Computed tomographic evaluation of odontoid process: implications for anterior screw fixation of odontoid fractures in an adult population

Abstract

Introduction Odontoid diameter in some individuals may not be large enough to accommodate two 3.5-mm cortical screws for anterior odontoid fracture fixation. The study was performed to evaluate, in a Brazilian population, the diameter of the odontoid process and the feasibility of using two 3.5-mm cortical screws for anterior odontoid fracture fixation. Materials and methods Computed tomographic (CT) scans of 88 adult patients (aged 18-78 years) were analyzed; 40 patients (45%) were male (mean age: 43.08 years) and 48 (55%) were female (mean age: 43.39 years). The minimum external and internal anteroposterior and transverse diameters of the odontoid process on sagittal and coronal planes were measured on CT multiplanar reconstructions of the cervical spine. Results The mean value of the minimum external anteroposterior diameter was 10.83 ± 1.08 and 7.53 ± 1.10 mm for the minimum internal anteroposterior diameter. The mean value of the minimum external transverse diameter was 9.19 ± 0.91 and 6.07 ± 1.08 mm for the minimum internal transverse diameter. The mean AP diameter was significantly larger than the mean transverse diameter; 57 (65%) individuals had the minimum external transverse diameter [9.0 mm that would allow the insertion of two 3.5-mm cortical screws with tapping, and five (6%) individuals had the minimum internal transverse diameter [8.0 mm that would allow the insertion of two 3.5-mm cortical screws without tapping. Conclusions The insertion of two 3.5-mm cortical screws was possible for anterior fixation of odontoid fracture in 57 (65%) individuals of our study, and there was no statistical difference between males and females.

Morphometric analysis of the odontoid process: using computed tomography—in the Greek population

“…Those data are not different from those of the literature concerning the distribution between men and women [3] ( Table 1). …”

“…The desired transverse diameter that can safely accommodate two 3.5-mm screws is accepted to be 9.0 mm [4,5,11]. Though 95 % of the odontoid processes in the Caucasian population could safely accommodate two 3.5-mm screws, [4] 33 % of the Malaysian [5] and 35 % of the Brazilian [3] populations were unsuitable for the same. This number was as high as 89.1 % in the Greek population.…”

“…Most of these fractures are treated conservatively, but an unstable one, which is at risk of pseudarthrosis, has to be stabilized operatively [7]. Indications and technique of application of screw(s) are well described [1,3,12]. A stable and painless cervical spine and maintenance as much as possible of its normal range of motion is the optimal goal after a fracture of the odontoid process.…”

“…It is known that patients with an odontoid diameter of [9.00 mm are suitable for this technique. So, it is of importance to know the exact diameter of the odontoid process before proceeding with such technique, as there are differences in its size [3][4][5].…”

Cervical pedicle morphometry in a Latin American population

“…As many other morphometric anatomical differences found in different races and ethnicities, [13,14,18] we believe that data extracted from previous studies should be used with caution because they might not apply universally.…”