Feasibility of C2 Vertebra Screws Placement in Patient With Occipitalization of Atlas

Abstract

Occipitalization of atlas (OA) is a congenital disease with the possibility of anomalous bony anatomies and the C2 pedicle screw insertion is technically challenging. However, there are no existing literatures clarified the dimensions and angulations of the C2 pedicles, lamina and lateral masses for screw insertion in patients with OA. Therefore, the aim of this study was to assess the morphometric features of C2 for screw placement in OA to guide the use of surgical screws.Measurements of the OA patients on the computer tomography (CT) images including lamina angle, length and thickness, pedicle angle, length and thickness, and lateral mass thickness and length of the axis vertebra. The OA patients data were compared with age and gender matched cohort of randomly selected patients in a control group without OA. The picture archiving and communication system was used for all patients who had received cervical CT scanning between January 2001 and January 2015. Measurements were performed independently by 2 experienced observers who reviewed the CT scans and recorded the patients with OA. Statistical analysis was performed at a level of significance P < 0.05.A total of 73 patients (29 males and 44 females) were eligible to be included in the OA group. In most of the measurements the pathological cohort had significantly smaller values compared to the control group (P < 0.05). In the OA group, only 45% of the pedicles and 88% of the lamina had thicknesses bigger than 3.5 mm. Both groups had all pedicle and lamina lengths bigger than 12 mm. Regarding the length of the lateral mass, no value was bigger than 12 mm in the OA group, whereas 40% of the values in the control group were bigger than 12 mm. The average pedicle and laminar angles were 37° and 49° in the patients with OA, respectively.The variable anatomy in patients with OA needs to be taken into account when performing spinal stabilization as the C2 bony architectures are significantly smaller than normal. Anatomically, translaminar screw is a more viable option in comparison with pedicle screw for C2 fixation in OA. Nevertheless, the suitability should be fully assessed prior to surgery.

Traumatic Craniocervical Dissociation in Patients with Congenital Assimilation of the Atlas to the Occiput

“…The patients had smaller size of C2 pedicles, Case Reports in Orthopedics particularly on the right side for screw placement. Ji et al [14] describe in their study that the C2 pars/pedicle architectures are significantly smaller in patients with assimilation of the atlas than in the normal population. They suggested that translaminar screw is the more viable option in comparison with pedicle screw for C2.…”

Abiotrophia defectiva, an infrequent cause of cardioembolic stroke

“…Several morphometric studies have investigated the feasibility of the lamina and the spinous process of C2 to admit two crossing screws; many of these studies focused on the size of the lamina, which is a limiting factor for this technique [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] . Nor should we forget the dimensions of the spinous process as a second limiting factor.…”

CT Evaluations for C2 Pedicle Screw Fixation: Multiplanar Computerized Tomography Measurements in 100 Moroccan Patients

“…The mean PTW is slightly greater on the left side as compared to the right side [2]. However, many CT study concluded in a that there was no significant difference in transverse diameter between the right and left pedicles in both male and female patients [3,12,19]. Therefore, it is important to keep the gender and race of patients in mind when evaluating and planning for transpedicular screw fixation.…”

“…This accounts for the difference pedicle length reported in those studies. In previous anatomical [9][10][11] as CT evaluation [6,12] reports investigators defined the length as the distance from the posterior surface of the C-2 inferior articulating process to the anterior surface of the vertebral body (range 25.4 mm -28.8 ± 3.4 mm). Howington JU et al [1] chose to define the length as the distance from the posterior surface of the inferior articulating process to the junction of the pedicle with the vertebral body (mean 7.9 mm, range 6.4 to 9 mm).…”

“…Pedicle fracture and/or damage of the neurovascular structures may occur if the size of the screw is not less than 2 or 3 mm as that of the pedicle. For this reason, the minimal pedicle dimensions as well as the outer and inner pedicle diameter must be determined [12,21].…”