Ossification patterns of the C1 (atlas) and C2 (axis) vertebrae children.

Purpose: This retrospective study aimed to assess ossification patterns and synchondrosis fusion timelines of the C1 and C2 vertebrae in pediatric age group, to help differentiate injuries from normal variations and serve as a guide when evaluating incompletely fused synchondrosis.

Materials And Methods: The study analyzed 432 CT examinations of children aged 0-72 months, conducted at a single institution between January 2010 and January 2018. The focus was assessment of the visibility and fusion of the three ossification centers and three synchondroses of the atlas, and six ossification centers and four synchondroses of the axis, based on age.

Results: Complete ossification of the anterior arch of the atlas was observed in 60.4 % of patients, increasing with age from 11.1 % in the 0-12 months age group to 97.3 % in the 61-72 months age group. Patency of the ventrolateral synchondrosis of the atlas decreased from 100 % in the 0-12 months age group to around 30 % in the 61-72 months age group. Subdental synchondrosis and neurocentral synchondrosis of the axis were patent in 47.0 % and 50.6 % of patients, respectively, both decreasing with age. The apicodental synchondrosis of the axis remained mostly patent (98.1 %). Overall, there was a trend of decreasing patency in synchondroses and increasing ossification with advancing age.

Conclusion: These findings provide a better understanding of normal ossification patterns and timelines, facilitating the accurate distinction between normal variations and traumatic injuries.