Os odontoideum; a congenital abnormality of the axis; case report.
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A series of 123 patients suffering traumatic spondylolisthesis of the axis is reported. This lesion is associated with extension and axial loading injury, and there is a high incidence of injuries of the face or scalp and of associated fractures of the upper cervical spine. There is a low incidence of neurological injury, which seems paradoxical in the presence of what appears to be gross instability, but protection from extremes of flexion and extension may be adequate treatment. Union is usual regardless of displacement. Traction is a safe means of treatment, but early waking in a halo support reduces time in hospital without jeopardizing the result. Operation is needed only for chronic instability with or without pain, and anterior interbody fusion of C2--3 is than preferred in order to preserve rotation at the atlanto-axial joints.
The retrospective analysis of 131 patients suffering from a fracture of the ring of the axis is reported. The injury was classified into three types according to radiological displacement and stability. Associated injuries and neurological deficit are discussed and a theory of pathogenesis presented. Guidelines for the management of each type of fracture are proposed.
Twenty-three adults with fractures of the odontoid process are reviewed. Te possible reasons for the high rate of non-union in reported series are considered: these include the type of fracture, its displacement, the presence of a gap at the fracture site, imperfect reduction and inadequate immobilisation. Type 2 fractures (at the base of the odontoid process) are the commonest and also the most liable to nonunion. In their treatment, reduction is important; as seen in the lateral radiograph at least two-thirds of the fracture surfaces should be in contact. Skull traction is not advised and halo-cast fixation is the treatment of choice; with this method 87.5 per cent of recent odontoid fractures united.
Thirty-seven patients treated for os odontoideum are reviewed. In 20 patients the treatment was conservative and in 17 consisted of occipitocervical or atlanto-axial fusion. Two patients died after the operation and another, who lived abroad, was lost to follow-up. The remaining 34 patients were followed up for an average of eight years: 19 improved, 14 were unchanged and one deteriorated. In the subgroup of 25 patients without cord signs, there were no significant differences between the two modes of treatment. Analysis of the radiological features of the upper cervical spine in 21 patients revealed a minimal sagittal diameter of less than 13 millimetres to be associated with a high risk of permanent cord damage. There was no correlation with the degree of instability per se. On the basis of this analysis, guidelines are suggested for the management of patients with an os odontoideum.
We report a case of transverse fracture through the body of the axis. This fracture was unstable, had been produced by extension forces and was managed conservatively. The classification of such fractures is discussed.
Posterior cervical wiring is commonly performed for patients with spinal instability, but has inherent risks. We report eight patients who had neurological deterioration after sublaminar or spinous process wiring of the cervical spine; four had complete injuries of the spinal cord, one had residual leg spasticity and three recovered after transient injuries. We found no relation between the degree of spinal canal encroachment and the severity of the spinal-cord injury, but in all cases neurological worsening appeared to have been caused by either sublaminar wiring or spinous process wiring which had been placed too far anteriorly. Sublaminar wiring has substantial risks and should be used only at atlantoaxial level, and then only after adequate reduction. Fluoroscopic guidance should be used when placing spinous process wires especially when the posterior spinal anatomy is abnormal.
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A case of atlanto-axial subluxation in a 17 year old boy with rheumatic disease is reported. The subluxation could not be reduced by cervical traction. Posterior fixation with acrilic and wire was unable to prevent the appearance of signs of spinal cord compression. The odontoid process was removed through a transoral approach leading to neurologic recovery. Treatment of atlanto-axial subluxation is discussed, emphasis being given to the indications for anterior descompression.
OBJECTIVE: To evaluate the results of surgical treatment using pedicle screws going through C2 pedicles for fixating the spondylolisthesis of the axis in patients who presented pseudoarthrosis after clinical treatment, or who have no condition for fixation with "halo vest", due to serious head trauma. METHOD: Ten patients have been operated from June 1998 to April 2002, nine suffering from traumatic spondylolisthesis of the axis caused by car accident and one horse fall. Four of those patients have undergone clinical treatment and presented signs of pseudoarthrosis, suffering intense pain at the movement of the cervical spine. Two of them presented moderate head trauma with multiple fractures of the skull. Another one was submitted to a surgical treatment for an acute extradural hematoma. Three patients presented a serious dislocation of C2 over C3. The patients were submitted to arthrodesis of the fractures with two screws, placed on the C2 pedicles, which allowed a better approximation of the fractures with the alignment of C2-C3. Two other patients required additional fixation with a plate on the lateral masses of C3. RESULTS: Nine patients had a good post surgery evolution with satisfactory consolidation of the fractures and disappearance of the symptoms. One patient had a good evolution but still has cervical pain resulting from strain. CONCLUSION: The fixation of the traumatic spondylolisthesis of the axis using screws in C2 pedicles and through fractures traces is a good option for treating patients who present pseudoarthrosis after clinical treatment or who present contraindication to the "halo vest", such as skull fracture or great lacerations in the scalp.
The axis from twenty-two cadavera was removed at autopsy and was sectioned in the sagittal plane to a thickness of one millimeter with use of a surface-stained block-grinding technique. Combined two and three-dimensional analysis included an evaluation of the volume of the trabecular bone, the trabecular interconnection, and the cortical thickness as well as qualitative investigation of the structure of the cancellous bone. The body of the axis, the base of the odontoid process, and the odontoid process were analyzed separately. The base of the odontoid process is a region of least resistance for fractures because of its unique microarchitecture. The mean volume of trabecular bone of the base of the odontoid process is 55 per cent less than that of the axis and the odontoid process. The base also has a markedly poorer trabecular interconnection and a cortical thickness that is one-third that of the odontoid process. In all of the specimens, trabeculae that were disconnected from the trabecular lattice (trabeculae with free ends) were demonstrated in the base of the odontoid process. The formation of microcallus in six (27 per cent) of the specimens supports the hypothesis that microfractures occur as a result of stress peaks, mechanical fatigue, and the relative insufficiency of bone in the static condition. Therefore, the base of the odontoid process can be considered as a site of predilection for fractures.
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A case of unilateral dysplasia of the superior articular facet of the axis due to incomplete or delayed ossification is described in a child. This may result in asymmetry of the articular surfaces of the axis in adult life and be a cause of torticollis. To our knowledge, no similar case has been reported.
This paper describes a technique for analyzing movement of the cervical spine. The method consists of superimposition of two films representing the cervical spine in the end positions of the movement under investigation (e.g., flexion and extension). From tracings of selected structures, movement is represented in the form of movement diagrams. Knowledge of cervical spine dynamics is helpful in understanding muscle and ligament function as well as the shape of components in various postures.
The results of a computer analysis of 399 patients with documented fractures and/or dislocations of the cervical spine are summarized. Vertebral arch fractures were present in half of all patients with radiographic evidence of cervical spine trauma. Two-thirds of the patients had two or more injuries. Isolated disk injuries were rare and, when present, were characterized by a vacuum sign. The dens fracture, with or without atlantoaxial dislocation, was rarely associated with injury elsewhere in the cervical spine. The study suggests that the routine five-film cervical spine examination is inadequate to detect the most common traumatic lesions. Thus vertebral arch views (pillar views) should be obtained if there is evidence to suggest hyperextension as the mechanism of injury. In addition, the study underscores the importance of aggressively searching for multiple abnormalities.
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