ABSTRACT

Background Data:

The unique anatomy of the craniovertebral junction, the perceived high risk of vascular and neurological complications, and the anatomical variations require the morphological analysis of the occipital bone.

Purpose:

The purpose of this study was to present morphometric analysis of the pediatric occipital bones and to provide guidance for pediatric occipitocervical fusion.

Materials - Methods:

We retrospectively reviewed the records of pediatric patients who had undergone head CT scanning due to various reasons. Patients with traumatic fractures, congenital abnormality, tumor or other diseases and problematic CT images were excluded. Occipital bone thicknesses were determined at three levels (each level having 5 points) starting from the external occipital protuberance (EOP) (Level 0) and extending inferiorly for 2 cm by 1-cm decrements (Level 1 and Level 2).

Results:

Among 300 CT scans, 70 were found to be suitable for the study. There were 50 males and 20 females, with a mean age of 9.9 ± 4.40 years (range 2–17 years). The external occipital protuberance (EOP) had the greatest thickness, with mean values of 10.3 ± 2.99 mm (range, 5.0-18.5 mm) in males and 9.9 ± 2.41 mm (range, 5.1–14.1 mm) in females. At each level, the midline was always thicker than the lateral regions at each age group (p<0.001). The midline thickness at Level 0, 1 and 2 were thicker in males compared to females (p=0.011, p=0.045 and p=0.032, respectively). Positive correlation was found between age and occipital bone thickness (r=0.828 and p<0.001 for EOP, r=0.770 and p<0.001 for midline at Level 1, r=0.792 and p<0.001 for midline at Level 2) and the other points showed similar findings.

Conclusion:

Safe zones with thicknesses > 8 mm for screw insertion were found only at the midline in children older than 5 years of age and preoperative evaluation of occipital thickness should be performed in every patient considering the individual variability.