Murat Özcan YAY, Ilgaz AKDOĞAN, Mehmet Yetiş ÇALIK, Süleyman AKILLI
Journal of Turkish Spinal Surgery - 2026;37(3):123-129
Objective: This study aimed to evaluate the morphometric characteristics of dry human atlas (C1) and axis (C2) vertebrae and to assess their potential relevance for safe C1-C2 screw placement. Materials and Methods: This descriptive osteometric and anatomical study included 35 dry human C1 vertebrae and 25 dry human C2 vertebrae. All measurements were performed directly on dry bones using a digital caliper with 0.01 mm precision. Right- and left-sided parameters were measured separately. Continuous variables were expressed as mean +/- standard deviation and minimum-maximum values. Right-left comparisons were performed using paired-samples t-tests, with p<0.05 considered statistically significant. Results: In C1, significant side-to-side differences were observed in the outer and inner distances of the vertebral artery groove, in the horizontal thickness of the lateral mass, and in the diameter of the vertebral foramen. The outer distance of the vertebral artery groove and the lateral mass horizontal thickness were significantly greater on the right side, whereas the inner distance of the vertebral artery groove and the vertebral foramen diameter were significantly greater on the left side. In C2, significant differences were found only in the anteroposterior diameter of the vertebral canal and in lamina length, both of which were greater on the right side. No significant bilateral differences were observed in most of the remaining C1 and C2 parameters. Conclusion: Dry human C1 and C2 vertebrae exhibited measurable bilateral morphometric variations, particularly in parameters related to the C1 vertebral artery groove and in C2 lamina length. These findings may contribute to anatomical knowledge relevant to craniovertebral junction surgery and support individualized, side-specific preoperative evaluation before screw fixation.
