiley & Sons Australia, Ltd.)

Introduction: Os odontoideum refers to a rounded ossicle detached from a hypoplastic odontoid process at the body of the axis. The aetiology has been debated and believed to be either congenital or acquired (resulting from trauma). Os odontoideum results in incompetence of the transverse ligament and thus predisposes to atlantoaxial instability and spinal cord injury., Methods/results: Three cases of children with severe dystonic cerebral palsy presenting with myelopathic deterioration secondary to atlantoaxial instability due to os odontoideum are presented. This observation supports the hypothesis of os odontoideum being an acquired phenomenon, secondary to chronic excessive movement with damage to the developing odontoid process., Conclusion: In children with cerebral palsy and dystonia, pre-existing motor deficits may conceal an evolving myelopathy and result in delayed diagnosis of clinically significant atlantoaxial subluxation., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objective: Pediatric cervical spine injuries (CSI) can be devastating, and children < 8 years are particularly at risk for upper CSI given unique anatomical differences. Diagnosis of these injuries can be delayed due to variable clinical presentations and a paucity of existing literature. The authors aimed to characterize the spectrum of pediatric upper CSI., Methods: This was a retrospective, single-center case series of trauma patients aged < 16 years who were assessed at a level I pediatric trauma center and diagnosed with upper CSI between 2000 and 2020. Patients were included if they had evidence of bony or ligamentous injury from the occiput to C2 on imaging or autopsy. Data were obtained from manual chart review and analyzed using descriptive statistics., Results: In total, 502 patients were screened and 202 met inclusion criteria. Of these, 31 (15%) had atlanto-occipital (AO) joint distractions, 10 (5%) had atlanto-axial (AA) joint distractions, 31 (15%) had fractures of C1-2, and 130 (64%) had ligamentous injury without joint distraction. Of the patients with AO injury, 15 patients had complete dislocation. They presented as hemodynamically unstable with signs of herniation and 14 died (93%). In contrast, 16 had incomplete dislocation (subluxation). They usually had stable presentations and survived with good outcomes. Of the patients with AA injury, 2 had complete dislocation, presented with arrest and signs of herniation, and died. In contrast, 8 patients with subluxation mostly presented as clinically stable and all survived with little residual disability. The most common fractures of C1 were linear fractures of the lateral masses and of the anterior and posterior arches. The most common fractures of C2 were synchondrosis, hangman, and odontoid fractures. Overall, these patients had excellent outcomes. Ligamentous injuries frequently accompanied other brain or spine injuries. When these injuries were isolated, patients recovered well., Conclusions: Among upper CSI, AO and AA joint injuries emerged as particularly severe with high mortality rates. Both could be divided into complete dislocations or incomplete subluxations, with clear clinical differences and the former presenting with much more severe injuries. Lateral cervical spine radiography should be considered during resuscitation of unstable trauma patients to assess for these CSI subtypes. Fractures and ligamentous injuries were clinically heterogeneous, with presentations and outcomes depending on severity and associated injuries.

Atlanto-axial instability is a common disease that affects toy-breed dogs. Most cases of atlanto-axial instability are congenital. Furthermore, patients with atlanto-axial instability are predisposed to other concurrent diseases. Therefore, this study aimed to retrospectively determine the presence of concurrent diseases in cases with atlanto-axial instability using imaging data and analyze the relationship between clinical parameters and the incidence of complex malformations. The clinical data and imaging findings of 41 toy-breed dogs diagnosed with atlanto-axial instability were analyzed using their medical records and imaging data. Occipital dysplasia (17/27), atlanto-occipital overlapping (22/34), dens dysplasia (27/41), Chiari-like malformation (8/34), syringomyelia (5/34), lateral ventricular enlargement (20/36), and intracranial arachnoid cyst (5/35) were observed in patients with atlanto-axial instability. The body weight of the patients in the groups with atlanto-occipital overlapping and lateral ventricular enlargement was lower than that of those in the groups without these diseases (1.78 ± 0.71 vs 2.71 ± 1.15 kg, P = 0.0269, 1.60 ± 0.40 vs 2.75 ± 1.08 kg, P = 0.001, respectively). Furthermore, when the correlation between the total number of concurrent diseases and the age at onset and body weight was examined, it became clear that lower body weight was associated with the incidence of a greater number of concurrent diseases. Thus, the findings of this study suggest that toy-breed dogs are more likely to present with complex malformations and should be evaluated carefully with additional examinations and treatment methods., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Itoh et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Purpose: Craniocervical junction instability in a paediatric population presents a formidable challenge to the neurosurgeon. With a variety of anatomical variations, diminutive bony and ligamentous structures, possible superimposed syndromic abnormalities, the craniocervical junction is a technically challenging region to operate within. We aimed to review our series of patients to identify the common pathologies necessitating craniocervical fusion along with the use of intraoperative image guidance., Methods: We performed a retrospective review of twenty-one patients, with a mean age of 8.1 years, undergoing craniocervical fixations, involving either occipitocervical fusion or atlantoaxial fixation, from a single institution over a twelve-year period. The presentation, preoperative investigations, indication for surgery, surgical procedure, use of intraoperative navigation and clinical and radiological results were examined., Results: Twelve patients underwent primary C1-2 fixation, with the remaining 9 undergoing occipitocervical fusion. Five patients underwent surgery for traumatic instability, seven for os odontoideum, six for congenital anomalies and three for post-infectious instability. Follow up for 20 patients averaged 34 months (range 2-93 months). Five patients had Trisomy 21 and all underwent C1-2 fixation. Frameless stereotactic image guidance was utilised in five patients. No patients suffered immediate complications resulting from craniocervical junction fusion. Patients were observed to either neurologically improve ( n  = 6), or arrest their neurological deterioration following surgical intervention ( n  = 14), with concomitant radiological evidence of osseous fusion at follow up in 18 of 20 patients (90%). Two patients (10%) had radiological evidence of screw lucency, but neither required intervention because of being asymptomatic., Conclusions: Craniocervical fixation in a paediatric population is a viable and safe treatment modality for the management of disorders requiring stabilisation at the craniocervical junction. Our experience of utilising frameless stereotaxy in the setting of grossly distorted anatomical landmarks is also reported.

Purpose: We describe our experience with management of basilar invagination (BI) with the atlantoaxial dislocation (C1/C2) joint reduction technique, including posterior atlantoaxial internal fixation., Materials and Methods: From 2008 to 2018, eleven patients with atlantoaxial dislocation (AAD) and BI underwent surgical reduction using C1/C2 the joint reduction technique with a fibular graft/peek cage placement followed by C1 lateral mass/C2 pedicle screw fixation. In two cases that we originally planned to perform C1/C2 joint reduction, occiput-C2 pedicle screw fixation was performed instead due to intraoperative challenges. Post-operative course and surgical complications will be discussed., Results: A total of 13 patients, with an average age of 30.46 ± 13.23 years (range 12-57), were operated. In one patient, iatrogenic vertebral artery injury occurred without any neurological complication. JOA score improved from 10.45 ± 1.128 to 15.0 ± 1.949 ( p  < 0.0001, paired t-test). All radiological indices were improved ( p at least < 0.001). No construct failure was seen in any of the patients with C1-2 facet joint distraction technique during follow-up, and no additional anterior decompression surgery was required., Conclusions: C1/C2 joint reduction technique with fibular graft/cervical PEEK cage of BI patients together with AAD seems to be an effective and safe surgical method of treatment.

Purpose: To present the clinical features and treatment strategy of degenerative atlantoaxial subluxation (DAAS)., Methods: Patients with DAAS treated in our institution from 2003 to 2020 were retrospectively reviewed. We utilized the Japanese Orthopedic Association (JOA) scale to evaluate the neurologic status and distance of Ranawat et al. (DOR) to measure vertical migration., Results: We recruited 40 patients with > 2 years of follow-up and an average age of 62.3 ± 7.7 years. All the patients had myelopathy; only one patient had moderate trauma before exacerbation of symptoms, and the duration of symptoms was 34 ± 36 months. The most frequent radiological features were vertical migration of C1 (100%), sclerosis (100%), and narrowing of the atlantoaxial lateral mass articulations (100%). Two patients underwent transoral release combined with posterior reduction and fusion, and 38 patients underwent posterior reduction and fusion with C1 lateral mass screws-C2 pedicle screws and plate systems only. Forty cases (100%) achieved a solid atlantoaxial fusion, and 38 cases (95%) achieved anatomic atlantoaxial reduction. The JOA score increased from 9.3 ± 2.6 to 14.8 ± 2.1 (P < 0.01). DOR increased from 14.5 ± 2.5 to 17.8 ± 2.2 mm at the final follow-up (P < 0.01). Loosening of the locking caps was detected in one case, bony fusion was achieved, and harvest-site pain was reported in five patients., Conclusion: DAAS differs from other types of AAS and presents with anterior subluxation combined with vertical subluxation arising from degenerative changes in the atlantoaxial joints. We recommend anatomic reduction as an optimal strategy for DAAS., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objectives: To propose a surface reconstruction algorithm based on a differential manifold (a space with local Euclidean space properties), which can be used for processing of clinical images and for modeling of the atlantoaxial joint. To describe the ideal anatomy of the lateral atlantoaxial articular surface by measuring the anatomical data., Methods: Computed tomography data of 80 healthy subjects who underwent cervical spine examinations at our institution were collected between October 2019 and June 2022, including 46 males and 34 females, aged 37.8 ± 5.1 years (28-59 years). A differential manifold surface reconstruction algorithm was used to generate the model based on DICOM data derived by Vision PACS system. The lateral mass articular surface was measured and compared in terms of its sagittal diameter, transverse diameter, articular surface area, articular curvature and joint space height., Results: There was no statistically significant difference between left and right sides of the measured data in normal adults (P > 0.05). The atlantoaxial articular surface sagittal diameter length was (15.83 ± 1.85) and (16.22 ± 1.57) mm on average, respectively. The transverse diameter length of the articular surface was (16.29 ± 2.16) and (16.49 ± 1.84) mm. The lateral articular surface area was (166.53 ± 7.69) and (174.48 ± 6.73) mm 2 and the curvature was (164.03 ± 5.27) and (153.23 ± 9.03)°, respectively. The joint space height was 3.05 ± 0.11mm, respectively. There is an irregular articular space in the lateral mass of atlantoaxial, and both upper and lower surfaces of the articular space are concave. A sagittal plane view shows that the inferior articular surface of the atlas is mainly concave above; however, the superior articular surface of the axis is mainly convex above. In the coronal plane, the inferior articular surface of the atlas is mostly concave above, with most concave vertices located in the medial region, and the superior articular surface of the axis is mainly concave below, with most convex vertices located centrally and laterally., Conclusion: A differential manifold algorithm can effectively process atlantoaxial imaging data, fit and control mesh topology, and reconstruct curved surfaces to meet clinical measurement applications with high accuracy and efficiency; the articular surface of the lateral mass of atlantoaxial mass in normal adults has relatively constant sagittal diameter, transverse diameter and area. The distance difference between joint spaces is small, but the shape difference of articular surfaces differs greatly., (© 2023. The Author(s).)

Background: Atlantoaxial rotatory fixation (AARF) is extremely rare in adults, and there is no consensus on the ideal treatment of adult AARF because of its rarity. We presented a case series of three adult AARFs and reviewed the literature on adult AARFs. We suggest treatment guidelines for the injury based on the literature review., Methods: We compiled a series of three adult AARFs seen in our hospital. We also utilized the NCBI library to retrieve literature on adult AARF from 2000 to 2021. We included articles on adult AARF, which described the number of days from injury to diagnosis, Fielding classification, occurrence of associated cervical injuries, and details of treatment and the results., Results: Thirty adult AARFs reports fulfilled the criteria and 32 patients were analyzed. Eighteen patients had Fielding Type 1 AARF and were diagnosed within 1 month of injury. Among them, 13 cases healed with conservative treatment. Patients with acute AARF of Fielding Type 1 who underwent manual reduction healed successfully. All patients that required more than 1 month from injury to diagnosis underwent surgery. All cases with AARF Fielding Types 2, 3, and 4 failed conservative treatment., Conclusion: The case series and literature review suggest that early diagnosis of adult AARF is essential for successful closed reduction, and the Fielding classification may help determine treatment strategy. Furthermore, this study showed that not only traction but also manual reduction may be a useful treatment for early diagnosed AARF Fielding Type 1 without complications. Level of Evidence: III ., Competing Interests: Disclosures: The authors report no potential conflicts of interest related to this study., (Copyright © The Iowa Orthopaedic Journal 2023.)

Objective: Craniovertebral junction (CVJ) pathology by virtue of its complexity is a surgical challenge in the realm of neurosurgery. We analyzed the need for transoral odointectomy in view of their C1-C2 joint coronal and sagittal angle of 58 patients with complex CVJ anomalies treated surgically. The clinical and radiological outcome of the patients was assessed and a treatment algorithm is proposed., Methods: A total of 58 cases were included in the Prospective study over the period of 2 years. Patients were evaluated clinically, investigated, and operated with reduction and rigid internal fixation with screws and rod. The clinical outcome was measured by Modified Japanese orthopedic association score(mJOA) and radiologically by conventional craniometrics indices. Paired 't' test used for statistical analysis., Results: Mean age of patients: 30 years, with mean, follow up: 20.5 months. 46(80%) patients were operated by posterior and 12(20%) by combined approach (anterior transoral with posterior). Occipitocervial fixation was done in 15(25.8%) cases and C1-C2 fixation in 43(74.2%) cases. As compared to patients with low coronal angle, the patient with coronal angle >65° needed anterior decompression (87.5%) and all (100%) had Occipitocervical fixation. Clinical outcome analysis showed significant improvement in mean mJOA score (preop 11.9 Vs postop 14.6) after surgery. All craniometrics indices were significantly improved after surgery. The overall complication rate was 10% with a mortality of 1.7%. 6 months follow up completed in all patients with a 100% fusion rate., Conclusion: Occipitocervical fixation and anterior decompression is required in increased C1-C2 joint CA (>65°) for bony realignment and adequate decompression. Measurement of C1-C2 joint coronal and sagittal angle in complex CVJ anomalies will easily anticipate the surgeon regarding the need for anterior decompression inform of transoral odointectomy.

Background: Odontoid fractures in association with a C1-C2 rotatory luxation reports are seldom found in the literature. The fusion between the lateral mass of C1 and C2 could be of interest to ensure adequate treatment in these particular cases. We report 23 cases where there was coexistence of an odontoid fracture and rotatory subluxation, which were treated surgically using cages between C1 and C2 or just traditional Goel-Harms technique. We evaluated the radiologic fusion rate, reoperation rate, and complications., Methods: This was a single-center, retrospective, cohort study of patients with C2 fractures (mixed type and C1-C2 rotatory luxation according to the Fielding classification) who were treated surgically. Radiologic computed tomography scans were used to assess fusion (presence of bridging trabecular bone end plate or pseudoarthrosis) between 6 months and 1.5 years after the surgery., Results: Twenty-three patients were diagnosed with C2 fractures and C1-C2 rotatory luxation that were treated surgically and were suitable for the analysis; 11 patients underwent C1-C2 fusion with intra-articular cages, and 12 underwent a classical Goel-Harms technique. The fusion rate at the C1-C2 joint was higher in the cages group. Only 12 patients exhibited fusion at the level of the odontoid fracture., Conclusions: C2 fractures associated with C1-C2 rotatory dislocation are rare. The fusion rate at the level of the odontoid in these patients appears to be lower than that reported in patients without rotatory dislocation. It may be of special interest to obtain a clear fusion at the C1-C2 joint, where this type of implant seems to offer an advantage., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Atlantoaxial joint is a possible affected site during rheumatoid arthritis (RA) and, in this work, we evaluated its occurrence and associated characteristics in a "real-life" cohort. By a medical records review study of RA patients longitudinally followed-up, the occurrence of severe atlantoaxial joint involvement was estimated (incidence proportion and incidence rate per 1000 person-years at risk). Regression analyses were also exploited to evaluate possible associated factors. Based on these findings, a prospective recruitment was performed to build a descriptive cross-sectional study in evaluating a subclinical atlantoaxial joint involvement in patients with the same clinical characteristics. Retrospectively, 717 patients (female 56.6%, age 64.7 ± 12.3 years) were studied. The incidence proportion of severe atlantoaxial joint involvement was 2.1% [1.5-2.5], occurring in 15 out of 717 patients, and identified by both MRI and CT scan. Considering over 3091 person-years, an incidence rate of 5.2 × 1000 [2.9-8.3] person-years was estimated. Regression analyses suggested that male gender, a longer disease duration, ACPA positivity and extra-articular manifestations resulted to be significantly associated with a severe atlantoaxial joint involvement. Given these findings, 30 asymptomatic patients were selected according to these clinical characteristics and underwent MRI of cervical spine. To date, almost 50% of these asymptomatic patients showed a subclinical atlantoaxial joint involvement. The occurrence of the severe atlantoaxial joint involvement in RA patients was estimated in a "real-life" setting. Male gender, ACPA positivity, long disease duration, and extra-articular manifestations could be associated with the severe atlantoaxial joint involvement in RA. MRI could provide a useful clinical tool to early evaluate the atlantoaxial joint involvement in RA, also in asymptomatic patients., (© 2023. The Author(s).)

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

Competing Interests: None

Background: Basilar invagination (BI) is a common disease in the craniocervical junction (CVJ) area. Posterior fossa decompression with/without fixation is a controversial surgical strategy for BI type B. This study aimed to evaluate the efficacy of simple posterior fossa decompression in treating BI type B., Methods: This study retrospectively enrolled BI type B patients who underwent simple posterior fossa decompression at Huashan Hospital, Fudan University between 2014.12 and 2021.12. Patient data and images were recorded pre- and postoperatively (at the last follow-up) to evaluate the surgical outcomes and craniocervical stability., Results: A total of 18 BI type B patients (13 females), with a mean age of 44.2±7.9 years (range 37-62 years), were enrolled. The mean follow-up period was 47.7±20.6 months (range 10-81 months). All patients received simple posterior fossa decompression without any fixation. At the last follow-up, compared with preoperation, the JOA scores were significantly higher (14.2±1.5 vs. 9.9±2.0, p = 0.001); the CCA was improved (128.7±9.6° vs. 121.5±8.1° p = 0.001), and the DOCL was reduced (7.9±1.5 mm vs. 9.9±2.5 mm, p = 0.001). However, the follow-up and preoperative ADI, BAI, PR, and D/L ratio were similar. No patients had an unstable condition between the C1-2 facet joints that was observed in the follow-up CT and dynamic X-ray., Conclusions: In BI type B patients, simple posterior fossa decompression could improve neurological function and will not induce CVJ instability in BI type B patients. Simple posterior fossa decompression could be a satisfactory surgical strategy for BI type B patients, but preoperative CVJ stability assessment is crucial., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

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

Background: The aim of this study was to describe clinical and imaging features of atlantoaxial subluxation (AAS) and the associated risk factors in patients with rheumatoid arthritis (RA)., Methods: We conducted a retrospective and comparative study including 51 RA patients with AAS and 51 RA patients without AAS. Atlantoaxial subluxation was defined by the presence of an anterior C1C2 diastasis on the cervical spine radiograph in hyperflexion and/or an anterior, posterior, lateral or rotatory C1C2 dislocation on MRI with/without inflammatory signal., Results: In G1, clinical presentations revealing AAS were mainly neck pain (68.7%) and neck stiffness (29.8%). MRI revealed: diastasis C1C2 (92.5%), periodontoid pannus (92.5%), odontoid erosion (23.5%), vertical subluxation (9.8%) and spinal cord involvement (7.8%). A collar immobilisation and corticosteroid boluses were indicated in 86.3% and 47.1% of cases. C1-C2arthrodesis was performed in 15.4% of cases. Atlantoaxial subluxation was significantly associated with: age at disease onset (p = 0.009), history of joint surgery (p = 0.012), disease duration (p = 0.001), rheumatoid factor (p = 0.01), anti-cyclic citrullinated peptide (p = 0.02), erosive radiographic status (p < 0.005), coxitis (p < 0.001), osteoporosis (p = 0.012), extra-articular manifestations (p < 0.001), and high disease activity (p = 0.001). Multivariate analysis identified RA duration (p < 0.001, OR = 1.022 CI[1.01-1.034]) and erosive radiographic status (p = 0.01, OR = 21.236 CI[2.05-219.44]) as predictive factors of AAS., Conclusion: Our study showed that longer disease duration and joint destruction are the major predictive factors of AAS. Early treatment initiation, tight-control and regular monitoring of cervical spine involvement are required in these patients., (© 2023 John Wiley & Sons Ltd.)

Background Context: Physiological ranges and dynamic changes of atlantoaxial rotation (ROT C1/2 ), total cervical spine rotation (ROT Cs ) and the percentage of ROT C1/2 from ROT Cs (ROT Cperc ) for different age groups have not yet been investigated in a sufficiently sized cohort. Furthermore, it is not clear whether demographic variables such a sex, smoking status or diabetes affect ROT C1/2 , ROT Cs and ROT Cperc ., Purpose: Obtain physiological ranges of ROT C1/2 , ROT Cs and ROT Cperc for different age groups and determine their age-based dynamics. Investigate whether ROT C1/2 , ROT Cs and ROT Cperc are affected by sex, smoking status or diabetes., Design: Observational cross-sectional study., Patient Sample: Patients undergoing elective CT examinations of the head and neck region between August 2020 and January 2022., Outcome Measures: Ranges of motion of ROT C1/2 , ROT Cs and ROT Cperc in degrees., Methods: A total of 308 subjects underwent dynamic rotational CT examinations of the upper cervical spine. Patients were divided into three age categories A1 (27-49 years), A2 (50-69 years) and A3 (≥70 years). Category A3 was further divided into B1 (70-79 years) and B2 (≥80 years). Values of ROT C1/2 , ROT Cs and ROT Cperc were compared between all age groups, males and females, smokers and nonsmokers, diabetics a nondiabetics. Dynamics of ROT C1/2 , ROT Cs related to age and sex were visualized using scatterplot and trendline models., Results: ROT C1/2 significantly decreased from group A1 (64.4°) to B2 (46.7°) as did ROT Cs from A1 (131.2°) to B2 (97.6°). No significant differences of ROT perc were found between groups A1-B2 with values oscillating between 49% and 51%. Smoking and diabetes did not significantly affect ROT C1/2 , ROT Cs and ROT Cperc , females had significantly higher ROT Cs than males. Males and females demonstrated a different dynamic of ROT C1/2 and ROT Cs demonstrated by out scatterplot and trendline models., Conclusions: Both ROT C1/2 and ROT Cs significantly decrease with age, whereas ROT Cperc remains stable. Females demonstrated higher ROT Cs and their decrease of ROT C1/2 and ROT Cs occurred in higher age groups compared to males. The functional repercussions atlantoaxial fusion are variable based on patient age and sex and should be taken into account prior to surgery., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Down syndrome, also known as trisomy 21, is associated with congenital cervical spine abnormalities, including atlantoaxial instability with or without os odontoideum, atlanto-occipital instability, and hypoplasia of the atlas. Herein, we report a case of Down syndrome complicated by congenital atlanto-occipital dislocation. The patient presented with severe cervical myelopathy at 13 years of age after a 10-year follow-up. Radiography and computed tomography revealed os odontoideum protruding into the foramen magnum and congenital anterior atlanto-occipital dislocation. Additionally, a bifurcated internal occipital crest with a thinned central portion of the occipital bone was noted. Magnetic resonance imaging revealed kyphotic alignment of the spinal cord with severe compression at the foramen magnum level. As the neurological impairment was partially improved by halo vest immobilization, we performed in situ O-C2 fusion with an iliac autograft and decompression of the foramen magnum and posterior arch of C1. An improvement was observed immediately after surgery. Two years after surgery, radiography and computed tomography showed solid O-C2 segment fusion. The accumulation of similar cases is essential for determining the prognosis or optimal treatment for this rare congenital condition., (© 2023. The Author(s).)

Study Design: Retrospective cohort study., Objective: To verify the clinical efficacy of a novel transoral stepwise release technique (TSRT) for the treatment of irreducible atlantoaxial dislocations (IAAD)., Summary of Background Data: Anterior release for IAAD remains challenging, with a 3.2 times higher complication rate than posterior release. However, there are some patients who cannot achieve successful reduction from a posterior approach and require the higher-risk anterior release. Our work presents a novel anterior release technique that aims to minimize iatrogenic injury and associated complications from an anterior release., Materials and Methods: IAAD cases who were treated with TSRT were retrospectively studied. Primary outcomes included fusion rate, complications, and neurological function over the course of a minimum 1-year follow-up. Radiographic differences between preoperative and postoperative imaging were also considered. A preoperative prediction model for the actual release grade was developed using multivariate logistic regression based on demographic factors and the craniovertebral abnormalities identified on preoperative images, evaluating the need for higher-grade TSRT release., Results: We included 201 IAAD cases, with 42% (84/201) demonstrating degeneration of the atlantoaxial joint or anterior-hook-like dens. The reduction was achieved in all cases, with 80% (160/201) of cases only requiring relatively low-grade or grade I types TSRT release. Degeneration of the atlantoaxial joint was significantly associated with the need for higher-grade TSRT release (odds ratio:16.68, CI: 2.91-94.54, P = 0.002). The overall complication rate was 4.5% (9/201). Over the course of follow-up, the fusion rate reached 98.5%, and the American Spinal Injury Association and Japanese Orthopedic Association scores were significantly improved to 97.28 and 16.25 ( P < 0.01 and P < 0.01), respectively., Conclusion: This study demonstrated that our novel TSRT anterior release technique demonstrated complication rates similar to those published in the literature for posterior release. TSRT can be used as an alternative to posterior release techniques for refractory cases or when a posterior approach is not considered viable., Competing Interests: The authors report no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)