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.

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.

Análisis morfométrico del axis para la fijación atlantoaxial / Morphometric analysis of the axis for atlantoaxial fixation

El objetivo de este estudio fue evaluar de manera integral los parámetros morfométricos de la vértebra axis (C2) en la población mexicana involucrados en la realización de procedimientos quirúrgicos con el fin de proveer datos cuantitativos indispensables en su abordaje quirúrgico. Para este estudio se utilizaron un total de 576 vértebras axis (C2) de población mexicana contemporánea. Las mediciones de las vértebras se efectuaron bilateralmente utilizando un vernier digital milimétrico con una precisión de 0.01 mm (Mitutoyo Digimatic w/Absolute Encoders- Series 500). Un total de 576 vértebras axis (C2), fueron medidas de manera bilateral, todas nuestras mediciones se reportaron en mm. El promedio del ancho del pedículo fue de 8,96 mm con una DE ± 2,11 mm. El promedio de la altura del pedículo fue de 10,82 mm con una DE de ± 1,89 mm. El promedio de la altura del proceso odontoideo fue de 16,90 mm con una DE de ± 2,99 mm. El promedio del ancho del proceso odontoideo fue de 9,99 mm con una de DE de ± 0,80 mm. El promedio del diámetro de la faceta articular fue de 8,44 mm con una DE de ± 1,04 mm. El promedio del diámetro AP del cuerpo vertebral fue de 15,11 mm con una DE de ± 1,88 mm. El promedio del diámetro trasverso del cuerpo vertebral fue de 17,93 mm con una DE de ± 2,22 mm. El promedio de la altura del cuerpo vertebral fue de 18,54 mm con una DE de 2,38 mm. El promedio de la altura de las láminas fue de 11,53 mm con una DE de ± 1,39 mm. El promedio del ancho de las láminas fue de 6,10 mm con una DE de ± 1,44 mm. Los resultados obtenidos en nuestras mediciones demuestran una variación con los resultados de otros autores en diferentes estudios de piezas osteológicas y de estudios de imagen del axis (C2), lo que sugiere, con el fin de reducir los riesgo de daño a estructuras neurovasculares, utilizar técnicas y medidas especiales para la estabilización atlantoaxial de la población mexicana.

The aim of the study was to evaluate the morphometric parameters of the axis vértebra (C2) in the Mexican population involved in the performance of surgical procedures in order to provide essential quantitative data in their surgical approach. A total of 576 axis vertebrae (C2) of contemporary Mexican population were used for this study. The measurements of the vertebrae were made bilaterally using a millimeter digital vernier with an accuracy of 0.01 millimeters (Mitutoyo Digimatic w / Absolute Encoders - Series 500). A total of 576 axis vertebrae (C2) were measured bilaterally, all our measurements were reported in millimeters. The average width of the pedicle was 8.96 mm with a SD ± 2.11 mm. The average height of the pedicle was 10.82 mm with a SD of ± 1.89 mm. The average height of the odontoid process was 16.90 mm with a SD of ± 2.99 mm. The average width of the odontoid process was 9.99 mm with a SD of ± 0.80 mm. The average diameter of the articular facet was 8.44 mm with a SD of ± 1.04 mm. The average diameter of the AP of the vertebral body was 15.11 mm with a SD of ± 1.88 mm. The average transverse diameter of the vertebral body was 17.93 mm with a SD of ± 2.22 mm. The average height of the vertebral body was 18.54 mm with a SD of 2.38 mm. The average height of the lamina was 11.53 mm with a SD of ± 1.39 mm. The average width of the lamina was 6.10 mm with a SD of ± 1.44 mm. The results obtained in our measurements show a variation with the results of other authors in different studies of osteological pieces and studies of the axis image (C2), which suggests the use of techniques and special measures for the atlantoaxial stabilization of the Mexican population in order to reduce the risk of damage to neurovascular structures.

Clinical application of atlantoaxial pedicle screw placement assisted by a modified 3D-printed navigation template

OBJECTIVES: To investigate the primary clinical value of atlantoaxial pedicle screw placement assisted by a modified 3D-printed navigation template. METHODS: We retrospectively analyzed the cases of 17 patients treated from June 2015 to September 2016 with atlantoaxial pedicle screw placement assisted by a modified 3D-printed navigation template. All procedures were performed prior to surgery, including thin-slice CT scanning, medical image sampling and computerized 3D modeling of the atlantoaxial joint, optimal pedicle screw trajectory determination, and anatomical trait acquisition for the atlantoaxial pedicle, spinous process of the axis, vertebral lamina and posterior lateral mass, and design of a reverse template. During surgery, a navigation template was tightly attached to the atlantoaxial joint to assist in pedicle screw placement. Surgeons subsequently used an electric drill to remove the template through a guide channel and then placed the atlantoaxial pedicle screw. Observed indexes included the VAS score, JOA improvement rate, surgery duration, and blood loss. RESULTS: Surgery was successful in all 17 patients, with an average operation duration of 106±25 min and an average blood loss of 220±125 ml. Three days postoperatively, the VAS score decreased from 6.42±2.21 to 3.15±1.26. Six months postoperatively, the score decreased to 2.05±1.56. The postoperative JOA score increased significantly from 7.68±2.51 to 11.65±2.72 3 d after surgery and to 13.65±2.57 after 6 months. Sixty-eight pedicle screws were inserted successfully, with 34 in the atlas and 34 in the axis. According to the Kawaguchi standard, 66 screws were in grade 0 (97.06%), and 2 were in grade 1 (2.94%). The pre- and postoperative transverse and sagittal screw angles showed no significant differences. CONCLUSIONS: Atlantoaxial pedicle screw placement assisted by a modified 3D-printed navigation template is worth recommending due to the improved accuracy in screw placement, improved patient safety and beneficial clinical effects.

The anatomic study on replacement of artificial atlanto-odontoid joint through transoral approach / 华中科技大学学报（医学）（英德文版）

In order to provide anatomical basis for transoral approach (TOA) in dealing with the ventro lesions of craniocervical junction, and the design and application of artificial atlanto-odontoid joint, microsurgical dissecting was performed on 8 fresh craniocervical specimens layer by layer through transoropharyngeal approach. The stratification of posterior pharyngeal wall, course of vertebral artery, adjacent relationship of atlas and axis and correlative anatomical parameters of replacement of artificial atlanto-odontoid joint were observed. Besides, 32 sets of atlanto-axial joint in adults' fresh bony specimens were measured with a digital caliper and a goniometer, including the width of bony window of anterior arch of atlas, the width of bony window of axis vertebra, the distance between superior and inferior two atlas screw inserting points, the distance between two axis screw inserting points etc. It was found that the width of atlas and axis which could be exposed were 40.2+/-3.5 mm and 39.3+/-3.7 mm respectively. The width and height of posterior pharyngeal wall which could be exposed were 40.1+/-5.2 mm and 50.2+/-4.6 mm respectively. The distance between superior and inferior two atlas screw inserting points was 28.0+/-2.9 mm and 24.0+/-3.5 mm respectively, and the distance of bilateral axis screw inserting points was 18.0+/-1.2 mm. The operative exposure position through TOA ranged from inferior part of the clivus to the superior part of the C3 vertebral body. Posterior pharyngeal wall consisted of 5 layers and two interspaces: mucosa, submucosa, superficial muscular layer, anterior fascia of vertebrae, anterior muscular layer of vertebrae and posterior interspace of pharynx, anterior interspace of vertebrae. This study revealed that it had the advantages of short operative distance, good exposure and sufficient decompression in dealing with the ventro lesions from the upper cervical to the lower clivus through the TOA. The replacement of artificial atlanto-odontoid joint is suitable and feasible. The design of artificial atlanto-odontoid joint should be based on the above data.

Posterior C1-C2 plating: a novel technique for posterior C1-C2 fusion Preliminary results

Posterior transarticular C1-C2 screw fixation is the most popular technique for instrumented atlantoaxial fusion. The construct is usually augmented by a sort of sublaminar C1-C2 wire fixation. In spite of this augmentation, construct failure with pseudarthrosis still can be encountered and presents a real challenge. to introduce a new technique for C1-C2 fusion in which a special plate is used for fixing the arch of Cl to the lateral mass of C2. The transarticular screw fixation is done through the caudal hole in the plate. The author designed a plate [Lotus Cervical Plate, LCP] for posterior C1-C2 fixation [Intraplant Company, Germany]. The proximal end of the plate is U-shaped. Fixation to the atlas is achieved by contouring the u-shaped end of the plate to seize the arch of C1. A locking mini-screw is inserted in the arch of C1. The transarticular C1-C2 screw fixation is done through the distal hole of the plate. The plate was applied in 10 patients with atlantodental instability due to rheumatoid arthritis. Two of them were revision cases and presented with pseudarthrosis and metal failure after attempted transarticular fixation [Magerl technique] augmented with sublaminar fixation. Two plates of suitable lengths were used for the C1-C2 fixation. A corticocancellous bone graft was fixed between the decorticated posterior arch of C1 and the lamina of C2. The period of follow up ranged between 12 months and 20 months [mean: 15.20 months, sd.2.49] The technique was safe. Fusion was evident 3 months after the operation. Apart from remodelling of the graft, no metal failure occurred. From the biomechanical point of view C1-C2 plating is stiffer than transarticular C1-C2 fixation even when the latter is augmented by sublaminar fixation. The introduced technique can supplant the traditional augmentation of Magerl technique using wire or cable particularly in severe C1-C2 instabilities

Atlantoaxial fixation: overview of all techniques.

Over the past century, steady advances have been made in fixating an unstable atlantoaxial complex. Current options for fixation of the atlantoaxial complex include posterior clamps, posterior wiring techniques, C1-C2 transarticular screw fixation, posterior C1 lateral mass screw with C2 pars or pedicle screw fixation, and anterior transoral C1 lateral mass to C2 vertebral body fixation.

Craniovertebral realignment for basilar invagination and atlantoaxial dislocation secondary to rheumatoid arthritis.

OBJECTIVE: We present our experience of treating nine consecutive cases of rheumatoid arthritis involving the craniovertebral junction by atlantoaxial joint manipulation and attempts towards restoration of craniovertebral region alignments. MATERIAL AND RESULTS: Between November 2001 and March 2004, nine cases of rheumatoid arthritis involving the craniovertebral junction were treated in our department of neurosurgery. Six patients had basilar invagination and 'fixed' atlantoaxial dislocation and three patients had a retroodontoid process pannus and mobile and incompletely reducible atlantoaxial dislocation. The patients ranged from 24 to 74 years in age. Six patients were males and three were females. Neck pain and spastic quadriparesis were the most prominent symptoms. Surgery involved attempts to reduce the atlantoaxial dislocation and basilar invagination by manual distraction of the facets of the atlas and axis. Reduction of the atlantoaxial dislocation and of basilar invagination and stabilization of the region was achieved by placement of bone graft and metal spacers within the joint and direct inter-articular plate and screw method of atlantoaxial fixation. Following surgery all the patients showed symptomatic improvement and restoration of craniovertebral alignments. Follow-up ranged from four to 48 months (average 28 months). CONCLUSION: Manipulation of the atlantoaxial joints and restoring the anatomical craniovertebral alignments in selected cases of rheumatoid arthritis involving the craniovertebral junction leads to remarkable and sustained clinical recovery.

Instabilidade atlanto-axial na síndrome de Down. Relato de 10 casos tratado s cirurgicamente / Atlantoaxial instability in Down sindrome. A reporte of 10 cases treated surgically

Os autores apresentam dez pacientes portadores da síndrome de Down, com instabilidade atlanto-axial, submetidos à artrodese por via posterior. Dos dez pacientes, sete (70 por cento) evoluíram com consolidaçäo da artrodese após a primeira cirurgia e três (30 por cento) necessitaram de uma segunda intervençäo para assegurar um bom resultado final. Esses três casos apresentavam anomalias congênitas associadas à instabilidade atlanto-axial e, nesses casos, os autores chamam a atençäo para a necessidade de imobilizaçäo mais rígida no pós-operatório, para evitar a näo consolidaçäo da artrodese.

Atlanto-axial dislocation in children

The authors present 14 cases of C1 C2 dislocations in children (8 boys and 6 girls; mean age, 6.9 years) seen at the Orthopedics and Traumatology Institute of the University Hospital, Faculty of Medicine, University of Säo Paulo from 1978 to 1990. In view of the disappointing results obtained by conservative treatment in 6 of the 14 patients, the authors recommend early atlanto-axial arthrodesis in cases of C1 C2 dislocation in children

Tratamento cirúrgico da subluxaçäo atlanto-axial / Surgical treatment of atlanto-axial subluxation

Os autores apresentam a experiência no tratamento cirúrgico de 4 pacientes portadores de compressäo ventral do tecido nervoso pelo odontóide devido a subluxaçäo atlanto-axial. As causas mais comuns de subluxaçäo atlanto-axial no adulto säo os traumatismos e artrite reumatóide. Em 3 dos casos apresentados a etiologia foi atribuída à disgenesia do odontóide (hipoplasia, os osteoideum e ossiculum terminale) e em um caso houve a contribuiçäo de anormalidades congênitas. Todos os pacientes apresentavam predominantemente manifestaçöes clínicas de lesöes do trato piramidal e alteraçöes da sensibilidade profunda. Os exames neurorradiológicos mostraram deslocamento posterior do odontóide em todos os casos. Um dos pacientes com subluxaçäo redutível foi submetido a artrodese occipitocervical por via posterior. Os outros 3, com subluxaçöes irredutíveis, foram submetidos a ressecçäo transoral do odontóide. Um destes casos apresentou instabilidade atlanto-axial pós-operatória e foi submetido a artrodese occipitocervical por via posterior. Dois pacientes melhoraram clinicamente, 1 permaneceu inalterado e 1 faleceu por complicaçöes cardiorespiratórias. Com base nas referências da literatura e nos problemas observados nos casos tratados, os autores discutem a escolha da tática cirúrgica mais adequada para o tratamento destes pacientes