Frecuencia de Ponticulus posticus en Telerradiografías Laterales de Cráneo / Frequency of Ponticulus posticus in Digital Lateral Cephalograms

En el arco posterior del atlas se describe una variación de tejido óseo denominada Ponticulus posticus (PP), la cual se ha relacionado con el desarrollo de dolor cervical. El objetivo de este estudio fue determinar la frecuencia de PP en telerradiografías laterales digitales. Este estudio correspondió a un estudio observacional descriptivo, donde se analizaron 450 telerradiografías laterales digitales obtenidas de la base de datos del Servicio de Imagenología Oral y Maxilofacial de la Facultad de Odontología de la Universidad Andrés Bello, Viña del Mar, Chile. Se analizó la presencia de PP en cada cefalograma, y se utilizó la clasificación de Cederberg y Stubbs para determinar los grados de osificación. Se aplicó la prueba de Chi-cuadrado para establecer una asociación entre la presencia de PP con el sexo y la edad. De las 450 telerradiografías laterales el 42,4 % presenta PP, con una mayor prevalencia entre el rango de 21-40 años. En cuanto al grado de osificación, el grado 2 fue el tipo más prevalente (25 %), seguido del grado 4 (9,5 %), el grado 3 (8 %). No se encontró asociación entre la presencia de PP con edad y género (P > 0,05). La PP es frecuente en la población y se observa a diferentes edades sin predilección por sexo.

SUMMARY: A bony tissue variation called Ponticulus posticus (PP) is described in the posterior arch of the atlas, which has been associated with the development of cervical pain. The aim of this study was to determine the frequency of PP in digital lateral cephalograms. This study was an observational descriptive study, in which 450 digital lateral cephalograms obtained from the database of the Oral and Maxillofacial Imaging Service of the Faculty of Dentistry of the Andrés Bello University, Viña del Mar, Chile, were analyzed. The presence of PP was analyzed in each cephalogram, and the Cederberg and Stubbs classification was used to determine the degrees of ossification. The Chi-square test was applied to establish an association between the presence of PP with gender and age. Of the 450 lateral cephalograms, 42.4 % presented PP, with a higher prevalence in the 21-40 year range. In terms of the degree of ossification, grade 2 was the most prevalent type (25 %), followed by grade 4 (9.5 %), and grade 3 (8 %). No association was found between the presence of PP with age and gender (P > 0.05). PP is common in the population and is observed at different ages without a sex preference.

Posterior cervical pedicle screw rod short-segment internal fixation for the treatment of atlantoaxial fracture and dislocation / 中国骨伤

OBJECTIVE@#To investigate the clinical efficacy of posterior cervical pedicle screw short-segment internal fixation for the treatment of atlantoaxial fracture and dislocation.@*METHODS@#The clinical data of 60 patients with atlantoaxial vertebral fracture and dislocation underwent surgery between January 2015 and January 2018 were retrospectively analyzed. The patients were divided into study group and control group according to different surgical methods. There were 30 patients in study group, including 13 males and 17 females, with an average age of (39.32±2.85) years old, were underwent short-segment internal fixation with posterior cervical pedicle screws. There were 30 patients in control group, including 12 males and 18 females, with an average age of (39.57±2.90) years old, were underwent posterior lamina clip internal fixation of the atlas. The operation time, intraoperative blood loss, postoperative ambulation time, hospitalization time and complications between two groups were recorded and compared. The pain visual analogue scale(VAS), Japanese Orthopedic Association(JOA) score of neurological function, and fusion status were evaluated between two groups.@*RESULTS@#All patients were followed up for at least 12 months. The study group was better than control group in operation time, intraoperative blood loss, postoperative off-bed activity time, and hospital stay (P=0.000). One case of respiratory tract injury occurred in study group. In control group, 2 cases occurred incision infection, 3 cases occurred respiratory tract injury, and 3 cases occurred adjacent segmental joint degeneration. The incidence of complications in study group was lower than that in control group (χ2=4.705, P=0.030). At 1, 3, 7 days after operation, VAS of study group was lower than that of control group(P=0.000). At 1, 3 months after operation, JOA score of study group was higher than that of control group(P=0.000). At 12 months after operation, all the patients in the study group achieved bony fusion. In control group, there were 3 cases of poor bony fusion and 3 cases of internal fixation fracture, the incidence rate was 20.00%(6/30). The difference between two groups was statistically significant (χ2=4.629, P=0.031).@*CONCLUSION@#Posterior cervical short-segment pedicle screw fixation for atlantoaxial fracture and dislocation has the advantages of less trauma, shorter operation time, fewer complications, and less pain, and can promote the recovery of nerve function as soon as possible.

Biomechanical evaluation of four surgical techniques for ventral stabilization of the atlantoaxial joint in dogs

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

A new classification of atlas fracture based on CT reconstruction and its clinical significance / 中华骨科杂志

Objective:To investigate the clinical significance of a new classification system for atlas fractures based on pre- and post-treatment CT features, with a focus on diagnosis and treatment.Methods:A retrospective analysis was conducted on 75 cases of cervical vertebra fractures treated at the Sixth Hospital of Ningbo City between January 2015 and December 2020. The study included 44 males and 31 females, with an average age of 53.3±13.0 years (range: 27-81 years). The fractures were classified according to the Landells classification, resulting in 12 cases of type I, 13 cases of type II, 33 cases of type III, 9 cases that were difficult to classify due to fracture lines located at anatomical junctions, and 8 cases that could not be classified using the Landells classification due to diverse injury mechanisms. To establish a new preliminary classification for cervical vertebra fractures, the researchers considered whether the fracture line in the CT images involved the facet joint surface of the atlas, the impact on bilateral half-rings, and the displacement distance of the fracture ends. Five spinal surgeons were randomly selected to classify the CT images of the 75 patients using the new classification method. After one month, the imaging data of the 75 cases of cervical vertebra fractures were randomized and reclassified to assess the reliability and repeatability of the classification.Results:The new cervical vertebra fracture classification method comprised three types based on whether the fracture line involved the facet joint surface of the atlas: type A (no involvement of the facet joint surface of the atlas), type B (involvement of one side of the facet joint surface with intact contralateral half-ring), and type C (involvement of one side of the facet joint surface with fractured contralateral half-ring). Additionally, based on the maximum displacement distance between the fracture ends (>4 mm), six subtypes were identified: subtype 1 (≤4 mm displacement) and subtype 2 (>4 mm displacement). Consequently, the subtypes were classified as A1, A2, B1, B2, C1, and C2. According to the new classification method, the 75 patients included 17 cases of A1, 12 cases of A2, 7 cases of B1, 13 cases of B2, 12 cases of C1, and 14 cases of C2. The classification demonstrated excellent consistency, as assessed by the five doctors, with Kappa values of 0.85 and 0.91 for reliability and repeatability, respectively. At the final follow-up, all conservatively treated patients achieved bone healing, while four surgically treated patients experienced non-union of the fracture ends but exhibited good fusion between the atlas and axis. The remaining surgically treated patients achieved bony union without complications such as loosening or fracture of internal fixation.Conclusion:The new cervical vertebra fracture classification method, based on CT imaging features, comprehensively covers common clinical cases of cervical vertebra fractures and demonstrates excellent consistency. It provides valuable clinical guidance for the diagnosis and treatment of cervical vertebra fractures.

Diagnosis and treatment of atlantoaxial dislocation / 中华骨科杂志

Atlantoaxial dislocation is a pathological anatomical condition caused by the loss of stability between the atlantoaxial joints, which is a serious disabling disease in spine surgery, and may even endanger the patient's life. The causes of atlantoaxial dislocation include traumatic, congenital, inflammatory, degenerative, tumor, and other factors. Since the symptoms and signs are not specific in clinic, imaging examination is particularly important. Atlantoaxial dislocation is mainly classified according to the etiology, the relative position of atlas and axis, and the difficulty of reduction. Accurate classification is of great significance for the selection of treatment options. There is no popular guideline for surgical indications of atlantoaxial dislocation. Patients presenting with related symptoms or spinal cord dysfunction are generally recognized surgical indications in clinical practice. With the continuous improvement and optimization of atlantoaxial screw placement, reduction and fusion technology, supplemented by new equipment in spine surgery, the surgery-related risks and complications have been greatly reduced, and the surgical treatment of atlantoaxial dislocation can obtain good reduction and fusion results. This tutorial summariz the etiology, diagnosis, classification, treatment, complications, and prognosis of atlantoaxial dislocation, in order to provide a more complete and refined reference for clinical diagnosis and treatment.

Anterior cervical release and posterior fixation for the treatment of irreducible atlantoaxial dislocation with retropharyngeal internal carotid artery / 中华骨科杂志

Objective:To investigate the clinical effect of anterior cervical release and posterior fixation in the treatment of irreducible atlantoaxial dislocation with retropharyngeal internal carotid artery.Methods:Thirteen patients with irreducible atlantoaxial dislocation of retropharyngeal internal carotid artery from January 2015 to July 2019 were treated with anterior cervical release and posterior fixation. There were 8 males and 5 females, aged from 34 to 65 years with an average of 46.1±12.6 years. Positive, lateral and dynamic X-ray films, MR and CTA were performed before operation. There were 4 cases with bilateral retropharyngeal internal carotid artery and 9 cases with unilateral retropharyngeal internal pharyngeal artery. The time of operation, the amount of bleeding and intraoperative and postoperative complications were recorded. The main observations were Japanese Orthopaedic Association (JOA) score, atlantodental interval (ADI), Chamberlain line (CL), and changes in the morphology of the retropharyngeal internal carotid artery and implant fusion.Results:All the operations completed successfully. The operation time was 210-260 min, the average was 245±21 min; the blood loss was 350-600 ml, the average blood loss was 490±107 ml. There was no injury of internal carotid artery, vertebral artery, spinal cord or nerve root during the operation. All patients were followed up for 9 to 24 months, with an average of 15.1±6.2 months. Preoperative JOA score was 6.9±2.3 points, 1 month after operation was 13.5±2.5 points, and the last follow-up was 14.3±2.1 points. The difference was statistically significant ( F=30.91, P<0.001). The difference between 1 month after operation and before operation was statistically significant ( P<0.001), and the improvement rate of JOA score was 75.6%±15.2%. There was no significant difference between the last follow-up and 1 month after operation ( P>0.05). The preoperative ADI was 8.9±2.2 mm, 1 month after operation was 1.1±0.8 mm, and the last follow-up was 1.2±0.9 mm. The difference was statistically significant ( F=114.69, P<0.001). The difference between 1 month after operation and before operation was statistically significant ( P<0.001), and ADI had returned to normal level. There was no significant difference between the last follow-up and 1 month after operation ( P>0.05). The preoperative CL was 11.7±4.8 mm, 1 month after operation was 1.6±2.1 mm, and the last follow-up was 1.8±2.3 mm. The difference was statistically significant ( F=34.19, P<0.001). The difference between 1 month after operation and before operation was statistically significant ( P<0.001), and the position of odontoid process returned to normal level. There was no significant difference between the last follow-up and 1 month after operation ( P>0.05). Bone graft fusion was received at 6 to 12 months after operation, with an average of 10.2 months. Conclusion:CTA examination should be performed before anterior release of atlantoaxial dislocation to understand the position and shape of internal carotid artery. Anterior cervical release combined with posterior bone graft fusion is an effective method for the treatment of irreducible atlantoaxial dislocation with retropharyngeal internal carotid artery without increasing the risk of internal carotid artery injury.

The clinical characteristics and treatment of "sandwich" atlantoaxial dislocation / 中华骨科杂志

Objective:To evaluate the specialty of the clinical features, treatment procedure, clinical outcome, and prognosis in the patients with "sandwich" atlantoaxial dislocation (AAD).Methods:From 2008 to 2018, 160 cases with "sandwich" AAD were retrospectively selected from the case series of AAD in Peking University Third Hospital. The case series had 80 males and 80 females. The mean age at the initial visit was 35.5±14.6 years (range, 5-77). The clinical courses, treatment methodology and prognosis were reviewed. And the surgical approach, posterior fixation segment and the recovery of neurological function were mainly summarized. The atlantodental interval (ADI), the distance by which the odontoid exceeded the Chamberlain line and the cervical-medullary angle were analyzed.Results:The most common symptoms included weakness or numbness of the limbs (67.5%, 108/160), unstable gait (30%, 48/160) and vertigo (20%, 32/160). Among all, 130 cases (81.3%, 130/160) had myelopathy, with the Japanese Orthopaedic Association (JOA) scores from 4 to 16 (mean JOA scores 13.5±2.5). Cranial neuropathy was involved in 20 cases (12.5%). Radiological findings showed brainstem and/or cervical-medullar in 130 cases (81.3%), syringomyelia in 37 cases (23.1%) and Chiari malformation in 30 cases (18.8%). Computed tomography angiography (CTA) was performed in 90 cases, which showed vertebral artery anomalies in 55 cases (61.0%) and excessive medialized internal carotid artery in 5 cases (5.6%). All cases had no spinal cord or vertebral artery injury. The surgery included posterior occipito-cervical fusion (reducible dislocation, 145 cases), and transoral release followed by posterior fusion (irreducible dislocation, 15 cases). Fifty-seven cases were treated using alternative fixation technique. The average follow-up time was 50.5±22.4 months (range, 24 to 120 months). All of 152 cases (95.0%) achieved solid atlantoaxial fusion; there was no obvious osseous fusion formation on postoperative images in 6 cases (3.8%), but no atlantoaxial instability was found on dynamic radiographs; screw loosening happened in 2 patients (1.2%). Nine patients (5.6%) suffered complications, including 4 cases with recurrent dislocation, 2 screw loosening, 2 cases with bulbar paralysis and 1 wound infection. The mean postoperative JOA was 15.1±1.8 (range, 5-17), and the mean neurological improvement rate was 42.9%±33.3% in the patients with myelopathy.Conclusion:"Sandwich" AAD, a subgroup of AAD, has unique clinical features: earlier onset age and more severe myelopathy. The incidence of bone and vascular malformation is higher. So alternative surgical plan and hybrid fixation should be prepared for this subgroup of AAD.

Subclassification and clinical treatment options of refractory atlantoaxial dislocation / 中华骨科杂志

Objective:To subdivide clinical classification of refractory atlantoaxial dislocation, and evaluate the reliability of new subdivide clinical classification of refractory atlantoaxial dislocation.Methods:From January 2010 to December 2018, 48 patients with refractory atlantoaxial dislocation were treated, including 19 males and 29 females, aged 16 to 65 years, with an average of 39.2±13.3 years. According to the changes of relative anatomical position of C 1 and C 2 under general anesthesia with heavy traction of 1/6 body weight, subdivide clinical classification of refractory atlantoaxial dislocation were proposed, and refractory atlantoaxial dislocation was divided into traction loosening type (atlantoaxial angle≥5°) and traction stabilization type (atlantoaxial angle<5°). The traction loosening type was directly reduced by posterior atlantoaxial screw-rod fixation and fusion without anterior or posterior soft tissue release. For traction stabilization type, transoral soft tissue release was performed first, and then transoral anterior reduction plate fixation and fusion or posterior atlantoaxial screw-rod fixation and fusion were performed. Atlantodental interval (ADI) and atlantoaxial angle (AAA) were measured and collected before and after surgery to evaluate atlantoaxial reduction. The space available for the spinal cord (SAC) were measured to evaluate spinal cord compression. Visual analogue score (VAS) was used to evaluate the neck pain levels, and Japanese Orthopaedic Association (JOA) scores was used to evaluate the neurological function. American Spinal Cord Injury Association impairment scale (AIS) was used to evaluate the degree of spinal cord injury. One week, 3, 6, 12 months postoperatively and the annual review of the X-ray and CT scan were checked, in order to evaluate the reduction, internal fixation and bone graft fusion. Results:Among all 48 cases, 22 cases were traction loosening type, of which posterior atlantoaxial screw-rod fixation and fusion were performed in 16 cases and occipitocervical fixation and fusion in 6 cases. 26 cases were traction stabilization type, and they all underwent anterior transoral release, and then, anterior TARP fixation and fusion were performed in 24 cases and posterior screw-rod fixation and fusion in the other 2 cases. X-ray, CT and MRI images and of all patients 1 week after surgery showed good atlantoaxial reduction and decompression of spinal cord. In each of the two types, there was one case lost to follow-up. For 46 cases in follow-up, the follow-up time ranged from 6 to 72 months, with an average of 38.0±17.2 months. Among 46 cases, 21 cases of traction loosening type showed that, ADI reduced from preoperative 9.9±2.2 mm to 2.3±0.9 mm at 3 months after surgery and 2.3±1.0 mm at the last follow-up, AAA increased from preoperative 57.9°±12.3° to 91.0°±2.2° at 3 months after surgery and 90.9°±2.2° at the last follow-up, SAC increased from preoperative 9.8±1.3 mm to 15.1±0.7 mm at 3 months after surgery and 14.9±0.7 mm at the last follow-up, VAS score reduced from preoperative 1.5±2.1 to 0.7±1.0 at 3 months after surgery and 0.3±0.6 at the last follow-up, and JOA score increased from preoperative 10.2±1.7 to 13.3±1.3 at 3 months after surgery and 14.9±1.5 at the last follow-up. Twenty-five cases of traction stabilization type presented that, ADI reduced from preoperative 9.7±2.0 mm to 2.1±1.4 mm at 3 months after surgery and 2.1±1.3 mm at the last follow-up, AAA increased from preoperative 55.8°±9.2° to 90.9°±1.4° at 3 months after surgery and 90.9°±1.3° at the last follow-up, SAC increased from preoperative 10.5±1.0 mm to 15.4±0.5 mm at 3 months after surgery and 14.8±2.8 mm at the last follow-up, VAS score reduced from preoperative 1.7±2.1 to 0.7±0.9 at 3 months after surgery and 0.3±0.5 at the last follow-up, and JOA score increased from preoperative 10.1±1.3 to 12.9±1.5 at 3 months after surgery and 14.4±1.3 at the last follow-up. In the traction loosening type, all the 10 grade D patients were improved to grade E at the last follow-up. In the 2 grade C patients of traction stabilization type before surgery, 1 patient was improved to grade E, 1 patient was improved to grade D, and all 11 patients with grade D were improved to grade E at the last follow-up. Bony fusion was obtained in all patients from 3 to 6 months, with an average of 4.4±1.5 months. During follow-up period, no looseness of internal fixation or redislocation happened.Conclusion:Refractory atlantoaxial dislocation can be divided into traction loosening type and traction stabilization type. For traction loosening type, satisfactory reduction can be achieved by using posterior atlantoaxial screw-rod system without soft tissue release. For traction stabilization type, anterior release is preferable, and then anterior TARP or posterior screw-rod can be used to achieve satisfactory reduction.

Evidence-based guideline for clinical diagnosis and treatment of acute combination fractures of the atlas and axis in adults (version 2023) / 中华创伤杂志

The acute combination fractures of the atlas and axis in adults have a higher rate of neurological injury and early death compared with atlas or axial fractures alone. Currently, the diagnosis and treatment choices of acute combination fractures of the atlas and axis in adults are controversial because of the lack of standards for implementation. Non-operative treatments have a high incidence of bone nonunion and complications, while surgeries may easily lead to the injury of the vertebral artery, spinal cord and nerve root. At present, there are no evidence-based Chinese guidelines for the diagnosis and treatment of acute combination fractures of the atlas and axis in adults. To provide orthopedic surgeons with the most up-to-date and effective information in treating acute combination fractures of the atlas and axis in adults, the Spinal Trauma Group of Orthopedic Branch of Chinese Medical Doctor Association organized experts in the field of spinal trauma to develop the Evidence-based guideline for clinical diagnosis and treatment of acute combination fractures of the atlas and axis in adults ( version 2023) by referring to the "Management of acute combination fractures of the atlas and axis in adults" published by American Association of Neurological Surgeons (AANS)/Congress of Neurological Surgeons (CNS) in 2013 and the relevant Chinese and English literatures. Ten recommendations were made concerning the radiological diagnosis, stability judgment, treatment rules, treatment options and complications based on medical evidence, aiming to provide a reference for the diagnosis and treatment of acute combination fractures of the atlas and axis in adults.

A case of bow hunter's syndrome and a systematic literature review / 中华骨科杂志

Objective:A clinical case of rotational vertebral artery occlusion (bow hunter's syndrome, BHS) caused by left C 1 osteophyte was reported, and the epidemiological characteristics, diagnosis and treatment methods, and clinical outcomes of BHS were further analyzed. Methods:The clinical data, diagnostic methods, treatment options, and clinical outcomes of the above-mentioned BHS patient are described. The literature from 1978 to 2021 was retrieved, the BHS patients involved were taken as the research objects, and the data of onset age, gender, etiology, site of onset, diagnosis method, treatment method, and clinical outcomes of each selected patient were collected. The data were subdivided through systematic analysis.Results:A patient with rotational compression of the left vertebral artery associated with the left osteophyte of the atlas was presented. 3D-CT showed that the vertebral artery was compressed by the left osteophyte of the atlas. Dynamic digital subtraction angiography (dDSA) showed mild stenosis of the distal V2 segment of the left vertebral artery. When his head turned to the left, the distal V2 segment of the left vertebral artery was compressed and the blood flow was interrupted. After his head was in a neutral position, the blood flow was restored. Because the symptoms could not be relieved after conservative treatment, posterior C 1 osteophyte resection was used to decompress the vertebral artery, and the symptoms disappeared after the operation, and the short-term follow-up results were good. All of the 87 articles and 126 patients have been studied. The median age was 55.0 years (IQR: 43.5, 65.0 years) and the peak age of onset was 51 to 60 years old. The gender difference has been uncovered and the sex ratio was 1.9∶1 (male∶female). Among the 126 patients, 65 patients had vertebral artery occlusion or stenosis located in the C 1-C 2 segment; 66 patients involved the left vertebral artery, 45 patients involved the right vertebral artery, and 15 patients involved bilateral vertebral arteries. DSA was used to confirm BHS in 114 of 126 patients. The follow-up time was 0.25-114 months, with an average of 16.6 months. Thirty-six patients were treated conservatively, and 12 patients had residual symptoms; 33 patients underwent fusion surgery, and all patients' symptoms were relieved after surgery; 54 patients underwent simple decompression surgery, and 4 patients had residual symptoms after surgery; 4 patients received endovascular surgery, and their symptoms were relieved after surgery. Conclusion:Patients with BHS are rare clinically, often involving C 1-C 2 and the left vertebral artery is more likely to be involved. The peak age of onset was 51 to 60 years old. DSA is the gold standard for the diagnosis of BHS. For BHS caused by abnormal bone structure, intervertebral disc herniation, joint instability, etc., decompressive surgery of the vertebral artery or C 1-C 2 segment fusion is the most common treatment modality.

Efficacy comparison of posterior atlas uniaxial and polyaxial screw instrumentation and fusion with bone graft for Gehweiler type IIIb atlas fracture / 中华创伤杂志

Objective:To compare the efficacy of posterior atlas uniaxial and polyaxial screw instrumentation and fusion with bone graft for Gehweiler type IIIb atlas fracture.Methods:A retrospective cohort study was performed to analyze the clinical data of 36 patients with Gehweiler type IIIb atlas fracture admitted to Henan Provincial People′s Hospital from January 2015 to October 2020. There were 29 males and 7 females, with age range of 23-82 years [(48.8±15.5)years]. All patients were treated with posterior atlas screw-rod internal fixation and fusion with bone graft, of which 14 received atlas uniaxial screw internal fixation (uniaxial screw group) and 22 received atlas polyaxial screw internal fixation (polyaxial screw group). The operation time and intraoperative blood loss were compared between the two groups. The atlas fracture union rate and atlantoaxial posterior arch bone fusion rate were compared between the two groups at 3 months and 6 months after operation. The anterior atlantodental interval (ADI), basion-dens interval (BDI) and lateral mass displacement (LMD) were compared between the two groups to evaluate the reduction of fracture fragments before operation, at 1, 3, 6 months after operation and at the last follow-up. At the same time, the visual analogue scale (VAS) and neck dysfunction index (NDI) were compared between the two groups to evaluate neck pain and functional recovery. The postoperative complications were observed.Results:All patients were followed up for 12-44 months [(27.2±9.9)months]. There was no significant difference in operation time or intraoperative blood loss between the two groups (all P>0.05). The atlas fracture union rate and atlantoaxial posterior arch bone fusion rate were 85.7% (12/14) and 78.6% (11/14) in uniaxial screw group at 3 months after operation, insignificantly different from those in polyaxial screw group [72.7% (16/22) and 77.3% (17/22)] (all P>0.05). All patients in the two groups achieved bone union and fusion at 6 months after operation. There was no significant difference in ADI between the two groups before and after operation (all P>0.05). The BDI in the two groups did not differ significantly before operation ( P>0.05), but a significantly higher value was found in uniaxial screw group at 1, 3, and 6 months after operation and at the last follow-up [(5.9±1.3)mm, (5.8±1.3)mm, (5.9±1.2)mm and (5.8±1.2)mm] than in polyaxial screw group [(3.1±0.6)mm, (3.1±0.6)mm, (3.1±0.6)mm and (3.1±0.6)mm] (all P<0.01). The two groups did not differ significantly before operation ( P>0.05), but LMD at 1, 3, and 6 months after operation and at the last follow-up was (1.6±0.8)mm, (1.5±0.8)mm, (1.5±0.7)mm and (1.5±0.9)mm in uniaxial screw group, significantly lower than that in polyaxial screw group [(4.8±1.6)mm, (4.6±1.6)mm, (4.9±1.6)mm and (4.9±1.6)mm] (all P<0.01). There was no significant difference in VAS between the two groups before operation ( P>0.05). The VAS at 1, 3, and 6 months after operation and at the last follow-up was 3.0(3.0, 4.0)points, 2.0(1.0, 2.0)points, 1.0(0.8, 2.0)points and 1.0(0.0, 1.3)points in uniaxial screw group and was 3.5(3.0, 4.0)points, 2.0(2.0, 3.0)points, 2.0(1.0, 2.0)points and 2.0(1.0, 3.0)points in polyaxial screw group. In comparison, the VAS scored much lower in uniaxial screw group than in polyaxial screw group at 6 months after operation and at the last follow-up (all P<0.01). There was no significant difference in NDI between the two groups before operation ( P>0.05). The NDI at 1, 3, and 6 months after operation and at the last follow-up was 34.9±6.3, 23.4±6.2, 13.9±2.7 and 9.4±2.8 in uniaxial screw group and was 33.2±6.1, 24.4±6.3, 18.1±4.1 and 12.7±3.2 in polyaxial screw group, showing a significantly lower NDI in uniaxial screw group than in polyaxial screw group at 6 months after operation and at the last follow-up (all P<0.01). The complication rate was 21.4% (3/14) in uniaxial screw group when compared to 22.7% (5/22) in polyaxial screw group ( P>0.05). Conclusion:For Gehweiler type IIIb atlas fracture, both techniques can attain atlas fracture union and atlantoaxial posterior arch bone fusion, but the posterior atlas uniaxial screw instrumentation and fusion is superior in reduction of atlas fracture displacement and lateral mass separation, neck pain relief and functional improvement.

Subluxación rotatoria atloaxoidea o síndrome de Grisel. A propósito de un caso / Rotatory subluxation of the atlantoaxial joint or Grisel's syndrome. Case report

La tortícolis es una contractura involuntaria unilateral del esternocleidomastoideo y de la musculatura posterior del cuello que causa la inclinación de la cabeza hacia un lado. Se han descrito múltiples causas de torticolis siendo una de ellas la subluxación atloaxoidea atraumática asociada a un proceso de carácter inflamatorio en la región de cabeza y cuello, llamada síndrome de Grisel. Aunque la mayoría de los pacientes suelen recuperarse sin secuelas tras tratamiento médico existe la posibilidad de complicaciones graves con déficits funcionales, de ahí la importancia de la realización de un diagnóstico y tratamiento precoz.

Torticollis is an unilateral involuntary contracture of the sternocleidomastoid and posterior neck musculature that causes the head tilts to the one side. Multiple causes of torticolis have been described, one of them being the non-traumatic rotatory subluxation of the atlantoaxial joint associated with an inflammatory process in the head and neck region, called Grisel's syndrome. Although most patients usually recover without sequels after medical treatment, there is the possibility of serious complications with functional deficits, that is why the importance of an early diagnosis and treatment of this potology.

Imaging anatomical study and clinical application of transoral axis slide and rotation osteotomy technique / 中华骨科杂志

Objective:To introduce a novel technique note about anterior decompression through transoral axis slide and rotation osteotomy (ASRO) and identify its imaging parameters related to osteotomy, and to explore its clinical application value.Methods:CT data of cervical spine of 90 subjects were collected, including 54 males and 36 females. The age ranged from 26 to 72 years, with an average age of 48.7 years. The Mimics software was used to reconstruct the atlantoaxial three-dimensional model. We plan to perform osteotomy on both sides of the axis of the vertebral body in the anteroposterior direction and the ASRO related anatomical parameters were measured, including the minimum osteotomy angle, the maximum osteotomy angle, the minimum and maximumdistance between the osteotomy trajectory and the inner side of the articular surface, the length of the upper articular surface of the axis side mass, the depth of osteotomy at the highest point and lowest point of the axial osteotomy surface and the minimum osteotomy depth. A 56-year-old female patient was admitted to the hospital due to atlantoaxial dislocation with failure of occipital-cervical fusion, difficulty walking, weakness and hypoaesthesia in four limbs. Imaging revealed that narrow space between the transversal walking wire and upper-posterior of the odontoid process, compressing the spinal cord from the front and the back respectively. The ASRO technique was performed on the patient under neuro-electrophysiological monitoring, and the osteotomy angle, osteotomy depth, narrowest width of the upper cervical spinal canal, the medullary, spinal cord angle were measured and Japanese Orthopaedic Association Scores (JOA) cervical myelopathy evaluation were performed after the operation to evaluate the surgical treatment effect.Results:The minimum osteotomy angle and the maximum osteotomy angle was 14.7°± 4.36° and 33.0°± 8.67°. The minimum and maximumdistance between the osteotomy trajectory and the inner side of the articular surface, and the length of the upper articular surface of the axis side mass was 6.0±1.80 mm, 12.2±3.17 mm, and 17.2±1.90 mm, the ratio of the former two to the latter was 34%±8.7% and 70%± 15.0%. The depth of osteotomy at the upper edge, lower edge and narrowest place of the axial osteotomy surface were 6.0±1.80 mm, 12.2±3.17 mm and 17.2±1.90 mm. The postoperative imaging of the patient showed that the osteotomy angle was 17.1° on left side and 16.5° on right side, and the depth of osteotomy at the upper edge, lower edge and narrowest place of the axial osteotomy surface were 17.1 mm, 13.2 mm, and 9.1 mm on left side, and 17.4 mm, 11.8 mm, 8.46 mm on right side. All measured values met the ranges which were shown in the imaging anatomical study. The narrowest width of the upper cervical spinal canal increased from 6.58 mm to 15.28 mm, the medullary spinal cord angle increased from 131.7° to 153.8°postoperatively, and the cervical spine JOA score recovered from 6 points to 14 points, suggesting that the postoperative spinal canal space is obvious increased, the compression on the front of the spinal cord was significantly reduced. The patient's symptoms improved significantly.Conclusion:ASRO technique is a good choice for salvage of failed posterior occipitocervical fusion and some irreducible atlantoaxial dislocation because of the anterior bony fusion. It could direct decompress the spinal cord anteriorly, avoid the odontoid resection, which is a safe and feasible new technique.

Research progress of causes and strategies in revision surgery for atlantoaxial dislocation / 中国骨伤

Atlantoaxial dislocation (AAD) is a kind of life-threatening atlantoaxial structural instability and a series of neurological dysfunction caused by common multidisciplinary diseases. The operation risk is extremely high because it is adjacent to the medulla oblongata and the location is deep. With the increase of the number of operations in the upper cervical region, postoperative complications such as failure of internal fixation, non fusion of bone graft and poor prognosis gradually increase.Incomplete primary operation, non fusion of bone graft, infection and congenital malformation are the potential causes. In addition, considering the objective factors such as previous graft, scar formation and anatomical marks changes, revision surgery is further difficult. However, there is currently no standard or single effective revision surgery method. Simple anterior surgery is an ideal choice in theory, but it has high risk and high empirical requirements for the operator;simple posterior surgery has some defects, such as insufficient reduction and decompression;anterior decompression combined with posterior fixation fusion is a more reasonable surgical procedure, but many problems such as posterior structural integrity and multilevel fusion need to be considered.This article reviews the causes and strategies of AAD revision surgery.

A radiological study between anterior and posterior surgery in patients with basilar invagination and atlantoaxial dislocation / 中华骨科杂志

Objective:To analyze the improvement of patients with basilar invagination and atlantoaxial dislocation that treated by anterior or posterior surgery.Methods:50 patients with basilar invagination and atlantoaxial dislocation that underwent simple anterior or posterior surgery from 2009 to 2021 were included. There were 34 females and 16 males with a mean age of 45.04 years (range, 18-65 years). All patients underwent thin- slice CT scan of the neck. Preoperative and postoperative measurements of atlantoaxial joint distance, atlantoaxial joint angle, atlantoaxial joint displacement, Claus' Height, atlas-dens interval, space available for the cord, cervicomedullary angle, C 0-C 2 angle, and C 2-C 7 angle were measured. Then, the data were analyzed by independent sample t test. Results:25 patients (7 males, 18 females) were included in the anterior surgery group, and 25 patients (9 males, 16 females) were included in the posterior surgery group. The mean age of the two groups was 45.24±9.86 years and 44.72±14.06 years, respectively, showing no statistical difference. The mean last follow-up time of the anterior and posterior surgery group was 6.48±3.14 months and 7.04±2.87 months, respectively. The odontoid distance, atlas-dens interval, space available for the cord and cervicomedullary angle in 2 groups were significantly improved after surgery ( P<0.05), while there were no significant differences in the above parameters between 2 groups ( P>0.05). In the anterior surgery group, the distance and angle of atlantoaxial joint were increased, and the atlantoaxial joint displacement decreased significantly. While in the posterior surgery group, only the atlantoaxial joint space increased ( P<0.05). The C 0-C 2 angle was significantly increased and the C 2-C 7 angle was significantly decreased in the anterior surgery group ( P<0.05), but there was no significant difference in these parameters in the posterior surgery group ( P>0.05). In addition, there was no significant difference in parameters between the two groups at the last follow-up compared with those immediately after surgery. Conclusion:Both anterior and posterior surgery can improve the compression of the spinal cord in patients with basilar invagination and atlantoaxial dislocation. Anterior surgery may be more adequate for the extension and reduction of the atlantoaxial joint space, however, excessive enlargement of the lordosis angle in upper cervical may lead to the reduction of the lordosis in lower cervical.

Minimally invasive treatment of cervical1-2 epidural neurilemmoma / 北京大学学报(医学版)

OBJECTIVE@#To explore the minimally invasive surgical method for cervical1-2 epidural neurilemmoma.@*METHODS@#The clinical features, imaging characteristics and surgical methods of 63 cases of cervical1-2 epidural neurilemmoma from July 2010 to December 2018 were reviewed and analyzed. Pain and numbness in occipitocervical region were the common clinical symptoms. There were 58 cases with pain, 30 cases with numbness, 3 cases with limb weakness and 2 cases with asymptomatic mass. Magnetic resonance imaging (MRI) showed that the tumors located in the cervical1-2 epidural space with diameter of 1-3 cm. The equal or slightly lower T1 and equal or slightly higher T2 signals were found on MRI. The tumors had obvious enhancement. Individualized laminotomy was performed according to the location and size of the tumors, and axis spinous processes were preserved as far as possible. Resection of tumor was performed strictly within the capsule.@*RESULTS@#Total and subtotal resection of tumor were achieved in 60 and 3 cases respectively, and no vertebral artery injury was found. The operation time ranged from 60 to 180 minutes, with an average of 92.83 minutes. The hospitalization time ranged from 3 to 9 days, with an average of 5.97 days. All tumors were confirmed as neurilemmoma by pathology. There was no postoperative infection or cerebrospinal fluid leakage. There was no new-onset dysfunction except 9 cases of numbness in the nerve innervation area. The period of follow-up ranged from 6 months to 8 years (median: 3 years). All the new-onset dysfunction recovered completely. Pain disappeared in all of the 58 patients with pain. Numbness recovered completely in 27 patients while slight numbness remained in another 3 patients. Three patients with muscle weakness recovered completely. The spinal function of all the patients restored to McCormick grade Ⅰ. No recurrence was found on MRI. No cervical spine instability or deformity was found on X-rays.@*CONCLUSION@#It is feasible to resect cervical1-2 epidural neurilemmoma by full use of the anatomical space between atlas and axis and individual laminotomy. It is helpful to prevent cervical instability or deformity by minimizing the destruction of cervical2 bone and preserving normal muscle attachment to cervical2 spinous process. Strict intracapsular resection can effectively prevent vertebral artery injury.

Application of posterior arch of the atlasrch resection for high-level cervical dumbbell schwannoma surgery / 中国骨伤

OBJECTIVE@#To investigate the feasibility and clinical effect of hemi-resection of posterior arch of atlas in the upper cervical spinal dumbbell-shaped schwannomas.@*METHODS@#A retrospective analysis was performed on 13 patients with high level cervical dumbbell schwannomas from January 2005 to December 2018, including 10 males and 3 females, aged 19 to 67 years old. The occipital foramen to the C@*RESULTS@#The operation was successfully completed in 13 cases of this group. No vertebral artery injury or spinal cord injury occurred during the operation. All 13 patients were followed up for more than 12 months. No local recurrence was found. Both the VAS and the JOA score were significantly improved compared with those before surgery. The ASIA classification before operation was:1 case of grade C, 6 cases of grade D, 6 cases of grade E;the latest follow up was 3 cases of ASIA grade D and 10 cases of E.@*CONCLUSION@#The posterior arch of the atlas hemisection can remove the upper cervical dumbbell schwannoma in one stage. The short-term clinical effect is good, and there are no complications such as cervical instability.

Treatment strategy and curative effect analysis of os odontoideum complicated with atlantoaxial joint dislocation / 中国骨伤

OBJECTIVE@#To explore the treatment strategy and clinical efficacy for os odontoideum complicated with atlantoaxial dislocation.@*METHODS@#The clinical data of 17 patients with os odontoideum complicated with atlantoaxial dislocation surgically treated from January 2006 to January 2015 were retrospectively analyzed, including 7 males and 10 females, aged 17 to 53 (43.1±11.3) years old;course of disease was 3 to 27(10.2±6.9) months. All patients received cranial traction before operation, 12 of 14 patients with reducible dislocation were treated by posterior atlantoaxial fixation and fusion, and 2 patients with atlantooccipital deformity were treated by posterior occipitocervical fixation and fusion;3 patients with irreducible alantoaxial dislocation were treated by transoral approach decompression combined with posterior atlantoaxial fixation and fusion. The operation time, intraoperative blood loss and perioperative complications were recorded. Visual analogue scale (VAS) and Japanese Orthopaedic Association (JOA) score were used to evaluate the change of neck pain and neurological function. Atlantoaxial joint fusion rate was evaluated by CT scan.@*RESULTS@#The operation time of posterior fixation and fusion ranged from 86 to 170 (92.2±27.5) min, and the intraoperative blood loss was 200-350 (250.7±65.2) ml. No vertebral artery injury and spinal cord injury were recorded. Among the patients underwent atlantoaxial fixation and fusion, 1 patient with reducible dislocation fixed by C@*CONCLUSION@#Surgical treatment of os odontoideum complicated with atlantoaxial dislocation can achieve satisfactory results, improve the patient's neurological function and improve the quality of life, however the surgical options needs to be individualized.

Agenesis of the posterior arch of the atlas: an incidental finding in a polytraumatized patient / Agenesia de arco posterior de atlas: um achado acidental em um paciente politraumatizado / Agenesia del arco posterior del atlas: un hallazgo incidental en un paciente politraumatizado

ABSTRACT The first cervical vertebra is subject to numerous anatomical variations. One of these is posterior arch agenesis, which is classified into five distinct morphological types. Together, all types of posterior arch agenesis comprise only 4% of atlas variations. Furthermore, complete agenesis of the posterior arch associated with the presence of the posterior tubercle is rare. This work reports a case of posterior arch agenesis with the presence of the posterior tubercle in a 33 year-old male victim of a motor vehicle collision. Despite being asymptomatic, this anatomical variation can present with headaches and neck pain. It is mostly found as an incidental finding in imaging studies performed by the emergency team and, as a result, it is often misdiagnosed as a C1 fracture. Knowledge of the variations relating to the first cervical vertebra is therefore essential to avoid delays in diagnosis and treatment of polytraumatized patients. Level of evidence V; Case report.

RESUMO A primeira vértebra cervical é alvo de inúmeras variações anatômicas. Uma destas inclui a agenesia do seu arco posterior, que é classificada em cinco tipos morfológicos distintos. Apesar de uma incidência de 4% na população em geral, a agenesia completa do arco posterior, associada à presença do tubérculo posterior do atlas, é rara. Objetivou-se no presente trabalho relatar a agenesia completa do arco posterior com a presença do tubérculo posterior da primeira vértebra cervical em um paciente de 33 anos de idade, que sofreu um acidente automobilístico. Em geral, essa condição é assintomática, porém, essa variação anatômica pode causar sintomas como dores de cabeça. Na maioria dos casos, é um achado acidental em exames de imagem realizados pela equipe de emergência. Como resultado, a agenesia de arco posterior de atlas pode ser interpretada erroneamente como uma fratura. Portanto, o conhecimento das variações anatômicas da primeira vértebra cervical é essencial para evitar erro no diagnóstico e tratamento de pacientes politraumatizados. Nível de Evidência V; Relato de caso.

RESUMEN La primera vértebra cervical puede presentar numerosas variaciones anatómicas. Una de ellas es la agenesia del arco posterior, que se clasifica en cinco tipos morfológicos distintos. En conjunto, todos los tipos de agenesia del arco posterior comprenden solo el 4% de las variaciones del atlas. Además, la agenesia completa del arco posterior asociada con la presencia del tubérculo posterior es rara. Este trabajo relata un caso de agenesia del arco posterior con presencia del tubérculo posterior en un paciente del sexo masculino de 33 años de edad que sufrió un accidente automovilístico. A pesar de ser asintomática, esta variación anatómica puede causar dolores de cabeza y cuello. Se encontra principalmente como hallazgo incidental en pruebas de imagen realizadas por el equipo de emergencia y como resultado, a menudo se diagnostica erróneamente como una fractura de C1. El conocimiento de las variaciones anatómicas de la primera vértebra cervical es, por lo tanto, esencial para evitar retrasos en el diagnóstico y tratamiento de pacientes politraumatizados. Nivel de Evidencia V; Relato de caso.

Intraoperative three-dimensional fluoroscopy based navigation assisted C1, 2 transarticular screw placement for the treatment of atlantoaxia instability / 中华骨科杂志

Objective@#To evaluate the accuracy of transarticular screw fixation using intraoperative three-dimensional fluoroscopy-based navigation (ITFN) and to evaluate the clinical outcomes of this treatment method.@*Methods@#Data of 56 patients(26 males and 30 females) with atlantoaxial instability who were treated by C1, 2 transarticular screw fixation using ITFN from November 2005 to October 2015 were retrospectively analyzed. The mean age of the patients was 44.5 years (range, 9-68 years). There were 44 cases with congenital malformation, 4 with old odontoid fracture, 7 with spontaneous dislocation, and 1 with rheumatoid arthritis. C2 isthmus width and height were measured on preoperatively obtained CT scans, and screw positioning was evaluated on postoperatively obtained CT scans, and classified into three types: ideal position (type I), acceptable position (type II) and unacceptable position (type III). A novel grading system is proposed based on previous study and grading system, and the difficulty of placing C1, 2 transarticular screw using ITFN was classified into three types: easy (total score 0), median (total score 1) and hard (total score 2, 3). Pain scores were assessed using the visual analogue scale. Myelopathy was assessed using the Nurick scale and Odom’s criteria.@*Results@#The isthmus width was 5.46±1.86 mm on the right side and 5.38±1.36 mm on the left side. The isthmus height was 4.89±1.33 mm on the right side and 4.97±1.17 mm on the left side. According to the grading system, 78, 11, and 23 of the sides were classified into easy, median and hard groups respectively. One hundred and seven transarticular screws were placed in 56 patients, and 71.03% of which were ideal screws, and 28.97% were acceptable screws. Five patients had unilateral screws placed. There was no significant difference in screw positioning among the three groups (χ2=0.46, 0.54, 1.18; P=0.50, 0.46,0.28). The mean follow-up period was 44.7 months (range, 6-120 months). At the latest follow-up, according to Nurick score, there are 30 patients scoring 0, 25 patients scoring 1, and 1 patient scoring 2. According to Odom’s criteria, outcomes were as follows: excellent, 66.1%; good, 26.8%; fair, 7.1%; and poor, 0%. All patients with preoperative neck pain had symptom relief or improvement, with more than 89.33% improvement in visual analogue scale scores. No dural laceration, injury to the vertebral artery, spinal cord, or hypoglossal nerve were noted.@*Conclusion@#ITFN is a safe, accurate, and effective tool for transarticular screw placement in patients with atlantoaxial instability.