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Fractures of the odontoid process of the axis create problems of specific osteosynthesis. The different techniques described so far require an external support and limit the movements of the cranio-cervical joint. These 2 drawbacks are avoided by direct screw fixation of the odontoid process in cases where conditions are favourable to this procedure.
Pyogenic osteomyelitis of the odontoid process is a rare condition requiring a high index of suspicion for diagnosis. The three cases presented illustrate that patients with severe neck pain, aggravated by rotation, and persistent fever without apparent source should be studied carefully to exclude infection of the C1-C2 area. The unusual anatomy of the C1-C2 articulation may make routine diagnostic studies difficult to interpret. Computed tomography, magnetic resonance imaging, and 111In-labeled white blood cell scans may improve diagnostic accuracy. Treatment includes rigid immobilization, high dose antibiotics, and surgical stabilization in selected cases.
Six cases of spontaneous fracture of the odontoid process in rheumatoid arthritis are presented. Fifty-one patients with atlantoaxial subluxation in rheumatoid arthritis underwent surgery between 1981 and 1990. This included six patients (in 10%) who had subluxation accompanied by fracture of the odontoid without apparent trauma. The mean patient age was 58 years and all had a long history of rheumatoid arthritis. No trauma was considered to be the cause of the fracture. This is a fracture caused by erosion and osteoporosis of the odontoid process due to rheumatoid synovitis, aging and steroid therapy. In addition, another cause is a dynamic load produced from the instability accompanying atlantoaxial subluxation working on the odontoid in cervical extension. It is important remember that the odontoid process is susceptible to spontaneous fracture.
Fracture of the odontoid process in young children is possibly not as rare as hitherto believed. In this paper, two more patients with this fracture are presented, and an important diagnostic clinical sign is described. Both patients sustained the injury by falling from heights no greater than sixty-one to ninety-one centimeters. In each instance, injury to the cervical spine was suspected but initial roentgenograms failed to reveal any fracture. The patients were quite comfortable when lying supine and when fully erect. Each child strongly resisted any attempt at extension of the neck and cried bitterly when brought to either the erect or the recumbent position unless the head was passively supported. This a valuable clinical sign when injury to the odontoid process is suspected. Subsequent roentgenograms confirmed the diagnosis in each instance.
We reviewed eleven patients less than seven years old with fractures of the odontoid process in an effort to establish a more standard form of treatment for the injury and to determine what complications, if any, occur as a result of fractures of the odontoid process in pediatric patients. Our study showed that children with odontoid fractures that are recognized and treated promptly usually do well. The fracture can usually be reduced by passive manipulation or by the "hanging head technique". Support in the reduced position for two to three months in a Minerva jacket or halo cast should be long enough to permit healing. Our study suggests that fractures of the odontoid process in young patients almost always heal.
In the year 1981, J. Böhler completed for the first time a screw fixation for unstable fractures of the odontoid process of the axis. This surgical technique preserves the anatomy and the physiology of the articulation between the atlas and the axis, as a guarantee for a good functional recovery. It is not a very difficult technique when performed by a trained surgeon with a very good X-ray image intensification for the per-operative control. We have treated 32 unstable fractures of the odontoid process without any neurological complication per- or post-operatively. We had a follow-up on only 29 cases. In 19 cases the fracture healed in leading to a good bone union, complete mobility and no residual pain. Seven patients complained of residual pain or a limitation in cervical movement, because of the association with other cervical fractures, an age superior of 70 years, or a major initial instability. In 2 cases the authors noted a non-union and a secondary displacement because of technical faults at the beginning of their experience. These good results determined the authors to prefer the direct screw fixation for the unstable fractures of the odontoid process, to the posterior arthrodesis which leads to functional limitations.
A clinical study of fractures of the odontoid process showed a 62 per cent failure on union. Of many features studied, only displacement and its direction had a definite bearing on non-union of the fracture. Blood supply was considered as a possible etiological factor. The blood supply of the human odontoid was elucidated by means of studying 19 human autopsies by means of microangiography. The dog was found to have a similar blood supply and hence, was used as the experimental model. Two osteotomies were performed; one below the accessory ligaments and one above the accessory ligaments. All osteotomies carried out below the accessory ligament united and all carried out above failed to unite. Microangiographic studies revealed however, that avascular necrosis was not the cause of non-union. Further anatomic studies revealed that different size gaps occurred depending on the level of the osteotomy, with a large gap occurring in the osteotomy of the odontoid which was performed above the accessory ligament. First the result of immobilization and the healing of the odontoid osteotomy was derived, by carrying out an instant occipito-cervical fusion by means of wire loops and methylmethacrylate. In distinction to the free floating apical segment of non-immobolized spines, with a high odontoid osteotomy, the occipito-cervical fusion resulted in a dense fibrous tissue stabilizing the apical fragment but at no time was bony union observed. A final attempt was to secure immobilization and reduce the gap, by carrying out only a partial osteotomy. The osteotomy was performed in such a way that the posterior cortex was left intact. Union occurred in all instances. The fracture gap and movement play a definite role in the pathogenesis of pseudarthrosis of the odontoid process. Where gap and movement were eliminated, union occurred. It is difficult to transpose this experimental situation to the clinical one, for the assessment of gap clinically, is only radiographic. This method is much too imprecise to be of value in this assessment. The fact however, that a high rate of non-union is associated with a high degree of displacement, supports the experimental thesis.
Studies on the morphology of the odontoid process by various methods strongly suggest a functional adaption of this bony element. With regard to the inclination of the dens axis and the varying position of its articular facets, a modified trabecular system can be observed. Photoelastic experiments confirm that these modifications are correlated with two specific kinds of mechanical stress. The straight odontoid process is only subjected to stress due to compression, but the dorsally inclined dens to bending stress. Based on the morphological and experimental findings, flexion and extension between the first and second vertebrae (in addition to rotation as the principle movement) are discussed.
The authors describe a case of direct screw fixation of the odontoid process via an anterolateral retropharyngeal subhyoid pre-sternomastoid approach and discuss the indications for this operation. In this particular case, immobilization by a cervical collar or a halo vest was not chosen because of its constraining character and the risk of secondary displacement and pseudarthrosis. C1-C2 or occipitospinal arthrodesis, whether performed via a posterior, lateral or anterior approach, is difficult to perform and always leads to a functional handicap. The transoral approach does not allow direct screw fixation of the dens. Dens screwing via an anterior pre-sternomastoid subhyoid approach is the most logical and least disabling technique. The subhyoid approach is much simpler than the suprahyoid approach. This technique is used in fractures of the odontoid process with an ablique downward and backward fracture line, with or without arch fracture of C1, and allows screwing perpendicular to the fracture line. Considering the present results and the literature, the double screw fixation does not seem to be justified.
Clinical and roentgenologic studies were performed in 69 children with Down's syndrome, without the separate odontoid process, that could be followed for more than 5 years. At the follow-up examination, the atlanto-odontoid process interval (AOI) in flexion, neutral, and extension of the cervical vertebrae significantly decreased when compared with the one at the initial examination. This was particularly obvious up to 5 years of age. Although 14 of 69 cases (20.3%) had atlanto-axial instability at the initial examination, this decreased to four cases (5.8%) at the follow-up examination. However, there were two cases of atlanto-axial instability who were over 10 years of age. There was no significant difference in the minimum sagittal diameter (MSD) at the atlantal level between each position at both the initial and follow-up examinations. Moreover, there was a tendency for the MSD of the cases of positive instability at the follow-up examination to be smaller than those of the cases of negative instability. The degree of ligament laxity improved with increasing age and there was statistically the negative correlation. Although there was a tendency for the AOI to decrease with improvement of the degree of ligament laxity, the correlation could not be confirmed.
The objective of this study is to analyse the advantages and disadvantages of different surgical technics of odontoid process fracture stabilization. We try to find the best indications for each of them. We won't consider stable odontoid fractures which haven't treated by surgical therapy. A review of ninety acute dens fractures since 1979 has been analysed before 1985, the most of our injured person had a surgical stabilization by posterior approach. The analysis of our results had incited us, since that date, to vary our indications, by taking possibilities of anterior approach into consideration. So, have been realized 55 C1-C2 lacings, 20 of which with bone graft, 12 occipito-cervical arthrodesis, 10 screw fixations of odontoid process, 9 atlanto-axial arthrodesis by screw fixations, 2 posterior fixations by CD pediatric instrumentation, 1 Knodt instrumentation, 1 osteosynthesis by trans-oral exposure. Patients have been seen again, 1 month, 3 month, 6 month, 1 year later. Results have been estimated: Clinically by cervical mobility study in rotation and by local pain (16 excellent results, 24 good results, 27 middle results, and 23 bad results); Radiologically by analysis of specific complications of each technic (8 secondary removing, 6 incomplete deplacement corrections, 4 excessive corrections, 3 pseudarthrosis). We have regrouped global results technic by technic. We propose a therapeutic planning in which each technic can find the best result. The objective is to assure an effective retention by preserving movings of superior cervical spine.
In eighteen patients who had long-standing severe rheumatoid polyarthritis, cranial subluxation of the odontoid process was caused by erosion and collapse of both the occipitocervical and the atlantoaxial facet joints. In five of the patients, the subluxation caused impairment of cranial nerves. One patient was tetraparetic. Six patients had a posterior fusion of the spine; of these, three also had laminectomy of the atlas. Operative treatment seemed to arrest the subluxation, but there was appreciable functional improvement in only four of the six patients. During an average of four years of follow-up, in the twelve conservatively treated patients, the cranial subluxation of the odontoid process progressed, on average, from 8.6 to 10.5 millimeters.
Aneurysmal bone cysts (ABCs) are relatively uncommon, benign lesions. Fully 50% occur in long bones and 20% in the vertebral column, mostly in patients under 20 years of age. We report a case of an ABC in the odontoid process of a 74-year-old who sought treatment for pain and myelopathy. This is the first case reported of an ABC of the odontoid process.
For a satisfactory direct screw fixation of fractures of the odontoid process it is necessary to use a screw of the proper total length and thread length, but such an optimal ready-made screw is not always available. The authors describe a technique of intra-operative screw trimming using a high-speed diamond drill. This adjustment is easily and quickly performed. It enables the screw to act as a compression screw, which facilitates fusion of the fractured surfaces.
The authors present a retrospective analysis of 128 cases of odontoid process injury treated at the University of Minnesota and affiliated hospitals between the years 1967 and 1983. Of these 128 cases, 110 were acute fractures, while 18 patients suffered from old, unstable odontoid injuries. Motor vehicle accident was the leading cause of injury, and the largest group of patients was in their second decade. Type II fractures were the most commonly encountered type of injury, and anterior subluxation was the most common displacement. Posterior subluxation, however, had the highest incidence of associated neurological deficit. Regarding treatment, the 110 acute fracture patients fell into the following groups: 16 patients died during the acute phase, 14 patients underwent early posterior cervical fusion, and 80 patients underwent a course of external skeletal fixation. The remaining 18 patients with old unstable injuries underwent posterior cervical fusion. An analysis of the results in these groups led to the elucidation of certain factors that likely are important in determining the treatment of each individual patient. These factors include age of the patient, type of odontoid fracture, direction and degree of fracture displacement, and diagnostic delay. Fracture reduction and halo immobilization are the treatments preferred for patients who are diagnosed within 1 week of injury, who are less than 65 years of age and who have anteriorly, nondisplaced, or minimally posteriorly subluxed (less than 2 mm) Type II fractures, or who have any Type III injury.(ABSTRACT TRUNCATED AT 250 WORDS)
The authors report two cases of herniated intervertebral disc presenting as a mass posterior to the odontoid process and causing myelopathy in previously healthy elderly women. The differential diagnosis of a mass at the craniovertebral junction is reviewed, and the implications of these cases are discussed.
In order to analyse the normal signal intensity of the medullary space of the odontoid process (dens) relative to age, the craniovertebral junction of 33 asymptomatic volunteers in six age groups was examined by means of magnetic resonance imaging. To avoid partial-volume effects 3-mm slices were used in sagittal and axial planes. The signal intensities relative to cerebral white matter varied from 0.51 to 1.23 in the sagittal plane and 0.56 to 1.51 in the axial plane. The signal intensities relative to muscle varied from 0.76 to 2.40 in the sagittal plane and 0.96 to 2.30 in the axial plane. The signal intensities relative to fat varied from 0.22 to 0.62 in the sagittal plane and 0.23 to 0.68 in the axial plane. No correlation with age of the volunteers was found. The normal medulla of the dens may exhibit a low signal intensity on T1-weighted images irrespective of age.
A case of a fresh type II fracture (Anderson & D'Alonzo) of the odontoid process treated with direct screw fixation is reported. A 52-year-old man complained of severe neck pain following a hit on his forehead incurred in a falling accident. Neurological examination was normal. Cervical spine x-ray films and axial CT scans revealed a fracture at the base of the dens. It was slightly oblique leftup and rightdown, and the dens fragment was displaced 3mm lateral to the right. One week after the injury, this odontoid fracture was directly fixed with a compression screw by an anterior cervical approach. Immediately after the operation, his neck pain disappeared. He had only 4 days of bed rest and 2 months of external immobilization with a simple neck collar. He returned to his previous job 2 months after surgery without any limitation of his neck movement. At follow-up examination 16.5 months after the operation, x-ray films demonstrated complete fusion of the fracture and no problem about the screw such as displacement or breakage. Direct screw fixation of an odontoid fracture via a transcervical approach was thought to be a reasonable method of treatment. For proper assembly of this method, the following two points are particularly recommended: a screw insertion perpendicular to the fracture plane and the use of an optimal screw with both the desired total and thread lengths.