Morphometric Study of Axis Vertebra in Subjects of Indian Origin

Background: The axis vertebra, exhibits complex and extensive variability in the morphology and there are vital neurovascular structures in its proximity. Knowledge of this variability is important for neurosurgeons, orthopaedicians, otorhynologists and other physicians who in everyday practice are in contact with disorders of the spine and their consequences. Objective: The aim was to evaluate various morphometric dimensions of axis vertebrae and to compare with the available data. Material and Methods: 50 dried human axis vertebrae of Indian origin, available in the Department of Anatomy, Dayanand Medical College and Hospital, Ludhiana were studied. Various dimensions were taken with vernier calipers, metric scale and graph paper. The dimensions were measured in millimetres and statistically analysed with paired t-test. Results: The mean of maximum anteroposterior diameter (max.APD) and maximum transverse diameter (max.TD) of Superior Articular Facet (SAF) was measured as 17.42mm±1.73 and 15.31mm±1.44 on the right side, 17.64mm±1.51 and 15.17mm±1.48 on left side. The mean Distance from Lateral most edge of SAF to Midline was measured as 22.56mm ± 2.37 and 22.40mm ± 2.16 on the right and left sides, respectively. The mean Distance from Tip of Transverse Process to Midline was 26.45mm ± 2.85 on the right and 26.03mm ± 2.64 on the left side. The mean Height of Dens was measured as 13.83mm ± 1.52, mean Width of Dens as 9.57mm ± 0.85. Width of Pedicle was measured as 10.52mm ± 1.99 and 10.61mm ± 1.67on right and left sides, respectively. Conclusion: The knowledge of these dimensions can provide useful information for safe planning of osseous fixation.