Features and clinical significance of the ossification centres in the odontoid process based on micro-computed tomography

Background: Microscopic structures of the ossification centres of the odontoid process were studied from the micro-computed tomography (CT) images of the axis, and the potential influence of the ossification centres with different microscopic structures on odontoid process fractures was analysed.Materials and methods: Eighteen odontoid process specimens were randomly collected and scanned by micro-CT. The obtained images were then input into the software for further observation and measurement. Incomplete absorption of the ossification centres in the base was observed, along with the anatomic structure of the regions with incomplete ossification and structural parameters of the trabecular bones.Results: The microscopic structures of the trabecular bones in the ossification centres in the base of the odontoid process could be clearly visualised from the micro-CT images. Among the 18 odontoid process specimens, 11 specimens were found with incomplete absorption of the ossification centres in the axis, the prevalence reaching up to 61%. Regions with incomplete ossification varied in size and morphology, and their three-dimensional morphology was predominantly oval. Of all structural parameters examined for the trabecular bones, there were only significant differences in the degree of anisotropy between the regions with incomplete absorption of ossification centres and the average vertebral trabecularbones (p < 0.05).Conclusions: Incomplete absorption of the ossification centres in the base of the odontoid process is a relatively prevalent condition. The cavitation effect of the trabecular bones may be the primary cause for odontoid process fractures