The internal trabecular bone structure of the odontoid process of the axis. A retrospective single-center comparative study in patients following cervical trauma

Background Odontoid C2 fractures account for 9% to 15% of adult cervical spine fractures. The aim of this study is to report the incidence of a previous described Y-shaped trabecular bone structure (TBS) in the odontoid process in a larger sample of patients who performed a CT cervical scan following a cervical trauma to investigate if its absence can increase the risk of the odontoid process fracture of the axis. Methods A retrospective review of 245 patients who performed a CT cervical scan in our University Hospital, as results of cervical spine injury, was performed during a 12-month period between May 2020 and May 2021. Results The presence of a Y-shaped TBS at the odontocentral synchondrosis level was observed in 165 patients that is 67.3% of whole population included in this study. Eighteen patients (7.3%) reported an odontoid type II C2 fracture. Among patients with odontoid type II C2 fracture, the Y-shaped TBS at the odontocentral synchondrosis level was observed in 8 (44.4%) of them. The presence of the Y-shaped TBS at the odontocentral synchondrosis level was statistically more frequently observed in patients without odontoid process fracture (69.2% Vs 30.8%) compared to patients who developed odontoid process fracture (44.4 % Vs 55.6%) after a cervical trauma (p = 0.03). Conclusions This study showed the crucial role of this Y-shaped TBS in biomechanical structural dynamics of the C1-C2 joint and its significant clinical relevance in odontoid fractures of the axis.