Posterior atlantoaxial fixation of osteoporotic odontoid fracture: biomechanical analysis of the Magerl versus harms techniques in a cadaver model.

BACKGROUND CONTEXT: Odontoid fractures are among the most common cervical spine fractures in the elderly and are associated with increased morbidity and mortality. Clinical evidence suggests improved survival and quality of life after operative intervention compared to nonoperative treatment. PURPOSE: This study seeks to examine the stability of an osteoporotic Type II odontoid fracture following posterior atlantoaxial fixation with either the Magerl transarticular fixation technique or the Harms C1 lateral mass screws C2 pedicle screw rod fixation. STUDY DESIGN: Biomechanical cadaveric study. METHODS: Eighteen cadaveric specimens extending from the cephalus to C7 were used in this study. Reflective marker arrays were attached to C1 and C2 and a single marker on the dens to measure movement of each during loading with C2-C3 and occiput-C1 being allowed to move freely. A biomechanical testing protocol imparted moments in flexion-extension, axial rotation, and lateral bending while a motion capture system recorded the motions of C1, C2, and the dens. The spines were instrumented with either the Harms fixation (n=9) or Magerl fixation (n=9) techniques, and a simulated Type II odontoid fracture was created. Motions of each instrumented spine were recorded for all moments, and then again after the instrumentation was removed to model the injured, non-instrumented state. RESULTS: Both Harms and Magerl posterior C1-C2 fixation allowed for C1, C2, and the dens to move as a relative unit. Without fixation the dens motion was coupled with C1. No significant differences were found in X, Y, Z translation motion of the dens, C1 or C2 during neutral zone motions between the Magerl and Harms fixation techniques. There were no significant differences found in Euler angle motion between the two techniques in either flexion-extension, axial rotation, or lateral bending motion. CONCLUSIONS: Our findings suggest that both Harms and Magerl fixation can significantly reduce dens motion in Type II odontoid fractures in an osteoporotic cadaveric bone model. CLINICAL SIGNIFICANCE: Both Harms and Magerl posterior atlantoaxial fixation techniques allowed for C1, C2, and the dens to move as a relative unit following odontoid fracture, establishing more anatomic stability to the upper cervical spine.

Neurological outcome following delayed traction and fixation in severe tetraparesis consecutive to posterior decompression for Chiari malformation: a case report.

BACKGROUND: Chiari malformation type 1 (CM1) is a congenital hindbrain malformation characterized by herniation of the cerebellar tonsils below the foramen magnum. The term Chiari type 1.5 is used when herniation of the brainstem under the McRae line and anomalies of the craniovertebral junction are also present. These conditions are associated with several symptoms and signs, including headache, neck pain, and spinal cord syndrome. For symptomatic patients, surgical decompression is recommended. When radiographic indicators of craniovertebral junction (CVJ) instability or symptoms related to ventral brainstem compression are present, CVJ fixation should also be considered. CASE DESCRIPTION: We report the case of a 13-year-old girl who presented with severe tetraparesis after posterior decompression for Chiari malformation type 1.5, followed 5 days later by partial C2 laminectomy. Several months after the initial surgery, she underwent two fixations, first without and then with intraoperative cervical traction, leading to significant neurological improvement. DISCUSSION AND CONCLUSION: This case report underscores the importance of meticulous radiological analysis before CM surgery. For CM 1.5 patients with basilar invagination, CVJ fixation is recommended, and C2 laminectomy should be avoided. In the event of significant clinical deterioration due to nonadherence to these guidelines, our findings highlight the importance of traction with increased extension before fixation, even years after initial destabilizing surgery.

Current Concepts in the Treatment of Traumatic C2 Vertebral Fracture : A Literature Review.

The integrity of the high cervical spine, the transition zone from the brainstem to the spinal cord, is crucial for survival and daily life. The region protects the enclosed neurovascular structure and allows a substantial portion of the head motion. Injuries of the high cervical spine are frequent, and the fractures of the C2 vertebra account for approximately 17-25% of acute cervical fractures. We review the two major types of C2 vertebral fractures, odontoid fracture and Hangman's fracture. For both types of fractures, favorable outcomes could be obtained if the delicately selected conservative treatment is performed. In odontoid fractures, as the most common fracture on the C2 vertebrae, anterior screw fixation is considered first for type II fractures, and C1-2 fusion is suggested when nonunion is a concern or occurs. Hangman's fractures are the second most common fracture. Many stable extension type I and II fractures can be treated with external immobilization, whereas the predominant flexion type IIA and III fractures require surgical stabilization. No result proves that either anterior or posterior surgery is superior, and the surgeon should decide on the surgical method after careful consideration according to each clinical situation. This review will briefly describe the basic principles and current treatment concepts of C2 fractures.

Feasibility of Two-Screw Anterior Fixation for Odontoid Fractures in a Chinese Population: A Morphometric Study Based on Computed Tomography.

Background: To evaluate the feasibility of treating odontoid fractures in the Chinese population with two cortical screws based on computed tomography (CT) scans and describe a new measurement strategy to guide screw insertion in treating these fractures. Methods: A retrospective review of cervical computed tomographic scans of 128 patients (aged 18-76 years; men, 55 [43.0%]) was performed. The minimum external transverse diameter (METD), minimum external anteroposterior diameter (MEAD), maximum screw length (MSL), and screw projection back angle (SPBA) of the odontoid process were measured on coronal and sagittal CT images. Results: The mean values of METD and MEAD were 10.0 ± 1.1 mm and 12.0 ± 1.0 mm, respectively, in men and 9.2 ± 1.0 mm and 11.0 ± 1.0 mm, respectively, in women. Both measurements were significantly higher in men (p < 0.001). In total, 87 individuals (68%) had METD > 9.0 mm that could accommodate two 3.5-mm cortical screws. The mean MSL value and SPBA range were 34.4 ± 2.9 mm and 13.5°-24.2°, respectively, with no statistically significant difference between men and women. Conclusions: The insertion of two 3.5-mm cortical screws was possible for anterior fixation of odontoid fractures in 87 patients (68%) in our study, and there was a statistically significant difference between men and women.

Outcomes of Odontoid Process Fracture Surgery.

BACKGROUND: Odontoid fractures are found in two age groups. In younger patients, they occur following traffic accidents, falls from a height and during sports. In older patients with poor bone quality, they are usually caused by falls from one's own height. Most fractures are stable and do not require surgical treatment. Unstable, severely displaced fractures with neurological deficits require surgical treatment. The aim of the study was to evaluate the surgical and functional outcomes of treatment of odontoid fractures with a cannulated screw. MATERIALS AND METHODS: The study enrolled 20 patients that underwent surgery in the years 2020-2022. The patients were divided into two groups: below 60 (group A) and over 60 years of age (group B). Patients were assessed at one day pre-op, one day post-op, 6 weeks following surgery and 3 months following surgery. Imaging studies were performed to assess the angulation and degree of displacement of bone fragments. After the fracture was surgically fixed with a cannulated screw, bone union and the stability of fracture fixation were assessed. Preoperative and postoperative pain intensity as per a VAS, functional status assessed with the NDI questionnaire, quality of life (EQ-VAS) and neurological status (ASIA scale) were compared. RESULTS: Good functional and surgical results were obtained in both groups of patients. Performance and quality of life improved, while pain intensity decreased in all patients. In 3 patients with post-traumatic paresis, the dysfunctions gradually subsided. No general medical or perioperative complications were observed. Bone union of the fracture was achieved in 40% of patients in group B and in 80% in group A. Achieving union did not determine the functional status of patients. On functional radiographs, all places of fixation were stable. CONCLUSIONS: 1. Odontoid fracture fixation with a single cannulated screw is a safe method of treatment. It provided a high union rate and good stability of the fracture. 2. Fracture non-union was noted more often in the group of older patients, but it did not negatively impact quality of life and performance.

Low-Threshold-For-Surgery Versus Primarily-Conservative Treatment for Odontoid Fractures in the Elderly: Evaluating Practice Variation in The Netherlands.

STUDY DESIGN: Retrospective cohort study. OBJECTIVES: Odontoid fractures are the most common cervical spine fractures in the elderly. The optimal treatment remains controversial. The aim of this study was to compare results of a low-threshold-for-surgery strategy (surgery for dislocated fractures in relatively healthy patients) to a primarily-conservative strategy (for all patients). METHODS: Patient records from 5 medical centers were reviewed for patients who met the selection criteria (e.g. age ≥55 years, type II/III odontoid fractures). Demographics, fracture types/characteristics, fracture union/stability, clinical outcome and mortality were compared. The influence of age on outcome was studied (≥55-80 vs ≥80 years). RESULTS: A total of 173 patients were included: 120 treated with low-threshold-for-surgery (of which 22 primarily operated, and 23 secondarily) vs 53 treated primarily-conservative. No differences in demographics and fracture characteristics between the groups were identified. Fracture union (53% vs 43%) and fracture stability (90% vs 85%) at last follow-up did not differ between groups. The majority of patients (56%) achieved clinical improvement compared to baseline. Analysis of differences in clinical outcome between groups was infeasible due to data limitations. In both strategies, patients ≥80 years achieved worse union (64% vs 30%), worse stability (97% vs 77%), and - as to be expected - increased mortality <104 weeks (2% vs 22%). CONCLUSIONS: Union and stability rates did not differ between the treatment strategies. Advanced age (≥80 years) negatively influenced both radiological outcome and mortality. No cases of secondary neurological deficits were identified, suggesting that concerns for the consequences of under-treatment may be unjustified.

Type II Odontoid Fractures: Is the Anterior Screw a Good Solution for all Patients? A Case Series of 60 Consecutive Patients.

OBJECTIVE: Type II odontoid fracture is the most common fracture type, and its treatment remains challenging. The objective of this study was to evaluate the results of anterior screw fixation for type II odontoid fractures in patients aged over and below 60 years. METHODS: A retrospective analysis of consecutive patients diagnosed with type II odontoid fractures who were surgically treated using the anterior approach by a single surgeon was conducted. Demographic characteristics, including age, sex, type of fracture, time from trauma to surgery, length of stay (LoS), fusion rate, complications, and reoperation, were evaluated. Surgical outcomes were compared between patients over and below 60 years of age. RESULTS: Sixty consecutive patients underwent odontoid anterior fixation during the analysis period. The mean age of patients was 49.58 ± 23.22 years. Twenty-three (38.3%) patients were aged over 60 years, and the minimum follow-up period was two years. Of the patients, 93.3% developed bone fusion, which was observed in 86.9% of patients over 60 years. Complications related to hardware failure occurred in six (10%) patients. Transient dysphagia was observed in 10% of the cases. Three (5%) patients required reoperation. Patients over 60 years had a significantly increased risk of dysphagia compared with those below 60 years (P = 0.0248). There was no significant difference between the groups regarding nonfusion rate, reoperation rate, or LoS. CONCLUSIONS: Anterior fixation of the odontoid showed high fusion rates with a low rate of complications. It is a technique to be considered for treating type II odontoid fractures in selected cases.

[Minimally invasive surgery for invaginated CII odontoid process]. / Miniinvazivnaya khirurgiya invaginirovannogo zubovidnogo otrostka CII pozvonka.

Odontoidectomy is indicated for anterior compression of the brainstem by invaginated odontoid process. This procedure can currently be performed via transoral microsurgical and transnasal endoscopic access. OBJECTIVE: To analyze the results of endoscopic transnasal odontoidectomy. MATERIAL AND METHODS: We assessed treatment outcomes in 10 patients with anterior compression of the brainstem by invaginated odontoid process. All patients underwent endoscopic transnasal odontoidectomy. RESULTS: Brainstem decompression was achieved in all cases. CONCLUSION: Currently, endoscopic transnasal approach is gradually replacing the transoral one in some patients requiring anterior odontoidectomy. Analysis of literature data reflects the development of this technique taking into account various features of surgical treatment including optimization of dimensions of surgical field, attempts to perform C1-sparing surgeries and analysis of sufficient size of trepanation. Nasopalatine and nasoclival lines are used to select optimal access. Nevertheless, the choice of access depends on equipment of the hospital and surgical experience in most cases.

Morphometric analysis of odontoid process among Arab population: a retrospective cone beam CT study.

Objective: This study aims to evaluate the feasibility of using cone beam computed tomography (CBCT) scans to assess the odontoid process diameter in the Arab population and to determine whether one or two cortical screws can be used for treating odontoid fractures. Methods: The odontoid process of 142 individuals aged 12-75 years, including 72 males (mean age: 35.5) and 70 females (mean age: 36.2), were analyzed using CBCT scans. The sagittal and coronal CBCT views were used to evaluate the antero-posterior (AP) and transverse diameters of the odontoid process. Results: Males had substantially bigger transverse and AP diameters of the odontoid process than females (p < 0.05 & P < 0.01 respectively). Among the sample, 97 individuals (67.4%) had external transverse diameter (METD) of less than 9 mm which is slightly bigger than that of Indians and 48 individuals (31.83%) had enough room for two 3.5 mm or two 2.7 mm screws as their METD was more than 9 mm like that of Greek and Turkish. Age had no significant impact on the morphometric measurements of the odontoid process. Conclusion: More than sixty percent of the sample had METDs of less than 9 millimeters, indicating that a single 4.5-mm Herbert screw may be suggested for fixing fractured odontoid processes in the Arab population.

Experiencia en patología cervical alta en el Hospital Guillermo Almenara Irigoyen 2016 - 2021

Introducción : El complejo C0-C1-C2 es responsable de la transición de la carga axial, con función biomecánica única, siendo afectada por múltiples patologías, que por lo general la literatura no las considera como un solo ítem, sino que lo desarrolla según su etiología, pero en nuestro estudio se ha considerado en 5 grupos: traumática, congénita, inflamatoria reumática, neoplásica y degenerativa. Objetivo : Determinar las características epidemiológicas, clínicas y del tratamiento en la patología cervical alta. Materiales y métodos : Se incluyeron a todos los pacientes con diagnóstico clínico radiológico de alguna patología cervical alta que hayan sido sometidos a tratamiento quirúrgico entre 2016 y 2021 en el Hospital Almenara. Se usó el test "t" de student y de chi cuadrado. Se dividió a los pacientes en alguno de los 5 grupos antes mencionados. Resultados : Se consideraron 31 pacientes, con una edad media de 51.16 años. La patología cervical alta más frecuente fue la traumática con el 35.48%. El déficit motor se presentó en el 51.61% y el déficit sensitivo se presentó en el 54.84%. La cirugía más frecuente fue la fijación cervical alta con el 43.89%. La tasa de complicaciones fue del 16.13% con una mortalidad del 0%. Conclusiones : La patología cervical alta es rara, siendo la del tipo traumática la más frecuente, pero un manejo oportuno y adecuado permite un mejor pronóstico funcional del paciente.

Introduction : The C0-C1-C2 complex is responsible of axial load transition, and its biomechanical function is unique, it is affected by multiple pathological conditions; and generally speaking, the literature does not consider these conditions as a single item, it describes them according to etiology. For our study we considered five groups: trauma-related, congenital, rheumatic-inflammatory, neoplastic, and degenerative. Objective : To determine epidemiological, clinical, and therapy-related characteristics in upper cervical pathological conditions. Materials and methods : All patients with a clinical-radiological diagnosis of any upper cervical pathological condition that had undergone surgery between 2016 and 2021 in Guillermo Almenara Hospital were included. Student's t test and chi square methods were used. patients were divided into one of the five aforementioned groups. Results : Thirty-one patients were included in the study; their mean age was 51.16 years. The most frequent upper cervical pathological condition was trauma-related, with 35.48%. Motor deficit occurred in 51.61% of all patients, and sensitive deficit occurred in 54.84%. The most frequently surgical procedure performed was upper cervical fixation, in 43.89% of all patients. Complication rate was 16.13%, and mortality was 0%. Conclusions : Upper cervical pathological conditions are rare, trauma-related conditions are most frequent, but timely and adequate management allow us to achieve better functional prognosis for these patients.

The endoscopic transnasal approach to the lesions of the craniocervical junction: two case reports.

The endoscopic endonasal approach (EEA) to the craniovertebral junction (CVJ) has recently been considered a safer alternative and less invasive approach than the traditional transoral approach because the complications associated with the latter are avoided or minimized. Here, we present two challenging cases of CVJ pathologies. The first case involved os odontoideum associated with anterior displacement of the occipitocervical junction where the EEA was used, followed by C0-C1-C2 fusion using a posterior approach to decompress the CVJ, and was complicated by rhinorrhea and Candida albicans meningitis. The second case involved basilar invagination with syringomyelia previously treated using a posterior approach, where aggravation of neuropathic symptoms required combined treatment with EEA and occipitocervical fusion of C0-C2-C3-C4, with the postoperative course challenged by operative site infection requiring drainage with debridement and antibiotic therapy. The EEA is an alternative approach for accessing the CVJ in well-selected patients. Knowledge of EEA complications is crucial for the optimal care of patients.

Prevalence and radiographic features of atlantoaxial dislocation in adult patients with Kashin-Beck disease.

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

Crowned dens syndrome as a rare cause of anterior neck pain after transurethral resection of the prostate: a case report.

We describe the case of a 79-year-old man who presented with progressive aggravation of severe axial neck pain and fever 3 days after transurethral resection of the prostate (TURP), despite maintaining neutral neck posture during surgery. Laboratory examination revealed markedly elevated C-reactive protein levels and erythrocyte sedimentation rates. Computed tomography revealed crown-like calcifications surrounding the odontoid process. We diagnosed crowned dens syndrome (CDS) as the cause of acute-onset neck pain after TURP. The patient was treated with nonsteroidal anti-inflammatory drugs for 5 days, and his symptoms resolved completely. CDS is a rare disease characterized by calcific deposits around the odontoid process with acute onset of severe neck pain and restricted motion. Evidence of inflammation on serological testing and fever are typical of CDS. However, the prevalence and pathophysiology of CDS remain unclear. We hypothesized that systemic inflammation after prostate surgery may have induced a local inflammatory response involving calcification around the odontoid process.

Real-time ultrasound guidance in the endoscopic endonasal resection of a retro-odontoid pannus: Technical note and case illustration.

Background and Objectives: Odontoidectomy is a surgical procedure indicated in the setting of various pathologies, with the main goal of decompressing the ventral brain stem and spinal cord as a result of irreducible compression at the craniovertebral junction. The endoscopic endonasal approach has been increasingly used as an alternative to the transoral approach as it provides a straightforward, panoramic, and direct approach to the odontoid process. In addition, intraoperative ultrasound (US) guidance is a technique that can optimize safety and surgical outcomes in this context. It is used as an adjunct to neuronavigation and provides intraoperative confirmation of decompression of craniovertebral junction structures in real time. The authors aim to present the use and safe application of real-time intraoperative US guidance during endonasal endoscopic resection of a retro-odontoid pannus. Methods: A retrospective chart review of a single case was performed and presented herein as a case report and narrated operative video. Results: A minimally invasive US transducer was used intraoperatively to guide the resection of a retro-odontoid pannus and confirm spinal cord decompression in real time. Postoperative examination of the patient revealed immediate neurological improvement. Conclusions: Intraoperative ultrasonography is a well described and useful modality in neurosurgery. However, the use of intraoperative US guidance during endonasal endoscopic approaches to the craniovertebral junction has not been previously described. As demonstrated in this technical note, the authors show that this imaging modality can be added to the ever-evolving armamentarium of neurosurgeons to safely guide the decompression of neural structures within the craniocervical junction with good surgical outcomes.

Does the Surgical Approach Matter in Treating Odontoid Fractures? A Comparison of Mechanical Complication Rates Between Anterior Versus Posterior Surgical Approaches: A Meta-Analysis and Systematic Review.

Objective: Odontoid fractures are treated surgically through the anterior or posterior approach. Each surgical approach has its advantages and disadvantages, so the preferred approach remains debatable. There are few meta-analyses or systemic reviews on the mechanical complications of surgical treatment for odontoid fractures. This meta-analysis aimed to compare the operation-related morbidity, including mechanical complications, and mortality of patients with odontoid fractures, treated via the anterior or posterior approach. Methods: A systematic search was performed on PubMed/Medline, Embase, and the Cochrane Library for the studies up to October 2023 on the complication rate of the surgical treatment of odontoid fractures, related to the surgical approach. The risk ratios (RR) with the 95% confidence intervals (CIs) were pooled to assess the mechanical complication rates, other complications, revision surgery, and mortality, depending on the surgical approach. Results: A total of 1,519 studies were retrieved using the search strategy, and 782 patients from 15 articles were included in this meta-analysis. Mechanical complications were significantly more frequent in the anterior surgical group with low heterogeneity. The incidences of fracture nonunion and revision surgery were also higher in the anterior surgery group. However, there was no significant difference in systemic complications and mortality rates between the two groups. Conclusion: The posterior approach was more advantageous than the anterior approach in terms of mechanical complications, fusion rates, and incidence of revision surgery. However, further studies, should be performed to strengthen these results.

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.

Acute traumatic lateral atlantoaxial dislocation associated with locked atlas lateral mass and odontoid process fracture: A clinical case study and literature review.

Background: Traumatic atlantoaxial dislocation combined with locked atlas lateral mass and odontoid process fracture is a complex injury and is extremely rare. We describe the surgical technique by presenting a clinical case study in managing a traumatic lateral atlantoaxial dislocation combined with a locked atlas lateral mass and a type II odontoid fracture (Grauer type IIB). Case description: This is a clinical case study of a 38-year-old female patient who presented with severe neck pain without neurological deficit following a traffic accident. Computed tomography showed a type IIB odontoid fracture and a lateral C1-C2 dislocation with a laterally locked left lateral mass at the C1-C2 level. Emergency management included protecting the cervical spine and applying gradually increasing skull traction. The locked lateral mass and laterally-dislocated C1-C2 facet joints were partially reduced. An intraoperative joint reduction operation with leverage technique was then performed. Posterior C1-C2 fixation (a modified Harms-Goel technique) and fusion with iliac bone graft were then executed. Outcome: Postoperatively, neck pain improved significantly. The atlantoaxial joint was successfully reduced and stabilized. Solid bony fusion was confirmed by a radiographic study at the 1-year follow-up. Conclusions: Based on a review of current literature, traumatic lateral atlantoaxial dislocation combined with a locked atlas lateral mass and type IIB odontoid fracture is rarely seen. It is an extremely unstable injury. Our proposed leverage technique used in conjunction with a modified Harms-Goel technique is an effective alternative treatment. This approach can assist surgeons in the management of these difficult cases.

Análise biomecânica das fixações atlantoaxiais: estudo experimental / Análise biomecânica das fixações atlantoaxiais: estudo experimental

Introdução: o tratamento cirúrgico de pacientes com fraturas do processo odontoide tem sido controverso. As principais técnicas cirúrgicas para o segmento C1-C2 incluem além da artrodese cervical (aramagem tipo Gallie, parafusos transarticulares e aramagem tipo 88), a fixação direta com parafuso no processo odontoide. Objetivo: comparar a estabilidade mecânica destes quatro tipos de osteossínteses do segmento atlantoaxial (C1-C2). Metodologia: vinte segmentos atlantoaxiais de cadáveres humanos adultos foram preparados com fraturas do tipo 2 de Anderson e D'Alonso e divididos em quatro grupos: aramagem tipo Gallie (aG); parafusos transarticulares (pT); parafuso no processo odontoide (pD); aramagem tipo 88 (a88). Os corpos de prova foram submetidos a esforços de flexocompressão em máquina universal de ensaios mecânicos para análise de resistência, elasticidade e deformações. Resultados:na fase de acomodação, os parafusos no processo odontoide apresentaram pouquíssima mobilidade com cargas baixas. Na fase de elasticidade, não houve diferença significativa entre as construções testadas. Com relação à resistência máxima suportada pelas construções, houve uma diferença estatisticamente significativa a favor da aramagem tipo Gallie. Conclusão: nossos testes mostraram que em relação à acomodação houve diferença significativa entre a aramagem tipo Gallie e o parafuso no processo odontoide; e quanto à resistência máxima, entre a aramagem tipo Gallie e o parafuso transarticular.

Introduction: the surgical treatment of patients with fractures of the odontoid process has been controversial. The main surgical techniques for C1-C2 are: Gallie wiring, transarticular screw, direct odontoid process screw and 88 posterior laminar wiring. Objective: to compare the mechanical stability of these four types of atlantoaxial segment osteosynthesis (C1/C2). Methodology: twenty atlantoaxial segments of adult human cadavers were prepared with Anderson and D'Alonso type II fractures and divided into four groups: Gallie wiring; transarticular screw; odontoid process screw; 88 wiring. After being fixed with each osteosynthesis technique, they were submitted to flexocompression efforts in a universal mechanical testing machine for analysis of strength, elasticity and deformations. Results: in the accommodation phase, the odontoid process screws showed very little mobility with low loads. In the elasticity phase, there was no significant difference between the constructions tested. With regard to the maximum resistance supported by the constructions, there was a statistically significant difference in favor of Gallie wiring. Conclusion: Our tests showed a significant difference between Gallie wiring and odontoid process screw in accommodation; and between the Gallie wiring and the transarticular screw in maximum resistance test

Investigating Type B Basilar Invagination Through Cephalic Indices.

OBJECTIVE: We sought to compare the diagnostic accuracy of cephalic indices for type B basilar invagination (BI). METHODS: This retrospective study examined head and neck magnetic resonance imaging sequences of 31 Group B BI cases and 96 controls. Two examiners blinded to diagnostic data evaluated the cephalic indices of each magnetic resonance imaging sequence, described as width/length (WLI) and height/width (HWI). The distance of the odontoid process apex to Chamberlain line and clivus canal angle were measured. The interexaminer and intraexaminer reproducibility of the cephalic indices was calculated using intraclass correlation coefficient. The diagnostic accuracy was discerned by the receiver operating characteristic (ROC) curve. All analyses were scrutinized with a 95% confidence interval. RESULTS: Cephalic indices showed interexaminer and intraexaminer reproducibility ≥94%. The areas under the ROC curve were 0.639 (WLI) and 0.874 (HWI) (95% confidence interval: P < 0.05). The HWI showed a sensitivity of 74.7% and a specificity of 85.5% for the cutoff criterion ≤58. The WLI presented a sensitivity of 53.3% and a specificity of 66.7% for the cutoff criterion ≥86. CONCLUSIONS: The HWI showed the largest area under the ROC curve in comparison with the WLI, with robust sensitivity and specificity values, indicating that the proportions between cranial height and width can help clinicians in investigating type B BI.