The odontoid process of the ninety axis were measured to observe the morphological features in Koreans. The results are as follows. 1. Height of the ordontoid of process of axis was 14.1±1.3mm, and the degree of the height of the odontoid process to the height of axis was frequency of 38.2±2.6%. 2. Transverse diameter of odontoid process of the most axis (87.8%) was thinner at the lower part than at the upper part. And the difference of the thickness of upper part and lower part was 1.2±0.7mm. In anteroposterior diameter, lower part was thinner than upper part in frequency of 55.6%, and the difference of upper part and lower part was 1.0±0.5mm in the transverse diameter, 0.6±0.5mm in the anteroposterior diameter, therefore the thickness of the anteroposterior diameter. 3. The articular surface of the odontoid process of the axis articulating with the anterior arch of atlas was 8.9±1.7mm in the maximal length and 7.1±1.6mm in the maximal breadth.
Odontoid Process*

Anomalous development of the odonteid precess is an uncommon clinical occurence that can seriously impair the integrity af the atlantoaxial articulation. Absence of the odontoid process may be either congenital or acquired, but clinically the etiology is of little importance as the clinical signs and symptoms and the treatment are identical in both. We experienced a case of congenital absence of the odontoid process and good result was obtained from the posterior atlantoaxial fusion with hale-cast.
Odontoid Process

OBJECTIVE: It is debatable whether an anterior oblique fracture orientation is really a contraindication to anterior odontoid screw fixation. The purpose of this study was to investigate the feasibility of anterior odontoid screw fixation of type II and rostral shallow type III fracture with an anterior oblique fracture orientation. METHODS: The authors evaluated 16 patients with type II and rostral shallow type III odontoid fracture with an anterior oblique fracture orientation. Of these 16 patients, 8 (group 1) were treated by anterior odontoid screw fixation, and 8 (group 2) by a posterior C1-2 arthrodesis. RESULTS: Of the 8 patients in group 1, seven patients achieved solid bone fusion (87.5%), and one experienced screw back-out of the C-2 body two months after anterior screw fixation. All patients treated by posterior C1-C2 fusion in group 2 achieved successful bone fusion. Mean fracture displacements and fracture gaps were not significantly different in two groups. (p=0.075 and 0.782). However, mean fracture orientation angles were 15.3+/-3.2 degrees in group 1, and 28.6+8.1 degrees in group 2 (p=0.002), and mean fragment angulations were 3.2+/-2.1 degrees in group 1, and 14.8+/-6.7 degrees in group 2 (p=0.001). CONCLUSION: Even when the fracture lines of type II and rostral shallow type III fractures are oriented in an anterior oblique direction, anterior odontoid screw fixation can be feasible in carefully selected patients with a relatively small fracture orientation angle and relatively small fragment angulation.
Humans ; Odontoid Process ; Orientation

The Odontoid process fracture has been treated by prolonged external immobilization of by internal fixation and fusion. We reported congential and traumatic odontoid process fracture which were successfully treated by transoral fusion. Operative preparation, technique and postoperative management are described by in detail.
Immobilization ; Odontoid Process*

Atlanto-axial dislocation with the fracture of the odontoid process has been considered as an uncommon lesion and a high incidence of nonunion of fractures of the odontoid process or high incidence of neurological involvement or death has been reported. With the advent of radiology, this fracture has been diagnosed early with increasing frequency. This paper is presented because very excellent result of union of the odontoid process treated with wiring and posterior atlanto-axial fusion by means of Brooks technic was obtained in our case.
Dislocations ; Incidence ; Odontoid Process

OBJECTIVE: This study was designed to determine the most reliable cephalometric measurement technique in the normal population and patients with basilar invagination (BI). METHODS: Twenty-two lateral radiographs of BI patients and 25 lateral cervical radiographs of the age, sex-matched normal population were selected and measured on two separate occasions by three spine surgeons using six different measurements. Statistical analysis including intraclass correlation coefficient (ICC) was carried out using the SPSS software (V. 12.0). RESULTS: Redlund-Johnell and Modified (M)-Ranawat had a highest ICC score in both the normal and BI groups in the inter-observer study. The M-Ranawat method (0.83) had a highest ICC score in the normal group, and the Redlund-Johenll method (0.80) had a highest ICC score in the BI group in the intra-observer test. The McGregor line had a lowest ICC score and a poor ICC grade in both groups in the intra-observer study. Generally, the measurement method using the odontoid process did not produce consistent results due to inter and intra-observer differences in determining the position of the odontoid tip. Opisthion and caudal point of the occipital midline curve are somewhat ambiguous landmarks, which induce variable ICC scores. CONCLUSION: On the contrary to other studies, Ranawat method had a lower ICC score in the inter-observer study. C2 end-plate and C1 arch can be the most reliable anatomical landmarks.
Humans ; Odontoid Process ; Pathology* ; Spine

The authors analyzed the surgical results of posterior C1-C2 fusion in 18 cases of atlantoaxial instability. Posterior C1-C2 wiring with bone fusion(11 cases), C1-C2 transarticular screw fixation(6 cases), and occipitocervical fusion(1 case) have been performed for unstable odontoid process fractures(10 cases), transverse ligament injury(4 cases), os odontoideum(3 cases), rheumatoid C1-2 instability(1 case). Follow-up examination was performed in all patientts after a mean postoperativeduration of 39.9 months. Follow-up x-rays showed successful stabilization in 17 cases(94%). Postoperative neurological evaluation showed improvement in 16 cases(89%), stabilization in 2 cases(11%) and there was no major operative complication.
Follow-Up Studies ; Ligaments ; Odontoid Process

There are some debates on the best method of treatment of C-2 fractures. Clinical findings and results of treatment were evaluated in forty-three patients with C-2 fractures. These fractures were classified into five types according to the classification by Benzel4);1) odontoid fractures(14), 2) horizontal C-2 body fractures(13), 3) sagittally oriented vertical C-2 body fractures (2), 4) coronally oriented vertical C-2 body fractures(8), 5) traumatic spondylolisthesis of the axis(6). Primary fusion appears to be justified in odontoid process fractures due to a high rate of non-union. In horizontal C-2 body fractures, unilateral facet dislocation was visible in six patients which was the cause of malalignment in closed reduction. In sagittally oriented vertical C-2 body fractures, combined facet fractures were always visible because the mechanism of injury was axial compression. The choice of management schemes may depend on the mechanism of injury and fracture type defined by Benzel.
Classification* ; Dislocations ; Humans ; Odontoid Process ; Spondylolisthesis

Several different methods of posterior wiring and fusion have been advocated for treatment of the odontoid process fractures, regardless of direction of displacement. Between 1983 and 190, 8 cases of type II odontoid process fracture underwent posterior wiring and fusion at Kyungpook National University Hospital. Among them, three cases were posteriorly displaced fractures. For these three cases, the authors modified wiring method and applied acrylic resin. The authors thought this procedure is not complex and a good method for posteriorly displaced type II fractures in which conventional posterior wiring may actually create a tration effect that further displaces the fractured odontoid into the spinal canal.
Gyeongsangbuk-do ; Odontoid Process* ; Spinal Canal

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.
Axis, Cervical Vertebra ; Decompression* ; Dislocations* ; Odontoid Process