Sex-specific differences in ossification patterns of the atlas and axis: a computed tomography study

Area of Science:

• Pediatric Radiology
• Orthopedic Anatomy
• Developmental Biology

Background:

• Ossification patterns of the first two cervical vertebrae (C1-C2) exhibit developmental changes.
• Understanding sex-specific differences in C1-C2 ossification is crucial for pediatric diagnostics.

Purpose of the Study:

• To investigate sex-specific differences in the ossification patterns of the first two cervical vertebrae in Chinese children.
• To establish normative data for C1-C2 vertebral fusion sequences and identify common ossification variants.

Main Methods:

• Retrospective analysis of cervical computed tomography (CT) images from 910 Chinese children (<16 years).
• Stratification into sex and 1-year age groups for detailed evaluation of synchondrosis ossification and variants.
• Assessment of C1 and C2 vertebrae, including neurocentral, posterior, and dentoneural synchondroses.

Main Results:

• Females exhibited earlier fusion of C1 neurocentral and posterior synchondroses compared to males.
• The fusion sequence for C2 vertebrae was consistently posterior, neurocentral, and dentoneural synchondroses.
• Anterior arch variants in C1 and C2 were observed, with no significant sex-based differences in variant prevalence.

Conclusions:

• Cervical vertebrae C1 and C2 ossification occurs earlier in females than males.
• Fusion follows a posterior-to-anterior and caudal-to-cephalad pattern in both sexes.
• Congenital ossification variants are common and must be differentiated from traumatic injuries.