Magnesium alloy-and titanium alloy-made transoralpharyngeal atlantoaxial reduction plate systems for atlantoaxial dislocation: a three-dimensional finite element analysis / 中华创伤杂志

ObjectiveTo evaluate biomechanical properties of transoralpharyngeal atlantoaxial reduction plate (TARP) prepared from magnesium alloy and titanium alloy for the atlantoaxial dislocation by using three-dimensional finite element analysis and to exam the feasibility of using magnesium alloy for preparation of TARP system so as to provide a theoretical basis for clinical surgery.MethodsA patient with typical atlantoaxial fracture dislocation was involved in the study,and received thin CT scan with clinically used titanium alloy TARP system for obtaining DICOM image data.Three-dimensional finite element analysis software was imported to simulate magnesium alloy and titanium alloy TARP systems for reduction and fixation.Then,stress changes of the atlas,axis,internal fixators and C2/3 zygapophysial joints were determined with three-dimensional finite element analysis and analyzed statistically.Results ( 1 ) The finite element model of atlantoaxial dislocation reduction and fixation had lifelike outline and good geometric similarity.There were 53 586 nodes and 180 784 units.(2) During the simulation of head in neutral position,the stress concentration region was C2/3 zygapophysial joints followed by the anterior arch,posterior arch and lateral mass of atlas respectively,and C2 vertebral arch again.( 3 )Magnesium alloy and titanium alloy TARP systems showed significant difference in stress distribution (P ＜0.05).Conclusions(1)The atlantoaxial model established according to its structure information on CT can be used for biomechanical experiments.(2) For the treatment of atlantoaxial dislocation using the existing titanium TARP system,maintaining the integrity of anterior and posterior arch of atlas and confirming the bone fusion in lateral mass can better keep the stability of the atlantoaxis.After atlantoaxial fusion,the increased stress of the zygapophysial joints of the adjacent segments accelerates structural degeneration,which should be closely followed up.( 3 ) Magnesium alloy TARP system for fixation and reduction shows the fall in peak value of the stress concentration region,and improvement of the uniformity of stress distribution as compared with titanium alloy TARP.

Neurologic Manifestations of Atlanto-axial Subluxation in the Patients with Rheumatoid Arthritis

BACKGROUND: Atlanto-axial dislocation (AAD) is a common complication of rheumatoid arthritis (RA). Diverse or different patterns of neurological manifestations including brainstem signs, myelopathy, vertebrobasilar insufficiency, and radiculopathy are expected in each type of AAD. This study is designed for the evaluation of neurological manifes-tations of AAD in RA, and for the comparison of clinical profiles with radiological findings. METHODS: Thirty patients compatible with radiological criteria of AAD were selected. The age, sex, symptom duration, and neurological signs were evaluated in the clinical profiles. Based on the neurological signs, the patients were classified into three groups. Radiological classifications of AAD were done according to the direction of AAD (anterior, vertical, lateral, mixed) and degrees of dislocation (grade I, II, III). Correlational analysis was performed as a measure of association with the clinical profiles and radiological findings. RESULTS: Neurological manifestations were present/found in 50% of the patients. Each types of AAD were distributed into the following groups:; anterior - 76.7%, mixed - 13.3%, lateral -10%, pure vertical - 0% in our study. The various groups determined by the neurological signs may be correlated with the severity of AAD, especially in the anterior type (> 8mm) and mixed type. Neurological signs were not noted in the pure lateral type. Vascular signs such as vertebrobasilar insufficiency (VBI) were more common in the anterior-AAD, but myelopathic or brainstem signs were more common in the mixed type. CONCLUSIONS: Diverse neurological findings exist in AAD. Different and characteristic manifestations are also noted in each type of AAD. Critical neurological signs including myelopathic, brainstem signs and VBI are prominent in severe anterior-AAD or mixed type.

Neurologic Manifestations of Atlanto-axial Subluxation in the Patients with Rheumatoid Arthritis

BACKGROUND: Atlanto-axial dislocation (AAD) is a common complication of rheumatoid arthritis (RA). Diverse or different patterns of neurological manifestations including brainstem signs, myelopathy, vertebrobasilar insufficiency, and radiculopathy are expected in each type of AAD. This study is designed for the evaluation of neurological manifes-tations of AAD in RA, and for the comparison of clinical profiles with radiological findings. METHODS: Thirty patients compatible with radiological criteria of AAD were selected. The age, sex, symptom duration, and neurological signs were evaluated in the clinical profiles. Based on the neurological signs, the patients were classified into three groups. Radiological classifications of AAD were done according to the direction of AAD (anterior, vertical, lateral, mixed) and degrees of dislocation (grade I, II, III). Correlational analysis was performed as a measure of association with the clinical profiles and radiological findings. RESULTS: Neurological manifestations were present/found in 50% of the patients. Each types of AAD were distributed into the following groups:; anterior - 76.7%, mixed - 13.3%, lateral -10%, pure vertical - 0% in our study. The various groups determined by the neurological signs may be correlated with the severity of AAD, especially in the anterior type (> 8mm) and mixed type. Neurological signs were not noted in the pure lateral type. Vascular signs such as vertebrobasilar insufficiency (VBI) were more common in the anterior-AAD, but myelopathic or brainstem signs were more common in the mixed type. CONCLUSIONS: Diverse neurological findings exist in AAD. Different and characteristic manifestations are also noted in each type of AAD. Critical neurological signs including myelopathic, brainstem signs and VBI are prominent in severe anterior-AAD or mixed type.

Transoral Approach of Atlanto-Axial Pyogenic Abscess

A case of atlanto-axial dislocation caused by a pyogenic abscess was presented. A pyogenic abscess in the cervical region is rare and surgical treatment is indicated if the sign of spinal cord compression is present. The lesion was removed by transoral approach and effective decompression was obtained. We reviewed the literatures and discussed the advantage and applications of transoral approach in detail.

Atlanto-Axial Dislocation with Spinal Cord Compression in a Mongoloid Child: A Case Report

Mongolism, which represents about 5% to 10% of all cases of mental deficiency, is a disease entity in which the mental development is associated in a unique way with a large number of physical defects including central nervous system. Tishler and Martel(1965) directed attention to anomalies of the cervical portion of the spine in mongologid patients. Ligament laxity or malformation of the transverse atlanta ligament may allow the CI vertebra to subluxate forward with or without spinal cord compression. The most proper management is reduction by skeletal traction and posterior spinal fusion(C1-2, C1-3, Occiput-C2).

Transoral Decompression and Anterior Fusion of Atlanto-axial Dislocation due to Os Odontoideum: Case Report

The Os odontoideum is a developmental anomaly of the axis in which the odontoid process is divided transversely. The Atlanto-axial dislocation due to Os odontoideum is presented. At first, we have performed the posterior atlanto-axial fusion with wire fixation. But the posterior fusion failed in realignment and did not adequately decompress the deformed cord by encroachment on its ventral surface. Next time, we have experienced further improvement following transoral decompression and anterior fusion.

A Case of Atlanto-axial Dislocation due to Os Odontoideum

A patient who had an atlanto-axial dislocation due to an os odontoideum is presented. She was operated on successfully with preliminary realignment of the dislocation by skeletal traction and subsequent posterior cervical fusion with wiring and iliac bone.

Transoral Fusion of Atlanto-axial Dislocation

The transoral approach to the upper cervical spine is an established but little used route. We have reported a case of traumatic atlanto-axial dislocation which was successfully treated by transoral fusion. Operative preparation, technique applications of the procedure are discussed.

Transoral Fusion of Atlanto-axial Dislocation

The transoral approach to the upper cervical spine is an established but little used route. We have reported a case of traumatic atlanto-axial dislocation which was successfully treated by transoral fusion. Operative preparation, technique applications of the procedure are discussed.

Experience of preventing infection in atlanto-axial operations with transoropharyngeal approach: a report of 80 cases / 解放军医学杂志

Objective To summarize the experience of preventing infection in atlanto-axial operations via transoropharyngeal approach. Methods The methods and experiences of prevention of infection in 80 cases of atlanto-axial dislocation operated on via transoropharyngeal approach were retrospectively summarized and analyzed. Result There was no infection in all the 80 cases. Conclusion As long as preventive measures were perfectly taken, the post-operative infection could be effectively prevented and the transoropharyngeal operation would be safe.

Internal Wiring Fixation of Atlantoaxial Dislocation Caused by Odontoid Fracture in a Child

Although most patients with cervical fractures have damaged the lower cervical spine, there remain a significant number whose injury involve the atlanto-axial level. Since the diagnosis of fracture of he odontoid process was initially missed frequently, it is worth emphasizing the importance of adequate radiological studies for this potentially lethal lesion in head injury patient. The treatment for fractures of the odontoid process has consisted of reduction followed by immobilization using skeletal traction, a plaster case or halo device, or internal fixation by surgical intervention. The advantages of early surgical treatment to minimize external immobilization or prolonged bed confinement are generally accepted but the surgical techniques have varied widely. The authors have managed a case of traumatic atlanto-axial dislocation in a child combined with severe brain injury by internal fixation using wire only after reduction of the dislocation was accomplished by skeletal traction. The available literature regarding this injury is reviewed.