Morphometric Study Of Second Cervical Vertebra- A Dry Bone Study

Abstract

Background: Amongst the seven cervical vertebrae, axis is one of the atypical cervical vertebra. Axis vertebra shows unique features, it includes modification of its body to odontoid process or dens, roomy vertebral canal; unique superior articulating facets make it different than others. The head rotates around the dens of an axis along with the atlas vertebra at the atlantoaxial joint, which permits the head to move freely.

Functionally cervical vertebrae protect the spinal cord, balance the movement of head and protect the vertebral arteries passing through their foramen transversarium. The intervertebral disc present between vertebral body acts as shock absorber.

Person in their life suffers from various disorders of cervical spine like degenerative disorders, disc pathologies, accidental injuries, osteoarthritis; spinal canal stenosis. Sometimes for treatment, surgical interventions are required. As per the literature there is racial variation is found in the dimensions of cervical vertebrae, and the space for surgical intervention is anatomically very complicated and significant. To avoid the fatal complications the instruments designed for the process must be according to the dimensions. The dimensions are also required for the anterior neurosurgical approach for the cervical reconstructions. Unfortunately, the implants are used globally, and it was observed that population variations exist in the measurements of the vertebrae. The study is carried out to provide a data of various dimensions of axis vertebra and to see the parameters which show the racial differences.

Present study is carried out with prior Ethics committee permission letter. It includes 100 dry human axis vertebrae from different medical colleges (Indian origin).Measurements are taken using digital vernier calliper and goniometer. Results are analyzed with appropriate statistical tests. Measurements are taken in millimeter, and angle in degree.

Results: Height of dens mean and SD is (14.67 ± 2.16) mm, circumference of dens Mean and SD is (33.12 ± 5.89) mm, width of dens Mean and SD is (9.95± 1.12) mm and total height of axis Mean and SD is (34.44 ±3.88) mm. In vertebral canal there is AP diameter Mean and SD is (18.19± 2.03), Transverse diameter is Mean and SD is (21.50 ±2.09). There was no statistically any significant difference about measurements of superior articulating facets of right and left side with p value much higher than(0.05). Range of dense –axis sagittal angle is 1 to 14.5 degree. Width of spinous process is more than length of spinous process. On comparison with other studies the width of dens and anterior-posterior, transverse diameter of the vertebral canal of Axis shows racial differences.

Conclusion: The dimensions will help the spine surgeons while dealing with the patients with cervical region pathology. It will also help in implants, screw, instruments designing. As the Racial differences are there in morphometry the study will helpful while treating patients of Indian origin. The findings of this study will help in Forensic and Anthropological point of view.