Atlantoaxial instability and retroodontoid mass--two case reports.
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Two relatively elderly male patients (61 and 78 years) suffered moderately severe trauma to the head 1 and 3 years, respectively, prior to presentation with progressive quadriparesis and neck pain. Investigations revealed retroodontoid ligamentous hypertrophy and subtle mobile atlantoaxial dislocation. Following atlantoaxial fixation, both patients showed remarkable and sustained neurological improvement. These cases provide further evidence that retroodontoid ligamentous hypertrophic mass lesion could be secondary to instability of the atlantoaxial region. (+info)
The treatment of odontoid fractures with a significant displacement.
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OBJECTIVE: The purpose of this study was to determine the treatment features of odontoid fractures with a significant displacement. MATERIAL AND METHODS: Thirty-seven patients with acute odontoid fractures were treated in Kaunas University of Medicine Hospital between 1998 and 2003. Seventeen persons with displacement of fragments less than 5 mm or 5 mm (according to E. A. Seybold and J. C. Bayley method) were in the first group. Twenty patients with displacement of fragments more than 5 mm were in the second group. The attempt of closed reduction of the cervical spine axis was performed for all patients. If successful closed reduction was achieved, patients were placed in halo-vest device for 8 weeks. If closed reduction failed, patient was operated according to W. E. Gallie. Postoperatively, all patients wore a halo-vest device during the first 8 weeks. RESULTS: Demographics including age, sex, neurological condition, and associated spinal fractures were similar in patients from these groups (p>0.05). Successful closed reduction of the cervical spine axis was achieved in 11 (64.7%) patients from the first group and in 13 (65%) patients from the second group (p>0.05). Six (35.3%) patients from the first group and seven (35%) from the second group were treated with immediate C1-C2 posterior fusion (p>0.05). Two (16.7%) from twelve patients from the second group were treated by external immobilization by halo-vest device and had nonunion of fracture 8 weeks after the treatment. All operated patients had a solid fusion. CONCLUSIONS: If closed reduction of the odontoid fracture with a significant displacement was achieved then external immobilization by halo-vest device can be used. Posterior fusion is the treatment of choice for irreducible odontoid fractures. (+info)
Type I odontoid fracture--case report.
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A 17-year-old man presented with sleeping tendency, tenderness of the back of the neck, and left upper monoplegia after a motorcycle accident. Three-dimensional computed tomography on the 2nd hospital day clearly revealed a type I odontoid fracture. His injuries were treated conservatively and he was discharged on the 60th hospital day, with sequelae due to the cervical root avulsion injuries. Type I odontoid fracture is rare and may be caused by coronal distraction of the head and neck area. (+info)
CT evaluation of the pattern of odontoid fractures in the elderly--relationship to upper cervical spine osteoarthritis.
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Odontoid fractures are common in the elderly following minor falls. Almost all of them have osteoarthritis of the cervical spine below the axis vertebra. As a result, there is increased stress on the spared upper cervical spine, resulting in a higher incidence of injuries. As movement in the upper cervical spine involves participation of five joints, degeneration in any one particular joint may affect the biomechanics of loading of the upper cervical spine. We aimed to analyse the relationship of odontoid fractures to the pattern of upper cervical spine osteoarthritis in the elderly. We studied the CT-scan images of the cervical spine in 23 patients who were over the age of 70 years and had odontoid fractures. In each patient, the type of odontoid fracture and the characteristics of the degenerative changes in each joint were analysed. Twenty-one of 23 patients had Type-II odontoid fractures. The incidence of significant atlanto-odontoid degeneration in these individuals was very high (90.48%), with relative sparing of the lateral atlantoaxial joints. Osteoporosis was found in 13 of 23 patients at the dens-body junction and in seven of 23 patients at the odontoid process and body of the axis. With ageing, progressively more severe degenerative changes develop in the atlanto-odontoid joint. These eventually obliterate the joint space and fix the odontoid to the anterior arch of the atlas. In contrast, the lateral atlantoaxial joints are hardly affected by osteoarthritis. Thus, ultimately, atlantoaxial movements including atlantoaxial rotation are markedly limited by osteoarthritis of the atlanto-odontoid joint. However, there is still potential for movement in the lateral atlantoaxial joints, as they remain relatively free of degenerative change. The vulnerability of the atlantoaxial segment is further increased by markedly limited rotation below the axis vertebra due to severe facet-joint degeneration. As a consequence, a relatively low-energy trauma to the lateral part of the face, for instance by a fall, will induce forced atlantoaxial rotation. This, with the marked limitation of movement at the atlanto-odontoid joint, will produce a torque force at the base of the odontoid process leading to a Type II fracture. (+info)
The borders of the odontoid process of C2 in adults and in children including the estimation of odontoid/body ratio.
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The odontoid process of C2 projects upward from the superior roof of the body of C2. There is a confusion about the inferior border of the odontoid. The aims of this clinical study were to describe the inferior border of the odontoid process based on the remnant of dentocentral synchondrosis in adults, and the estimation of the odontoid/body ratio in pediatric and adult ages. Sixty-six cases were included for this study. Forty-four of them were in adult ages and the remaining 22 of them were in pediatric ages. The region of occiput, C1, C2, and C3, was examined with the magnetic resonance imaging (MRI) in all cases. The length of the odontoid process was estimated by using radiological images of MR from the tip of the odontoid to the remnant of dentocentral synchondrosis. The portion located under the level of synchondrosis was considered as the body of C2. The average length of the odontoid was 18. 6 mm in pediatric and 21. 3 mm in adult cases. In adult females, the length of the odontoid process (19. 1 mm in length) was smaller than those of adult males (23. 6 mm in length). The average ratio of odontoid/body was two in pediatric and 1.8 in adult cases. This study demonstrated that the neck of the odontoid segment at the level of superior articulating facets is not the synchondrosis between the odontoid process and the body of C2. The synchondrosis is located well below the level of superior articulating facets. It can be demonstrated with sagittal and coronal images of MR in both of pediatric and adult individuals. (+info)
Odontoid lateral mass asymmetry: do we over-investigate?
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OBJECTIVES: This study aimed to evaluate the necessity for further radiological investigation in patients with suspected traumatic rotatory subluxation of the atlanto-axial complex on plain radiography following acute cervical trauma and outline guidelines for assessment of patients with atlanto-axial asymmetry on plain radiography. METHODS: A retrospective review of all patients who had undergone atlanto-axial CT scanning as a result of radiographic C1-C2 asymmetry following cervical spine trauma. The plain x ray and CT images were reviewed retrospectively and correlated with the clinical presentation and outcome. RESULTS AND CONCLUSION: Records of 29 patients (16 men, 13 women; age range 21-44 years) were reviewed. All patients were found to have atlanto-odontoid asymmetry on the initial plain x ray. CT images of none of the patients revealed rotatory subluxation. Ten patients (32%) were found to have congenital odontoid lateral mass asymmetry. All patients were treated conservatively without any further intervention. On review, in 19 patients the orientation of the x ray beam in combination with head rotation was found to be at fault. Approximately 1050 trauma cervical spine x rays were taken in the department where this study was conducted over the period 1999-2001. This study identified 10 patients out of a total of 29 as having congenital odontoid lateral mass asymmetry. This represents approximately 1% of the patients attending the emergency department. Thus congenital odontoid lateral mass asymmetry should be considered in the differential diagnosis following acute cervical trauma. (+info)
Subdental synchondrosis and anatomy of the axis in aging: a histomorphometric study on 30 autopsy cases.
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During skeletal development the two ossification centers of the odontoid process are separated from the corpus of the axis by a subdental synchondrosis. This synchondrosis is thought to close and disappear spontaneously in adolescence although this has never been studied in detail. The basis of the dens is of clinical relevance as type II dens fractures are located here. To characterize the morphological architecture of the axis with particular attention to the subdental synchondrosis, the complete axis was harvested from thirty age-matched and gender-matched patients of the three different age groups at autopsy. The subdental synchondrosis and the bone structure of the dens, the basis of the dens and the body of C2 were analyzed by radiography, histology and quantitative histomorphometry. At the macroscopic level the persistency of the subdental synchondrosis in the adult cervical spine was detected in 87% (26 of 30) of the specimens. Histomorphometry revealed a residual disc blastema with an average size of 25.8% of the sagittal depth of the basis of the dens at this level. Bony integration of the synchondrosis was poor throughout all ages. Histologically a cartilaginous matrix composition of the subdental synchondrosis persisted throughout all groups. The trabecular microarchitecture demonstrated a significant reduction of bone volume and trabecular number as well as an increased trabecular separation within the basis of the dens as compared to the corpus or the dens of C2. This histomorphometric data regarding a poor integration of the synchondrosis into the trabecular network and the reduced bone mass within the basis of the dens might offer a previously underestimated explanation for the occurrence of type II dens fractures and their association with pseudoarthrosis, respectively. (+info)
Os odontoideum with bipartite atlas and segmental instability: a case report.
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We report on the case of a 15-year-old adolescent who presented with a transient paraplegia and hyposensibility of the upper extremities after sustaining a minor hyperflexion trauma to the cervical spine. Neuroimaging studies revealed atlantoaxial dislocation and ventral compression of the rostral spinal cord with increased cord signal at C1/C2 levels caused by an os odontoideum, as well as anterior and posterior arch defects of the atlas. The patient underwent closed reduction and posterior atlantoaxial fusion. We describe the association of an acquired instability secondary to an os odontoideum with an anteroposterior spondyloschisis of the atlas and its functional result after 12 months. The rare coincidence of both lesions indicates a multiple malformation of the upper cervical spine and supports the theory of an embryologic genesis of os odontoideum. (+info)